Preface

Abdominal ultrasound is a noninvasive bedside diagnostic tool that helps to discover many abdominal problems. It is safe and painless even in the early stages of pregnancy.

The development of ultrasound had its beginning in 1790 with the recognition of echolocation used by bats. Biologist Lazzaro Spallanzani first discovered that bats hear by listening for the return of the high-frequency sound they emit to detect objects and food. A breakthrough came in 1880 when physicist Pierre Curie and his brother Jacques Curie studied the properties of crystalline structure to demonstrate a piezoelectric effect, which was the scientific basis of the first transducer. This device generated a high-frequency sound and received its echo back. Ultrasound maps the body's structures based on the travel time and intensity of the ultrasound waves returning to the transducer from a given direction.

Diagnostic ultrasound began to be used in medicine for the first time during and shortly after World War II; the term SONAR (Sound Navigation and Ranging) was first used then as well. At that time, medicine began to realize the benefits of using ultrasound for detecting organ pathology.

The principle of ultrasound is to send ultrasound waves of particular frequencies into the body. When these waves meet the various structures of the body, the tissue will reflect, refract, absorb or transmit the wave. A special acoustic character can identify different tissue based on how much the tissue reflects or transmits the sound wave. Highly reflective structures show up as a white acoustic echo on the screen, while non-reflective structures appear as a black echo on the screen.

As we know, few people read a textbook from cover to cover. Most read one or more chapters that they find interesting. With this in mind, we designed the book so that each chapter provides complete, illustrative knowledge in itself. Each chapter is related to the scanning of one particular organ in the abdomen, and each organ is discussed from a different point of view. In each chapter, there is a new update of knowledge or technique. All chapters contain ultrasound images of real patients in recent work, and they are organized in the way that sonographers usually follow in scanning.

The content contained within this volume is relevant across many specialties, including radiology and internal medicine, and is useful for physicians and medical residents and students alike.

 We want to express our deep thanks to the authors and mentors who gave their own time, effort and experience to write their chapters; they are clear, straightforward and organized. Mostly, we thank all of our patients who allowed us to use their information and be our main tool in this illustrative book. We hope that all our efforts will contribute to relieving your suffering and improving your health.

**II**

**Section 6**

Intestinal Ultrasound **89**

**Chapter 6 91**

High-Frequency Ultrasound Imaging of the Intestine in Normal

*by Philip C. Njemanze, Josephine T. Njemanze, Clara C. Ofoegbu, Chinwendu C. Darlington, Esther Nneke, Ijeoma A. Onweni, Uchechi V. Ejiogu, Chinenye U. Mgbenu, Nneoma E. Ukeje,* 

Subjects and Patients with Intestinal Parasites

*Anthonia C. Amadi and Doris C. Amaefule*

Last but not least, I would like to thank my beautiful, supportive family who has been by my side through every step. They truly are a blessing.

#### **Samia Ali Abdo Gamie**

Professor, Pro of Internal Medicine, Helwan University, Cairo, Egypt

#### **Enas Mahmoud Foda**

Professor, Pro of Internal Medicine, Ain Shams University, Cairo, Egypt

**1**

Section 1

Introduction

Section 1 Introduction

**3**

**Chapter 1**

*Samia Ali Abdo Gamie*

**1. Introduction**

between 2 and 18 MHz [1].

called the inverse piezoelectric effect [2].

that is referred to as tissue echogenicity [3].

frequency for superficial structures [5].

Introductory Chapter: Common

Medical ultrasound is an imaging modality using high-frequency sound waves to recognize unique tissue characteristics. The normal human range of audible sound is from 20 Hz to 20 KHz; in contrast the frequency used in medical ultrasound is >20,000 Hz. The frequency range that is used for medical imaging is generally

Piezoelectric effect discovered by Pierre and Jacques Curie in 1880 is the basic principle of ultrasound transducer. They discovered that when pressure is applied to quartz or some certain crystals, it creates an electrical charge in that material. Curie's brothers soon discovered the inverse piezoelectric effect; when an electric field was enforced onto crystal leads, it led to a disorder in the crystal lead—now

Piezoelectric transducer generates the ultrasound beam as a pulse travels through the tissue; the echo signals return to the transducer after undergoing absorption, reflection, and refraction depending on the tissue structure, leading to a real grayscale image formation. The basic rules in image formation can be summarized as follows. First, ultrasound pulse travels in a straight line, so echo signals travel in a narrow beam, giving a real-time scanning. Second, as the velocity of the ultrasound is constant, the distance is directly proportional to how far the structure is from the transducer. Third, the echo strength is related to the tissue reaction with the ultrasound waves; the reflected waves give the echo brightness on the screen

Physics of the ultrasound is essential for all physicians to understand and interpret ultrasound images. Frequency is the number of the sound waves per second. It usually remains constant maintaining the frequency of the original source, but the velocity of the ultrasound wave changes depending on the physical properties of the medium. These variations in velocity introduce artifacts into the image, mainly attributed to bone and fat. The frequency of transducer determines the resolution of the ultrasound image. The resolution of the ultrasound machine is its ability to detect and display two close structures as distinct. Higher-frequency transducers have higher resolution, but its ability to penetrate to deep structures is low; therefore it is used for superficial structures. On the other hand, low-frequency transducers can penetrate to deep structures with lesser resolution; therefore it is suitable for deeper structures. Using high transducers of high frequency to screen deep structures results in more attenuation to the image of the deep tissue [4]. Choosing the proper transducer for a proper image of different organs is based on this rule of thumb regarding the transducer's frequency. Therefore, always use a sector transducer from 3.5 to 5 MHz to screen deep abdominal structures but higher

Pitfalls and How to Overcome

#### **Chapter 1**

## Introductory Chapter: Common Pitfalls and How to Overcome

*Samia Ali Abdo Gamie*

#### **1. Introduction**

Medical ultrasound is an imaging modality using high-frequency sound waves to recognize unique tissue characteristics. The normal human range of audible sound is from 20 Hz to 20 KHz; in contrast the frequency used in medical ultrasound is >20,000 Hz. The frequency range that is used for medical imaging is generally between 2 and 18 MHz [1].

Piezoelectric effect discovered by Pierre and Jacques Curie in 1880 is the basic principle of ultrasound transducer. They discovered that when pressure is applied to quartz or some certain crystals, it creates an electrical charge in that material. Curie's brothers soon discovered the inverse piezoelectric effect; when an electric field was enforced onto crystal leads, it led to a disorder in the crystal lead—now called the inverse piezoelectric effect [2].

Piezoelectric transducer generates the ultrasound beam as a pulse travels through the tissue; the echo signals return to the transducer after undergoing absorption, reflection, and refraction depending on the tissue structure, leading to a real grayscale image formation. The basic rules in image formation can be summarized as follows. First, ultrasound pulse travels in a straight line, so echo signals travel in a narrow beam, giving a real-time scanning. Second, as the velocity of the ultrasound is constant, the distance is directly proportional to how far the structure is from the transducer. Third, the echo strength is related to the tissue reaction with the ultrasound waves; the reflected waves give the echo brightness on the screen that is referred to as tissue echogenicity [3].

Physics of the ultrasound is essential for all physicians to understand and interpret ultrasound images. Frequency is the number of the sound waves per second. It usually remains constant maintaining the frequency of the original source, but the velocity of the ultrasound wave changes depending on the physical properties of the medium. These variations in velocity introduce artifacts into the image, mainly attributed to bone and fat. The frequency of transducer determines the resolution of the ultrasound image. The resolution of the ultrasound machine is its ability to detect and display two close structures as distinct. Higher-frequency transducers have higher resolution, but its ability to penetrate to deep structures is low; therefore it is used for superficial structures. On the other hand, low-frequency transducers can penetrate to deep structures with lesser resolution; therefore it is suitable for deeper structures. Using high transducers of high frequency to screen deep structures results in more attenuation to the image of the deep tissue [4]. Choosing the proper transducer for a proper image of different organs is based on this rule of thumb regarding the transducer's frequency. Therefore, always use a sector transducer from 3.5 to 5 MHz to screen deep abdominal structures but higher frequency for superficial structures [5].

Practical image orientation is performed in two planes sagittal plane and transverse plane. Using the transducer in the sagittal plane, the left side of the image represents the cranial plane. Meanwhile putting the transducer in a transverse plane, the left side of the image represents the right side of the patient. Abdominal examination is usually started while the patient is lying comfortably in supine position, and then they must be examined on both sides. Systematic scanning is important; scanning of all organs and all areas is essential to complete your mental checklist in an ultrasound report.

Preparation for abdominal ultrasound generally requires fasting for 8 h, decreasing the gas in the intestine. Also, for the gall bladder and biliary tree exploration, fasting is essential for screening. Other conditions such as emergency ultrasound require no special preparations. In each chapter of this book, if any special preparation for screening the organ is required, it will be mentioned.

In practice, ultrasound artifacts are common; thus understanding these artifacts' physics is vital to help correct it to improve the images, leading to good interpretation for a correct diagnosis. The artifacts arise either from improper operator technique or from the physics of ultrasound transmission and traveling. Identification of the artifact from improper technique is the first step, so it can be avoided. The second step is to know how the physics' artifacts can be corrected, keeping in mind that some of these artifacts may be good clues for proper diagnosis of structures with special characteristics. In this book, in each chapter, we try to explain some of these artifacts and how to avoid them. Potential US artifact correction is important for image quality improvement, optimal interpretation, and diagnosis.

