**7. Examples of MRI protocols and applications by SE sequence**

The obtained images are recorded and photographed on film (Figure 14). The final appearance will depend not only on intrinsic properties of tissues but also on technical aspects such as

44 Imaging and Radioanalytical Techniques in Interdisciplinary Research - Fundamentals and Cutting Edge Applications

pulse sequences or time factors that are chosen and machine quality.

**Figure 14.** MRI obtained in SE sequence in the axial plane of the skull [19].

central nervous system and skeletal muscle.

For each type of exam of any region of the human body, there is a specific protocol to obtain MR images, most are used for detecting soft-tissue lesions of the structures that make up the This method has been widely used in the diagnosis of diseases located in the structures of the nervous and musculoskeletal systems. Thus, MRI is an imaging method that provides excellent contrast between soft tissues, due to its high spatial resolution. Therefore, from the anatomical point of view, MRI is the best choice for evaluation of the structures that make up the muscu‐ loskeletal system. The protocols on Table 1 and Table 2 were used to acquire the images of the following images which represents examples of very interesting applications of MRI.


**Table 1.** Exam protocol and values of technical parameters and tissue for evaluation of lesions in the lower limb (0.5 Tesla MRI). Body and head coils.


**Figure 15.** MRI of the right foot showing edema in subcutaneous tissue characterized by (A) hyposignal on T1 (B) hy‐ perintense on T2, and (C) enhanced on post-contrast T1. Musculature and perimuscular areas preserved [16].

Spin Echo Magnetic Resonance Imaging http://dx.doi.org/10.5772/53693 47

Tissue lesion and inflammatory processes related to the musculoskeletal system cause changes in the relaxation times T1 and T2 and reflects the signal intensity. The inflammatory processes increase the signal intensity on T2-weighted images and the swelling causes an increase of

**Figure 16.** MRI showing the left calf. The injury is consistent with subcutaneous tissue and perimusculare region mild haemorrhage characterized by (A) isointese to hyperintense signal on T1, (B) hyperintense signal on T2, and (C) en‐ hanced on post-contrast T1. The presence of blood in the perimuscular region is well visualized on relaxation time T2.

Bleeding observed in subcutaneous and muscle tissues is generally different from that resulting from the degradation process known in the pathologies of the central nervous system. In these pathologies, the bleeding is presented in various stages of degradation and is known as oxyhemoglobin and/or deoxyhemoglobin, (intracellular or free) methemoglobin, and hemosiderin. Thus, these various stages interfere with the lesion signal intensity and stage

As to the skeletal muscle, it may present in the form from an iso to hyperintense signal at all

It is noted that in these images the edema in association with haemorrhage usually presents

water in the tissues that determines the signal changes observed [22].

interpretation [24,25].

relaxation times before and after contrast injection [16].

themselves with signal hyperintensity on the T2-weighted images.

**Table 2.** Exam protocol and values of technical parameters and tissue for evaluation of upper limb injuries (0.5 Tesla MRI). Elbow in shoulder coil.

### **7.1. Application to musculoskeletal tissue lesions**

The MR images on the axial plane (AX) show the skeletal muscle and central nervous system. In the sequence, lesions diagnosed as edema and blood in subcutaneous, perimus‐ cular, and muscular tissues and central nervous system structures in pre- and postcontrast T1 and T2 times (Figures 15, 16 &17). Edema presents as a hypointense signal on pre-contrast T1 time and enhanced on pre-contrast T1 time and hyperintense on T2 time. Lesions identified as haemorrhagic lesions present a hypersignal on pre- and post-con‐ trast T1 and T2 times [21,22,23].

The edema corresponds to an increase of water content into the extracellular space and/or into the intracellular compartment. T2-weighted sequences are the main time interval that detects this increase in the form of an intense area of hypersignal in [21,22,23].

In haemorrhagic lesions or in the presence of degradation components of blood in any tissue often give the hyperintense signal on T1 and T2. They are a consequence of a local vascular injury [22,23].

