Addition of the Long-Axis Information to Short-Axis Contours Reduces Interstudy Variability of Left-Ventricular Analysis in Cardiac Magnetic Resonance Studies

OBJECTIVES: To reduce interstudy variability using long-axis information for correcting short-axis (SA) contours at basal and apical level for left-ventricular analysis by magnetic resonance imaging. MATERIALS AND METHODS: A total of 20 patients with documented heart failure and 20 volunteers underwent magnetic resonance imaging examination twice for measuring endocardial end-diastolic volume, endocardial end-systolic volume, mass, and ejection fraction. The boundary of the left ventricle, the mitral valve plane, and apex were marked manually on the 2- and 4-chamber long-axis images. Automatic epicardial and endocardial contour detection was performed on the SA images using the intersection of the outlines from the long axis as starting positions. The same observer compared the interstudy variability of this method with analysis that was based on the SA images only. RESULTS: The interstudy variability decreased when information from the long axis was included; for end-systolic volume, 9.6% versus 4.7% (P = 0.00014); for end-diastolic volume, 4.9% versus 2.5% (P = 0.0011); for mass, 7.4% versus 5.0% (P = 0.11); and for ejection fraction 12.2% versus 5.6% (P = 0.0017), respectively. CONCLUSIONS: Identification of the mitral valve plane and apex on long-axis images to limit the extent of volume at the base and the apex of the heart reduces interstudy variability for left-ventricular functional assessment.