Artifacts can be classified into two: One, related to the beam and the resolution, and the other, related to the location and the attenuation. Here are some common examples of these artifacts, their clinical relevance, their physical mechanism, and how to make alteration.

Beam- and resolution-related artifacts

**Beamwidth artifact**: Lateral resolution is the ability to detect two close points in the transverse plane as two distinct points. It leads to lateral blurring of the image and aberrant echoes from adjacent highly echogenic objects. It can be reduced by focusing the sound selection. Focusing improves the beamwidth, so it becomes narrower at the target focal zone [6].

**Section thickness artifact:** It is the ability to distinguish two vertical beams as two distinct points. It is called elevation resolution as the point planes are perpendicular to the transducer plane. It appears like debris in anechoic structure as cyst or ascites. It can be overcome by putting it in a focal zone with a standoff pad [7].

**Secondary lobe artifacts:** It mimics debris in anechoic structures. It is from the reflected echo that comes back from ultrasound waves that are transmitted outside the beam. It can be corrected by reducing the gain [8].

Location characteristics ultrasound artifact

**Reverberation artifact**: It appears as multiple bright parallel lines at regular intervals that decrease in intensity as the depth increase. It is due to reflections between highly reflective interfaces in parallel (reverberates). It may be useful in the detection of air in abnormal locations, as in pneumatosis, pneumoperitoneum, and pneumobilia. It can be reduced by decreasing gain, changing the angle of insonation, or using multiple windows [9].

**Comet tail artifact:** Adenomyomatosis, based on the same principle of reverberation artifact. It is caused by highly reflective interfaces that are closely spaced, so the individual echoes cannot be distinguishable. This artifact is useful as it considered a fingerprint for identification and diagnosis of cholesterol crystals in adenomyomatosis of the gallbladder (**Figure 1**) [10].

**5**

**Figure 1.**

*Introductory Chapter: Common Pitfalls and How to Overcome*

decreasing gain or changing the angle of insonation [11].

order correction schemes such as time gain compensation.

*Aschoff sinuses. This finding is diagnostic of adenomyomatosis.*

Accentuation and attenuation characteristics of ultrasound artifacts **Increased transmission (accentuation)**: It is due to increased intensity of echoes distal to a low-attenuating structure. It is useful in practice to differentiate between cystic and solid structures. Distal to cystic structure there is an increased echo intensity, as the ultrasound waves pass through the cystic structure without any disturbance or loss. This accentuation is important to confirm the diagnosis of the anechoic cystic lesion (**Figure 3**). It can be increased by using tissue harmonic

**Ring-down artifacts:** It arises from resonant vibrations within trapped air bubbles. These vibrations produce a continuous sound wave transmitted back to the transducer; it appears as a streak or series of parallel bands deep to a focus of gas. It can be useful in identifying abnormal foci of air, e.g., pneumoperitoneum and portal venous gas. Also, it can be indicative of appendicitis if it is detected in the

**Mirror image artifact:** It mimics disease, such as pseudo-thickened bowel wall and lesions in the lung. It is due to reflections of a highly reflective structure, e.g., the diaphragm, producing a mirror-like image of an object. The second image is generated along that path, deeper than the true site of the structure due to increased time of the return echo. A common example is in the case of a liver lesion near the diaphragm; the transmitted beam is reflected off the diaphragm and will be faced with a liver lesion that reflects it to the diaphragm again as well as the transducer. The image on the screen contains two lesions similar on both sides of the diaphragm and the same distance from it (**Figure 2**). This type of artifact may be corrected by

**Attenuation artifacts:** Attenuation is a loss of ultrasound energy and amplitude as it goes deeper through the tissue. Therefore, echo from deeper structure comes weaker than the echo from the superficial structure; the ultrasound machine is computerized to amplify the return echo from the deeper structures. If the tissue is reflective, as in the case of a fat tissue, less echo reaches the deeper structure, and screening will be difficult. This attenuation is adequately compensated by first-

**Acoustic shadowing:** It is due to a reduction in echo strength distal to a highly

*Longitudinal US image of the gallbladder shows comet tail artifact caused by cholesterol crystals in Rokitansky-*

reflective object. Three types of acoustic shadowing, clean, partial, and dirty,

*DOI: http://dx.doi.org/10.5772/intechopen.87964*

appendix [11].

imaging [12].

*Essentials of Abdominal Ultrasound*

checklist in an ultrasound report.

diagnosis.

how to make alteration.

Beam- and resolution-related artifacts

the beam. It can be corrected by reducing the gain [8]. Location characteristics ultrasound artifact

adenomyomatosis of the gallbladder (**Figure 1**) [10].

insonation, or using multiple windows [9].

narrower at the target focal zone [6].

Practical image orientation is performed in two planes sagittal plane and transverse plane. Using the transducer in the sagittal plane, the left side of the image represents the cranial plane. Meanwhile putting the transducer in a transverse plane, the left side of the image represents the right side of the patient. Abdominal examination is usually started while the patient is lying comfortably in supine position, and then they must be examined on both sides. Systematic scanning is important; scanning of all organs and all areas is essential to complete your mental

Preparation for abdominal ultrasound generally requires fasting for 8 h, decreasing the gas in the intestine. Also, for the gall bladder and biliary tree exploration, fasting is essential for screening. Other conditions such as emergency ultrasound require no special preparations. In each chapter of this book, if any special prepara-

Artifacts can be classified into two: One, related to the beam and the resolution, and the other, related to the location and the attenuation. Here are some common examples of these artifacts, their clinical relevance, their physical mechanism, and

**Beamwidth artifact**: Lateral resolution is the ability to detect two close points in the transverse plane as two distinct points. It leads to lateral blurring of the image and aberrant echoes from adjacent highly echogenic objects. It can be reduced by focusing the sound selection. Focusing improves the beamwidth, so it becomes

**Section thickness artifact:** It is the ability to distinguish two vertical beams as two distinct points. It is called elevation resolution as the point planes are perpendicular to the transducer plane. It appears like debris in anechoic structure as cyst or ascites. It can be overcome by putting it in a focal zone with a standoff pad [7].

**Secondary lobe artifacts:** It mimics debris in anechoic structures. It is from the reflected echo that comes back from ultrasound waves that are transmitted outside

**Reverberation artifact**: It appears as multiple bright parallel lines at regular intervals that decrease in intensity as the depth increase. It is due to reflections between highly reflective interfaces in parallel (reverberates). It may be useful in the detection of air in abnormal locations, as in pneumatosis, pneumoperitoneum, and pneumobilia. It can be reduced by decreasing gain, changing the angle of

**Comet tail artifact:** Adenomyomatosis, based on the same principle of reverberation artifact. It is caused by highly reflective interfaces that are closely spaced, so the individual echoes cannot be distinguishable. This artifact is useful as it considered a fingerprint for identification and diagnosis of cholesterol crystals in

In practice, ultrasound artifacts are common; thus understanding these artifacts' physics is vital to help correct it to improve the images, leading to good interpretation for a correct diagnosis. The artifacts arise either from improper operator technique or from the physics of ultrasound transmission and traveling. Identification of the artifact from improper technique is the first step, so it can be avoided. The second step is to know how the physics' artifacts can be corrected, keeping in mind that some of these artifacts may be good clues for proper diagnosis of structures with special characteristics. In this book, in each chapter, we try to explain some of these artifacts and how to avoid them. Potential US artifact correction is important for image quality improvement, optimal interpretation, and

tion for screening the organ is required, it will be mentioned.

**4**

**Ring-down artifacts:** It arises from resonant vibrations within trapped air bubbles. These vibrations produce a continuous sound wave transmitted back to the transducer; it appears as a streak or series of parallel bands deep to a focus of gas. It can be useful in identifying abnormal foci of air, e.g., pneumoperitoneum and portal venous gas. Also, it can be indicative of appendicitis if it is detected in the appendix [11].

**Mirror image artifact:** It mimics disease, such as pseudo-thickened bowel wall and lesions in the lung. It is due to reflections of a highly reflective structure, e.g., the diaphragm, producing a mirror-like image of an object. The second image is generated along that path, deeper than the true site of the structure due to increased time of the return echo. A common example is in the case of a liver lesion near the diaphragm; the transmitted beam is reflected off the diaphragm and will be faced with a liver lesion that reflects it to the diaphragm again as well as the transducer. The image on the screen contains two lesions similar on both sides of the diaphragm and the same distance from it (**Figure 2**). This type of artifact may be corrected by decreasing gain or changing the angle of insonation [11].

Accentuation and attenuation characteristics of ultrasound artifacts

**Increased transmission (accentuation)**: It is due to increased intensity of echoes distal to a low-attenuating structure. It is useful in practice to differentiate between cystic and solid structures. Distal to cystic structure there is an increased echo intensity, as the ultrasound waves pass through the cystic structure without any disturbance or loss. This accentuation is important to confirm the diagnosis of the anechoic cystic lesion (**Figure 3**). It can be increased by using tissue harmonic imaging [12].

**Attenuation artifacts:** Attenuation is a loss of ultrasound energy and amplitude as it goes deeper through the tissue. Therefore, echo from deeper structure comes weaker than the echo from the superficial structure; the ultrasound machine is computerized to amplify the return echo from the deeper structures. If the tissue is reflective, as in the case of a fat tissue, less echo reaches the deeper structure, and screening will be difficult. This attenuation is adequately compensated by firstorder correction schemes such as time gain compensation.

