Operative Use of Thoracic Ultrasound in Respiratory Medicine: A Clinical Study

Abstract

For over 15 years, thoracic ultrasound has been applied in the evaluation of numerous lung diseases, demonstrating a variable diagnostic predictive power compared to traditional imaging techniques such as chest radiography and CT. However, in unselected pulmonary patients, there are no rigorous scientific demonstrations of the complementarity of thoracic ultrasound with traditional and standardized imaging techniques that use radiation. In this study 101 unselected pulmonary patients were evaluated blindly with ultrasound chest examinations during their hospital stay. Other instrumental examinations, carried out during hospitalization, were standard chest radiography, computed tomography (CT), and, when needed, radioisotopic investigation and cardiac catheterization. The operator who performed the ultrasound examinations was unaware of the anamnestic and clinical data of the patients. Diffuse fibrosing disease was detected with a sensitivity, specificity and diagnostic accuracy of 100%, 95% and 97%, respectively. In pleural effusions, ultrasound showed a sensitivity, specificity and diagnostic accuracy of 100%. In consolidations, the sensitivity, specificity and diagnostic accuracy were 83%, 98% and 93%, respectively. Low values of sensitivity were recorded for surface nodulations of less than one centimeter. Isolated subpleural ground glass densities were identified as White Lung with a sensitivity of 72% and a specificity of 86%. Only the associations Diffuse ultrasound findings/Definitive fibrosing disease, Ultrasound Consolidation/Definitive consolidation and non-diffuse ultrasound artefactual features/Definitive vascular pathology (pulmonary hypertension, embolism) were statistically significant with adjusted residuals of 7.9, 7 and 4.1, respectively. The obtained results show how chest ultrasound is an effective complementary diagnostic tool for the pulmonologist. When performed, as a complement to the patient's physical examination, it can restrict the diagnostic hypothesis in the case of pleural effusion, consolidation and diffuse fibrosing disease of the lung.

Keywords: diagnosis; lung; respiratory medicine; sonography; ultrasound.

Figure 1

Example of the location of ultrasound (US) findings on the thoracic surface through a graphic scheme with differently colored landmarks, to obtain a superficial topography comparable to CT images. Three schemes of three different patients are shown in A, B and C.

Figure 2

The image on the left shows vertical artifacts in a subject with idiopathic pulmonary fibrosis with a strongly irregular pleural line (red arrow). The image on the right shows B-lines (red arrows) with a regular pleural line in a subject with heart failure.

Figure 3

Ultrasound and CT scans of two patients with fibrosing lung disease. The black arrows indicate the position of the probe on the chest. The two CT and ultrasound scans are coplanar. In (a) a minor fibrotic involvement is present while in (b) a small nodulation (red circle) is evident.

Figure 4

Image (a) shows an ultrasound scan of a patient with large pleural effusion and a coarse vegetation on the diaphragmatic surface (metastatic carcinoma in red circle). Image (b) shows lung consolidation with poor ventilation (pneumonia in red circle). Image (c) shows a large lung consolidation (lung cancer). Image (d) shows pleural neoplasia (mesothelioma in red circle).

Figure 5

Image (a) shows lung consolidation with associated artifacts in a red circle (pneumonia). Image (b) shows lung consolidation with associated pleural effusion (lung cancer in red circle). The red arrow in image (c) shows a large finely corpuscular pleural effusion (mesothelioma). The red arrow in image (d) shows a single nodule emerging on the pleural surface with a regular pleural line.

Figure 6

Ultrasound scans of a patient with mesothelioma. On the left, the CT scan shows only pleural effusion (red arrow). The upper right ultrasound scan clearly shows the pleural effusion (red arrow) and diaphragmatic nodulations (red circle). The lower right ultrasound scan shows a parietal pleural nodule (red circle).