The HARP-MRI pulse sequence acquired multiframe harmonic phase images in real time over two heartbeats, yielding 2D myocardial strain measurements highly correlated (r=0.832) with conventional tagged MRI.
Effect estimate: r = 0.832
The harmonic phase (HARP) method provides automatic and rapid analysis of tagged magnetic resonance (MR) images for quantification and visualization of myocardial strain. In this article, the development and implementation of a pulse sequence that acquires HARP images in real time are described. In this pulse sequence, a CINE sequence of images with 1-1 spatial modulation of magnetization (SPAMM) tags are acquired during each cardiac cycle, alternating between vertical and horizontal tags in successive heartbeats. An incrementing train of imaging RF flip angles is used to compensate for the decay of the harmonic peaks due to both T(1) relaxation and the applied imaging pulses. The magnitude images displaying coarse anatomy are automatically reconstructed and displayed in real time after each heartbeat. HARP strain images are generated offline at a rate of four images per second; real-time processing should be possible with faster algorithms or computers. A comparison of myocardial contractility in non-breath-hold and breath-hold experiments in normal humans is presented.
Sampath et al. (Fri,) conducted a other in Healthy volunteers (n=6). HARP-MRI pulse sequence vs. Conventional 1-1 SPAMM tagged MRI was evaluated on Correlation of Lagrangian circumferential strain between breath-hold HARP-MRI and conventional tagging (r = 0.832). The HARP-MRI pulse sequence acquired multiframe harmonic phase images in real time over two heartbeats, yielding 2D myocardial strain measurements highly correlated (r=0.832) with conventional tagged MRI.