Thrombus volume and Hounsfield unit density as a predictor of pulmonary embolism in patients with deep vein thrombosis

Background There is a lack of studies evaluating the association between thrombus volume and density of deep vein thrombosis (DVT) and pulmonary embolism (PE). Purpose To assess the clinical value of thrombus volume and density for prediction of PE in patients with DVT. Material and Methods Among the patients with DVT, those without PE were classified as the “DVT-only group” and those with PE were classified as the “DVT-PE group.” Thrombus volume and Hounsfield unit (HU) density of DVT was measured by drawing free-hand volume of interests within the thrombus. Multivariate regression and receiver operating characteristic (ROC) analysis was used to evaluate the predictive value of thrombus volume and density for PE. Results Of the included 145 patients (mean age=41.7 ± 10.3 years), there were 87 patients in the DVT-only group and 58 patients in the DVT-PE group. The DVT-PE group showed a significantly higher DVT density (67.4 ± 8.6 HU vs. 57.3 ± 10.4 HU; P < 0.001) and larger DVT volume (16.4 ± 13.9 cm 3 vs. 12.8 ± 10.1 cm 3 ; P = 0.016) than the DVT-only group. On multivariate analysis, thrombus density was the only associated factor for PE. ROC analysis showed that thrombus density ≥61.8 HU was the optimal cutoff for predicting PE with an area under the curve (AUC) of 0.774 and thrombus volume ≥14.0 cm 3 was the cutoff with an AUC of 0.638. Conclusion Though the results of our study should be considered within the limitations, DVT density could be a predictor for acute PE. Further studies are needed to clarify the clinical value of quantitative features of DVT including thrombus volume as an imaging biomarker for PE.