DETECTION AND QUANTIFICATION OF PULMONARY-ARTERY HYPERTENSION WITH MR-IMAGING - RESULTS IN 23 PATIENTS

OBJECTIVE. A study was performed to determine the value of MR imaging in detecting pulmonary artery hypertension and in determining pulmonary artery pressure semiquantitatively. SUBJECTS AND METHODS. MR studies were performed in 23 patients with pulmonary artery hypertension to measure right ventricular function (right ventricular ejection fraction, end-diastolic and end-systolic volumes, stroke volume), right ventricular wall thickness, and the diameters of the great vessels. The findings were compared with similar MR measurements made in eight control subjects. The cause of the pulmonary hypertension was primary pulmonary hypertension (eight patients), combined mitral valve disease (five patients), dilative cardiomyopathy (four patients), chronic pulmonary embolism (four patients), atrial septal defect (one patient), and pulmonary fibrosis (one patient). MR studies were done on a 0.5-T magnet using a double-angulation projection (equivalent to a four-chamber view) with a multislice-multiphase spin-echo technique and a blood flow-sensitive fast gradient-echo sequence. Pulmonary artery pressures were verified by catheterization of the pulmonary artery. RESULTS. In patients with pulmonary artery hypertension, MR imaging showed right ventricular enlargement with hypertrophy, right atrial enlargement, and abnormal septal motion. Fast gradient-echo images showed tricuspid regurgitation in all cases. In cases in which the mean pressures in the pulmonary artery were greater than 70 mm Hg, systolic slow-flow phenomena were detected. Linear correlations were seen between the mean pressure in the pulmonary artery and the end-diastolic thickness of the right ventricular wall (r = .83, p less-than-or-equal-to .0001), the diameter of the inferior vena cava (r .73, p less-than-or-equal-to .0001), and the diameter of the main pulmonary artery (r =.48, p less-than-or-equal-to .02). CONCLUSION. Our results show that MR imaging is a useful noninvasive technique for the detection of pulmonary artery hypertension and for the semiquantitative assessment of pulmonary artery pressure.