**5. Pneumothorax**

Expiratory erect chest radiographs are the initial examination of choice in suspected pneumo‐ thoraces, but the sensitivity of diagnosis was ranging between 50% and 90% [9, 10]. The diagnosis of a pneumothorax on the frontal radiograph is most difficult in critically ill patients where the patient is semi-recumbent and unable to comply with expiratory breath holding. Chest US may be help in the diagnosis of pneumothoraces. Normal parietal and visceral pleura slide over each other during respiration and a pneumothorax is suspected when this 'Gliding sign' is absent in chest US [11]. A recently published systemic review, chest US had a sensitivity of 90.0% and a specificity of 98.2% [12]. The confirmation of lung gliding has a 100% negative predictive value for the absence of pneumothorax [13]. The use of M-mode can also objectify the presence or absence of lung gliding. In the normal lung, the familiar "sea-shore" or "sandybeach" sign appearance will confirm the presence of lung gliding (Figure 4). In the pneumo‐ thorax, the "bar code" or stratosphere sign (Figure 5) is seen [14]. The "curtain sign" describes the variable obscuring of underlying structures by air-containing tissue that movement of airfluid level denoting a hydropneumothorax (Figure 6).

**Figure 4.** Lung sliding (on M-Mode sonography). P, pleura. Panel (A) shows the granular 'sea-shore' appearance of normal lung sliding. Panel (B) shows the horizontal 'bar-code' appearance that occurs with loss of lung sliding

**Figure 5.** Pneumothorax. Chest US reveals stratosphere sign

#### **5.1. Pulmonary lesions**

There was no transudative pleural effusion with complex septated or homogenously echogenic pattern [5]. The ability of chest US to detect underlying disease was comparable to that of computed tomography (CT) in pleural and parenchymal lesions [6]. The applications of sonographic appearances in effusions of febrile patients in the intensive care unit (ICU) can determine the necessity of thoracentesis in high risk patients with effusion in ICU [7]. This study reported that complex nonseptated and relatively hyperechoic, complex septated and homogenously echogenic pleural effusion patterns might predict the possibility of empyema in febrile patients in the ICU. The sonographic septation in lymphocyte-rich exudative pleural effusions can help us differentiate tuberculosis pleurisy from malignant pleural effusion [8].

**Figure 3.** Sonographic appearance of pleural effusion (PE). The effusion can be subclassified as anechoic (A), complex nonseptated with spots(arrows) floating inside effusion. D, diaphragm (B), complex septated (arrows) (C), and homo‐

Expiratory erect chest radiographs are the initial examination of choice in suspected pneumo‐ thoraces, but the sensitivity of diagnosis was ranging between 50% and 90% [9, 10]. The diagnosis of a pneumothorax on the frontal radiograph is most difficult in critically ill patients where the patient is semi-recumbent and unable to comply with expiratory breath holding. Chest US may be help in the diagnosis of pneumothoraces. Normal parietal and visceral pleura slide over each other during respiration and a pneumothorax is suspected when this 'Gliding sign' is absent in chest US [11]. A recently published systemic review, chest US had a sensitivity of 90.0% and a specificity of 98.2% [12]. The confirmation of lung gliding has a 100% negative predictive value for the absence of pneumothorax [13]. The use of M-mode can also objectify the presence or absence of lung gliding. In the normal lung, the familiar "sea-shore" or "sandybeach" sign appearance will confirm the presence of lung gliding (Figure 4). In the pneumo‐ thorax, the "bar code" or stratosphere sign (Figure 5) is seen [14]. The "curtain sign" describes the variable obscuring of underlying structures by air-containing tissue that movement of air-

genously echogenic (D)

86 Advancements and Breakthroughs in Ultrasound Imaging

**5. Pneumothorax**

fluid level denoting a hydropneumothorax (Figure 6).

The normal aerated lung is difficult to image because the dramatic change in acoustic impe‐ dance between chest wall and lung results in specular reflection of ultrasound waves at the pleura. However, consolidated lung has a tissue density and echo-texture similar to liver, analogous to pathological hepatisation. This removes the change in acoustic impedance at the pleural interface, and ultrasound waves pass directly into the affected lung. When patient with lobar or segmental pneumonia and the lesion is adjacent to pleura or in the pleural effusion, the pneumonia may be detected by chest US. A marked consolidation with air-bronchogram and treelike ramifications is easily seen (Figure 7). Within the consolidated area, hyperechoic (white) foci may be visible, again representing a change in acoustic impedance, but this time at the tissue interface between solid lung and air-filled bronchi. Subpleural nodule also can be seen in chest US (Figure 8).

