Cine MR imaging: potential for the evaluation of cardiovascular function

Abstract

MR imaging is valuable in defining cardiac anatomy in a variety of cardiac abnormalities. However, evaluation of cardiac function by this technique has been limited by long imaging times and low temporal resolution. New, recently described pulse sequences shorten imaging time considerably and improve temporal resolution. This paper reports our early experience with cine MR imaging of the heart, a technique of gradient-recalled acquisition in the steady state (GRASS) that uses low flip angles and gradient-recalled echoes. Images were obtained in 36 subjects (14 normal volunteers and 22 patients with coronary artery or valvular heart disease) and displayed in a cinegraphic mode for assessment of cardiac function. The acquisition of 10 to 12 levels, covering the whole heart with up to 24 time frames per level, required a maximum imaging time of only 30 min. Because systole and diastole were readily identified, and the contrast between blood and surrounding structures was excellent, systolic wall thickening, wall motion, and motion of the cardiac valves were visualized easily. Regions of myocardial infarcts were clearly visible and characterized by lack of systolic wall thickening and/or diastolic wall thinning. Turbulence caused signal loss within the flowing blood, which usually had higher signal intensity than myocardium. Therefore, turbulent blood flow in valvular regurgitation and in valvular and subvalvular stenosis could be detected. Cine MR imaging is a promising new technique for the evaluation of myocardial and valvular function.