Data are limited regarding its utility, and no advantage over alternative imaging or serum tests has been demonstrated. MR Elastography Abdomen MR elastography is currently the most accurate imaging modality for the diagnosis and staging of hepatic fibrosis [24,25]. MR elastography compares favorably with US shear wave elastography (SWE), in part, because of improved performance in patients with obesity [26]. MR elastography does have limitations in patients with hepatic iron deposition and patients imaged at 3T due to susceptibility artifacts, which can result in undersampling of the liver or nondiagnostic evaluations. Stiffness measurement may also be confounded by parenchymal edema, inflammation, cholestasis, cardiogenic hepatic congestion, recent meal, and other factors [27]. MRI Abdomen Conventional MRI can be used to assess the same structural changes as those visualized on CT, with the added advantage of greater visibility of bands of fibrosis on both noncontrast and contrast-enhanced sequences [28]. However, its utility for detecting early liver fibrosis remains limited because these changes do not occur until fibrosis has progressed to a very advanced stage. A number of advanced MRI techniques have been assessed for detecting liver fibrosis. Diffusion-weighted imaging has been used to assess the restriction of free water proton movement in the hepatic parenchyma as a marker of collagen deposition, the microscopic manifestation of liver fibrosis. A meta-analysis of studies on diffusion- weighted imaging for this application showed that diffusion-weighted imaging was most useful for detecting advanced fibrosis but had lower performance for detecting early fibrosis (sensitivity 77%, specificity 78%) [29]. Additionally, questions about the optimal acquisition technique and image processing methodologies (apparent diffusion coefficient, intravoxel incoherent motion, etc) remain unresolved.
Chronic Liver Disease. Data are limited regarding its utility, and no advantage over alternative imaging or serum tests has been demonstrated. MR Elastography Abdomen MR elastography is currently the most accurate imaging modality for the diagnosis and staging of hepatic fibrosis [24,25]. MR elastography compares favorably with US shear wave elastography (SWE), in part, because of improved performance in patients with obesity [26]. MR elastography does have limitations in patients with hepatic iron deposition and patients imaged at 3T due to susceptibility artifacts, which can result in undersampling of the liver or nondiagnostic evaluations. Stiffness measurement may also be confounded by parenchymal edema, inflammation, cholestasis, cardiogenic hepatic congestion, recent meal, and other factors [27]. MRI Abdomen Conventional MRI can be used to assess the same structural changes as those visualized on CT, with the added advantage of greater visibility of bands of fibrosis on both noncontrast and contrast-enhanced sequences [28]. However, its utility for detecting early liver fibrosis remains limited because these changes do not occur until fibrosis has progressed to a very advanced stage. A number of advanced MRI techniques have been assessed for detecting liver fibrosis. Diffusion-weighted imaging has been used to assess the restriction of free water proton movement in the hepatic parenchyma as a marker of collagen deposition, the microscopic manifestation of liver fibrosis. A meta-analysis of studies on diffusion- weighted imaging for this application showed that diffusion-weighted imaging was most useful for detecting advanced fibrosis but had lower performance for detecting early fibrosis (sensitivity 77%, specificity 78%) [29]. Additionally, questions about the optimal acquisition technique and image processing methodologies (apparent diffusion coefficient, intravoxel incoherent motion, etc) remain unresolved.