Detection of Deep Vein Thrombosis by Follow-up Indirect Computed Tomography Venography after Pulmonary Embolism

BACKGROUND Information regarding the incidence and risk factors for deep vein thrombosis (DVT) detected by follow-up computed tomographic (CT) venography after pulmonary embolism (PE) is sparse. The aim of the present study was to identify the predictors of DVT in follow-up CT images, and to elucidate their clinical significance. METHODS Patients with PE were classified into the following three cohorts based on the time of indirect CT venography follow-up: within 1 month, 1 to 3 months, and 3 to 9 months after the initial CT scan. Each cohort was subdivided into patients with or without DVT detected by follow-up CT. Clinical variables were compared between the two groups. RESULTS Follow-up CT revealed DVT in 61% of patients with PE within 1 month, in 15% of patients with PE at 1 to 3 months, and in 9% of patients with PE at 3 to 9 months after the initial CT scan. Right ventricular (RV) dilation on the initial CT (odds ratio [OR], 8.30; 95% confidence interval [CI], 1.89-36.40; p=0.005) and proximal DVT at the initial presentation (OR, 6.93; 95% CI, 1.90-25.20; p=0.003) were found to independently predict DVT in follow-up CT images within 1 month, proximal DVT at the initial presentation was found to independently predict DVT in follow-up CT images at 1 to 3 months (OR, 6.69; 95% CI, 1.53-29.23; p=0.012), and central PE was found to independently predict DVT in follow-up CT images at 3 to 9 months (OR, 4.25; 95% CI, 1.22-4.83; p=0.023) after the initial CT scan. Furthermore, the detection of DVT by follow-up CT independently predicted the recurrence of venous thromboembolism (VTE) (OR, 4.67; 95% CI, 2.24-9.74; p<0.001). CONCLUSION Three months after PE, DVT was not detected by follow-up CT in most patients with PE. RV dilation on the initial CT, central PE, and proximal DVT at the initial presentation were found to predict DVT on follow-up CT, which might predict VTE recurrence.