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 cm³ vs. 12.8 ± 10.1 cm³; 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 cm³ 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.