**Section planes AX LOC COR T1 AX T2 AX T1**

SE 320

**7.1. Application to musculoskeletal tissue lesions**

**TR in ms**

MRI). Elbow in shoulder coil.

trast T1 and T2 times [21,22,23].

injury [22,23].

**FOV** 25 15 25 22 22

46 Imaging and Radioanalytical Techniques in Interdisciplinary Research - Fundamentals and Cutting Edge Applications

**TE in ms** 25 30 40 25 25

**TE(2º) in ms** - - 80 - -

**Interval** 7 5 5 8 8

**Number of sections** 4 12 13 12 12

**Thickness in mm** 5 5 5 5 5

**NAQ** 1 2 2 4 4

**(F1)** - - 10-8 - -

**Matrix** 192x192 192x192 256x192 192x160 192x160

**Table 2.** Exam protocol and values of technical parameters and tissue for evaluation of upper limb injuries (0.5 Tesla

The MR images on the axial plane (AX) show the skeletal muscle and central nervous system. In the sequence, lesions diagnosed as edema and blood in subcutaneous, perimus‐ cular, and muscular tissues and central nervous system structures in pre- and postcontrast T1 and T2 times (Figures 15, 16 &17). Edema presents as a hypointense signal on pre-contrast T1 time and enhanced on pre-contrast T1 time and hyperintense on T2 time. Lesions identified as haemorrhagic lesions present a hypersignal on pre- and post-con‐

The edema corresponds to an increase of water content into the extracellular space and/or into the intracellular compartment. T2-weighted sequences are the main time interval that

In haemorrhagic lesions or in the presence of degradation components of blood in any tissue often give the hyperintense signal on T1 and T2. They are a consequence of a local vascular

detects this increase in the form of an intense area of hypersignal in [21,22,23].

SE 2000 SE 750

SE 750 **AX T1 GDL**

SE 750

**Figure 15.** MRI of the right foot showing edema in subcutaneous tissue characterized by (A) hyposignal on T1 (B) hy‐ perintense on T2, and (C) enhanced on post-contrast T1. Musculature and perimuscular areas preserved [16].

Tissue lesion and inflammatory processes related to the musculoskeletal system cause changes in the relaxation times T1 and T2 and reflects the signal intensity. The inflammatory processes increase the signal intensity on T2-weighted images and the swelling causes an increase of water in the tissues that determines the signal changes observed [22].

**Figure 16.** MRI showing the left calf. The injury is consistent with subcutaneous tissue and perimusculare region mild haemorrhage characterized by (A) isointese to hyperintense signal on T1, (B) hyperintense signal on T2, and (C) en‐ hanced on post-contrast T1. The presence of blood in the perimuscular region is well visualized on relaxation time T2.

Bleeding observed in subcutaneous and muscle tissues is generally different from that resulting from the degradation process known in the pathologies of the central nervous system. In these pathologies, the bleeding is presented in various stages of degradation and is known as oxyhemoglobin and/or deoxyhemoglobin, (intracellular or free) methemoglobin, and hemosiderin. Thus, these various stages interfere with the lesion signal intensity and stage interpretation [24,25].

As to the skeletal muscle, it may present in the form from an iso to hyperintense signal at all relaxation times before and after contrast injection [16].

It is noted that in these images the edema in association with haemorrhage usually presents themselves with signal hyperintensity on the T2-weighted images.

**Figure 17.** MRI of the right forearm indicating extravasation of blood into muscle tissue characterized by (A) isoin‐ tense to hyperintense signal on T1-weighted image (B) hyperintense signal on T2-weighted image (C) enhanced on post-contrast T1-weighted image [23].

