Radiologic approach using Hounsfield unit to access the pulmonary embolism associated with proximal lower extremity deep vein thrombosis

Abstract

Purpose: Proximal lower extremity deep vein thrombosis (pLE-DVT) is a well known condition that can worsen the clinical course of patients with pulmonary embolism (PE). The purpose of this study was to evaluate the feasibility of using Hounsfield units (HFU) for predicting the risk of concurrent PE associated with pLE-DVT.

Methods: PE was evaluated using pulmonary artery CT angiography and lower extremity CT venography to confirm patients with pLE-DVT. The patients were classified into group A (pLE-DVT without PE) and group B (pLE-DVT with PE), and analyzed to clarify clinical risk factors, including HFU ratio, associated with PE in patients with pLE-DVT. Statistical analyses utilized the multivariable logistic regression model, and receiver operating characteristic (ROC) curve analysis.

Results: We examined 81 patients (age; 59.8 ± 16.9 years, 61.7% male) with pLE-DVT with and without PE. The prevalence of concurrent PE with pLE-DVT was 64.2%. The demographics and clinical characteristics showed no difference between the two groups. Of all the findings, the percentage of neutrophils was negatively associated with PE (neutrophil, p=0.006), and was a condition associated with suspected PE in Wells’ score. The HFU ratios were significantly and independently associated with PE (Wells’ score, p=0.001; HFU ratio, p=0.003). ROC curve analysis showed that the cut-off value using HFU ratio was 45.5.

Conclusion: HFU ratio can be used as a clinical tool to consider the possibility of PE associated with pLE-DVT.