“gliding sign” with a focal interstitial disease and multiple B lines accompanied those anterior characteristics [49].

Malignant pleural mesothelioma appears sonographically as nodular, planar or irregular and diffuse pleural thickening. It is often associated with pleural effusion [34, 35]. Invasion of the chest wall or the diaphragm can be detected by ultrasound [50]. The defnitive diagnosis can be done by thoracoscopy established in more than 90% of cases or by percutaneous biopsies under ultrasound guidance achieving nearly the same accuracy [51, 52].

Pleural metastases are usually seen as hypoechoic nodular, round-shaped, or brand-­ based polyp at the lower part of the pleura or over the diaphragmatic pleura with or without pleural effusion. Presence of pleural effusion sonographically as malignant pleural effusion increases the probability to have a malignant spread disease. Breast cancer or bronchial carcinomas are mostly the causes. Chest ultrasound can help to guide a biopsy or to avoid pleural masses choosing the ideal port of entry for diagnostic thoracoscopy procedures [35].

Pneumothorax

The diagnosis of a pneumothorax by ultrasonography is not equivalent to the detection of pleuraluid and requires more experience. What we expect to see in a uid pleural effusion is not applicable to the presence of air between visceral and parietal pleura.

While CT is the gold standard for diagnosis of pneumothorax, ultrasound has the advantage of being rapidly available at the bedside, and therefore useful particularly in the intensive care unit (ICU) or emergency department. A meta-analysis found ultrasound to be both more sensitive and specifc in the diagnosis of pneumothorax than plain chest radiography, with an estimated sensitivity of 88% and specifcity of 100%, as compared to 52% and 99%, respectively, with chest x-ray [53]. Furthermore, Galbois et al. show that ultrasound is more accurate at assessment of residual pneumothorax post drainage, with 39% of ultrasound detected and subsequently proven residual pneumothoraces missed by chest x-ray [54].