**Acoustic shadowing:** It is due to a reduction in echo strength distal to a highly reflective object. Three types of acoustic shadowing, clean, partial, and dirty,

#### **Figure 1.**

*Longitudinal US image of the gallbladder shows comet tail artifact caused by cholesterol crystals in Rokitansky-Aschoff sinuses. This finding is diagnostic of adenomyomatosis.*

#### **Figure 2.**

*Longitudinal US image shows an echogenic lesion in the right hepatic lobe (hepatic hemangioma), and a duplicated echogenic lesion (arrow) on the other side equidistant from the diaphragm mimics lesion in lung parenchyma.*

#### **Figure 3.**

*Transverse US image of the liver shows anechoic hepatic cysts. The hepatic parenchyma distal to the cysts is falsely displayed as increased intensity (arrow) secondary to increased through-transmission artifact.*

are used to describe the shadow of stones, calcification, and air, respectively. It is very helpful in practice to identify the clear shadow as a dark band due to all the ultrasound waves being absorbed. Its presence can help detect stones in echogenic structures such as kidney stones. Also, a shadow is important to differentiate a

**7**

**Figure 4.**

*Introductory Chapter: Common Pitfalls and How to Overcome*

gall bladder (GB) stone (**Figure 4**), with its clear shadow, from a non-shadowing polyp or a sludge ball in GB. Dirty shadowing is seen in the case of highly refracting structure like gas. In clinical practice, it is important to increase the shadowing to help with the diagnosis of important pathology, so the focal zone and beam width

**The edge (refraction) artifact:** It occurs in rounded structures like a cyst or urinary bladder as the ultrasound refracted at its edges results in shadows at both edges (**Figure 5**). These artifact shadows are corrected, and the shadows disappear by changing the angle of the ultrasound beam after identification of the artifact. **Anisotropy:** It commonly occurs in tendons and, to a lesser extent, muscles, ligaments, and nerves. It appears as a hypoechoic area in a structure that has anisotropy. This phenomenon can be misinterpreted as a discontinuation of the course's structure. As the ultrasound beam is perpendicular to the tendon throughout its course, the tendon is uniformly hyperechoic. If the tendon is curved, the ultrasound beam is not perpendicular to the tendon; the tendon becomes hypoechoic and disappears. These phenomena can be overcome by changing the transducer position (heel-to-toe movement to make the transducer perpendicular on the tendon along

Understanding of these artifacts will minimize any misinterpretation in the report, and in certain situations it helps in the diagnosis. In this book, we used some of these artifact expressions for diagnosis or for explaining how to avoid any

Standardized evaluation of abdominal ultrasound should optimally take place after overnight fasting in most of the ultrasound techniques; however, this is not a condition in urgent situations. In an emergency ultrasound, no special preparation is required. In routine clinical practice, fasting is important to avoid interfering bowel gas; also, it is recommended to assess the abdomen from a more lateral aspect through both flanks. Keeping in mind the need to take precautions, and being systematic in scanning, will provide clues to reach the correct diagnosis and avoid

Starting ultrasound examination of the abdomen, it is usually done in a systematic manner. Your guide for scanning must be based on your mental checklist in the examination. Start by the right side considering the liver the acoustic window of the right upper quadrant of the abdomen. Go through the anatomical four areas of the abdomen, namely, the right upper quadrant, the left upper quadrant, the right lower quadrant, and the left lower quadrant. Intestinal loops can be screened in the

*Longitudinal US image of the gallbladder shows echogenic gallstones with clear shadow.*

*DOI: http://dx.doi.org/10.5772/intechopen.87964*

are important to be adjusted in these cases [11].

its course) [13].

misinterpretation.

mistakes during scanning.

#### *Introductory Chapter: Common Pitfalls and How to Overcome DOI: http://dx.doi.org/10.5772/intechopen.87964*

*Essentials of Abdominal Ultrasound*

**Figure 2.**

*parenchyma.*

**6**

**Figure 3.**

are used to describe the shadow of stones, calcification, and air, respectively. It is very helpful in practice to identify the clear shadow as a dark band due to all the ultrasound waves being absorbed. Its presence can help detect stones in echogenic structures such as kidney stones. Also, a shadow is important to differentiate a

*Transverse US image of the liver shows anechoic hepatic cysts. The hepatic parenchyma distal to the cysts is falsely displayed as increased intensity (arrow) secondary to increased through-transmission artifact.*

*Longitudinal US image shows an echogenic lesion in the right hepatic lobe (hepatic hemangioma), and a duplicated echogenic lesion (arrow) on the other side equidistant from the diaphragm mimics lesion in lung*  gall bladder (GB) stone (**Figure 4**), with its clear shadow, from a non-shadowing polyp or a sludge ball in GB. Dirty shadowing is seen in the case of highly refracting structure like gas. In clinical practice, it is important to increase the shadowing to help with the diagnosis of important pathology, so the focal zone and beam width are important to be adjusted in these cases [11].

**The edge (refraction) artifact:** It occurs in rounded structures like a cyst or urinary bladder as the ultrasound refracted at its edges results in shadows at both edges (**Figure 5**). These artifact shadows are corrected, and the shadows disappear by changing the angle of the ultrasound beam after identification of the artifact.

**Anisotropy:** It commonly occurs in tendons and, to a lesser extent, muscles, ligaments, and nerves. It appears as a hypoechoic area in a structure that has anisotropy. This phenomenon can be misinterpreted as a discontinuation of the course's structure. As the ultrasound beam is perpendicular to the tendon throughout its course, the tendon is uniformly hyperechoic. If the tendon is curved, the ultrasound beam is not perpendicular to the tendon; the tendon becomes hypoechoic and disappears. These phenomena can be overcome by changing the transducer position (heel-to-toe movement to make the transducer perpendicular on the tendon along its course) [13].

Understanding of these artifacts will minimize any misinterpretation in the report, and in certain situations it helps in the diagnosis. In this book, we used some of these artifact expressions for diagnosis or for explaining how to avoid any mistakes during scanning.

Standardized evaluation of abdominal ultrasound should optimally take place after overnight fasting in most of the ultrasound techniques; however, this is not a condition in urgent situations. In an emergency ultrasound, no special preparation is required. In routine clinical practice, fasting is important to avoid interfering bowel gas; also, it is recommended to assess the abdomen from a more lateral aspect through both flanks. Keeping in mind the need to take precautions, and being systematic in scanning, will provide clues to reach the correct diagnosis and avoid misinterpretation.

Starting ultrasound examination of the abdomen, it is usually done in a systematic manner. Your guide for scanning must be based on your mental checklist in the examination. Start by the right side considering the liver the acoustic window of the right upper quadrant of the abdomen. Go through the anatomical four areas of the abdomen, namely, the right upper quadrant, the left upper quadrant, the right lower quadrant, and the left lower quadrant. Intestinal loops can be screened in the

#### **Figure 5.**

*Transverse US image of the liver shows transverse image of gallbladder with false shadow edge artifact.*

"grid"-type pattern starting from the right side passing through the areas to the left side in a slow screening movement allowing to explore any intestinal pathology.

Ultrasound reports must fulfill all abdominal organs, with a full description of each in a systemic manner. A general outline of the sonographic description includes the architectures, the echogenicity of the parenchyma, and blood vessel distribution with a special comment on its variation from normal. The full screen of the organ is usually done with a complete orientation about the organ pathology. Any pathology is described as diffuse or localized, followed by detail descriptions of its site, size, echogenicity, regularity, and any special artifacts as mentioned above.

At the end of the report, there is a summary of the findings with your brainstorm conclusion. Ultrasound report is your mind checklist representing your systematic work and screening for the complete abdominal examination. Keep in mind that ultrasound findings are not histological but rather pathological. If from your clinical knowledge any additional investigation is required to confirm the diagnosis, it must be mentioned as a recommendation. Also, according to the ultrasound findings, a simple interventional process as ultrasound-guided biopsy procedures may be required. Also, good technical skills are needed for better interpretation of any valuable knowledge in the screening while avoiding the pitfalls and artifacts that can result in more confusion to the sonographers. In this text, many valuable technical skills are available from experts each in his field.

**9**

**Author details**

Samia Ali Abdo Gamie

Helwan University, Cairo, Egypt

provided the original work is properly cited.

\*Address all correspondence to: samia\_ali5@hotmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*Introductory Chapter: Common Pitfalls and How to Overcome*

*DOI: http://dx.doi.org/10.5772/intechopen.87964*

*Introductory Chapter: Common Pitfalls and How to Overcome DOI: http://dx.doi.org/10.5772/intechopen.87964*

*Essentials of Abdominal Ultrasound*

**Figure 5.**

"grid"-type pattern starting from the right side passing through the areas to the left side in a slow screening movement allowing to explore any intestinal pathology. Ultrasound reports must fulfill all abdominal organs, with a full description of each in a systemic manner. A general outline of the sonographic description includes the architectures, the echogenicity of the parenchyma, and blood vessel distribution with a special comment on its variation from normal. The full screen of the organ is usually done with a complete orientation about the organ pathology. Any pathology is described as diffuse or localized, followed by detail descriptions of its site, size, echogenicity, regularity, and any special artifacts as mentioned above. At the end of the report, there is a summary of the findings with your brainstorm conclusion. Ultrasound report is your mind checklist representing your systematic work and screening for the complete abdominal examination. Keep in mind that ultrasound findings are not histological but rather pathological. If from your clinical knowledge any additional investigation is required to confirm the diagnosis, it must be mentioned as a recommendation. Also, according to the ultrasound findings, a simple interventional process as ultrasound-guided biopsy procedures may be required. Also, good technical skills are needed for better interpretation of any valuable knowledge in the screening while avoiding the pitfalls and artifacts that can result in more confusion to the sonographers. In this text, many valuable

*Transverse US image of the liver shows transverse image of gallbladder with false shadow edge artifact.*

technical skills are available from experts each in his field.

