Diffusion tensor imaging of liver fibrosis in an experimental model

Abstract

Purpose To characterize changes in diffusion properties of liver using diffusion tensor imaging (DTI) in an experimental model of liver fibrosis. Materials and Methods Liver fibrosis was induced in Sprague-Dawley rats (n = 12) by repetitive dosing of carbon tetrachloride (CCl4). The animals were examined with a respiratory-gated single-shot spin-echo echo-planar DTI protocol at 7 T before, 2 weeks after, and 4 weeks after CCl4 insult. Apparent diffusion coefficient (ADC), directional diffusivities (ADC // and ADC⊥), and fractional anisotropy (FA) were measured. Liver histology was performed with hematoxylin-eosin staining and Masson's trichrome staining. Results Significant decrease (P < 0.01) in ADC was found at 2 weeks (0.86 ± 0.09 × 10-3 mm 2/s) and 4 weeks (0.74 ± 0.09 × 10-3 mm 2/s) following CCl4 insult, as compared with that before insult (0.97 ± 0.08 × 10-3 mm2/s). Meanwhile, FA at 2 weeks (0.18 ± 0.03) after CCl4 insult was significantly lower (P < 0.01) than that before insult (0.26 ± 0.05), and subsequently normalized at 4 weeks (0.26 ± 0.07) after the insult. Histology showed collagen deposition, presence of intracellular fat vacuoles, and cell necrosis/apoptosis in livers with CCl4 insult. Conclusion DTI detected the progressive changes in water diffusivities and diffusion anisotropy of liver tissue in this liver fibrosis model. ADC and FA are potentially valuable in detecting liver fibrosis at early stages and monitoring its progression. Future human studies are warranted to further verify the applicability of DTI in characterizing liver fibrosis and to determine its role in clinical settings. © 2010 Wiley-Liss, Inc.