Role of Dynamic CE-MRI and DWI in Characterization of Hypervascular Focal Hepatic Lesions in Cirrhotic Liver

Abstract Background: Various types of hypervascular lesions are commonly found among patients with liver cirrhosis, however differentiating between benign and malignant hypervascular lesions in liver cirrhosis remains a key problem in the care of individuals at risk for developing hepatocellular carcinoma. Patients with cirrhotic liver disease are always submitted to a regular check-up by abdominal ultrasound (US) for screening of hepatic focal lesions, if present triphasic CT scan is done to assess the pattern of enhancement as a reflection of its source of vascularity. A variety of hypervascular lesions can occur in cirrhotic liver, other than hepatocellular carcinoma (HCC), such as hemangiomas, focal nodular hyperplasia, intrahepatic cholangiocarcinoma, metastases or pseudo-lesions, such as perfusion anomalies, focal confluent fibrosis. While the primary concern of a radiologist is to avoid a false negative diagnosis of malignant hepatic focal lesions as benign lesions, decreasing false positive diagnosis is also of the same value in order to decrease tumor over diagnosis. Depending on triphasic CT or abdominal ultrasound in such lesions' differentiation is not always sufficient. Better tissue characterization by different MRI sequences including the diffusion sequences, apparent diffusion coefficient (ADC) values, and pattern of enhancement are highly recommended to avoid a false positive diagnosis of the arterially enhancing lesions for being HCC. Aim of Study: To assess the role of the addition of dynamic CE-MRI and DW-MRI to the conventional MRI in better characterization of hypervascular hepatic focal lesions in cirrhotic liver, and to assess the benefits of the quantitative evaluation of ADC values in better characterization of the benign and malignant hypervascular hepatic focal lesions. Patients and Methods: 25 cases of liver cirrhosis with 37 detected hepatic focal lesions, were examined with CT/US, if the final diagnosis was still hesitant a dynamic CE-MR was done, with DWI (b.0-500-1000) and their ADC maps were examined qualitatively and quantitatively by 2 experienced radiologists, (10 and 18 Yrs of experience. Results were recorded and ADC readings were analyzed on the ROC curve. The final results were diagnosed according to the standard of reference. Results: There was a statistically significant difference between benign and malignant ADC values, with a p-value of 0.003. A suggested cut-off value was 1.525 have resulted in 89% accuracy. While reading the dynamic contrast-enhanced MRI we have reached a diagnostic accuracy of 72.9%, how-ever, while reading the DWI and their ADC maps qualitatively we have reached 97.5%. Conclusion: Conventional MRI sequences combined with dynamic CE-MRI and DWI provide a more accurate diagnosis for hypervascular hepatic focal lesions. The quali-tative assessment of the DWI and their ADC maps, per se, have similar overall accuracy, and can be used without the CE-MRI sequences especially when it is contraindicated or not available. The quantitative ADC values were less accurate than the qualitative assessment of DW sequences. The higher the b value the better the detection of small malignant hepatic focal lesions, with less false negative lesions.