ACCURACY OF MR-ANGIOGRAPHY COMPARED WITH RADIONUCLIDE SCANNING IN IDENTIFYING THE CAUSE OF PULMONARY ARTERIAL-HYPERTENSION

OBJECTIVE, MR imaging has proven accurate in identifying patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, we kn ow of no attempt to distinguish patients with CTEPH from patients with other causes of pulmonary arterial hypertension (PAH). Primary pulmon ary hypertension (PPH) is the disease most frequently confused with CT EPH. We examined patients with CTEPH or PPH and control subjects to id entify MR imaging features that might distinguish CTEPH from PPH, to c ompare the accuracy of MR angiography (MRA) with that of radionuclide scanning, and to determine the cardiac and pulmonary vascular measurem ents in these groups. SUBJECTS AND METHODS. T1-weighted and two-dimens ional multiplanar spoiled gradient-recalled scans were obtained in 30 patients with CTEPH who had undergone conventional pulmonary angiograp hy, 10 patients with PPH, and 13 control subjects with no known vascul ar disease. Ventilation-perfusion scans were available in all patients with CTEPH and in six of the 10 patients with PPH. The MR scans were assessed independently by two radiologists who evaluated the appearanc e of segmental vessels and noted the presence of mosaic perfusion. Car diac chambers and pulmonary vessels were measured on T1-weighted spin- echo scans. RESULTS, The two radiologists used MR angiograms to reliab ly distinguish between patients with CTEPH and those with PPH. The acc uracy of MR angiograms matched that of ventilation-perfusion scans (92 %). On T1-weighted scans, the two radiologists used cardiac and pulmon ary vascular measurements to distinguish patients with PAH from contro l subjects but failed to distinguish between patients with CTEPH and t hese with PPH. CONCLUSION. MRA is useful in distinguishing patients wi th CTEPH from those with PPH. In this population, MRA had an accuracy that was identical to that of radionuclide scanning. Vascular and card iac measurements made on MR scans reliably identified patients with PA H but did not distinguish between patients with CTEPH and those with P PH.