**Figure 6.** Sonogram of a hydropneumothorax. Notice the gas–fluid and fibrin interface (arrow) between the bright hyperechoic line dorsally representing the pneumothorax and the ventral fluid and fibrin.

**Figure 7.** Air bronchogram. Notice the hypoechoic parenchyma and the small hyperechoic areas (A arrows) consistent with residual air in the bronchial tree. Color Doppler can distinguish between vessel and bronchus. V, vessel; B, bron‐ chus.

**5.2. Alveolar interstitial syndrome**

nals in pericavitary consolidation in a lung abscess (B).

resents visceral pleura.

according the BLUE protocol [17].

During previous studies, ultrasound imaging is not useful for pulmonary parenchyma imaging. Alveolar interstitial syndrome constitutes a group of diseases that is caused by an increase in lung fluid and/or a reduction in its air content. The result of this thickening of the interlobular septa causes a particular artifact that is seen arising from pleura line. The ultra‐ sound appearance of alveolar interstitial syndrome is a vertical artifact, called B-line. Presence of the comet-tail artifact (Figure 10) allowed diagnosis of alveolar-interstitial syndrome by chest ultrasound [16]. The major causes of alveolar interstitial syndrome include pulmonary edema, acute respiratory distress syndrome (ARDS), and interstitial fibrosis. In the advanced study, application of chest ultrasound in the patients with respiratory failure, chest ultra‐ sounds can help the clinician make a rapid diagnosis in patients with acute respiratory failure

(A) (B)

**Figure 9.** Lung abscess in chest US with Doppler. Chest US examination reveals a hypoechoic lesion with microbubble sign, which is surrounded by whole-lung parenchyma (arrows) (A). Color Doppler ultrasound can identify vessel sig‐

**Figure 8.** Transverse chest US scan shows a subpleural nodule (arrowheads). The linear hyperechoic area (arrow) rep‐

Ultrasound Diagnosis of Chest Diseaseses http://dx.doi.org/10.5772/55419 89

Chest US with color Doppler is a powerful tool for differentiating the peripheral air-fluid abscess from empyema [15]. The differentiation by chest radiograph alone is difficult when the empyema presents with an air-fluid level. Thoracic CT scanning can prove valuable in differentiating lung abscess from empyema; however, the problems of radiation exposure and contrast induced renal failure sometimes limit its application. The empyema can be detected by chest US with an image of a hypoechoic lesion with complex-septated effusions, passive atelectasis, width uniformity, and smooth luminal and outer margins. Color Doppler ultra‐ sound could not identify vessel signals in pericavitary atelectasis. The lung abscess in the US image reveals hypoechoic lesion with typical pulmonary consolidation, irregular wall width, and irregular luminal and outer margins. Color Doppler ultrasound could identify vessel signals in pericavitary consolidation (Figure 9).

**Figure 8.** Transverse chest US scan shows a subpleural nodule (arrowheads). The linear hyperechoic area (arrow) rep‐ resents visceral pleura.

**Figure 9.** Lung abscess in chest US with Doppler. Chest US examination reveals a hypoechoic lesion with microbubble sign, which is surrounded by whole-lung parenchyma (arrows) (A). Color Doppler ultrasound can identify vessel sig‐ nals in pericavitary consolidation in a lung abscess (B).

#### **5.2. Alveolar interstitial syndrome**

**Figure 7.** Air bronchogram. Notice the hypoechoic parenchyma and the small hyperechoic areas (A arrows) consistent with residual air in the bronchial tree. Color Doppler can distinguish between vessel and bronchus. V, vessel; B, bron‐

**Figure 6.** Sonogram of a hydropneumothorax. Notice the gas–fluid and fibrin interface (arrow) between the bright

hyperechoic line dorsally representing the pneumothorax and the ventral fluid and fibrin.

88 Advancements and Breakthroughs in Ultrasound Imaging

Chest US with color Doppler is a powerful tool for differentiating the peripheral air-fluid abscess from empyema [15]. The differentiation by chest radiograph alone is difficult when the empyema presents with an air-fluid level. Thoracic CT scanning can prove valuable in differentiating lung abscess from empyema; however, the problems of radiation exposure and contrast induced renal failure sometimes limit its application. The empyema can be detected by chest US with an image of a hypoechoic lesion with complex-septated effusions, passive atelectasis, width uniformity, and smooth luminal and outer margins. Color Doppler ultra‐ sound could not identify vessel signals in pericavitary atelectasis. The lung abscess in the US image reveals hypoechoic lesion with typical pulmonary consolidation, irregular wall width, and irregular luminal and outer margins. Color Doppler ultrasound could identify vessel

chus.

signals in pericavitary consolidation (Figure 9).

