Cardiac output by MR imaging: an experimental study comparing right ventricle and left ventricle with thermodilution

Cardiac output was measured by gated magnetic resonance imaging (MRI) and by thermodilution in four mongrel dogs. The entire heart was examined in contiguous slices at end-diastole and end-systole in a plane parallel to the interventricular septum. Each set of images was analyzed for chamber volume using a custom computer program to evaluate each pixel. No geometric assumptions were made. Cardiac output was calculated for right and left ventricles and compared with the thermodilution data. We found that the cardiac output of the right ventricle compared well with that of the left ventricle and that both fell within the range measured by thermodilution. Cardiac-gated MRI has the potential to assess the cardiac output of both the right and left ventricles. Comparison between right ventricular and left ventricular function will permit quantification of left to right shunting or unilateral ventricular volume overload.