Background: Standard ventilation and perfusion (V̇/Q̇) scintigraphy uses planar images for the diagnosis of pulmonary embolism (PE). To evaluate whether tomographic imaging improves the diagnostic accuracy of the procedure, we compared noncontrast perfusion single-photon emission CT ( -SPECT)/CT scans with planar V̇/Q̇ scans in patients at high risk for PE. Methods: Between 2006 and 2010, most patients referred for diagnosis of PE underwent both -SPECT/CT scan and planar V̇/Q̇ scintigraphy. All scans were reviewed retrospectively by four observers; planar scans were read with modifi ed Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II and Prospective Investigative Study of Pulmonary Embolism Diagnosis (PISA-PED) criteria. On -SPECT/CT scan, any wedge-shaped peripheral perfusion defect occupying <50% of a segment without corresponding pulmonary parenchymal or pleural disease was considered to show PE. The fi nal diagnosis was established with a composite reference standard that included ECG, ultrasound of lower-extremity veins, D-dimer levels, CT pulmonary angiography (when available), and clinical follow-up for at least 3 months. Results: One hundred six patients with cancer and mean Wells score of 4.4 had suffi cient follow-up; 22 patients were given a fi nal diagnosis of PE, and 84 patients were given a fi nal diagnosis of no PE. According to PIOPED II, 13 studies were graded as intermediate probability. Sensitivity and specifi city for PE were 50% and 98%, respectively, based on PIOPED II criteria; 86% and 93%, respectively, based on PISA-PED criteria; and 91% and 94%, respectively, based on Q̇SPECT/CT scan. Seventy-six patients had additional relevant fi ndings on the CT image of the Q̇SPECT/CT scan. Conclusions: Noncontrast Q̇SPECT/CT imaging has a higher accuracy than planar V̇/Q̇ imaging based on PIOPED II criteria in patients with cancer and a high risk for PE.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Critical Care and Intensive Care Medicine
- Cardiology and Cardiovascular Medicine