Role of Magnetic Resonance Imaging in Evaluation of Hepatocellular Nodules in Liver Cirrhosis

Abstract

C irrhotic livers are characterized by advanced fibrosis and formation of hepatocellular nodules which are classified histologically as either regenerative nodules, dysplastic nodules, or neoplastic lesions. However, their accurate characterization may be difficult even at histopathological analysis. Differential diagnosis may be facilitated by comparing the clinical and pathological findings with radiological imaging features. MR imaging is more useful than computed tomography and US in diagnosing the premalignant cirrhotic nodules from the malignant ones as it is the main issue for early detection and management of HCC. MRI provides better soft-tissue contrast and identification of different tissue properties by their signal appearance on different MR phases especially with the introduction of faster sequences while in MSCT we judge only on dynamic post contrast study. Moreover, a wide variety of contrast agents are currently available for use in MR imaging which provides greater sensitivity to these contrast media. For hepatic focal lesions detection and characterization, conventional MRI relies on T1-weighted, T2-weighted and dynamic gadolinium-enhanced T1-weighted imaging. Additionally, DW MRI in the liver is a relatively new and increasingly used imaging technique. It has the advantage that it can be obtained during a single breath-hold, there is no need to use contrast media, and it provides unique information that reflects tissue cellularity and organization. The ADC maps can also provide quantitative measurements of tissue water diffusivity which can be used not only for disease assessment, but also for the evaluation of disease response to treatment.