Automatic T2* determination for quantification of iron load in heart and liver: a comparison between automatic inline Maximum Likelihood Estimate and the truncation and offset methods

PURPOSE: To validate ironload T2* by automatic inline Maximum Likelihood Estimate (MLE) with k-space Rician noise correction, against the manual and automated truncation, as well as offset methods, in phantoms and in heart and liver in patients.

METHODS: Twenty-five patients and an iron-oxide phantom were scanned at 1.5T using 2 multi-echo gradient-echo sequences. All parameters were identical (voxel 2-3 × 2-3 × 10 mm(3) , 10 echoes, TR = 26 ms, FA = 20°, BW = 833 Hz, SENSE = 2) except for TE (cardiac: TE1 = 2·5 ms, ΔTE = 2·5 ms; liver: TE1 = 1·2 ms, ΔTE = 1·5 ms). Phantoms were scanned at 1 and 32 signal averages (NSA), with NSA32 representing low-noise reference.

RESULTS: Phantoms: MLE showed low variability between NSA1 and NSA32 (0·02 ± 0·29 ms, CI ±0·21 ms). Between methods, no difference was shown (MLE versus all: <0·31 ms, CI < ±0·35 ms).

PATIENTS: No differences were found between methods in heart (MLE versus all: <-0·22 ms, CI < ±0·75 ms) or liver (MLE versus all: <0·12 ms, CI < ±0·26 ms).

CONCLUSIONS: The automatic inline MLE method is comparable to the general reference standards for determining cardiac and liver T2* for ironload in man. An automatic inline method may simplify ironload assessment, particularly in centres seeing fewer cases.