Why MRI Contrast Agents Are Not Interchangeable for Detecting Brain Metastases

MRI contrast agents are often treated as interchangeable in clinical practice, but their relaxivity can vary considerably between products. That distinction carries different weight depending on what a scan is being used to detect. For benign lesions such as meningiomas or schwannomas, a weaker, cheaper, and safer contrast agent may be adequate. For small enhancing lesions, a category that includes brain metastases as well as non-oncologic findings such as demyelinating lesions in multiple sclerosis, the strength of the contrast agent used can determine whether a lesion is detected at all.

In an interview with CancerNetwork® at the 2026 SNO/ASCO CNS Metastases Conference, Josef Vymazal, MD, head of the Department of Radiology and deputy director for Science and Research at Faculty Hospital Motol and Homolka, and a full professor at Charles University in Prague, Czech Republic, explained why this distinction motivated his research group to focus on gadopiclenol, a contrast agent with the highest relaxivity currently available on the market. Vymazal presented findings from a prospective, single-center study which enrolled 156 patients, 73 of whom were female, with a mean age of 63.8 years (± 12.6), who underwent 3T MRI in 152 cases prior to stereotactic radiosurgery. All patients underwent standard postcontrast T1-weighted 3D SPACE acquisitions using the recommended dose of gadopiclenol (0.05 mmol/kg). Three blinded neuroradiologists independently evaluated all scans across 4 separate reading sessions, each conducted a minimum of 4 weeks apart, with detected lesions classified under both a strict, unanimous reference standard and a majority, 2-of-3 reference standard.

Vymazal noted that gadopiclenol’s potency allows it to be approved at half the dose typically used for other macrocyclic contrast agents, a property his team hypothesized would translate into improved detection of the smallest metastatic lesions.

Transcript:

CancerNetwork: What was the rationale behind focusing on this particular contrast agent for detecting brain metastases?

Vymazal: It is important to bear in mind that MR contrast agents are not equal. There is even more difference than in CT, and [it] is very important not only for radiologists but also for neuro-oncologists, for neurosurgeons, that there is a huge difference between individual contrast agents. In layman’s language, I can say that some of these contrast agents are very weak, and some of them are very strong. If the contrast agent is weak, it does not mean that it’s a bad contrast agent. It can be cheap, it can be very safe, and for detecting benign brain tumors like meningiomas or schwannomas, I really don’t care if the final image is a bit [grayer] or a bit [brighter]. But for detecting small enhancing lesions, which don’t have to be brain metastases in the first place, but can be also small demyelinating lesions like in multiple sclerosis, it is very important to use contrast agents that are strong—that have high relaxivity. We have been working with a contrast agent that has the highest relaxivity on the market. Maybe next year will be different, but now it has the highest relaxivity, so we assume that we will be able to detect the smallest metastatic lesions with this contrast agent. Because this contrast agent is so strong, so powerful, it is approved at half dose compared with other macrocyclic or contrast agents that are used in clinical practice.

Reference

Vymazal J, Ryznarova Z, Keller J, Liscak R, Rulseh A. Comparison of delayed and double-dose MRI for detection of brain metastases with gadopiclenol prior to stereotactic radiosurgery. Neurooncol Adv. 2026;8(Suppl 6):vdag161.062. doi:10.1093/noajnl/vdag161.062