Chronic thromboembolism: Diagnosis with helical CT and MR imaging with angiographic and surgical correlation

PURPOSE: To evaluate the accuracy of identification of central and segmental chronic thromboembolic disease on helical computed tomographic (CT) scans and on magnetic resonance (MR) images. MATERIALS AND METHODS: Radiologic findings in 55 patients suspected of having chronic thromboembolic pulmonary hypertension were analyzed; these included findings from angiography (n = 55), helical CT (n = 47), and MR imaging (n = 26). Forty patients underwent thromboendarterectomy. CT and MR images were independently interpreted by two readers for the presence of thromboembolic material in central and segmental vessels. Surgical findings and angiographic findings were the reference standards for disease in central and segmental vessels,respectively. RESULTS: Central vessel disease was determined more accurately with helical CT scans (accuracy of 0.79 for each of the two readers) than with angiograms (accuracy of 0.74) or with MR images (accuracy of 0.39 and 0.46 for two readers). Segmental vessel disease was also more accurately determined with CT scans (accuracy of 0.75 and 0.76 for two readers) than with MR images (accuracy of 0.61 and 0.57 for two readers). CONCLUSION: Helical CT is a useful alternative to conventional angiography for diagnosis of chronic thromboembolism but may not be sufficient for selecting candidates for surgery in all cases.