The purpose of this article is to support delegates attending the 2B FRCR AMA Radiology Viva Course and contains information on image appearance of Haemangioma, Focal Nodular Hyperplasia, Adenoma, Hepatocellular Carcinoma and Fibro-lamellar Carcinoma. The information has been kept to a minimum to support the FRCR 2B and not intended for delegates to use to report HPB imaging in Clinical Practice.
Haemangioma: are the most common solid liver lesion (prevalence 1-5%). The aetiology is unknown but there is a 4:1 ratio in women to men. Haemangioma are essentially considered benign and often identified incidentally on CT and ultrasound. The ‘classic appearance’ on ultrasound is a well-defined, homogenous echogenic lesion with clear margins and through transmission measuring less then 4cm. On CT they typically show centripetal enhancement. MR is considered the most sensitive test. The two most useful sequences for diagnosis are the T2 and contrast enhanced phases. On T2 haemangioma are high signal and on post contrast there is peripheral nodular enhancement and contrast filling. What is covered in the course. Atypical features of Haemangioma, Flash Haemangioma and Giant Haemangioma. When to do CT, ultrasound and MRI.
Focal nodular hyperplasia (FNH). These are the second most common liver lesions with an 8:1 prevalence in women to men. They are benign and are comprised of lobulated hepatic parenchyma surrounded by fibrous septa originating from a central scar. The lesions are heterogenous on ultrasound, normally less than 5cm in size. On CT there is enhancement in the arterial and portal venous phase. MRI is considered the most definitive test. The most useful sequence is the post contrast series. FNH, will show enhancement in the arterial phase without washout. They will retain contrast on the hepatobiliary phase. The central scar is sometimes visible on MRI. What is covered in the course. Practice cases, when to perform a CT, ultrasound or MR? MR contrast agents Dotarem vs Primovist?. Management of FNH.
Adenoma: Hepatic adenoma is a rare liver lesion. The incidence is higher in women compared to men and there is an association with the oral contraceptive pill and anabolic steroid use. On ultrasound adenoma appear heterogenous with clear margins. On CT scans adenoma can show arterial phase enhancement with washout of contrast on the portal venous phase. The most sensitive test to formulate the diagnosis is an MRI scan with hepatobiliary scan. Adenoma may show signal drop out on out of phase imaging indicating the presence of intra-lesional fat. On post contrast imaging the lesions typically show arterial phase enhancement but washout on the portal venous and delayed phase. The lesions do not retain contrast on the hepatobiliary phase unlike focal nodular hyperplasia. Adenomas are associated with malignant transformation and haemorrhage. There is also recorded decrease in size of adenoma on withdrawel of the pill or steroids. What is covered in the course. Adenoma vs Hypervascular metastasis vs HCC. How is a diagnosis made? How are these lesions managed?
Fibrolamellar carcinoma (FLC): these are rare neoplastic liver lesions more common in young people. They often present as large lesions. There is no association with hepatitis or underlying liver disease or cirrhosis unlike HCC. Patients can present with abdominal pain commonly. Jaundice etc are less common. Serum AFP is typically not elevated. Ultrasound appearance is non specific and can mimic other lesions. On CT the lesions typically appear large, are lobular, many contain calcification and also have a central stellate scar. Necrosis and haemorrhage is uncommon. Portal vein thrombosis is less likely. On CT the post contrast appearance is atypical i.e. some lesions show enhancement and washout but others do not. The most sensitive test to assess this further is an MRI scan. The lesions may show enhancement on the arterial phase but importantly do not retain contrast on the hepatobiliary phase.
Hepatocellular (HCC): This is the fifth most common malignancy worldwide. Pathophysiology involves the formation of a Regenerative Nodule transforming into a Dysplastic nodule then a HCC. Regenerative and Dysplastic nodules have non-specific appearance on CT and ultrasound. On MRI Regenerative nodules are low on T2, variable signal on T1 and can contain fat hence showing signal drop out on out of phase sequences. Dysplastic nodules are commonly low on T2 and variable signal on T1. There is enhancement on the arterial phase without evidence of washout. The diagnosis of HCC is mostly made on the enhancement characteristics. The classic lesion shows enhancement with washout on post contrast CT and MR. What is covered in the Course. Examples on imaging of HCC, Regenerative and Dysplastic Nodules. When to do CT, ultrasound and MRI