Multiexponential T 2 analyses in a murine model of hepatic fibrosis at 11.7 T MRI

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. Copyright © 2012 John Wiley & Sons, Ltd.