Gadolinium-based contrast agents (GBCAs) have an excellent safety profile. However, over the last 2 decades, two specific concerns have surfaced. GBCAs are associated with nephrogenic systemic fibrosis (NSF) and tissue retention of gadolinium. NSF is a rare fibrosing disorder with a poor prognosis, which is characterized by skin and subcutaneous thickening as well as systemic manifestations. The disease has been reported exclusively in patients with advanced renal disease, and it is associated with higher doses and specific types of GBCAs. The number of new cases of NSF has fallen over the past decade, presumably because of adherence by health care providers to regulatory guidelines, which continue to evolve. While gadolinium retention has been known to occur in the liver and bones, the relatively recent findings of deposition and retention in the brain have reignited the debate concerning the safety profile of GBCAs. Despite these concerns, there have been no proven health effects related to gadolinium deposition and retention other than NSF. The authors review the different categories of GBCAs available for commercial use, discuss NSF and gadolinium retention in the brain, and provide updates on the latest U.S. and European regulatory guidelines regarding use of these agents. Given the frequency with which GBCAs are used in clinical practice, it is imperative for all radiologists to learn the current guidelines to provide the safest and highest quality of patient care. ©

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We read with great interest the review on novel cryoablation therapy for cholecystitis by McNiel et al. 1 Surgical cholecystectomy is the gold standard of treatment for acute cholecystitis according to recently updated Tokyo guidelines. 2 We agree with McNiel et al that a definitive management of cholecystitis in patients who are not surgical candidates remains a significant clinical need.Traditionally, percutaneous cholecystostomy drainage (PCD) is performed when patients are considered poor surgical candidates. If there is no improvement of surgical candidacy, then PCD remains as a permanent drain. Percutaneous cholecystostomy drainage has many potential risks such as bleeding, bile leak, tube dislodgement, pain at the insertion site, cosmetic issues, and decreased quality of life.Although, as stated by McNeil et al, 1 cryoablation offers a novel method, this still requires PCD with several sessions with uncertain benefits at this stage.Endoscopic transpapillary gallbladder drainage via endoscopic retrograde cholangiopancreatography and endoscopic ultrasound-guided transmural gallbladder drainage (EUS-GBD) are two other minimally invasive alternative techniques for gallbladder drainage. Over the past few years, there has been progress in the EUS-GBD technique, including use of covered self-expanding metal stents and lumen-apposing metal stents. 3 Endoscopic ultrasound-guided transmural gallbladder drainage with creation of cholecystoduodenostomy or cholecystogastrostomy is a minimally invasive option for patients with cholecystitis who are poor surgical candidates. Previous studies have shown that EUS-GBD can sustain and improve quality of life when compared with PCD. 4 Endoscopic ultrasound-guided transmural gallbladder drainage offers a potential cost-saving benefit and morbidity benefit by demonstrating a decreased number of repeat interventions. Our group demonstrated that EUS-GBD is safer even in high-cirrhotic patients with low platelet counts. 5 The special design of the stent used in this procedure aids in good apposition of gallbladder to duodenum and stomach and reduces the risk of adverse events. Recent studies comparing the outcomes of EUS-GBD using lumenapposing metal stents with percutaneous cholecystostomy have reported results favoring EUS-GBD because of lower rates of adverse events with excellent long-term outcomes. 1,6 According to an international survey, patients overwhelmingly prefer an internal biliary drainage over a percutaneous drain. 7 Endoscopic ultrasound-guided drainage has evolved as a minimally invasive, definitive treatment option for management of cholecystitis in patients who are not surgical candidates.