A phantom validation of the FastHARP pulse sequence

The FastHARP magnetic resonance imaging pulse sequence, coupled with fast processing, has the potential to measure and display cardiac function in real-time during clinical dobutamine stress tests. In this paper, we present a preliminary validation of the tracking capability of material points using this imaging sequence. Points lying on a mesh embedded in a moving gel phantom are tracked manually using high-resolution images and are simultaneously tracked using HARP tools. The experiment proves that for this particular type of motion actuation, the points tracked in images using the FastHARP sequence followed by fast and automated HARP tracking tools are comparable to results obtained from images acquired in much longer times with very tedious analysis involving manual intervention.

1. INTRODUCTION

The ability to instantaneously detect the onset of an ischemic event is crucial to patient safety during cardiac exams. Tagged MRI [1] is a noninvasive imaging technique that provides reliable quantification and visualization of cardiac motion and deformation. However, a lengthy acquisition time followed by the need for tedious image analysis has hampered this technique's clinical applicability. The harmonic phase (HARP) imaging method [2], provides an efficient fast imaging solution and automatic post-processing methods for motion tracking and strain analysis. HARP uses the fact that the phase of the image corresponding to a (non-dc) spectral peak is directly related to the tissue motion. It is current practice to acquire a high-resolution tagged image (usually higher SPAMM) and then to use a bandpass filter to extract the desired spectral peak for HARP post-processing.