![]() ![]() 18-21 However, Gd retention has been shown to occur to some degree with all GBCAs, even in patients with normal renal function and an intact blood-brain barrier. Early studies investigating this phenomenon showed that Gd retention tends to be higher in patients who had received multiple and/or higher doses of a linear GBCA vs a macrocyclic GBCA. 17 Such enhancement was confirmed to be the result of trace quantities of Gd retained in the brain of patients who had received a contrast-enhanced scan in the past. Starting in 2014, several groups found that visible areas of T1 shortening could be identified on noncontrast MR images of the brain, specifically in the dentate, red nucleus, and globus pallidus. Effects of Stability and Relaxivity on Safety and Efficacy Greater Stability → Less Gd Release Here, we present discussions from a recent Expert Panel Forum focused on the safety and efficacy of GBCAs, as well as specific considerations related to GBCA selection for neuroimaging, pediatric imaging, body imaging, and breast imaging applications. Additional factors may include cost, ease of use, and approved indications, as well as any physician, pharmacy, and/or patient preferences. Familiarity with different safety and efficacy profiles of the various GBCAs can be beneficial in the clinical decision-making involved in GBCA selection. GBCA selection should be tailored to the individual patient and clinical setting following a careful risk-benefit analysis, implemented at the individual or protocol level by the radiologist. 16 (Table 1) This higher relaxivity has been demonstrated in dozens of studies to translate into superior performance for MR applications in the central nervous system, liver, breast, and vascular system (as summarized in the next section). The chelate structure also impacts the relaxivity, or r value, of the GBCA, which dictates the ability to provide contrast relative to background &emdash the higher the r1, the greater the signal intensity of the enhancing tissue or structure on T1-weighted images. In general, macrocyclic agents are more stable than linear agents and, therefore, are less likely to dissociate and release free Gd. ![]() Specifically, whether the chelate is linear or macrocyclic and ionic or nonionic impacts the size and stability of the Gd-chelate complex, as well as its distribution and elimination. The structure of each chelate imparts unique characteristics to that GBCA. Gadolinium-based contrast agents comprise a gadolinium (Gd) ion bound to an organic ligand to form a chelate. 9 The standard-relaxivity linear agents, Magnevist (gadopentetate dimeglumine) and OptiMARK (gadoversetamide), have been discontinued. 2-6 In addition, Clariscan™ (gadoterate meglumine), a generic version of Dotarem, has recently become available. (Table 1) These agents are the macrocyclic agents Dotarem® (gadoterate meglumine) Gadavist® (gadobutrol) and ProHance® (gadoteridol) the high-relaxivity linear agent MultiHance® (gadobenate dimeglumine) and the standard-relaxivity linear agent Omniscan™ (gadodiamide). 1 Currently, 6 general-use GBCAs are available and approved for a variety of MRI indications, including brain, body, and breast imaging in adults and children. With more than 450 million doses administered worldwide over the past 4 decades, GBCAs have a proven record of both safety and efficacy. Gadolinium-based contrast agents (GBCAs) are frequently administered to improve the sensitivity and/or specificity of diagnostic magnetic resonance imaging (MRI).
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