**8**

#### **Author details**

Samia Ali Abdo Gamie Helwan University, Cairo, Egypt

\*Address all correspondence to: samia\_ali5@hotmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### **References**

[1] Hangiandreou NJ. AAPM/RSNA physics tutorial for residents. Topics in US: B-mode US: Basic concepts and new technology. RadioGraphics. 2003;**23**:1019-1033

[2] Genovese M. Journal of Diagnostic Medical Sonography Ultrasound Transducers. 2016;**32**(1):48-53

[3] Manbachi A, Cobbold RSC. Development and application of piezoelectric materials for ultrasound generation and detection. Ultrasound. 2011;**19**(4):187-196

[4] Abu-Zidan FM, Hefny AF, Corr P. Clinical ultrasound physics. Journal of Emergencies, Trauma, and Shock. 2011;**4**(4):501-503

[5] Szabo TL, Lewin PA. Ultrasound transducer selection in clinical imaging practice. Journal of Ultrasound in Medicine. 2013;**32**:573-582

[6] Bertrand PB, Levine RA, Isselbacher EM, Vandervoort PM. Fact or artifact in two-dimensional echocardiography: Avoiding misdiagnosis and missed diagnosis. Journal of the American Society of Echocardiography. 2016;**29**(5):381-391

[7] Hoskins PR, Martin K, Thrush A. Diagnostic Ultrasound: Physics and Equipment. 2nd ed. Cambridge: Cambridge, England; 2010

[8] Middleton WD, Siegel MJ, Dahiya N. Ultrasound artifacts. In: Siegel MJ, editor. Pediatric Sonography. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011. pp. 21-42

[9] Baad M, Lu ZF, Reiser I, Paushter D. Clinical significance of US artifacts. RadioGraphics. 2017;**37**:1408-1423

[10] Bonatti M, Vezzali N, Lombardo F, Ferro F, Zamboni G, Tauber M, et al.

Gallbladder adenomyomatosis: Imaging findings, tricks and pitfalls. Insights into Imaging. 2017;**8**(2):243-253

[11] Feldman MK, Katyal S, Blackwood MS. US artifacts. RadioGraphics. 2009;**29**:1179-1189

[12] Rose JS, Bair AE. Fundamentals of ultrasound. In: Cosby KS, Kendall JL, editors. Practical Guide to Emergency Ultrasound. PA: Lippincott Williams and Wilkins; 2006. pp. 27-41

[13] Serafin-Król M, Maliborski A. Diagnostic errors in musculoskeletal ultrasound imaging and how to avoid them. Journal of Ultrasonography. 2017;**17**(70):188-196

**11**

Section 2

Knobology

Section 2 Knobology

**10**

*Essentials of Abdominal Ultrasound*

[1] Hangiandreou NJ. AAPM/RSNA physics tutorial for residents. Topics in US: B-mode US: Basic concepts and new technology. RadioGraphics. Gallbladder adenomyomatosis: Imaging findings, tricks and pitfalls. Insights into

[11] Feldman MK, Katyal S, Blackwood MS. US artifacts. RadioGraphics.

[12] Rose JS, Bair AE. Fundamentals of ultrasound. In: Cosby KS, Kendall JL, editors. Practical Guide to Emergency Ultrasound. PA: Lippincott Williams

Imaging. 2017;**8**(2):243-253

and Wilkins; 2006. pp. 27-41

[13] Serafin-Król M, Maliborski A. Diagnostic errors in musculoskeletal ultrasound imaging and how to avoid them. Journal of Ultrasonography.

2009;**29**:1179-1189

2017;**17**(70):188-196

[2] Genovese M. Journal of Diagnostic Medical Sonography Ultrasound Transducers. 2016;**32**(1):48-53

[4] Abu-Zidan FM, Hefny AF, Corr P. Clinical ultrasound physics. Journal of Emergencies, Trauma, and Shock.

[5] Szabo TL, Lewin PA. Ultrasound transducer selection in clinical imaging practice. Journal of Ultrasound in

[6] Bertrand PB, Levine RA, Isselbacher EM, Vandervoort PM. Fact or artifact in two-dimensional echocardiography: Avoiding misdiagnosis and missed diagnosis. Journal of the American Society of Echocardiography.

[7] Hoskins PR, Martin K, Thrush A. Diagnostic Ultrasound: Physics and Equipment. 2nd ed. Cambridge: Cambridge, England; 2010

[8] Middleton WD, Siegel MJ, Dahiya N. Ultrasound artifacts. In: Siegel MJ, editor. Pediatric Sonography. 4th ed. Philadelphia, PA: Lippincott Williams &

[9] Baad M, Lu ZF, Reiser I, Paushter D. Clinical significance of US artifacts. RadioGraphics. 2017;**37**:1408-1423

[10] Bonatti M, Vezzali N, Lombardo F, Ferro F, Zamboni G, Tauber M, et al.

Medicine. 2013;**32**:573-582

[3] Manbachi A, Cobbold RSC. Development and application of piezoelectric materials for ultrasound generation and detection. Ultrasound.

2003;**23**:1019-1033

**References**

2011;**19**(4):187-196

2011;**4**(4):501-503

2016;**29**(5):381-391

Wilkins; 2011. pp. 21-42

**13**

**Chapter 2**

**Abstract**

ALARA principle

**1. Introduction**

misdiagnosis.

The Influence of Ultrasound

Ultrasonography is a highly operator dependent imaging modality with a number of knobology variables that are under the control of the operator. Knobology is a terminology that describes the manipulation of ultrasound knobs and system controls in order to obtain the best image possible from diagnostic ultrasound. The inadequate use of knobology variables may impair image quality and can result in misdiagnosis. In abdominal sonography, selecting the appropriate application preset for abdominal examination is first step towards achieving an optimum image. The next step is to select an appropriate transducer frequency which must take the size of the patient into account. Transducer frequency is typically in the range of 3–5 MHz, but a lower frequency may achieve better depth penetration in larger patients. While the output power may improve image quality by increasing the intensity of transmitted sound energy, the impact is usually insignificant. The practice of using high output power should therefore be limited because of the risk of biologic effect. Other essential knobs for better image optimization include controlling the overall gain, time gain compensation, focal zone, dynamic range and tissue harmonic imaging. In the assessment of blood flow in abdominal vessels the regulation of the pulse repetition frequency, Doppler gain, imaging angle, and

Equipment Knobology in

Abdominal Sonography

*Yaw Amo Wiafe and Augustina Badu-Peprah*

wall filter improves the sensitivity of color and spectral Doppler.

**Keywords:** knobology, resolution, greyscale imaging, Doppler imaging,

Ultrasonography is a highly operator dependent imaging modality with a number of knobology variables that are under the control of the operator. Knobology is a terminology that describes the manipulation of ultrasound knobs and system controls in order to obtain the best image possible from diagnostic ultrasound. The inadequate use of knobology variables may impair image quality and can result in

This chapter explains the functions of the various ultrasound system controls and knobs and the impact they have on greyscale ultrasound imaging. It demonstrates the effect of transducer selection on image quality, and the role of knobology variables in image optimization. This includes a description of the Application Preset, Output Power, Overall Gain, Time Gain Compensation (TGC), Focus, Depth, Zoom, Dynamic Range and Tissue Harmonics. The influence of these

#### **Chapter 2**

## The Influence of Ultrasound Equipment Knobology in Abdominal Sonography

*Yaw Amo Wiafe and Augustina Badu-Peprah*

#### **Abstract**

Ultrasonography is a highly operator dependent imaging modality with a number of knobology variables that are under the control of the operator. Knobology is a terminology that describes the manipulation of ultrasound knobs and system controls in order to obtain the best image possible from diagnostic ultrasound. The inadequate use of knobology variables may impair image quality and can result in misdiagnosis. In abdominal sonography, selecting the appropriate application preset for abdominal examination is first step towards achieving an optimum image. The next step is to select an appropriate transducer frequency which must take the size of the patient into account. Transducer frequency is typically in the range of 3–5 MHz, but a lower frequency may achieve better depth penetration in larger patients. While the output power may improve image quality by increasing the intensity of transmitted sound energy, the impact is usually insignificant. The practice of using high output power should therefore be limited because of the risk of biologic effect. Other essential knobs for better image optimization include controlling the overall gain, time gain compensation, focal zone, dynamic range and tissue harmonic imaging. In the assessment of blood flow in abdominal vessels the regulation of the pulse repetition frequency, Doppler gain, imaging angle, and wall filter improves the sensitivity of color and spectral Doppler.

**Keywords:** knobology, resolution, greyscale imaging, Doppler imaging, ALARA principle

#### **1. Introduction**

Ultrasonography is a highly operator dependent imaging modality with a number of knobology variables that are under the control of the operator. Knobology is a terminology that describes the manipulation of ultrasound knobs and system controls in order to obtain the best image possible from diagnostic ultrasound. The inadequate use of knobology variables may impair image quality and can result in misdiagnosis.

