MR GRADIENT-ECHO VOLUMETRIC-ANALYSIS OF HUMAN CARDIAC CASTS - FOCUS ON THE RIGHT VENTRICLE

Purpose: Our goal was to assess the utility of different imaging direc tions in volumetric studies of the heart with MRI, in particular to id entify the optimal imaging plane for studies of the right ventricle. M ethod: We examined 12 sets of human four-chamber cadaveric cardiac cas ts. Gradient echo MRI was performed in four imaging planes: (a) perpen dicular to the right ventricular inflow tract; (b) perpendicular to th e right ventricular outflow tract; (c) in the left ventricular short a xis view; and (d) in the axial view. The Volumes of the right ventricl e and other cardiac cavities were determined with the method of discs. The true cast volumes were measured with the water displacement techn ique. The agreement between true and measured volumes and the repeatab ility of image analysis were determined using the Bland-Altman method. Results: There were no statistically significant differences between the measured and true right ventricular volumes irrespective of the im aging plane. The axial plane gave the smallest mean absolute differenc e from the true right ventricular volume (3.2 +/- 2.2 mi) and also the best repeatability of volume analysis (0.2 +/- 1.6 mi). However, the other imaging planes performed nearly as well, and the differences acr oss the planes were not statistically significant (p > 0.05). Also, in studies of the left ventricle and left and right atrium, the axial vi ew appeared to give the best results, but differences across the imagi ng planes remained small. Conclusion: The present studies of human car diac casts suggest that gradient echo MRT is well applicable to right ventricular volume measurements. Imaging the right ventricle in axial planes covering the entire heart gives good agreement with hue right v entricular volumes and excellent analysis reproducibility. However, ot her imaging directions perform nearly as well, and thus selection of t he imaging plane may not be of major importance to the accuracy of car diac volume measurements with MR.