Cardiac motion tracking using CINE harmonic phase (HARP) magnetic resonance imaging

This article introduces a new image processing technique for rapid analysts of tagged cardiac magnetic resonance image sequences. The method uses isol ated spectral peaks in SPAMM-tagged magnetic resonance images, which contai n information about cardiac motion. The inverse Fourier transform of a spec tral peak is a complex image whose calculated angle is called a harmonic ph ase (HARP) image. It is shown how two HARP image sequences can he used to a utomatically and accurately track material points through time. A rapid, se miautomated procedure to calculate circumferential and radial Lagrangian st rain from tracked points is described. This new computational approach perm its rapid analysis and visualization of myocardial strain within 5-10 min a fter the scan is complete. Its performance is demonstrated on MR image sequ ences reflecting both normal and abnormal cardiac motion. Results from the new method are shown to compare very well with a previously validated track ing algorithm. (C) 1999 Wiley-Liss, Inc.