Free‐breathing cine MRI

Standard MRI cine exams for the study of cardiac function are segmented over several heartbeats and thus require a breath‐hold to minimize breathing motion artifacts, which is a current limitation of this approach. The purpose of this study was to develop a method for the measurement and correction of respiratory motion that is compatible with cine imaging. Real‐time images were used to measure the respiratory motion of heart, to allow translations, rotations, and shears to be measured and corrected in the k‐space domain prior to a final gated‐segmented reconstruction, using the same data for both purposes. A method for data rejection to address the effects of through‐plane motion and complex deformations is described (respiratory gating). A radial k‐space trajectory was used in this study to allow direct reconstruction of undersampled real‐time images, although the techniques presented are applicable with Cartesian k‐space trajectories. Corrected and uncorrected free‐breathing gated‐segmented images acquired over 18 sec were compared to the current standard breath‐hold Cartesian images using both quantitative sharpness profiles (mm−1) and clinical scoring (1 to 5 scale, 3: clinically acceptable). Free‐breathing, free‐breathing corrected, and breath‐hold images had average sharpness values of 0.23 ± 0.04, 0.38 ± 0.04, and 0.44 ± 0.04 mm−1 measured at the blood–endocardium interface, and clinical scores of 2.2 ± 0.5, 4.2 ± 0.4, and 4.7 ± 0.5, respectively. Magn Reson Med 60:709–717, 2008. © 2008 Wiley‐Liss, Inc.