Diagnostic accuracy of V/Q and Q SPECT/CT in patients with suspected pulmonary embolism: a systematic review and meta-analysis

Background: Computed tomography (CT) pulmonary angiography has simplified the diagnostic approach to patients with clinically suspected acute pulmonary embolism (PE), but alternative imaging tests are still advocated. We aimed to systematically assess the diagnostic accuracy of ventilation/perfusion (V/Q) and Q single-photon emission CT combined with low-dose CT (SPECT/CT) for PE diagnosis. Methods: Studies evaluating the diagnostic accuracy of SPECT/CT for the diagnosis of acute PE were systematically searched in MEDLINE and EMBASE databases (up to August 2022). QUADAS-2 tool was used for risk of bias assessment of the primary studies. A bivariate random-effects regression approach was used for summary estimates of both sensitivity and specificity. PROSPERO registration number is CRD42021276538 Results: Eight studies, for a total of 1086 patients, were included. The risk of bias of all included studies was high. Weighted mean prevalence of PE was 27.1% at random-effect model. SPECT/CT bivariate weighted mean sensitivity was 96% (95% confidence interval [CI], 93-98%), with a bivariate weighted mean specificity of 95% (95% CI, 90-97%). At subgroup analysis, for V/Q SPECT/CT bivariate weighted mean sensitivity and specificity were 96% (95% CI, 89-98%) and 96% (95% CI, 91-99%), while for Q SPECT/CT they were 96% (95% CI, 92-98%) and 84% (95% CI, 66-93%), respectively. Conclusions: V/Q SPECT/CT has high sensitivity and specificity for the diagnosis of acute PE, meanwhile Q SPECT/CT has high sensitivity but limited specificity for the diagnosis of PE. Management studies will conclusively ascertain the actual role of SPECT/CT in the diagnostic workup of patients with suspected acute PE.