Intravoxel incoherent motion MRI for liver fibrosis assessment: a pilot study.

ABSTRACT

BACKGROUND: There has been a growing need for an imaging method for the accurate diagnosis and staging of liver fibrosis as a non-invasive alternative to liver biopsy. PURPOSE: To evaluate the feasibility of intra-voxel incoherent motion (IVIM) imaging for classifying the severity of liver fibrosis. MATERIAL AND METHODS: Fifty-seven patients who underwent navigator-triggered, diffusion-weighted imaging (DWI) of the liver on a 1.5-T system using nine b-values and had a reliable reference standard for the diagnosis of liver fibrosis (histopathologic findings [n = 27] or clinical findings for normal [n = 18] or cirrhotic liver [n = 12]), were included in our study. Liver apparent diffusion coefficient (ADC), pure diffusion (Dslow), perfusion fraction (f), and perfusion-related diffusion (Dfast), and the product f · Dfast were compared with the liver fibrosis stages (F). The accuracies of these parameters in diagnosing severe liver fibrosis (F ≥3) were evaluated using the receiver-operating characteristic (ROC) curve analysis. RESULTS: The liver fibrosis stages had the strongest negative correlation with f · Dfast (ρ = -0.52). All of the parameters, except for Dslow, were significantly lower in patients with F ≥3 than in those with F ≤2 (P ≤ 0.001). The area under the ROC curve for diagnosing severe fibrosis was the largest for f · Dfast (0.844) with an overall accuracy of 79.0% (45/57) at the optimal cutoff value and followed by f (0.834), Dfast (0.773), ADC (0.762), and Dslow (0.656). CONCLUSION: IVIM imaging is a promising method for classifying the severity of liver fibrosis, with the product f · Dfast being the most accurate parameter.