Diffusion MRI versus Contrast enhanced MRI in diagnosis of Hepatocellular Carcinoma (HCC)

Abstract

Hepatocellular carcinoma (HCC) is the commonest primary malignant cancer of the liver in the world. Given that the burden of chronic liver disease is expected to rise owing to increasing rates of alcoholism, hepatitis B and C prevalence and obesity-related fatty liver disease, it is expected that the incidence of HCC will also increase in the foreseeable future. HCC, like any other cancer, develops when there is a mutation to the cellular machinery that causes the cell to replicate at a higher rate and/or results in the cell avoiding apoptosis. In particular, chronic infections hepatitis B and/or C aid the of HCC by repeatedly causing the body's own immune system to attack the liver cells, some of which are infected by the virus, others merely by standers. These carcinogenetic changes can be detected and characterized by means of various clinical imaging techniques. For instance, cellular morphologic changes can be depicted using gray scale ultrasonography (US), unenhanced computed tomography (CT), and unenhanced magnetic resonance imaging (MRI) including diffusion weighted imaging (DWI). On the other hand, the application of contrast agents facilitates the evaluation of functional changes held in a nodule during hepatic carcinogenesis beyond morphologic changes.Contrast enhanced MRI with superparamagnetic iron oxide (SPIO) can depict the presence of Kupffer cells in a nodule. Changes in signal intensity on hepatobiliary images of Gd-EOB-DTPA-enhanced MRI correlate with organic anion transporting polypeptides (OATP 8) expression. Multiphase MRI with contrast agents provide the information related to hemodynamic changes in a nodule that are currently regarded as the most important diagnostic criteria for HCC in routine clinical practice. Contrast-enhanced magnetic resonance imaging (MRI) after bolus injection of gadolinium chelates is routinely used in many centers for the detection and characterization of hepatocellular carcinoma (HCC) lesions, mainly based on the increased arterial supply in most HCCs The reported sensitivity of MRI for HCC detection varies between 55% and 77.8%. Contrast-enhanced MRI is limited, however, by the possibility of false negatives (mainly for small lesions) and false positives (mainly related to nontumorous arterioportal shunts), which may decrease its diagnostic accuracy.