MultiexponentialT2analyses in a murine model of hepatic fibrosis at 11.7 T MRI

Abstract

This study evaluated the effects of hepatic fibrosis on the multiexponential T(2) (MET(2) ) 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 MET(2) analysis. Degrees of fibrosis were determined by a pathologist, as well as by digital image analysis. Scatterplot graphs comparing various features of the MET(2) signal decay with the degrees of fibrosis were generated, and correlation coefficients were calculated. Two distinct peaks of the MET(2) signal decay were identified in all liver specimens: a short T(2) component with a geometric mean T(2) (GMT(2) ) approximating 30 ms; and a long T(2) component with GMT(2) approximating 400 ms. Strong correlation was found between the degree of hepatic fibrosis and the amplitude of the short T(2) component, with a higher degrees of fibrosis associated with a lower amplitude. Moderate correlation was also found between hepatic fibrosis and the GMT(2) values of the long T(2) component, with higher degrees of fibrosis associated with lower GMT(2) values. The study of hepatic microenvironments using MET(2) analyses offers potential utility in the ongoing development of the noninvasive assessment of hepatic fibrosis using MRI.