BA, the congenital absence or destruction of intra- or extra-hepatic biliary system, affects about 5 - 10/100 000 live births. End stage liver cirrhosis developed in some BA patients later in life. As a result of liver cirrhosis, regenerative nodules may develop in cirrhotic liver including a specific type termed MRN. The clinical significance and pathological features of MRN have been discussed in some articles. However, the image features of MRN and how to differentiate them from HCC have yet to be elucidated.
A research article to be published on July 28, 2008 in the World Journal of Gastroenterology addresses this question. The research team led by Dr. Yu-Fan Cheng from Chang-Gung memorial hospital- Kaohsiung medical center found that MRN developed in about 5% BA patients and there was no malignant change within them based on the histopathological finding of 144 extracted livers. The authors also reviewed pre-transplantation image surveys including CT and MRI.
They found that the MRN may have typical and atypical images features in CT/MRI. Typical MRN which are found in about 5/8 are hyperdense on pre-contrast CT and hypointense on T2WI MRI as compared with surrounding liver parenchyma. They had intra-tumoral tubular vascular bundles and showed no enhancement. These features can be used to differentiate from HCC. Atypical MRN which are found in 3/8 showed arterial enhancement and may be interpreted as signs of malignant change. Liver biopsy may aid in making a decision before liver transplantation (LT).
LT should not be withheld in BA patients based solely on images because benign lesions may also have images which look like HCC. The combined use of alfa-feto-protein , images and sometimes liver biopsy are still helpful in pre-transplant survey. The result of this article implies that liver biopsy can be avoided if supported by the typical images of MRN and repeated biopsy is not necessary if the AFP value is incongruent with radiographic findings.