Severity Assessment Of Acute Pulmonary Embolism With Multi-slice CT Angiography

ObjectiveTo analyze the correlation factors between CT imaging features of pulmonary embolism (PE)and clinical severity stratification, and to explore the value of mufti-slice spiral CT pulmonary angiography in estimating the severity of acute pulmonary embolism.Materials and methodsFrom May 2005 to May 2007, 52 patients of acute pulmonary embolism underwent multi-slice CT pulmonary angiography. According to the clinical severity,52 patients with acute PE proved by CTPA were classified into two groups. including 29 critical and 23 non-critical patients. Embolism index, ratio of central pulmonary involvement, right ventricle maximum minor axis(RVMMA), left ventricle maximum minor axis(LVMMA)and ratio of RVMMA to LVMMA, namely RV:LV , interventricular septum displacement (rectilinear or convex toward LV) were analyzed comparatively. The correlation factors between CT imaging features and PE clinical severity stratification were explored. The correlation between RV:LV and embolism index of 52 patients was analyzed.Resultsarameters that showed significant difference between critical group and non-critical group were: embolism index (50.69%,24.26%, P=0.024),ratio of central pulmonary involvement (43.86% , 20.83% , P=0.015) , RVMMA (5.01cm ,3.69cm ,P=0.001), LVMMA(3.54cm , 4.11cm, P=0.036),RV: LV ratio (1.58,0.85, P=0.002), the proportion of interventricular septumdisplacement (72.40% [21/29], 17.42% [4/23] ,P=0.017). There was remarkable correlation between RV:LV and embolism index(r=0.64,P<0.05). The threshold value of CT obstruction for critical group is 48%(sensitivity: 69% ,specificity: 74%). kappa coefficient: 0.794.ConclusionMulti-slice spiral CT pulmonary angiography not only can be used to diagnose acute PE, but to evaluate the severity of PE. The higher the embolism index, RV: LV, and the ratio of central pulmonary involvement,the higher probability of serious hemodynamic changes in PE patients. The interventricular septum convexed toward LV are indicators for severe acute PE.