Lung Perfusion Assessment in Pulmonary Embolism: Novel Semi-Automatic Lung Perfusion Software in Computed Tomography Pulmonary Angiography Compared to Traditional Lung Perfusion Scintigraphy

Purpose: To compare the diagnostic performance of lung perfusion colormaps derived from computed tomography pulmonary angiography (cmCTPA) by novel semi-automatic post-processing software, with lung perfusion scintigraphy (LPS), for detection of lung perfusion defects (LPDs) in pulmonary embolism (PE). Patients and Methods: Consecutive patients from January 2016 to April 2020 who underwent both computed tomography pulmonary angiography (CTPA) and LPS within 7 days of each other, to rule out PE, were retrospectively enrolled. cmCTPA images were obtained from CTPA images using semi-automatic post-processing software (Pulmonary Artery Analysis, Intellispace Portal Release 11, Philips). The diagnosis of LPD was assessed on LPS images by two nuclear medicine physicians in consensus; CTPA and cmCTPA images were evaluated by two radiologists in consensus, blind to the LPS results. The spatial location of the LPD was assessed according to Boyden’s nomenclature. Agreement between LPS and cmCTPA in the diagnosis of LPD was tested using Cohen’s kappa. Results: Fifty-three patients were enrolled. The sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of cmCTPA were, respectively, 100%, 40%, 73%, and 100%; disease prevalence was 67%, accuracy was 77%, and positive and negative likelihood ratios were 1.67 and 0, respectively. An almost perfect agreement was found between cmCPTA and LPS in 13 segments (72%) and a substantial agreement was found in the remaining five segments (28%). Conclusion: cmCTPA, owing to its NPV (100%) and its overall high agreement in the number and location of LPDs compared to LPS, may have an upcoming role in the evaluation of lung perfusion in PE.