Saturday, June 20, 2009

Confluent Hepatic Fibrosis (CHF)

Multiphase CT scan of 13 year old male patient with known case of cirrhosis, non contrast image showing atrophy of left lobe with capsular retraction. Arterial phase image does not show any enhancement. Venous phase image shows faint wedge shaped enhancement in segment IVa (arrow head) and the delayed image shows progressive incresed and persistant enhancement in segment IVa (arrow). Rest of the liver shows lace like enhancement. No mass effect or vascular displacement. The findings are consistant with Confluent hepatic fibrosis (CHF).

CHF Can be seen on imaging in approximately 14% of patients with advanced cirrhosis who are candidates for liver transplantation. It is associated with volume loss seen as retraction of overlying hepatic capsule or total shrinkage of segment or lobe.

Imaging Findings:
CHF is seen incidentally in patients with advanced cirrhosis who undego pretransplant imaging or imaging to ruleout hepatocellular carcinoma. Best diagnostic clue for CHF is pre-contrast CT showing hypo attenuating lesion with volume loss that becomes isoattenuating or minimally hypoattenuating at post-contrast CT, especially if wedge-shaped, located in medial segment of left lobe &/or anterior segment of right lobe, in patients with advanced cirrhosis. In our case the non contrast images are not showing typical hypoattenuation lesion. Wedge-shaped lesions radiate from porta hepatis & extend tohepatic capsule. Peripheral lesions are remote from porta hepatis. Lobar or segmental involvement, most commonly in lateral segment of left lobe. Retraction of overlying capsule seen in 90% cases.
The lesions are isoattenuating on post contrast images in 80% and hperattenuating on delayed scans. They show delayed persistent enhancement due to variability in contrast enhancement of confluent fibrosis relates to relative vascularity & extent of fibrosis.

MR imaging does show morphological changes & characteristic locations that suggest diagnosis, but no more so than CT. Lesions appear as regions of hypointense signal relative to adjacent liver parenchyma on T1 imaes and hyperintense on T2 due to prominant edema. They show delayed progressive enhancement on administration of gadolinium.
Differential diagnosis for focal liver lesions with capsular retraction apart from CHF are Cholangiocarcinoma, Treated metastases and sclerosing cholangitis.

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