Harmonic phase versus sine-wave modulation for measuring regional heart function from tagged MRI images

Magnetic resonance imaging (MRI) tagging is a valuable technique for evaluating regional heart function. Currently, there are a number of different techniques for analyzing the tagged images. The purpose of this study is to compare the harmonic-phase (HARP) and sine-wave modeling (SinMod) tagging analysis techniques for evaluating myocardial strain and torsion in healthy controls and type-1 diabetes patients. All SinMod measurements were significantly larger than those by HARP (P<0.001). Nevertheless, there existed consistency in the measurements by each technique, as seen by the good correlation between the HARP and SinMod measurements in both normals (R≥0.52) and patients (R≥0.48), except for apical strain (patients and controls) and mid-ventricular strain in patients. The inter-observer agreement was better in SinMod than in HARP for both torsion and strain (except at apex). In conclusion, under current operating conditions, the results from the two techniques cannot be used interchangeably.