This chapter explains the functions of the various ultrasound system controls and knobs and the impact they have on greyscale ultrasound imaging. It demonstrates the effect of transducer selection on image quality, and the role of knobology variables in image optimization. This includes a description of the Application Preset, Output Power, Overall Gain, Time Gain Compensation (TGC), Focus, Depth, Zoom, Dynamic Range and Tissue Harmonics. The influence of these

#### *Essentials of Abdominal Ultrasound*

essential knobs and system controls on spatial resolution (including lateral and axial resolution) and Contrast resolution are explained. In addition, the utility of Doppler knobs for imaging abdominal blood vessels are also explained and demonstrated.

The need to adhere to the principle of As Low As Reasonably Achievable (ALARA) is also explained with emphasis on the imaging of neonates and children. Lastly, the chapter also emphasizes the potential detrimental effect of underutilizing ultrasound knobs and system controls in abdominal sonography.

#### **2. Switching-on the ultrasound machine**

Switching on the ultrasound machine is the first knob to press if the machine is switched off. By switching on the machine, the ultrasound system is given access to a source of electricity, which excites the tiny piezoelectric crystals within the connected transducer. These piezoelectric crystals emit sound waves as a result of their exposure to electricity. The sound waves produced by the piezoelectric crystals can then be transmitted into the human body, normally aided by a coupling gel which serves as an acoustic medium for eliminating the air between the surface of the transducer and the skin.

#### **3. Application preset**

Modern machines allow the operator to preset an application setting for a certain examination type. Ultrasound imaging is used for a wide range of medical applications. Aside its use in assessing the abdomen, it is also used in obstetrics and gynecology, cardiac and vascular examinations, and other small-part examinations such as breast, thyroid, and musculoskeletal imaging. Different sonographic settings are needed for the various examinations, due to their differences in terms of the depth of region of interest, tissue-type, and the size of organs and structures in that region. Because of the uniqueness of these examinations, adjusting the settings between patients for a different examination can be time consuming, and may compromise the adherence to ALARA principles. In addressing this limitation, the manufacturer makes it easier by allowing the operator to select the type of examination which will activate the pre-defined factory settings for the specific type of examination. By selecting the appropriate 'Application Preset' for abdominal examination, the pre-defined factory settings are activated for abdominal sonography. This automatically adjusts the basic settings for the selected examination, which include an adjustment of the transducer frequency, acoustic Output Power, Overall Gain, Dynamic Range, Depth and other related settings.

Performing an abdominal ultrasound with a different application preset may impair the image quality which could mislead image interpretation. For example, a user performing an obstetric examination may identify a need for including abdominal examination without switching to the abdomen preset. This may impair the image quality of the abdominal examination if careful adjustments of relevant knobology variables are not made. In **Figure 1a**, obstetric preset was used in imaging the kidneys of an obstetric patient who complained of flank pain during an obstetric ultrasound examination. Upon using the basic obstetric preset without further manipulation of essential knobs, there was the tendency of suspecting a focal lesion in the right kidney (see arrow in **Figure 1a**). However, a switch to the basic abdomen preset without further manipulation resulted in an improved image quality which shows a normal kidney (see arrow of **Figure 1b** in the same person).

**15**

**4. The transducer**

**Figure 1.**

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

It therefore suggests that much more manipulation of knobs will be required for selecting the 'wrong' application preset which may unduly extend the duration of

*(a) Image of the right kidney with OB preset suggests a focal change within kidney (see arrow). (b) Image of* 

Ultrasound images are produced from high frequency sound waves that are emitted by the transducer, typically in the range of 1–15 MHz [1, 2]. The frequency of the transducer is determined by the thickness of the piezoelectric crystals and the damping material behind them [3]. In producing a higher frequency, the manufacturer places a damping material behind very thin piezoelectric crystals in order to shorten the pulses of sound waves that are emitted [3]. However, shorter pulses of sound waves are unable to penetrate deeper because of shorter wavelength [3]. Due to this penetration limitation, different types of transducers are designed with different ranges of frequency. Higher frequency transducers offer better resolution at the expense of depth penetration, whilst lower frequency transducers offer better

the examination as a compromise on ALARA principles.

*the right kidney with abdomen preset suggests normal appearance (see arrow).*

depth penetration for poorer image resolution [2, 3].

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

#### **Figure 1.**

*Essentials of Abdominal Ultrasound*

demonstrated.

transducer and the skin.

**3. Application preset**

essential knobs and system controls on spatial resolution (including lateral and axial resolution) and Contrast resolution are explained. In addition, the utility of Doppler knobs for imaging abdominal blood vessels are also explained and

The need to adhere to the principle of As Low As Reasonably Achievable (ALARA) is also explained with emphasis on the imaging of neonates and children. Lastly, the chapter also emphasizes the potential detrimental effect of underutiliz-

Switching on the ultrasound machine is the first knob to press if the machine is switched off. By switching on the machine, the ultrasound system is given access to a source of electricity, which excites the tiny piezoelectric crystals within the connected transducer. These piezoelectric crystals emit sound waves as a result of their exposure to electricity. The sound waves produced by the piezoelectric crystals can then be transmitted into the human body, normally aided by a coupling gel which serves as an acoustic medium for eliminating the air between the surface of the

Modern machines allow the operator to preset an application setting for a certain examination type. Ultrasound imaging is used for a wide range of medical applications. Aside its use in assessing the abdomen, it is also used in obstetrics and gynecology, cardiac and vascular examinations, and other small-part examinations such as breast, thyroid, and musculoskeletal imaging. Different sonographic settings are needed for the various examinations, due to their differences in terms of the depth of region of interest, tissue-type, and the size of organs and structures in that region. Because of the uniqueness of these examinations, adjusting the settings between patients for a different examination can be time consuming, and may compromise the adherence to ALARA principles. In addressing this limitation, the manufacturer makes it easier by allowing the operator to select the type of examination which will activate the pre-defined factory settings for the specific type of examination. By selecting the appropriate 'Application Preset' for abdominal examination, the pre-defined factory settings are activated for abdominal sonography. This automatically adjusts the basic settings for the selected examination, which include an adjustment of the transducer frequency, acoustic Output Power, Overall

Performing an abdominal ultrasound with a different application preset may impair the image quality which could mislead image interpretation. For example, a user performing an obstetric examination may identify a need for including abdominal examination without switching to the abdomen preset. This may impair the image quality of the abdominal examination if careful adjustments of relevant knobology variables are not made. In **Figure 1a**, obstetric preset was used in imaging the kidneys of an obstetric patient who complained of flank pain during an obstetric ultrasound examination. Upon using the basic obstetric preset without further manipulation of essential knobs, there was the tendency of suspecting a focal lesion in the right kidney (see arrow in **Figure 1a**). However, a switch to the basic abdomen preset without further manipulation resulted in an improved image quality which shows a normal kidney (see arrow of **Figure 1b** in the same person).

Gain, Dynamic Range, Depth and other related settings.

ing ultrasound knobs and system controls in abdominal sonography.

**2. Switching-on the ultrasound machine**

**14**

*(a) Image of the right kidney with OB preset suggests a focal change within kidney (see arrow). (b) Image of the right kidney with abdomen preset suggests normal appearance (see arrow).*

It therefore suggests that much more manipulation of knobs will be required for selecting the 'wrong' application preset which may unduly extend the duration of the examination as a compromise on ALARA principles.

#### **4. The transducer**

Ultrasound images are produced from high frequency sound waves that are emitted by the transducer, typically in the range of 1–15 MHz [1, 2]. The frequency of the transducer is determined by the thickness of the piezoelectric crystals and the damping material behind them [3]. In producing a higher frequency, the manufacturer places a damping material behind very thin piezoelectric crystals in order to shorten the pulses of sound waves that are emitted [3]. However, shorter pulses of sound waves are unable to penetrate deeper because of shorter wavelength [3]. Due to this penetration limitation, different types of transducers are designed with different ranges of frequency. Higher frequency transducers offer better resolution at the expense of depth penetration, whilst lower frequency transducers offer better depth penetration for poorer image resolution [2, 3].

#### *Essentials of Abdominal Ultrasound*

Since most abdominal organs such as the liver, spleen, kidneys, pancreas and aorta are relatively deeper, lower frequency transducers are used for this type of examination. Unlike the transducers designed for other examinations, the transducers for abdominal examination (i.e. sector or curvilinear) have a divergent and wider far field. Aside the lower frequency of curvilinear and sector transducers which makes image resolution relatively poorer, there is also an increase in attenuation as the sound beam travels deeper. This may adversely affect the image resolution of abdominal sonography. It is therefore incumbent on the operator to make a careful choice between better image resolution and depth penetration.

The typical frequency range for curvilinear transducers is in the range of 2-5 MHz. In selecting a frequency for an abdominal examination, the operator should consider the size of the patient. If the patient is smaller in size, a higher frequency should be used for better spatial resolution. Particularly in neonates and children, a higher frequency is highly useful, as this is likely to produce better image resolution to shorten the duration of the examination in fulfillment of ALARA principles. Secondly, children are less likely to cooperate during the examination, therefore using a lower frequency such as 3 MHz for abdominal examination may unduly delay the examination because of the lack of patient cooperation and a poorer image resolution. **Figure 2a** and **b** demonstrates two images of the right and left kidneys

#### **Figure 2.**

*(a) Image of the right kidney of right and left kidney in a 3-year-old non-cooperating patient showing poorer image resolution because of lower transducer frequency of 2.5 MHz. (b) Image of the right kidney of right and left kidney in the 3-year-old non-cooperating patient showing better visualization of renal margins because of lower transducer frequency of 2.5 MHz.*

**17**

**Figure 3.**

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

obtained from a 3-year-old infant with the higher frequency obviously showing more details than the lower frequency. However, a low frequency of 3-4 MHz is often ideal for imaging the average-sized adult, whilst larger or much more obese adults

In addition, a linear transducer may also be used during abdominal ultrasound. Linear transducers use higher frequencies for imaging structures that are more superficial, such as the anterior abdominal wall and the surface of the liver. They

The acoustic output power of the machine must be considered at all times by the operator. As indicated above, selecting the appropriate preset for abdomen ultrasound will automatically adjust the output power to the recommended level. However, while it is important to observe the ALARA principle by using the minimum output power possible, the operator must not compromise image quality for output power reduction which may lead to misdiagnosis. In essence, there should be a balance between maximizing image quality with the minimum output power possible as a measure for reducing the risk of biological effect. Usually, the ultrasound

*(a) The appearance of the abdominal aorta at a reduced output power by 50%. (b) The appearance of the abdominal aorta when the output power increased was increased to 100 showed no significant difference %.*

may require as low as 2 MHz of frequency for adequate depth penetration.

