B-Lines in Assessment of Pulmonary Hypertension in Patients With Interstitial Lung Diseases: Feasibility of Transthoracic Lung Sonographic Signs

Objectives: This study was conducted to evaluate the value of sonographic B-lines (previously called "comet tail artifacts") in assessment of pulmonary hypertension in patients with interstitial lung diseases.

Methods: One hundred thirty-four patients with clinically diagnosed interstitial lung diseases complicated by pulmonary hypertension underwent transthoracic lung sonography and Doppler echocardiography for assessment of the presence of B-lines, the distance between them, and the pulmonary artery (PA) systolic pressure. A correlation analysis and a receiver operating characteristic curve analysis were performed.

Results: All patients had diffuse bilateral B-lines. The maximum number of B-lines seen in any positive zone (not a summation) was significantly correlated with the severity of PA systolic pressure (r= 0.812; P< .0001), and a linear regression equation could be demonstrated: that is, y = 6.06 x + 17.57, where x and y represent the number of B-lines and PA systolic pressure, respectively. A cutoff of more than 4 B-lines seen in any positive zone had 89.5% sensitivity, 85.0% specificity, and 87.2% accuracy in predicting elevated PA pressure (>30 mm Hg).

Conclusions: The number of B-lines is useful in assessment of pulmonary hypertension, especially when tricuspid regurgitation and pulmonary valve regurgitation do not exist or cannot be satisfactorily measured by Doppler echocardiography.