Robust motion correction for myocardial T1 and extracellular volume mapping by principle component analysis-based groupwise image registration

Abstract

Background: Myocardial tissue characterization by MR T1 and extracellular volume (ECV) mapping has demonstratedclinical value. The modified Look–Locker inversion recovery (MOLLI) sequence is a standard mapping technique, but itsquality can be negatively affected by motion.Purpose: To develop a robust motion correction method for T1 and ECV mapping.Study Type: Retrospective analysis of clinical data.Population: Fifty patients who were referred to cardiac MR exam for T 1 mapping.Field Strength/Sequence: 3.0T cardiac MRI with precontrast and postcontrast MOLLI acquisition of the left ventricle(LV).Assessment: A groupwise registration method based on principle component analysis (PCA) was developed to registerall MOLLI frames simultaneously. The resulting T 1 and ECV maps were compared to those from the original andmotion-corrected MOLLI with pairwise registration, in terms of standard deviation (SD) error.Statistical Test: Paired variables were compared using the Wilcoxon signed-rank test.Results: The groupwise registration method demonstrated improved registration performance compared to pairwiseregistration, with the T 1 SD error reduced from 31 6 20 msec to 26 6 15 msec (P < 0.05), and ECV SD error reducedfrom 4.1 6 3.6% to 2.8 6 2.0% (P < 0.05). In LV segmental analysis, the performance was particularly improved in lat-eral segments, which are most affected by motion. The running time of groupwise registration was significantly shorterthan that of the pairwise registration, 17.5 6 3.0 seconds compared to 43.5 6 2.2 seconds (P < 0.05).Data Conclusion: We developed an automatic, robust motion correction method for myocardial T 1 and ECV mappingbased on a new groupwise registration scheme. The method led to lower mapping error compared to the conventionalpairwise registration method in reduced execution time.