Estimation of left ventricular volume and mass by magnetic resonance imaging: comparison with quantitative biplane angiocardiography.

Magnetic resonance imaging (MRI) is well suited for the delineation of cardiac anatomy. In this study an estimation of left ventricular volume and muscle mass by MRI was attempted, using an iron-shielded resistance magnet (Bruker) with 0.23 T. Images were obtained with ECG gating. For image-processing our own software program was used. Slice images were 8 mm thick and spaced 16 mm. Volumes were standardized for a "normal" LV. Muscle mass was calculated directly from the systolic image as the difference between inner and outer ventricular outline. There was a wide range of volumes and mass (100-300 ml, 200-500 g). For comparison and validation conventional biplane left ventriculography was used. Fourteen patients were studied with MRI, but satisfactory studies were obtained in only 7. Correlation of MRI and angiographic volumes was good (r = 0.84). For left ventricular mass it was excellent (r = 0.94). Ventricular walls and cavities were clearly outlined. Even minor details of anatomy were recognized. Limitations of MR study included a narrow space for the patient within the system and the long duration of data acquisition time.