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

are also used in assessing the appendix.

**5. Output power**

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

obtained from a 3-year-old infant with the higher frequency obviously showing more details than the lower frequency. However, a low frequency of 3-4 MHz is often ideal for imaging the average-sized adult, whilst larger or much more obese adults may require as low as 2 MHz of frequency for adequate depth penetration.

In addition, a linear transducer may also be used during abdominal ultrasound. Linear transducers use higher frequencies for imaging structures that are more superficial, such as the anterior abdominal wall and the surface of the liver. They are also used in assessing the appendix.

#### **5. Output power**

*Essentials of Abdominal Ultrasound*

Since most abdominal organs such as the liver, spleen, kidneys, pancreas and aorta are relatively deeper, lower frequency transducers are used for this type of examination. Unlike the transducers designed for other examinations, the transducers for abdominal examination (i.e. sector or curvilinear) have a divergent and wider far field. Aside the lower frequency of curvilinear and sector transducers which makes image resolution relatively poorer, there is also an increase in attenuation as the sound beam travels deeper. This may adversely affect the image resolution of abdominal sonography. It is therefore incumbent on the operator to make a

careful choice between better image resolution and depth penetration.

The typical frequency range for curvilinear transducers is in the range of 2-5 MHz. In selecting a frequency for an abdominal examination, the operator should consider the size of the patient. If the patient is smaller in size, a higher frequency should be used for better spatial resolution. Particularly in neonates and children, a higher frequency is highly useful, as this is likely to produce better image resolution to shorten the duration of the examination in fulfillment of ALARA principles. Secondly, children are less likely to cooperate during the examination, therefore using a lower frequency such as 3 MHz for abdominal examination may unduly delay the examination because of the lack of patient cooperation and a poorer image resolution. **Figure 2a** and **b** demonstrates two images of the right and left kidneys

*(a) Image of the right kidney of right and left kidney in a 3-year-old non-cooperating patient showing poorer image resolution because of lower transducer frequency of 2.5 MHz. (b) Image of the right kidney of right and left kidney in the 3-year-old non-cooperating patient showing better visualization of renal margins because of* 

**16**

**Figure 2.**

*lower transducer frequency of 2.5 MHz.*

The acoustic output power of the machine must be considered at all times by the operator. As indicated above, selecting the appropriate preset for abdomen ultrasound will automatically adjust the output power to the recommended level. However, while it is important to observe the ALARA principle by using the minimum output power possible, the operator must not compromise image quality for output power reduction which may lead to misdiagnosis. In essence, there should be a balance between maximizing image quality with the minimum output power possible as a measure for reducing the risk of biological effect. Usually, the ultrasound

#### **Figure 3.**

*(a) The appearance of the abdominal aorta at a reduced output power by 50%. (b) The appearance of the abdominal aorta when the output power increased was increased to 100 showed no significant difference %.*

machine will display the output power on the screen at all times, allowing the operator to be constantly informed (**Figure 3a** and **b**). However, while increasing the power output may be useful, it may also be needless in many cases. The over-all Gain can play a better and safer role in image quality optimization than the output power. **Figure 3a** and **b** demonstrate that there is no significant difference between the appearance the abdominal aorta if the output power is reduced by 50% and the overall gain is about 30 decibels.

#### **6. Overall gain**

The overall gain is the recommended option to consider in place of increasing the output power. With the overall gain, image quality can be improved by adjusting the brightness of the entire field of view without increasing the intensity of transmitted sound energy. It achieves this by amplifying the echo-signals returning from the body after transmitting the sound waves. The overall gain can be considered as the 'microphone' in ultrasound imaging. The technology is similar to using a microphone to amplify someone's voice for the listener. Increasing or decreasing

**Figure 4.**

*(a) Adequate overall gain of 31 decibels with liver surface showing. (b) Too high overall gain of 60 decibels with liver surface missing.*

**19**

**Figure 5.**

*TGC slide in the yellow circle.*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

the overall gain may improve contrast resolution for adequate visualization of the image. However, just as a microphone can sometimes produce noise and become a nuisance, increasing the overall gain beyond a certain point will affect contrast and spatial resolution by making the image appear too bright. Nonetheless, it is a knob you cannot do without in image optimization. Most modern machines integrate the overall gain in the Bmode or 2D knob, but it is still a separate knob in some machines. Manipulate the overall gain by adjusting it 'up and down' and carefully observe the changes that occur as you control the knob. **Figure 4a** and **b** shows images of adequate versus high overall gain and the effect it has on assessing the

While the overall gain would adjust the brightness of the entire field of view, it may not address attenuation occurring at specific depths. Some structures in the body are much more affected by attenuation than others and would therefore need additional compensation for the loss of sound energy. For example, an optimum visualization of the left lobe of the liver requires a depth specific gain adjustment that is different from the gain compensation needed for optimum visualization of the right lobe. Hence the Time Gain Compensation (also known as Depth Gain Compensation), is a set of depth-specific slide controls that can be used for echo-signal amplification at different depths (see **Figure 5**). It allows the adjustment of echo-signals in the near-field, mid-field and far field to improve axial resolution. The TGC creates uniformity in the brightness of the echoes when used in conjunction with the overall gain. The best approach is to center all the TGC settings before adjusting the overall gain. After adjusting the overall gain, the TGC can then be adjusted to compensate for attenuation at

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

surface of the liver.

specific depth.

**7. Time gain compensation**

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

the overall gain may improve contrast resolution for adequate visualization of the image. However, just as a microphone can sometimes produce noise and become a nuisance, increasing the overall gain beyond a certain point will affect contrast and spatial resolution by making the image appear too bright. Nonetheless, it is a knob you cannot do without in image optimization. Most modern machines integrate the overall gain in the Bmode or 2D knob, but it is still a separate knob in some machines. Manipulate the overall gain by adjusting it 'up and down' and carefully observe the changes that occur as you control the knob. **Figure 4a** and **b** shows images of adequate versus high overall gain and the effect it has on assessing the surface of the liver.

#### **7. Time gain compensation**

*Essentials of Abdominal Ultrasound*

overall gain is about 30 decibels.

**6. Overall gain**

machine will display the output power on the screen at all times, allowing the operator to be constantly informed (**Figure 3a** and **b**). However, while increasing the power output may be useful, it may also be needless in many cases. The over-all Gain can play a better and safer role in image quality optimization than the output power. **Figure 3a** and **b** demonstrate that there is no significant difference between the appearance the abdominal aorta if the output power is reduced by 50% and the

The overall gain is the recommended option to consider in place of increasing the output power. With the overall gain, image quality can be improved by adjusting the brightness of the entire field of view without increasing the intensity of transmitted sound energy. It achieves this by amplifying the echo-signals returning from the body after transmitting the sound waves. The overall gain can be considered as the 'microphone' in ultrasound imaging. The technology is similar to using a microphone to amplify someone's voice for the listener. Increasing or decreasing

*(a) Adequate overall gain of 31 decibels with liver surface showing. (b) Too high overall gain of 60 decibels* 

**18**

**Figure 4.**

*with liver surface missing.*

While the overall gain would adjust the brightness of the entire field of view, it may not address attenuation occurring at specific depths. Some structures in the body are much more affected by attenuation than others and would therefore need additional compensation for the loss of sound energy. For example, an optimum visualization of the left lobe of the liver requires a depth specific gain adjustment that is different from the gain compensation needed for optimum visualization of the right lobe. Hence the Time Gain Compensation (also known as Depth Gain Compensation), is a set of depth-specific slide controls that can be used for echo-signal amplification at different depths (see **Figure 5**). It allows the adjustment of echo-signals in the near-field, mid-field and far field to improve axial resolution. The TGC creates uniformity in the brightness of the echoes when used in conjunction with the overall gain. The best approach is to center all the TGC settings before adjusting the overall gain. After adjusting the overall gain, the TGC can then be adjusted to compensate for attenuation at specific depth.

**Figure 5.** *TGC slide in the yellow circle.*

#### **8. Focal zone(s)**

During scanning, the system allows the operator to improve lateral resolution in a region of interest by adjusting the focal zone. This is an additional measure to minimize the effect of attenuation. However, while other controls such as the overall gain and TGC are effective for improving axial resolution, adjusting the focal zone is much more effective for improving lateral resolution. Lateral resolution refers to the ability to identify structures lying side-by-side as separate structures, while axial resolution refers to the ability to identify a structure lying on another structure as separate structures.

