To provide a comprehensive review of the hepatic focal lesions with delayed enhancement. To enhance the role of dynamic MRI in their differentiation with emphasis on characteristic features and presenting typical cases.

Introduction: Delayed enhancement is seen in a variety of benign and malignant hepatic focal lesions. MRI is considered an important non-invasive diagnostic tool. Dynamic imaging is essential for lesion detection and characterization. Gadolinium chelates are the most widely used and the least expensive MRI contrast agents. -Pharmacodynamics of gadolinium chelates contrast agents: Gadolinium chelates are extracellular agents. As the extracellular compartment is divided into intravascular and interstitial spaces, injected contrastagents enter the liver via the hepatic artery and portal vein and are freely redistributed from...

-Differential diagnosis of the most common delayed-enhancing hepatic focal lesions (Fig.4) 1-Malignant lesions: A-Intrahepatic cholangiocarcinoma (ICC): The second most common primary hepatic tumor after HCC. ICC may also be classified according to their growth pattern or morphologic subtype(Fig.5). 90% are adenocarcinomas with abundant fibrous stroma. The mass forming type is the most common (80%). -Mass forming Intrahepatic cholangiocarcinoma Hypointense on T1WI. Variablehyperintense on T2WI, depending on the relative proportions of fibrous stroma vs extracellular mucin and necrosis. The most common enhancement pattern is early arterial...

Dynamic MRI is a reliable diagnostic tool in differentiating delayed enhancing hepatic lesions. Analysis of the enhancement pattern by using a combination of early and delayed phases will improve the accuracy of lesion characterization and diagnosis.

M. H. A. Hassan Elsharkawy; Giza/EG - nothing to disclose A. H. A. Mohamed; Cairo/EG - nothing to disclose S. H. I. Desoukey; Giza/EG - nothing to disclose F. E. Balah; Giza/EG - nothing to disclose

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