Role of MRI in Evaluation of Spectrum of Liver Lesions in Cirrhotic Patients.

MRI provides better intrinsic soft-tissue contrast with more enhanced depiction of even subtly different tissue properties making lesion evaluation easy. Faster sequences which capture arterial sequences better, lack of ionizing radiation and simultaneous evaluation of background liver parenchyma and the liver lesions are additional advantages of using MRI as the imaging technique of choice. Comprehensive liver imaging using MRI now includes T1, T2-weighted imaging and in- and opposed-phase, in addition to dynamic post-contrast imaging with proper breath holding techniques. Wider variety of liver specific contrast agents is available for use in MR imaging with the gadolinium based agents being considered the most useful and practical, particularly for lesion characterization.

AIMS AND OBJECTIVES: To evaluate MRI spectrum of liver lesions in cirrhotic patients, Role of MRI in focal liver lesion evaluation and to differentiate benign versus malignant lesions.

MATERIALS AND METHODS: A prospective study of OPD or IPD patients who underwent imaging tests like Ultrasonography, or CT scan for suspected chronic liver disease was done. A total 35 patients were investigated (June 2014 - November 2016) with MRI abdomen done with the patient in supine position on a Philips Achieva 3.0T MRI scanner. Standard MRI abdomen protocol, including T2W TSE in axial and coronal plane, T2W fat suppressed (SPAIR) images in axial and coronal plane, T1W TFE, in- and out-of-phase imaging and Diffusion-weighted imaging (DWI) in axial plane along with pre-contrast baseline fat-suppressed T1W imaging in at least one plane was acquired. Breath-holding was required in few sequences. 0.1 mmol/kg Gadolinium based contrast (Gadobenate) was injected at the rate of 2.5 ml/sec followed by saline flush and dynamic contrast enhanced MRI (DCE-MRI) with post-contrast fat-suppressed T1W imaging was acquired.

RESULTS AND CONCLUSIONS: In cirrhosis, there is development of nodules which are initially only microscopically detectable. With progression of cirrhosis, there is development of radiologically detectable regenerative nodules, dysplastic nodules and hepatocellular carcinoma. Amongst these regenerative nodules are completely benign lesions whereas dysplastic nodules, though benign, are considered premalignant; and hepatocellular carcinoma is a malignant condition. Differentiation of benign versus malignant lesions is possible on the basis of enhancement pattern in dynamic contrast enhanced MRI. The signal characteristics of focal lesions and other findings like portal vein thrombosis are helpful, give additional clue to the diagnosis and also helpful in assigning LIRADS grade to a lesion. Also, MRI characterization after gadolinium based contrast injection was found to be similar to the previous imaging based on non-gadolinium contrast agents.