The focal zone normally appears at the lateral side of Bmode as a triangularshaped structure or a dot. It can be moved up or down by the operator and should be placed at the region of interest or posterior to that region. If a single focal zone is set too superficially a poorer image resolution will be observed in the far field (**Figure 6**). However if the focal zone placed below or at the level of region of interest, the resolution improves in the entire field of view (**Figure 6**). To improve lateral resolution in a wider region, more than one focal zones may be selected by the operator. However, increasing the number of focal zones also decreases the frame rate which has the tendency of slowing down the image production time to the detriment of temporal resolution. Thus using more focal zones slows down the scanning time which may not support the principles of ALARA in terms of keeping to a reasonable scanning time.

#### **Figure 6.**

*Poorer resolution when focal zone is positioned in the near is compared to focal zone positioned at the level of interest.*

#### **9. Depth**

The Depth is special a knob for adjusting the distance of the field of view. Structures within the field of view can be moved far or closer by adjusting the Depth. This is to ensure that the region of interest is closer enough for optimum visualization. It is also to avoid showing regions that are not relevant to the area of interest. **Figure 7a** is an example of a far depth image of the pancreas, with a wide irrelevant space showing behind the spine. This irrelevant space can be avoided by adjusting the

**21**

**Figure 7.**

*(a) Far depth. (b) Closer depth.*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

Depth closer for adequate visualization (**Figure 7b**). The structure of interest should always take the center stage by occupying about two-thirds of the field view. In order to avoid missing a pathology beyond the field of view, the best practice is to adjust the Depth for a far field of view before adjusting for a closer field of view. **Figure 8** is an example of how one can miss a pathology, if the Depth is not adjusted for adequate visualization beyond the field view. It demonstrates how a closer Depth would have

However, while moving the depth closer and far is necessary for evaluating various conditions and ruling out pathologies, moving the Depth closer has the tendency of generating noise which can worsen contrast resolution and may even mimic a pathology.

missed the pleural effusion if a far depth image was not assessed.

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

**Figure 7.** *(a) Far depth. (b) Closer depth.*

Depth closer for adequate visualization (**Figure 7b**). The structure of interest should always take the center stage by occupying about two-thirds of the field view. In order to avoid missing a pathology beyond the field of view, the best practice is to adjust the Depth for a far field of view before adjusting for a closer field of view. **Figure 8** is an example of how one can miss a pathology, if the Depth is not adjusted for adequate visualization beyond the field view. It demonstrates how a closer Depth would have missed the pleural effusion if a far depth image was not assessed.

However, while moving the depth closer and far is necessary for evaluating various conditions and ruling out pathologies, moving the Depth closer has the tendency of generating noise which can worsen contrast resolution and may even mimic a pathology.

*Essentials of Abdominal Ultrasound*

structure as separate structures.

to a reasonable scanning time.

**8. Focal zone(s)**

**20**

**Figure 6.**

*interest.*

**9. Depth**

*Poorer resolution when focal zone is positioned in the near is compared to focal zone positioned at the level of* 

The Depth is special a knob for adjusting the distance of the field of view. Structures within the field of view can be moved far or closer by adjusting the Depth. This is to ensure that the region of interest is closer enough for optimum visualization. It is also to avoid showing regions that are not relevant to the area of interest. **Figure 7a** is an example of a far depth image of the pancreas, with a wide irrelevant space showing behind the spine. This irrelevant space can be avoided by adjusting the

During scanning, the system allows the operator to improve lateral resolution in a region of interest by adjusting the focal zone. This is an additional measure to minimize the effect of attenuation. However, while other controls such as the overall gain and TGC are effective for improving axial resolution, adjusting the focal zone is much more effective for improving lateral resolution. Lateral resolution refers to the ability to identify structures lying side-by-side as separate structures, while axial resolution refers to the ability to identify a structure lying on another

The focal zone normally appears at the lateral side of Bmode as a triangularshaped structure or a dot. It can be moved up or down by the operator and should be placed at the region of interest or posterior to that region. If a single focal zone is set too superficially a poorer image resolution will be observed in the far field (**Figure 6**). However if the focal zone placed below or at the level of region of interest, the resolution improves in the entire field of view (**Figure 6**). To improve lateral resolution in a wider region, more than one focal zones may be selected by the operator. However, increasing the number of focal zones also decreases the frame rate which has the tendency of slowing down the image production time to the detriment of temporal resolution. Thus using more focal zones slows down the scanning time which may not support the principles of ALARA in terms of keeping

**Figure 8.** *Missing information on the right-side because of depth adjustment.*

#### **10. Zoom**

The zoom is used for magnifying the area of interest. Unlike the depth which magnifies by moving the area of interest closer, the zoom actually magnifies by making the region of interest appear bigger. Another limitation of the depth that is

**23**

**Figure 10.**

*(a) Narrow dynamic range. (b) Broad dynamic range.*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

addressed by the zoom is the ability to enlarge a specific region of interest. Without using the zoom, measuring some tiny structures may difficult because of poor spatial resolution. For instance, in measuring the thickness of the gallbladder wall, using the zoom improves the visualization of the wall for an accurate measurement

Some manufacturers use READ zoom for their magnification, while others use WRITE zoom. Both read zoom and write zoom can produce poorer image depending on the size of the area magnified. However, READ zoom produces the worse kind of images because it relies on stored images which enlarges the pixel density in that region (**Figure 9a**). On the other hand, WRITE zoom tries to maintain the pixel density by zooming the image live which produces a better spatial resolution. Operators should check the type of zoom in their machine in order to appreciate how much zooming can be done without compromising the

The Dynamic Range is a control on the ultrasound system that allows the operator to determine the range of shades of gray to be displayed on the monitor. Broad shades of gray displays a wider range of echo-intensity between bright and

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

(**Figure 9a** and **b**).

image quality.

**11. Dynamic range**

**Figure 9.** *(a) Read zoom. (b) Write zoom.*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

addressed by the zoom is the ability to enlarge a specific region of interest. Without using the zoom, measuring some tiny structures may difficult because of poor spatial resolution. For instance, in measuring the thickness of the gallbladder wall, using the zoom improves the visualization of the wall for an accurate measurement (**Figure 9a** and **b**).

Some manufacturers use READ zoom for their magnification, while others use WRITE zoom. Both read zoom and write zoom can produce poorer image depending on the size of the area magnified. However, READ zoom produces the worse kind of images because it relies on stored images which enlarges the pixel density in that region (**Figure 9a**). On the other hand, WRITE zoom tries to maintain the pixel density by zooming the image live which produces a better spatial resolution. Operators should check the type of zoom in their machine in order to appreciate how much zooming can be done without compromising the image quality.

#### **11. Dynamic range**

*Essentials of Abdominal Ultrasound*

*Missing information on the right-side because of depth adjustment.*

The zoom is used for magnifying the area of interest. Unlike the depth which magnifies by moving the area of interest closer, the zoom actually magnifies by making the region of interest appear bigger. Another limitation of the depth that is

**Figure 8.**

**10. Zoom**

**22**

**Figure 9.**

*(a) Read zoom. (b) Write zoom.*

The Dynamic Range is a control on the ultrasound system that allows the operator to determine the range of shades of gray to be displayed on the monitor. Broad shades of gray displays a wider range of echo-intensity between bright and

**Figure 10.** *(a) Narrow dynamic range. (b) Broad dynamic range.*

#### **Figure 11.** *Broad versus narrow dynamic range of IVC.*

dark and produces a smoother image overall, whilst narrow shades of gray displays a narrower range of echo-intensity between bright and dark and produces a higher contrast between two regions of different echogenicity. In abdominal sonography, a broad dynamic range is the most appropriate option for assessing the echotexture of homogeneous soft-tissue structures like the liver, pancreas and spleen. Narrow dynamic range is most appropriate for assessing anechoic structures such as the aorta and IVC. **Figure 10a** shows the effect of narrow dynamic range of the pancreas in comparison to the liver, and **Figure 10b** shows the effect of broad dynamic range on the pancreas which shows poor differentiation in echotexture in comparison to the liver. In **Figure 11** also shows the effect of long and short dynamic range on the appearance of the IVC.

#### **12. Tissue harmonic imaging**

Tissue harmonic Imaging (THI) is an additional control for image optimization in most ultrasound machines. It improves image quality by eliminating weak echoes that cloud the image when the fundamental frequency of the transducer is used. It replaces the returning echoes from the fundamental frequency with echoes in the harmonic frequency which improves spatial resolution. This eliminates side lobe artifacts and noticeable noise in the area of interest. It can therefore be used in conjunction with the utilization of other knobs that may generate noise. For example, noise generated by increasing the Depth can be instantly eliminated by activating THI. **Figure 12** also shows an increase in noise as a result of increasing the overall gain and Depth, and how it is instantly eliminated by the activation of THI. The activation of the THI in **Figure 12** instantly changed the settings from the fundamental frequency to the harmonic frequency. In **Figure 13**, you also appreciate the importance of THI, in terms of how it improves visualization of the margins of liver surface in comparison with the adjacent image which did not use THI.

**25**

**Figure 13.**

**Figure 12.**

**13. Freezing and cineloop**

*Improved liver margins with activated THI.*

storage is therefore recommended.

The ultrasound machine also has a freeze button which enables the operator to stop and evaluate the image quality before storage. Saving an image without freezing implies that the image was not evaluated for quality. Freezing the image before

The cineloop is additional control that helps with selecting the best of the image

frozen image. It displays image frames acquired in the last few seconds prior to

freezing. The cineloop can be highly useful when scanning children.

