IN-VITRO VERIFICATION OF MYOCARDIAL MOTION TRACKING FROM PHASE-CONTRAST VELOCITY DATA

The ability to track motion from cine phase contrast (PC) magnetic res onance (MR) velocity measurements was investigated using an in vitro m odel. A computer-controlled deformable phantom was used for the charac terization of the accuracy and precision of the forward-backward and t he compensated Fourier integration techniques. Trajectory accuracy is limited by temporal resolution when the forward-backward technique is used. With this technique the extent of the calculated trajectories is underestimated by an amount related to the motion period and the sequ ence repetition time, because of the band-limiting caused in the cine interpolation step. When the compensated Fourier integration technique is used, trajectory accuracy is independent of temporal resolution an d is better than 1 mm for excursions of less than 15 mm, which are com parable to those observed in the myocardium. Measurement precision is dominated by the artifact level in the phase-contrast images. If no ar tifacts are present precision is limited by the inherent signal-to-noi se ratio of the images. In the presence of artifacts, similar in magni tude to those observed in vivo, the reproducibility of tracking a 2.2 x 2.2 mm(2) region of interest is better than 0.5 mm, When the Fourier integration technique is used, the improved accuracy is accompanied b y a reduction in precision. We verified that tracking three-dimensiona l (3D) motion from velocity measurements of a single slice can lead to underestimations of the trajectory if there is a through-plane compon ent of the motion that is not truly represented by the measured veloci ties. This underestimation can be overcome if volumetric cine phase co ntrast velocity data are acquired and full three-dimensional analysis is performed. (C) 1998 Elsevier Science Inc.