Critical review of SPECT imaging in pulmonary embolism

Outcome studies have shown that pulmonary embolism can be safely excluded in patients with negative ventilation/perfusion (V/Q) single-photon emission computed tomography (SPECT). The effective radiation dose of V/Q SPECT is much less than with computed tomographic (CT) pulmonary angiography, which would make it preferable to CT angiography in many young female patients. The accuracy of V/Q SPECT, however, is difficult to assess, because most published investigations are limited by incorporation bias or partial verification bias, as well as other limitations in study design and reporting. Consequently, the accuracy of V/Q SPECT relative to planar V/Q scintigraphy or CT angiography has not been definitively determined. There is need for a prospective investigation of the accuracy of V/Q SPECT with consecutive patients, blinded interpretations, and an independent reference standard, or independent composite reference standard.