Mitral stenosis: evaluation with MR imaging after percutaneous balloon valvuloplasty. To evaluate the pathoanatomic findings of mitral valve stenosis and changes after percutaneous balloon valvuloplasty (PBV), magnetic resonance (MR) imaging was performed in 23 patients. The patients were imaged with a 2.0-T system within 1 week before and 3-10 days after PBV. The angle of the interatrial septum was measured on the transverse image to facilitate a successful transseptal puncture. On MR images, the mean transverse and anteroposterior diameters of the left atrium at the level of the aortic root in the ventricular diastolic phase decreased significantly after PBV. Areas of flow-related intraluminal signal intensity detected in the left atrial cavity of 17 patients (74%) before the procedure disappeared in 15 patients after the procedure. Other MR imaging findings after PBV were the disappearance of intraluminal signal intensity in the pulmonary artery, normal curvature of the interatrial and interventricular septa, and pericardial effusion as a complication. MR imaging was thought to provide useful information before and after PBV in patients with mitral stenosis. 