Although less sensitive than contrast-enhanced MRI, a noncontrast MRI (including MRCP) may be of use for this variant, as there are imaging findings seen on both C+ MRCP and C- MRCP. For example, both studies are useful in the assessment of subtle regions of peripheral biliary dilatation within the liver (seen in early manifestations of primary sclerosing cholangitis), in the detection of hepatolithiasis (which can occur secondary to surgical reconstructions and in the setting of recurrent pyogenic cholangitis), volume redistribution of the liver/inferior surface nodularity (seen in cirrhosis from varying underlying etiologies), detection of regions of peripheral fibrosis or other morphologic/signal abnormalities that can be associated with jaundice, and in unsuspected intra- or extrahepatic biliary strictures (from surgery or infectious etiologies) [127]. If there is concern for a previously unsuspected underlying hepatocellular disease, MRI shows a moderately high accuracy in detection of cirrhosis; a study comparing CT, MRI, and US (compared with explant livers resected for hepatocellular carcinoma at the time of transplant) found that CT had an accuracy of 67%, MRI an accuracy of 70.3%, and US an accuracy of 64% [44] for the detection of underlying cirrhosis. MRI is not very sensitive or specific for the diagnosis of acute hepatitis; however, several studies have found a significant relationship between the apparent diffusion coefficient and inflammation scores (ie, livers in the setting of acute hepatitis may have high signal on high b-value diffusion-weighted images) [128,129]. When imaging does not yield a cause for jaundice (ie, there is no biliary obstruction and no parenchymal process to explain jaundice), liver dysfunction or an infiltrative process must be excluded, and liver biopsy will be the most effective next step in diagnosis [12,32].
Jaundice. Although less sensitive than contrast-enhanced MRI, a noncontrast MRI (including MRCP) may be of use for this variant, as there are imaging findings seen on both C+ MRCP and C- MRCP. For example, both studies are useful in the assessment of subtle regions of peripheral biliary dilatation within the liver (seen in early manifestations of primary sclerosing cholangitis), in the detection of hepatolithiasis (which can occur secondary to surgical reconstructions and in the setting of recurrent pyogenic cholangitis), volume redistribution of the liver/inferior surface nodularity (seen in cirrhosis from varying underlying etiologies), detection of regions of peripheral fibrosis or other morphologic/signal abnormalities that can be associated with jaundice, and in unsuspected intra- or extrahepatic biliary strictures (from surgery or infectious etiologies) [127]. If there is concern for a previously unsuspected underlying hepatocellular disease, MRI shows a moderately high accuracy in detection of cirrhosis; a study comparing CT, MRI, and US (compared with explant livers resected for hepatocellular carcinoma at the time of transplant) found that CT had an accuracy of 67%, MRI an accuracy of 70.3%, and US an accuracy of 64% [44] for the detection of underlying cirrhosis. MRI is not very sensitive or specific for the diagnosis of acute hepatitis; however, several studies have found a significant relationship between the apparent diffusion coefficient and inflammation scores (ie, livers in the setting of acute hepatitis may have high signal on high b-value diffusion-weighted images) [128,129]. When imaging does not yield a cause for jaundice (ie, there is no biliary obstruction and no parenchymal process to explain jaundice), liver dysfunction or an infiltrative process must be excluded, and liver biopsy will be the most effective next step in diagnosis [12,32].