What class of gadolinium-based contrast agents does the ACR indicate does not require obtaining a patient's eGFR?

The ACR (American College of Radiology) guidelines classify gadolinium-based contrast agents into different groups based on their safety profile and the risks associated with their use, particularly concerning nephrogenic systemic fibrosis (NSF) in patients with renal impairment. Group 2 agents are specifically designed to have a very low risk of causing NSF, which allows for their use in patients without the need for an eGFR (estimated Glomerular Filtration Rate) assessment prior to administration. This simplifies the process of administering these contrast agents, especially in emergency situations or when time is of the essence.

In contrast, Group 1 agents are associated with a higher risk of NSF in patients with renal dysfunction, thus necessitating an eGFR determination to evaluate the patient's kidney function before use. Groups 3 and 4 also include agents that may have specific renal safety considerations, meaning that obtaining an eGFR would be standard practice for them as well.

Therefore, recognizing that Group 2 agents have a favorable safety profile which negates the need for renal function assessment is crucial to understanding the rationale behind the guidelines and their implications in clinical practice.