Diagnostic Accuracy of V/Q and Q SPECT/CT in Patients with Suspected Acute 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). The 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. The PROSPERO registration number is CRD42021276538.

Results:  Eight studies, for a total of 1,086 patients, were included. The risk of bias of all included studies was high. The weighted mean prevalence of PE was 27.1% at the random-effects model. The 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.

Conclusion:  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.