CHRONIC PULMONARY THROMBOEMBOLISM - DETECTION OF REGIONAL HYPOPERFUSION WITH CT

PURPOSE: To study the relationship of regional hypoperfusion and areas of decreased lung attenuation on computed tomographic (CT) scans of patients with chronic pulmonary thromboembolism. MATERIALS AND METHODS: Preoperative CT scans of five patients (four men and one woman, aged 29-72 years) with chronic pulmonary thromboembolism were reviewed and compared with axial single photon emission CT (SPECT) perfusion scans obtained at similar levels. Regions of varying attenuation and perfusion were scored on a three-point scale. RESULTS: In the five patients, 198 regions were identified. Of 176 abnormal regions at SPECT, 133 were abnormal at CT (sensitivity, 75.6%). Eleven of 22 regions interpreted as normal at SPECT were judged to have normal attenuation at CT (specificity, 50%). The overall accuracy of CT for detecting areas of hypoperfusion was 72.7% (P = .011). CONCLUSION: A mosaic pattern of lung attenuation at CT is a sign of variable regional perfusion and may suggest chronic pulmonary thromboembolism as a cause for pulmonary hypertension.