A method for assessing metabolic information on liver and bone marrow by use of double gradient-echo with spectral...

Our aim in this study was to create a noninvasive and practical method for evaluating metabolic information on the liver (iron content and lipid infiltration) and spine (bone mineral density and marrow fat degeneration) using double gradient-echo with and without the spectral fat suppression technique (double-GRE-FS). We arranged phantoms made of various concentrations of superparamagnetic iron oxide solution adjacent to neutral fat to obtain slice planes with various fat fractions using the partial volume effect. We obtained double-GRE-FS images and calculated the T2* values. The fat fraction was calculated from signal intensities of double-GRE-FS images after T2* decay, baseline, and slope corrections. We assessed the fat fraction and the relationship between R2* of the water component and the iron concentration. In addition, we evaluated those values in human bone marrow and liver, including a patient with liver steatosis. The actual fat fraction value was consistent with the fat fraction obtained with the double-GRE-FS method, and the calculated fat fraction was unaffected by the iron concentration. There was a strong positive correlation between R2* of the water component and the iron concentration. There was a negative correlation between the fat fraction and the bone mineral density, and the R2* was correlated with the bone mineral density. The calculated fat fraction in the liver steatosis patient was significantly higher than that in healthy volunteers. The double-GRE-FS makes it possible to assess the fat fraction and R2* simultaneously, and to obtain metabolic information on the liver and bone marrow.