Diagnostic utility of transthoracic Doppler ultrasound in the assessment of peripheral pulmonary lesions

Background
Transthoracic ultrasound is a safe, radiation-free, and cheap complementary radiological modality that helps in the detection of peripheral pulmonary nodules, masses, or consolidations adherent to the parietal pleura. As a complementary method, color Doppler sonography could offer further data regarding the cause of pleural-based pulmonary lesions detected according to the radiological findings.


Objective
To determine the sensitivity (Sn) and specificity (Sp) of Doppler US in the diagnosis of peripheral pulmonary lesions.


Patients and methods
This diagnostic study was conducted over 12 months and included 50 patients with peripheral lung lesions. Radiological investigations comprised chest radiography, chest computerized tomography (CT) scan with comment on side of lesion, lesion opacity (homogeneous or heterogeneous), margin (regular and irregular), and presence of air bronchogram, necrosis, and pleural effusion. Image-guided biopsies were taken from 27 patients suspected to have peripheral malignant lesions and underwent histopathological examination.


Results
CT scans showed that the lesion was located on the right side in 52% of cases, on the left side in 34%, bilaterally in 12%, and involved the mediastinum in 2%. Malignancy was found in 54% of cases. There were insignificant differences between benign and malignant cases regarding lesion side, opacity, or air bronchogram. The absence of vascularization was more frequent in malignant cases (37%) compared with 13% of benign cases, while the visualization of a vascular tree was more frequent in benign cases (78.3%) than in malignant cases (3.7%). US parameters displayed that there were no significant differences regarding the lesion side, Echo-pattern or echogenicity (P: 0.922, 0.276, 0.276, respectively). For detecting heterogeneity of lesions, the Sn of US was 90%, with Sp of 77.8%, positive predictive value of 87.9%, and negative predictive value of 82.4%. The diagnostic validity of detecting air bronchogram on US compared with CT displayed a Sn of 80%, Sp of 63.2%, positive predictive value of 63.2%, and negative predictive value of 90.3%.


Conclusion
Chest US with Doppler evaluation proved its value as a complementary method with its high specificity and diagnostic accuracy, a noninvasive, widely available, cost-efficient approach that can assist in the diagnosis of peripheral lung lesions.