Type:
Educational Exhibit
Keywords:
Not applicable, Neoplasia, Education and training, Diagnostic procedure, MR, Oncology, Liver, Abdomen, Abdominal Viscera
Authors:
M. H. A. Mohammed Hassan1, S. H. I. Desoukey1, A. H. A. Mohamed2, F. E. Balah1; 1Giza/EG, 2Cairo/EG
DOI:
10.26044/ecr2020/C-05782
Background
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 contrast agents enter the liver via the hepatic artery and portal vein and are freely redistributed from the vascular to the interstitial space (Fig.2).
Fig. 2: Diagram demonstrating pharmakodynamics of the extracellular contrast agents (red circles).
References: Department of diagnostic radiology,Theodor Bilharz research institute,Cairo/EG
-Delayed enhancement in hepatic lesions can be attributed to:
- Presence of abundant fibrous tissue in the tumor e.g. cholangiocarcinoma or hepatic parenchymal fibrosis e.g. confluent hepatic fibrosis. Contrast medium is retained by such fibrous stroma with large interstitial spaces because of the slow back diffusion of contrast media into the vascular space from fibrous tissue (Fig.3a).
- Longer retention of contrast agents in the large intravascular spaces as a result of slow flow or partial thrombosis e.g. hemangioma (Fig.3b).
Fig. 3: Diagram demonstrating causes of prolonged contrast retention on delayed MRI images.
References: Department of diagnostic radiology,Theodor Bilharz research institute, Cairo/EG