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MR imaging provides a reliable means to study right atrial volumes and phasic function.

The present study suggests that gradient echo MR imaging is well applicable to RV volume and mass measurements. The best imaging plane for volumetric analysis seems to be the TA plane and there was no significant difference between breath-hold and conventional imaging. To assess RV mass, we recommend RVIT view; the TIR sequence quickly produced images of better quality compared to gradient echo images but no significant difference between masses was found and repeatability of analysis was equally good with both methods.

The present studies of human cardiac casts suggest that gradient echo MRI is well applicable to right ventricular volume measurements. Imaging the right ventricle in axial planes covering the entire heart gives good agreement with true right ventricular volumes and excellent analysis reproducibility. However, other imaging directions perform nearly as well, and thus selection of the imaging plane may not be of major importance to the accuracy of cardiac volume measurements with MR.

Purpose: To validate a volumetric biventricular segmentation solution for multiaxis cardiac magnetic resonance (CMR) images. Materials and Methods:The study population comprised 40 subjects. Biventricular end-diastolic and -systolic phases were segmented from both short-axis and horizontal long-axis or transaxial cine CMR images. Segmentation was based on fitting nonrigidly a 3D surface model to multiaxis CMR images. Five segmentations were performed: two manual segmentations by experts, automatic segmentation, and two segmentations where a user was allowed to correct errors in the automatic segmentation for 2 minutes and without time limits. Volumetry, distance measures, and visual grading were used to evaluate the quality of the segmentation. Results:No difference was observed between automatic and manual segmentations in volumetric measures of the ventricles. The manual segmentation performed better for left-ventricular myocardial volume. The distance between surfaces as well as visual analysis did not show differences between automatic and manual segmentation for the endocardial border of the left ventricle but some corrections are needed for the right ventricle. CINE CARDIOVASCULAR MAGNETIC RESONANCE (CMR) imaging is an accurate and reproducible tool for assessment of cardiac chamber volumes, ventricular mass, and volumetric function. These measurements are valuable in diagnostics and follow-up of congenital and acquired myocardial and valvular diseases. ConclusionThe ventricular chambers are usually imaged with a contiguous stack of short-axis images from apex to base. The image analysis is done by manually delineating the left ventricular epicardial and endocardial borders in each section at end-diastole (ED) and end-systole (ES), and by summing up the individual volumes to give the left ventricular muscle volume, and ED and ES ventricular volumes. These volumes are used in calculating the stroke volume, ejection fraction, and muscle mass. The right ventricular volumes are assessed similarly. The interanalyst reproducibility of these measurements has been 4%-8% for the left ventricle (LV) (1,2) and 6%-17% (3) for the right ventricle (RV). The intraobserver repeatability has been 3%-6% (1,4) for the left and 4%-7% (3) for the right ventricular volumes. Usually the true apex is not included in the analysis and the left ventricular base is also sometimes omitted due to difficulties in the determination of the atrioventricular border. By these omissions the speed of analysis and the reproducibility improve, but the volumes are underestimated.The clinical use of volumetric analysis has been limited by the analysis time it requires. Even using only the ED and ES phases of the left ventricle, segmentation may take 30 minutes or more. A relatively short segmentation time of 13 minutes was recently reported for one commercial software tool (5). How-