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

*Noise from increased overall gain and depth is instantly eliminated THI activation.*

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

**Figure 12.** *Noise from increased overall gain and depth is instantly eliminated THI activation.*

**Figure 13.** *Improved liver margins with activated THI.*

#### **13. Freezing and cineloop**

The ultrasound machine also has a freeze button which enables the operator to stop and evaluate the image quality before storage. Saving an image without freezing implies that the image was not evaluated for quality. Freezing the image before storage is therefore recommended.

The cineloop is additional control that helps with selecting the best of the image frozen image. It displays image frames acquired in the last few seconds prior to freezing. The cineloop can be highly useful when scanning children.

*Essentials of Abdominal Ultrasound*

on the appearance of the IVC.

**Figure 11.**

**12. Tissue harmonic imaging**

*Broad versus narrow dynamic range of IVC.*

the adjacent image which did not use THI.

dark and produces a smoother image overall, whilst narrow shades of gray displays a narrower range of echo-intensity between bright and dark and produces a higher contrast between two regions of different echogenicity. In abdominal sonography, a broad dynamic range is the most appropriate option for assessing the echotexture of homogeneous soft-tissue structures like the liver, pancreas and spleen. Narrow dynamic range is most appropriate for assessing anechoic structures such as the aorta and IVC. **Figure 10a** shows the effect of narrow dynamic range of the pancreas in comparison to the liver, and **Figure 10b** shows the effect of broad dynamic range on the pancreas which shows poor differentiation in echotexture in comparison to the liver. In **Figure 11** also shows the effect of long and short dynamic range

Tissue harmonic Imaging (THI) is an additional control for image optimization in most ultrasound machines. It improves image quality by eliminating weak echoes that cloud the image when the fundamental frequency of the transducer is used. It replaces the returning echoes from the fundamental frequency with echoes in the harmonic frequency which improves spatial resolution. This eliminates side lobe artifacts and noticeable noise in the area of interest. It can therefore be used in conjunction with the utilization of other knobs that may generate noise. For example, noise generated by increasing the Depth can be instantly eliminated by activating THI. **Figure 12** also shows an increase in noise as a result of increasing the overall gain and Depth, and how it is instantly eliminated by the activation of THI. The activation of the THI in **Figure 12** instantly changed the settings from the fundamental frequency to the harmonic frequency. In **Figure 13**, you also appreciate the importance of THI, in terms of how it improves visualization of the margins of liver surface in comparison with

**24**

### **14. Additional controls for imaging abdominal blood vessels**

An abdominal ultrasound examination may also require the assessment of blood vessels and Doppler evaluation of blood flow. The fundamental knobs that influence both color and spectral Doppler imaging include the Doppler gain, pulse repetition period (PRF), and the wall filter. In assessing the presence of flow in smaller blood vessel, the minimum standard is to adjust the system for a higher Doppler gain, a lower PRF and a lower wall filter [4]. Careful manipulation is used in balancing these knobs, as a slight overlap between them can generate noise artifacts.

**Figure 14a** shows the poorer flow in the hepatic vein in comparison to the portal vein as a result of higher PRF. This is much improved in **Figure 14b** with decreased PRF.

In larger abdominal blood vessels such as the aorta, additional knob controls that are highly relevant include the imaging angle which must not be parallel to the surface of

**27**

**Figure 15.**

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

the transducer. **Figure 15a** and **b** shows the effect of imaging angle on color flow in the aorta which is absent when the vessel is parallel to the surface of the transducer.

In spectral Doppler Imaging, however, lower PRF may cause aliasing artifact, especially when the baseline is high [5]. This can be corrected by increasing the PRF of the spectral waveform and lowering the baseline. **Figure 16a** shows aliasing artifact of the Superior Mesenteric Artery (SMA) which was as a result of a lower PRF and a higher baseline. By increasing the PRF and lowering the baseline, a normal waveform of the SMA was obtained in **Figure 16b**. Other essential knobology settings which improves spectral waveform in the assessment of peak systolic velocity include using a smaller sample gate and ensuring an angle correct setting that aligns

with the vessel wall as demonstrated in **Figure 16a** and **b**.

*(a) Color flow showing in angled vessel. (b) Color flow absent in parallel vessel.*

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

#### **Figure 15.**

*Essentials of Abdominal Ultrasound*

generate noise artifacts.

decreased PRF.

**14. Additional controls for imaging abdominal blood vessels**

An abdominal ultrasound examination may also require the assessment of blood vessels and Doppler evaluation of blood flow. The fundamental knobs that influence both color and spectral Doppler imaging include the Doppler gain, pulse repetition period (PRF), and the wall filter. In assessing the presence of flow in smaller blood vessel, the minimum standard is to adjust the system for a higher Doppler gain, a lower PRF and a lower wall filter [4]. Careful manipulation is used in balancing these knobs, as a slight overlap between them can

**Figure 14a** shows the poorer flow in the hepatic vein in comparison to the portal vein as a result of higher PRF. This is much improved in **Figure 14b** with

In larger abdominal blood vessels such as the aorta, additional knob controls that are highly relevant include the imaging angle which must not be parallel to the surface of

*(a) High PRF with low flow sensitivity in hepatic vein. (b) Low PRF with high flow sensitivity in hepatic vein.*

**26**

**Figure 14.**

*(a) Color flow showing in angled vessel. (b) Color flow absent in parallel vessel.*

the transducer. **Figure 15a** and **b** shows the effect of imaging angle on color flow in the aorta which is absent when the vessel is parallel to the surface of the transducer.

In spectral Doppler Imaging, however, lower PRF may cause aliasing artifact, especially when the baseline is high [5]. This can be corrected by increasing the PRF of the spectral waveform and lowering the baseline. **Figure 16a** shows aliasing artifact of the Superior Mesenteric Artery (SMA) which was as a result of a lower PRF and a higher baseline. By increasing the PRF and lowering the baseline, a normal waveform of the SMA was obtained in **Figure 16b**. Other essential knobology settings which improves spectral waveform in the assessment of peak systolic velocity include using a smaller sample gate and ensuring an angle correct setting that aligns with the vessel wall as demonstrated in **Figure 16a** and **b**.

#### **Figure 16.**

*(a) Aliasing artifact in the superior mesenteric artery as a result of lower PRF and higher baseline. (b) Adequate waveform for assessing peak systolic velocity in the superior mesenteric artery, after increasing the PRF and lowering the baseline.*

#### **15. Conclusion**

Understanding the influence of knobology in ultrasound imaging is essential in abdominal sonography. The image quality can be optimized by selecting the appropriate application preset and transducer frequency. While using the highest output power may be useful, it is not necessary in many instances. The various knobology variables with direct influence on greyscale and color Doppler should be regularly manipulated by the operator for the best image possible in abdominal sonography.

**29**

**Author details**

Yaw Amo Wiafe1

provided the original work is properly cited.

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

1 Medical Imaging Section, Department of Medical Diagnostics, Kwame Nkrumah

2 Department of Radiology, Komfo Anokye Teaching Hospital, Kumasi, Ghana

\* and Augustina Badu-Peprah2

University of Science and Technology, Kumasi, Ghana

\*Address all correspondence to: wadart1@gmail.com

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography*

*DOI: http://dx.doi.org/10.5772/intechopen.83713*

*The Influence of Ultrasound Equipment Knobology in Abdominal Sonography DOI: http://dx.doi.org/10.5772/intechopen.83713*

### **Author details**

*Essentials of Abdominal Ultrasound*

**28**

**15. Conclusion**

*PRF and lowering the baseline.*

**Figure 16.**

sonography.

Understanding the influence of knobology in ultrasound imaging is essential in abdominal sonography. The image quality can be optimized by selecting the appropriate application preset and transducer frequency. While using the highest output power may be useful, it is not necessary in many instances. The various knobology variables with direct influence on greyscale and color Doppler should be regularly manipulated by the operator for the best image possible in abdominal

*(a) Aliasing artifact in the superior mesenteric artery as a result of lower PRF and higher baseline. (b) Adequate waveform for assessing peak systolic velocity in the superior mesenteric artery, after increasing the* 

> Yaw Amo Wiafe1 \* and Augustina Badu-Peprah2

1 Medical Imaging Section, Department of Medical Diagnostics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

2 Department of Radiology, Komfo Anokye Teaching Hospital, Kumasi, Ghana

\*Address all correspondence to: wadart1@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### **References**

[1] Merritt C. In: Rumack CM, Wilson SR, Charboeau JW, Levine D, editors. Diagnostic Ultrasound. 4th ed. Mosby: Elsevier; 2011. p. 3. Ch. 1

[2] Venables H. How does ultrasound work? Ultrasound. 2011;**19**(1):44-49. DOI: 10.1258/ult.2010.010051

[3] Kremkau FW. Diagnostic Ultrasound: Principles and Instruments. Philadelphia, USA: WB Saunders Company; 2005

[4] Kim MJ, Kim KW, Kim SY, Kim JK, Won HJ, Shin YM, Kim PN, Lee MG. Technical essentials of hepatic doppler sonography. Current Problems in Diagnostic Radiology. 1 Mar 2009;**38**(2):53-60. Available from: https://doi.org/10.1067/j. cpradiol.2007.08.008

[5] Kruskal JB, Newman PA, Sammons LG, Kane RA. Optimizing doppler and color flow US: Application to hepatic sonography. Radiographics. May 2004;**24**(3):657-675. Available from: https://doi.org/10.1148/rg.243035139

**31**

Section 3

Liver Ultrasound
