Lung Perfusion Projections: Why Lateral Views Matter

C. Lateral views allow detection of posterior and anterior segment defects that overlap on AP projections, improving detection and classification of PE

Multiple projections (8 standard views) are essential for V/Q lung scan interpretation because lung segments that overlap on anterior/posterior views are separated on lateral and oblique views. For example, the posterior basal and lateral basal segments of the lower lobes overlap each other on the posterior view but are separated on the lateral projections. Multiple views also allow more accurate classification of defect size (segmental vs. subsegmental) and extent, which directly determines PIOPED probability category. A single-view study significantly underestimates the number of perfusion defects and can lead to incorrect classification.