During previous studies, ultrasound imaging is not useful for pulmonary parenchyma imaging. Alveolar interstitial syndrome constitutes a group of diseases that is caused by an increase in lung fluid and/or a reduction in its air content. The result of this thickening of the interlobular septa causes a particular artifact that is seen arising from pleura line. The ultra‐ sound appearance of alveolar interstitial syndrome is a vertical artifact, called B-line. Presence of the comet-tail artifact (Figure 10) allowed diagnosis of alveolar-interstitial syndrome by chest ultrasound [16]. The major causes of alveolar interstitial syndrome include pulmonary edema, acute respiratory distress syndrome (ARDS), and interstitial fibrosis. In the advanced study, application of chest ultrasound in the patients with respiratory failure, chest ultra‐ sounds can help the clinician make a rapid diagnosis in patients with acute respiratory failure according the BLUE protocol [17].

pigtail catheter drainage is effective and had a shorter hospital stay than patients treated by chest tube drainage [20]. Moreover, US-guided pigtail catheter for secondary spontaneous pneumothorax (SSP) is also effective and has low complication rate. A higher treatment failure rate was noted in infectious related SSP patients [21, 22]. In mechanically ventilated patients, US-guided pigtail catheter drainage is also effective in treating iatrogenic pneumothorax [23].

Ultrasound Diagnosis of Chest Diseaseses http://dx.doi.org/10.5772/55419 91

Transthoracic needle biopsy with fluoroscopic or computed tomographic (CT) guidance is a well-established and safe method for diagnosing malignant and benign thoracic lesions. However, radiation exposure is considerable and the cost is relatively high, as compared with US guidance. US is as effective as CT for guidance of transthoracic biopsies of peripheral pulmonary lesions and mediastinal tumors and offers a number of advantages. Real-time US imaging allows for dynamic evaluation of vessels and localization of target lesions that move during respiration. In US-guided transthoracic biopsy, the tip of the needle can be monitored throughout the procedure and fine adjustments can be made quickly and precisely; this is especially beneficial for biopsy of small thoracic lesions [24, 25]. Pleural biopsy is required for unexplained pleural effusions, pleural thickening (whether focal or diffuse) and pleural masses. The advances in imaging of the pleura provided by US and CT have meant that radiologists now play an important role in pleural biopsy either directly or indirectly. In most instances biopsies are performed to establish whether or not pleural disease is due to malig‐ nancy or to evaluate a suspected inflammatory process such as tuberculosis. Because focal pleural thickening or pleural tumors can be easily identified by US, US-guided pleural biopsy is related to possible focal pleural involvement in various diseases such as pleural tumor, thickening pleura, and small amounts of pleural effusion [26]. Besides, in critically ill patients, chest US is helpful in diagnosis and is a useful diagnostic tool for critically ill patients with

Endobronchial ultrasound (EBUS) technology is a relatively new bronchoscopic method of visualizing the tracheobronchial tree, the surrounding pulmonary parenchyma, and the mediastinal structures, with a particular role in lung cancer diagnosis, staging, and treatment [28]. There are 2 types of probes used in EBUS: the peripheral or radial probe (RP) and the linear or convex probe (CP) EBUS, which have technical differences and distinct diagnostic abilities. Both are used for EBUS-guided biopsies and transbronchial needle aspirations (TBNA), which increases the diagnostic yield over conventional bronchoscopic techniques, thus providing advanced information on staging, diagnosis, and treatment. The 20-MHz RP-EBUS (Figure 11) is positioned inside a water-inflatable balloon and is inserted through the working channel of the bronchoscope. The RP-EBUS was first introduced to evaluate the central airway structure. With advances in technology, the small radial probes can now visualize and assist transbronchial biopsies of peripheral lung nodules without exposure to radiation. Kurimoto and colleagues [29] showed that using a guide sheath with radial probe EBUS and leaving it there to pass the forceps catheter through it could improve the diagnostic

**6.3. Ultrasound-guided biopsy**

chest disease [27].

**6.4. Endobronchial Ultrasound (EBUS)**

**Figure 10.** Lung comets. Lung comet tail, also known as 'B lines' (arrows) are indicative an alveolar interstitial syn‐ drome.
