Normal ventilation/perfusion lung scan in a patient with proven pulmonary embolus

Abstract

The sensitivity of the ventilation/perfusion (V/Q) lung scan in the diagnosis of pulmonary embolism (PE) is well documented (1–8). The most widely used scheme for interpretation of V/Q defects, devised by Biello and associates (9), classifies scans as normal, low, intermediate, and high probability based on specific radiographic criteria. Although the low probability scan is associated with arteriographic evidence of embolus in 4.8% to 7.7% of cases (5), it is extremely rare to obtain angiographic documentation of PE in a patient with a normal perfusion lung scan (1–8).