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 p atients 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 perfusi on were scored on a three-point scale. RESULTS: In the five patients, 198 regions were identified. Of 176 abnormal regions at SPECT, 133 wer e abnormal at CT (sensitivity, 75.6%). Eleven of 22 regions interprete d as normal at SPECT were judged to have normal attenuation at CT (spe cificity, 50%). The overall accuracy of CT for detecting areas of hypo perfusion was 72.7% (P = .011). CONCLUSION: A mosaic pattern of lung a ttenuation at CT is a sign of variable regional perfusion and may sugg est chronic pulmonary thromboembolism as a cause for pulmonary hyperte nsion.