Clinical risk stratification of acute pulmonary embolism: comparing the usefulness of CTA obstruction score and pulmonary perfusion defect score with dual-energy CT

To compare the ability of CT angiography (CTA) obstruction score and perfusion defect score on dual energy CT perfusion imaging (DEPI) for clinical risk stratification of patients with acute pulmonary embolism (PE). 55 patients diagnosed as acute PE either by CTA or DEPI were retrospectively enrolled. Patients were grouped into high-, intermediate-, and low-risk groups in accordance to the renewed guidelines of 2014. Consistency between DEPI and CTA in diagnosis of PE were assessed. Correlations between CT parameters and right-to-left ventricular (RV/LV) diameter ratio were evaluated. Difference of CTA obstruction score and perfusion defect score across three groups with different risks were analyzed. The consistent rate of DEPI with CTA was 75.4%, and the Kappa value was 0.412 (p = 0.000). 44.3% of partially obstructive PE showed on CTA did not lead to perfusion defect on DEPI. Perfusion defect score was significantly correlated with CTA obstruction score and with RV/LV (r = 0.622 and 0.599, respectively, p < 0.001), and CTA obstruction score had lower correlation with RV/LV (r = 0.403, p = 0.003). Perfusion defect score could distinguish low- from intermediate-risk groups (p = 0.011). However, CTA obstruction score could not distinguish the two groups (p = 0.149). DEPI had fine consistency with CTA to diagnose acute PE and offered additional information of physiologic changes. Comparing with CTA obstruction score, perfusion defect score could better correlate with right ventricular dysfunction, and could be a more promising biomarker for clinical risk stratification.