Less is better? Intraindividual and interindividual comparison between 0.075 mmol/kg of gadobenate dimeglumine and 0.1 mmol/kg of gadoterate meglumine for cranial MRI

Purpose To retrospectively compare a reduced dose (RD) (0.075 mmol/kg) of gadobenate dimeglumine (RD-gadobenate) with standard single dose (SSD) (0.1 mmol/kg) of gadoterate meglumine (SSD-gadoterate) for cranial MRI. Materials and methods Thirty-one patients (12 males; aged 52 ± 16 years) underwent cranial MRI with SSD-gadoterate and repeated the examination with RD-gadobenate after a median interval of 10 months. Signal-to-noise ratio (SNR) was obtained on contrast-enhanced images for enhancing lesions (n = 10) as well as for right and left transverse venous sinuses, internal carotid arteries, and parotid glands. Moreover, a consecutive series of 100 cranial MRI with SSD-gadoterate (49 males; aged 51 ± 19 years) was compared with a consecutive series of 100 cranial MRI with RD-gadobenate (45 males; aged 54 ± 18 years). Two blinded neuroradiologists (R1, R2) judged contrast enhancement as sufficient, good, or optimal. Wilcoxon, Mann-Whitney, χ², and Cohen κ statistics were used. Results At intraindividual analysis, median SNR ranged 57-88 for SSD-gadoterate and 79-99 for RD-gadobenate, the latter being systematically higher, the difference being significant for both transverse venous sinuses (p ≤ 0.011), not significant for both internal carotid arteries and both parotid glands, and enhancing lesions (p 0.101). The two series of interindividual analysis were not significantly different for gender/age (p > 0.415). Contrast enhancement was optimal in 59% (R1) and 76% (R2) of patients using RD-gadobenate, in 39% (R1) and 49% (R2) of patients using SSD-gadoterate (p ≤ 0.016), with substantial reproducibility (κ ≥ 0.606). Conclusion Both analyses showed an equal or better contrast enhancement when using RD-gadobenate compared to SSD-gadoterate for routine cranial MRI. The high relaxivity of gadobenate allowed for a 25% dose reduction.