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

Abstract

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. 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 2-3×2-3×10mm3 , 10 echoes, TR=26ms, FA=20°, BW=833Hz, SENSE=2) except for TE (cardiac: TE1 =2·5ms, ΔTE=2·5ms; liver: TE1 =1·2ms, ΔTE=1·5ms). Phantoms were scanned at 1 and 32 signal averages (NSA), with NSA32 representing low-noise reference. Phantoms: MLE showed low variability between NSA1 and NSA32 (0·02±0·29ms, CI±0·21ms). Between methods, no difference was shown (MLE versus all: <0·31ms, CI<±0·35ms). No differences were found between methods in heart (MLE versus all: <-0·22ms, CI<±0·75ms) or liver (MLE versus all: <0·12ms, CI<±0·26ms). 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.