Distinguishing Chronic Thromboembolic Pulmonary Hypertension From Other Causes of Pulmonary Hypertension Using CT

OBJECTIVE. The purpose of this study was to discern imaging findings that separate chronic thromboembolic pulmonary hypertension (CTEPH) from other causes of pulmonary hypertension (PH). MATERIALS AND METHODS. A total of 143 patients with proven PH (group 1, pulmonary arterial hypertension; group 2, PH due to left heart disease; group 3, PH due to lung disease; group 4, CTEPH; and group 5, PH due to unclear or multifactorial mechanisms) underwent MDCT angiography. The CT images were assessed for the presence of chronic pulmonary embolism (PE), disparity in segmental vessel size, mosaic perfusion, parenchymal densities, bronchial dilatation, and collateral arteries. RESULTS. The frequencies of vascular signs of chronic PE, disparity in segmental vessel size, mosaic perfusion, parenchymal densities, bronchial collateral arteries, and bronchial dilatation were statistically significantly higher in patients with CTEPH than in patients with nonthromboembolic PH. Vascular signs of chronic PE, mosaic perfusion, parenchymal densities, and bronchial dilatation without bronchial wall thickening were significantly more frequent in patients with CTEPH than in patients in groups 1, 2, 3, and 5. There was no significant difference in the frequencies of bronchial collateral arteries between patients with CTEPH and patients in groups 3 and 5. CONCLUSION. Most patients with CTEPH have direct vascular signs of chronic PE. Secondary signs include disparity in segmental vessel size, mosaic perfusion pattern, parenchymal densities, collateral bronchial arteries, and bronchial dilatation, which help distinguish CTEPH from other causes of PH.