Acquired Whole-lung Mismatched Perfusion Defects on Pulmonary Ventilation/Perfusion Scintigraphy.

Despite the increasing use of computed tomography pulmonary angiography to evaluate for pulmonary embolism (PE), ventilation/perfusion (V/Q) scintigraphy is still a fairly common examination. A rare finding on V/Q scintigraphy is whole-lung mismatched perfusion defect. Although this finding can occur with PE, it has an important, limited differential diagnosis. In this pictorial essay, we describe different causes of acquired whole-lung mismatched perfusion defect.