Multiexponential T2 analyses in a murine model of hepatic fibrosis at 11.7 T MRI

This study evaluated the effects of hepatic fibrosis on the multiexponential T2 (MET2) relaxation of ex vivo murine liver specimens using an 11.7 T MRI. This animal study was approved by the Institutional Animal Care and Use Committee. Eighteen male C57BL/6 mice were divided into control (n = 3) and experimental (n = 15) groups; the latter group was fed a 3,5-dicarbethoxy-1,4-dihydrocollidine-supplemented diet to induce hepatic fibrosis. Ex vivo liver specimens were imaged using an 11.7 T MRI scanner. A multi-echo spin-echo sequence was utilized for subsequent MET2 analysis. Degrees of fibrosis were determined by a pathologist, as well as by digital image analysis. Scatterplot graphs comparing various features of the MET2 signal decay with the degrees of fibrosis were generated, and correlation coefficients were calculated. Two distinct peaks of the MET2 signal decay were identified in all liver specimens: a short T2 component with a geometric mean T2 (GMT2) approximating 30 ms; and a long T2 component with GMT2 approximating 400 ms. Strong correlation was found between the degree of hepatic fibrosis and the amplitude of the short T2 component, with a higher degrees of fibrosis associated with a lower amplitude. Moderate correlation was also found between hepatic fibrosis and the GMT2 values of the long T2 component, with higher degrees of fibrosis associated with lower GMT2 values. The study of hepatic microenvironments using MET2 analyses offers potential utility in the ongoing development of the noninvasive assessment of hepatic fibrosis using MRI. Copyright © 2012 John Wiley & Sons, Ltd.