Comparative Evaluation of Lower Gadolinium Doses for MR Imaging of Meningiomas: How Low Can We Go?

BACKGROUND AND PURPOSE: Gadolinium-based contrast agents are widely used for meningioma imaging; however, concerns exist regarding their side effects, cost, and environmental impact. At the standard gadolinium dose, most meningiomas show avid contrast enhancement, suggesting that administering a smaller dose may be feasible. The purpose of this study was to evaluate the impact of a lower gadolinium dose on the differentiation between meningiomas and adjacent intracranial tissues.

MATERIALS AND METHODS: One hundred eight patients with presumed or confirmed meningiomas who underwent a brain MRI at multiple doses of gadolinium were included in the study. The patients’ MRIs were categorized into 3 groups based on the gadolinium dose administered: micro (approximately 25% of the standard dose), low (approximately 62% of the standard dose), and standard dose. Multireader qualitative visual assessment and quantitative relative signal differences calculations were performed to evaluate tumor differentiation from the cortex and from the dural venous sinus. The relative signal differences for each dose were analyzed by using ANOVA for quantitative assessment and the McNemar test for qualitative assessment. Additionally, noninferiority testing was used to compare the low and micro doses to the standard dose.

RESULTS: Decreasing the gadolinium dose to a low dose or micro dose resulted in a statistically significant decrease in signal difference between the tumor and the adjacent brain tissue (P < .02). However, on visual assessment, the low dose was noninferior to the standard dose. The proportion of cases with suboptimal differentiation was significantly higher for the micro dose than for the standard dose, both for the differentiation between the tumor and the cortex (P = .041) and the differentiation between the tumor and the sinus (P < .001).

CONCLUSIONS: Reducing the gadolinium dose to 62% of the standard level still allows for sufficient visual delineation of meningiomas from surrounding tissues. However, further reduction to 25% substantially compromises the ability to distinguish the tumor from adjacent structures and is, therefore, not advisable.