Objective Analysis of Tomographic Ventilation–Perfusion Scintigraphy in Pulmonary Embolism

Rationale: Ventilation–perfusion scintigraphy is highly sensitive for pulmonary embolism (PE), but its clinical usefulness is limited by its nondiagnostic rate. Objective analysis of single photon emission computed tomography (SPECT) three-dimensional scintigraphy may improve its diagnostic performance compared with subjective interpretation.Objectives: To determine the diagnostic accuracy of objective SPECT analysis in PE.Methods: We determined the ventilation/perfusion (V/Q) relationship using SPECT scintigraphy in a retrospective cohort of 73 patients. Measures of V/Q heterogeneity (logSDQ, logSDV, logSDVQR), including a novel parameter, the weighted median V/Q value, were calculated. Using receiver operating characteristic (ROC) analysis, each parameter's diagnostic accuracy was determined. The weighted median V/Q value was then assessed prospectively in a second cohort of 50 patients.Measurements and Main Results: In cohort 1, all parameters of V/Q heterogeneity were higher in patients with...