Automated T2* measurements using supplementary field mapping to assess cardiac iron content

Purpose: To develop and evaluate an algorithm that automatically identifies high-susceptibility areas and excludes them from T-2* measurements in the left ventricle (LV) for myocardial iron measurements. Materials and Methods: An autoregressive moving average (ARMA) model was implemented on multigradient echo scans of 24 patients (age range 3-45 years, 10 male/14 female). Voxels with relatively high susceptibility (>3 Hz/mm) were flagged and deselected from the T-2* calculations for iron quantification. The mean, standard deviation, and coefficient of variation (CoV) of the ARMA-defined region were compared to the CoV of four distinct regions of the LV and the entire LV using a Student's t-test ( = 0.05). Results: The CoV of T-2* values obtained by the ARMA method are comparable with that in the interventricular septum (IS), where susceptibility was the lowest (CoV = 0.31). The ARMA method provides a greater area (51.9 +/- 13.7% of the LV) to measure T-2* than that using the IS alone (21.1 +/- 3.4%, P < 0.0001). Areas where low susceptibility are measured corroborate with areas reported in previous studies that investigated T-2* variations throughout the LV. Conclusion: An automated method to measure T-2* relaxation in the LV with minimal effects from susceptibility has been developed. Variability is reduced while covering more regions for cardiac T-2* calculation. J. Magn. Reson. Imaging 2013;38:441-447. (c) 2012 Wiley Periodicals, Inc.