The value of the computed tomographic obstruction index in the identification of massive pulmonary thromboembolism.

PURPOSE In this study, the pulmonary arterial computed tomography obstruction index ratio, which indicates the degree and extent of thrombotic arterial occlusion, was calculated in cases with pulmonary thromboembolism. Our objectives were to investigate the value of this index for the identification of cases with massive pulmonary thromboembolism and to search for correlations between this index and clinical parameters. MATERIALS AND METHODS Data from 68 patients were evaluated retrospectively. For the clinical evaluation, the Wells scoring system was used. Pulmonary computed tomographic angiography examinations were acquired using an eight-channel multidetector computed tomography. The presence of arterial filling defects was recorded, and the clot burden was quantified based on the degree and extent of thrombotic arterial occlusion. RESULTS According to the Wells scoring system, the patients were assigned to low (n = 14), moderate (n = 34), and high clinical (n = 20) possibility groups, and the difference among the mean pulmonary arterial computed tomography obstruction index ratios of the three groups was significant (P = 0.001). A positive correlation was observed between the pulmonary arterial computed tomography obstruction index ratio and the Wells score (r = 0.470, P < 0.001). The pulmonary arterial computed tomography obstruction index ratio cut-off point was determined to be 40% for the discrimination of massive and nonmassive cases (sensitivity, 72.7%; specificity, 91.4%). CONCLUSION We found that in cases where the pulmonary arterial computed tomography obstruction index ratio was above 40%, a diagnosis of massive pulmonary thromboembolism was demonstrated. Furthermore, a positive correlation between the obstruction index and the Wells score suggested the use of a clinical evaluation as a means of developing a recommendation regarding the thrombotic load.