### **7.2. Tumor injuries detected in the central nervous system**

The vast majority of intracranial tumors present a high-protein density, a long T1 and T2, so generally there is a hypo signal on T1-weighted (short TE-TR) and a hyperintense signal on T2-weighted sequences (long TE-TR). Thus, the signal variations are not very specific (Figure 18 & 19). The application presented in Figure 18 an Figure 19 concerns the examination of rectal adenocarcinoma and meningioma of left ventricle fibrous trigonum respectively.

Cerebral edema can be of three types: vasogenic corresponding to a disruption of the bloodbrain barrier to the passage of a protein-rich filtrate in the brain extracellular spaces, nonspe‐ cific outcome of multiple pathological processes (primary tumors, metastases, haemorrhage, trauma, inflammatory processes and infection). It manifests as a hyperintense signal area of white matter, respecting the gray matter. The accomplishment of a sequence with strong T2 weighted can evidence that it is due to the edema's persistent hyperintense signal in contrast to the tumour´s decreasing signal. However, the sequences on T1 post-contrast are the ones bounding the lesion; the earliest manifestation form of infarction is the cytotoxic edema. The ischemia leads to an early failure of the membrane pump, which allows water and sodium to enter the cells. It presents itself as a hyperintense signal involving the white and gray matter

**Figure 19.** T1-weighted imaging sequences in sagittal plane (A) and T2-weighted imaging sequence in axial plane (C,

D) after contrast injection on T1-weighted sequence in frontal plane (B) [21].

(c) (d)

(a) (b)

)

Spin Echo Magnetic Resonance Imaging http://dx.doi.org/10.5772/53693 49

Interstitial edema is found in hydrocephalus with passage of transependymal water into the brain tissue from the ventricular cavities, essentially around the lateral ventricles [21].

The water being highly bound to the neighboring proteins displays a significant decrease of T1. The interstitial edema can be viewed paradoxically under the form of a hyperintense signal on T1-weighted sequences, while still naturally with hyperintense signal on T2-weighted

Thus, the contrast injection increases the specificity in the detection of lesions. The paramag‐ netic agents such as the gadolinium (GDL) associated with a chelating agent - diethylenetria‐ mine pentaacetic acid (DTPA) - is a safety water soluble. After its application, around 80% is excreted by the kidneys in three hours, and the remaining is recovered in stools and eliminated

[21,24,25,26].

sequences [21,27,28].

within a week [18].

**Figure 18.** A and B are frontal section images on T1-weighted imaging. C After contrast injection. The hyperin‐ tense tumor (A, B, C) gives the perfect location of both the metastasis and the hypointense perilesional edema‐ tous reactions [21].

Whatever the sequence used after contrast injection, the parenchymatous reaction edema is visualized with hypointense signal on T1 pre- and post-contrast (A, B) and with hyperintense signal on T2 (C, D). Note the displacement to the right of the median structures of the septum pellucidum.

**Figure 19.** T1-weighted imaging sequences in sagittal plane (A) and T2-weighted imaging sequence in axial plane (C, D) after contrast injection on T1-weighted sequence in frontal plane (B) [21].

**7.2. Tumor injuries detected in the central nervous system**

post-contrast T1-weighted image [23].

tous reactions [21].

pellucidum.

The vast majority of intracranial tumors present a high-protein density, a long T1 and T2, so generally there is a hypo signal on T1-weighted (short TE-TR) and a hyperintense signal on T2-weighted sequences (long TE-TR). Thus, the signal variations are not very specific (Figure 18 & 19). The application presented in Figure 18 an Figure 19 concerns the examination of rectal

**Figure 17.** MRI of the right forearm indicating extravasation of blood into muscle tissue characterized by (A) isoin‐ tense to hyperintense signal on T1-weighted image (B) hyperintense signal on T2-weighted image (C) enhanced on

48 Imaging and Radioanalytical Techniques in Interdisciplinary Research - Fundamentals and Cutting Edge Applications

(a) (b) (c)

**Figure 18.** A and B are frontal section images on T1-weighted imaging. C After contrast injection. The hyperin‐ tense tumor (A, B, C) gives the perfect location of both the metastasis and the hypointense perilesional edema‐

Whatever the sequence used after contrast injection, the parenchymatous reaction edema is visualized with hypointense signal on T1 pre- and post-contrast (A, B) and with hyperintense signal on T2 (C, D). Note the displacement to the right of the median structures of the septum

adenocarcinoma and meningioma of left ventricle fibrous trigonum respectively.

