Detection of pulmonary embolism on CT-angiography using contrast attenuation of pulmonary veins

Introduction: In areas of pulmonary embolism (PE), the enhancement of pulmonary veins on computed tomography pulmonary angiography (CTPA) should be decreased due to reduced arterial perfusion. The purpose of this study was to investigate the accuracy of contrast density measurements (differences) in all pulmonary veins and the left atrium for the prediction of PE. Material and methods: Seventy-five patients with PE and 22 patients without PE on CTPA were included. Four readers measured the enhancement of the blood in the pulmonary vein immediately before the entrance to the left atrium, right after the aperture, in the center of the left atrium, in the pulmonary trunk and in the aorta. Enhancement of the pulmonary veins with and without upstream PE, and ROC curves with HU thresholds for optimal sensitivity and specificity for PE were calculated. Results: More PEs were found in the right and lower lobes. PE-affected lobes demonstrated 13.8 +/- 45 HU less enhancement in the pulmonary vein, compared to a paired non-affected pulmonary vein of the same patient (P < 0.0001). On average, non-affected pulmonary veins demonstrated no difference in enhancement compared to each other: 0.2 +/- 21 HU. The optimal cutoff level in the ROC curve analysis for PE affection proved to be decreasing enhancement in the pulmonary vein of more than 10 HU compared to the atrium. Conclusion: Decreasing enhancement in the pulmonary vein of more than 10 HU compared to the atrium could provide additional information and confidence in the diagnosis of PE.