M-MODE MAGNETIC-RESONANCE-IMAGING - A NEW MODALITY FOR ASSESSING CARDIAC-FUNCTION

Magnetic resonance imaging (MRI) studies of the heart have been used f or some years, but there are few tools available to quantify cardiac m otion. A method has been developed that creates an M-mode MRI image, a nalogous to the one used in echocardiography, to display motion along a line as a function of time. The M-mode image is created from MRI ima ges acquired with an ordinary gradient echo cine sequence. In a cinema tographic display of the images, a cursor line can be positioned in or der to determine the orientation of the measurement. A resampling algo rithm then calculates the appearance of the M-mode image along the cur sor line. The MRI method has been compared to echocardiographic M-mode in a phantom study and by measuring mitral and tricuspid annulus moti on in 20 normal subjects. The phantom study showed no significant diff erences between MRI and echocardiographic M-mode measurements (differe nce < 1 mm). The annulus motion exhibits a similar pattern using both methods and the measured amplitudes are in close agreement. M-mode MRI provides similar information to echocardiography, but the cursor line can be placed arbitrarily within the image plane and the method is th us not limited to certain acoustic windows. This makes M-mode MRI a pr omising technique fdr assessing cardiac motion.