5/16/2023 0 Comments Mr contrast agents radiology![]() ![]() A central scar is usually present however, central scars can also be seen in other tumors. On MRI, FNH may have subtle, low signal intensity on T1-weighted images and minimal, high signal intensity on T2-weighted images. 1- 6 The contrast enhancement quickly equilibrates with the normal liver parenchyma during the portal venous phase, and the lesion may be difficult to visualize (Fig. The typical appearance of FNH is a diffusely homogeneous, hyperenhancing, slightly lobulated mass during the arterial phase of imaging (Fig. On ultrasound, they are typically echogenic with through transmission, but they may be hypoechoic in a fatty liver. On MRI, the lesions are usually well defined with high signal intensity on T2-weighted images. ![]() Small CHs may show more homogeneous flash filling during the early arterial phase. The degree, pattern, and temporal appearance of the enhancement are all helpful in the characterization of these masses.ĬHs typically show nodular or globular, discontinuous peripheral enhancement with progressive centripetal filling over time. Lesions that typically show arterial phase hyperenhancement include cavernous hemangioma (CH), focal nodular hyperplasia (FNH), hepatic adenoma (HA), hepatocellular carcinoma (HCC), fibrolamellar hepatocellular carcinoma (FL-HCC), and certain metastases (e.g., neuroendocrine tumors and breast cancer). Hepatic masses may be enhanced more than, less than, or equally to normal hepatic parenchyma this depends on the nature of the lesion, the timing of the scan with respect to the contrast bolus, and the attenuation of the liver during CT (e.g., normal attenuation versus low attenuation from fatty infiltration). However, the appearances may not always be typical. In many cases, a lesion can be diagnosed with certainty because of its characteristic appearance. Improvements in imaging technology and more widespread utilization of imaging techniques have led to increased detection of liver masses. AbbreviationsĬH, cavernous hemangioma CT, computed tomography FL-HCC, fibrolamellar hepatocellular carcinoma FNH, focal nodular hyperplasia HA, hepatic adenoma HCC, hepatocellular carcinoma MRI, magnetic resonance imaging NSF, nephrogenic systemic fibrosis. According to the morphology and enhancement characteristics, this mass is consistent with FNH. The enhancement during the hepatocyte phase suggests a tumor of hepatocyte origin with normally functioning hepatocytes. This mass retains contrast during the delayed hepatocyte phase. MRI with gadoxetate disodium during (B) the arterial phase, (C) the portal venous phase, and (D) the delayed hepatocyte phase shows a lobulated, hyperenhancing mass (arrows). (A) CT demonstrates a vague mass with some peripheral enhancement in the right lobe of the liver (arrows). In this context, the development of next-generation MR contrast agents should focus on high-stability and high-relaxivity GBCAs, such as gadopiclenol, which offer the possibility to adapt the administered Gd dose to each indication while ensuring an optimal patient safety.FNH: a 59-year-old woman with newly diagnosed renal cell carcinoma and a past history of oral contraceptive use. Despite the large research efforts to identify and develop alternative Gd-free MR agents, manganese- and iron-based contrast agents have failed to reach market approval. Altogether, GBCAs in combination with new MR techniques have found their place in the diagnostic pathway of various diseases. Besides, magnetic resonance imaging ( MRI) has benefited from MR technological advances, which provide alternative solutions to increase the MR signal, generate new contrasts on MRI scans, and accelerate their acquisition and analysis. Yet, following the recent discovery of Gd retention in brain, the same agencies adopted different positions ranging from suspension of marketing authorizations, changes in GBCA safety labeling, and performing preclinical and clinical studies to assess the potential long-term consequences of Gd accumulation on motor and cognitive functions. Approximately 10 years ago, the regulatory agencies decided to restrict the use of GBCAs to minimize the risk of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Despite their undisputable usefulness for disease diagnosis, gadolinium (Gd)-based contrast agents ( GBCAs) have gone through 2 major safety crises. ![]() This review summarizes 30 years of experience in the development and clinical use of magnetic resonance (MR) contrast agents. ![]()
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