1. To understand the role of different imaging techniques in the characterisation of focal liver lesions.
2. To be aware of malignant lesions which may mimic benign liver conditions.
3. To underline current guidelines for the characterisation of equivocal liver lesions.
Focal liver lesions are routinely encountered by clinical radiologists and represent a wide spectrum of pathology. Majority of these lesions are likely to be benign in nature, especially in the absence of chronic liver disease or primary cancer. A radiologist must be aware of common and uncommon imaging features of benign lesions across the various imaging modalities. Benign focal liver lesions can origin from all kind of liver cells: hepatocytes, mesenchymal and cholangiocellular line. Their features at imaging may sometimes pose difficulties in differential diagnosis with malignant primary and secondary lesions. In particular, the use of MDCT and MRI with extracellular and hepatobiliary contrast agents may non invasively help in correct interpretation and definition of hepatocellular or mesenchymal and inflammatory nature, allowing to choose the best treatment option. The correct differential diagnosis is based on the knowledge of the main diagnostic features. There are some malignant lesions which may mimic benign liver conditions. The most challenging lesions should be cystic lesions, hemangiomas, focal nodular hyperplasia and adenoma, whose features are not always so clear and unequivocal.
1. To learn about different types of cystic lesions in the liver, including giant biliary hamartomas or foregut cysts.
2. To understand the diagnostic approach to differentiate simple and complex cysts/cystic lesions.
3. To appreciate advantages and limitations of imaging for differentiating simple cysts from other cystic lesions.
The differential diagnosis of cystic liver lesions is as broad as their clinical significance, which ranges from benign to malignant and/or potentially lethal conditions. These lesions include foregut and ductal plate malformations, infectious conditions, primary and secondary neoplasms and traumatic/iatrogenic fluid collections. The number of lesions, morphology, fluid content characteristics, presence/absence of septae and/or solid components are the key imaging features for the diagnostic approach, and different imaging modalities pose different advantages and disadvantages for their characterisation. Given imaging characteristics may overlap between distinct conditions, patient history and laboratory data should be integrated to allow a more definitive diagnosis.
1. To learn about typical imaging findings of liver haemangioma.
2. To understand the atypical imaging findings of liver haemangiomas.
3. To appreciate the role of multiparametric and liver-specific contrast MRI in differentiation between haemangiomas and malignant lesions mimicking haemangiomas.
Haemangiomas are common focal liver lesions, generally detected in the workup of asymptomatic patients and do not require further workup, follow-up, or treatment. From the morphologic point of view, they can be classified as small (capillary) or large, with cavernous vascular spaces that may prone to show thrombosis, calcifications and hyalinisation. The polymorphic imaging appearance of haemangiomas depends on their histological features and flow pattern. The widespread use of cross-sectional imaging has allowed a better characterisation of this benign vascular tumour, and for this lecture, illustrative cases will be displayed especially using CT and multiparametric MRI including hepato-biliary contrast agents. Haemangiomas imaging findings may range from the commonly known aspects especially after extra-cellular Gd-chelates administration to atypical patterns where its recognition and positive diagnosis may not be so straightforward. The scope of the present lecture to present and discuss the patterns of those vascular liver lesions, describing normal findings, pitfalls, potential differentials, confounders and complications.
1. To learn the imaging features associated with FNH and adenoma on contrast-enhanced CT and MRI.
2. To understand how the imaging characteristics are related to the underlying pathological findings.
3. To appreciate the optimal use of liver-specific contrast media for distinguishing between FNH and adenoma, and current classification and pathological characteristics and its impact on the management.
FNH and hepatocellular adenoma (HCA) is liver lesions of hepatocellular origin. Whereas FNH commonly occurs, HCA is very rare. Distinguishing FNH from HCA is of great importance clinically, as FNH is considered a benign lesion and needs no further management. In contrast, HCA, according to its subtype, can be considered a borderline tumour due to the risk of haemorrhage, growth, and even malignant transformation, and therefore requires individualised management. The genotype/phenotype classification of HCA is an evolving issue, and there is now a recent HCA molecular classification by which to stratify patients according to the risk of complications. On imaging, HCA is no longer a distinct entity, and imaging features reflect the tumour subtypes. Contrast-enhanced MRI is much more accurate because of its ability to visualise the textural composition of the HCA. However, even after the administration of MRI hepatobiliary contrast agents, a small proportion of HCA subtypes still show either inhomogeneous uptake or inhomogeneous washout in the hepatobiliary phase (HBP); making them difficult to differentiate from FNH on the basis of imaging presentation alone. This may pose a diagnostic dilemma as both FNH and HCA tend to occur in women of child-bearing age. Clinical presentation and risk factors, male gender, patient age, the presence of storage disease, obesity, metabolic or inflammatory syndrome, hepatitis, alcohol abuse and tumour over five cms, as well as significant growth have been identified as factors associated with an HCA-subtype of higher malignant potential. In difficult cases, histology remains the gold standard.