Pulmonary embolism: imaging modalities--V/Q scan, spiral (helical) CT, and MRI.

Ventilation-perfusion (V/Q) imaging has been used as the screening test for pulmonary embolism (PE) for many years with diagnostic algorithms developed as a result of the Prospective Investigation of Pulmonary Embolism Diagnosis study. The primary conclusions were that high probability V/Q scans were reliable indicators for PE and normal or near-normal scans were reliable in the exclusion of PE. With the increasing availability of spiral (helical) computed tomography (CT) and many studies showing a high degree of accuracy for PE, there is much support for the replacement of V/Q by spiral CT. This article reviews the literature concerning V/Q scanning, spiral (helical) CT, and the future potential for magnetic resonance in the diagnosis of PE.