Noninvasive quantification of hepatic fat content using three-echo dixon magnetic resonance imaging with correction for T2* relaxation effects.

OBJECTIVE

To investigate three-echo T2*-corrected Dixon magnetic resonance imaging (MRI) for noninvasively estimating hepatic fat content (HFC) compared with biopsy.

MATERIALS AND METHODS

One hundred patients (50 men, 50 women; mean age, 57.7±14.2 years) underwent clinically indicated liver core biopsy (102 valid tissue samples) and liver MRI 24 to 72 hours later. MRI was performed at 1.5T (Magnetom Avanto, Siemens Healthcare, Erlangen, Germany) using Dixon imaging with T2* correction (work in progress, WIP-432.rev.1, Siemens Healthcare). An ultrafast breath-hold three-echo 3D-gradient echo sequence with TR/TE1/TE2/TE3 of 11/2.4/4.8/9.6 milliseconds, and online calculation of T2*-corrected water images (signal intensities of water [SIW]), fat images (SIF), and fat content map (SIFAT=10×SIF/(SIW+SIF)) was used. SIs of the calculated fat content map (SIFAT) were verified using the histologically quantified HFC (HFC(path)). Spearman correlation for HFC(path) and SIFAT was calculated. Stage of fibrosis, hepatic iron content, and patterns of liver fat (macrovesicular, microvesicular, mixed) and their influence on predicting HFC by MRI were determined.

RESULTS

Correlation between SIFAT and HFC(path) was rspearman=0.89. Agreement between HFC predicted by MRI and HFC(path) calculated by nonlinear saturation-growth regression was rspearman=0.89. Kruskal-Wallis analysis revealed no significant difference for SIFAT across fibrosis grades (P=0.90) and liver iron content (P=0.76). Regarding the cellular architecture of liver fat, the microvesicular pattern showed lower mean ranks in SI than macrovesicular and mixed patterns (P=0.01).

CONCLUSION

T2*-corrected Dixon MRI is a noninvasive tool for estimating HFC, showing excellent correlation with liver biopsy without being limited by liver iron content and fibrosis/cirrhosis.