Cerebral edema can be of three types: vasogenic corresponding to a disruption of the bloodbrain barrier to the passage of a protein-rich filtrate in the brain extracellular spaces, nonspe‐ cific outcome of multiple pathological processes (primary tumors, metastases, haemorrhage, trauma, inflammatory processes and infection). It manifests as a hyperintense signal area of white matter, respecting the gray matter. The accomplishment of a sequence with strong T2 weighted can evidence that it is due to the edema's persistent hyperintense signal in contrast to the tumour´s decreasing signal. However, the sequences on T1 post-contrast are the ones bounding the lesion; the earliest manifestation form of infarction is the cytotoxic edema. The ischemia leads to an early failure of the membrane pump, which allows water and sodium to enter the cells. It presents itself as a hyperintense signal involving the white and gray matter [21,24,25,26].

Interstitial edema is found in hydrocephalus with passage of transependymal water into the brain tissue from the ventricular cavities, essentially around the lateral ventricles [21].

The water being highly bound to the neighboring proteins displays a significant decrease of T1. The interstitial edema can be viewed paradoxically under the form of a hyperintense signal on T1-weighted sequences, while still naturally with hyperintense signal on T2-weighted sequences [21,27,28].

Thus, the contrast injection increases the specificity in the detection of lesions. The paramag‐ netic agents such as the gadolinium (GDL) associated with a chelating agent - diethylenetria‐ mine pentaacetic acid (DTPA) - is a safety water soluble. After its application, around 80% is excreted by the kidneys in three hours, and the remaining is recovered in stools and eliminated within a week [18].

The MRI scan is the method of choice for the evaluation of tumors. The sequence systematic practice, mainly of spin echo sequences in different space planes (particularly in axial and sagittal planes), and the intravenous injection of GDL allows a perfect assessment of the tumours [21,27,30].

The sequences with contrast images obtained on T1-weighted images are the most important to determine areas of injury with greater specificity. T2-weighted images allow accurately diagnosed injuries. Paramagnetic agents are of primary importance and its use in MRI provides

Spin Echo Magnetic Resonance Imaging http://dx.doi.org/10.5772/53693 51

MRI scans can be conducted in all regions of the body such as brain, spine, joints (shoulder, knee), extremities, chest, abdomen, and others. It is an excellent method for detecting tumours and other soft-tissue lesions based on the criteria of patient safety in relation to the magnetic field, pathology and site to investigate, as well as technical parameters and tissue, which are

The nomenclature represents the protocols used to acquire the images of tissues in MR spin

**FOV.** Field of view determine the size of the anatomy covered during the selection of the tissue

information about the behavior of the lesions.

critical in image acquisition.

**Nomenclature (list of symbol)**

**AX LOC.** Axial section plane locate

**SE.** Spin Echo sequence

**TR.** Repetition time

**Tl.** Inversion time

**TE.** Echo time

section

**IR.** Inversion-recovery sequence

**TE(2º).** Two sequences in echo time

**Interval.** Interval between slices to image quality

**Thickness.** Thikness of slices image quality

**Number of sections.** Number of slices to image quality

**COR LOC.** Coronal section plane locate

echo sequence of skeletal muscle and central nervous system.

**COR T1.** Coronal section plane tissue relaxation time T1

**GDL.** Contrast agent paramagnetic metal (gadolinium)

**AX T1.** Axial section plane tissue relaxation time TI pre-contrast

**AX T1 GDL.** Axial section plane tissue relaxation time T1 pos-contrast

**AX T2.** Axial section plane tissue relaxation time T2
