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2410. Does the Higher Relaxivity of Gadobenate Dimeglumine Permit Gadolinium Dose-Lowering in MRI of the Central Nervous System (CNS)?
Authors * Denotes Presenting Author
  1. Mark DeLano *; Michigan State University
  2. Maria Spampinato; Medical University of South Carolina
  3. Eric Chang; VA San Diego Healthcare System
  4. Richard Barr; Southwoods Imaging
  5. Richard Lichtenstein; Sarasota Memorial Hospital
  6. Miles Kirchin; Bracco Imaging SPA
  7. Gianpaolo Pirovano; Bracco Diagnostics, Inc.
Objective:
Concern over possible long-term risks associated with Gd retention has encouraged the use of lower Gd doses at many centers. Gadobenate dimeglumine (MultiHance) has higher r1-relaxivity than other gadolinium-based Contrast Agents (GBCAs) (1). Previous studies have suggested this higher relaxivity may permit Gd dose lowering, particularly for contrast-enhanced MRI of the central nervous system (CNS) (2-6). We aimed to compare 0.05 and 0.1 mmol/kg bodyweight doses of gadobenate at 1.5T and 3T in patients undergoing CE-MRI of the CNS.

Materials and Methods:
352 patients who had received either 0.05 or 0.1 mmol/kg gadobenate for routine CE-MRI of the CNS, and had available pre- and postdose T1-SE/FSE, and/or T1-GRE, and T2-SE/FSE, and FLAIR MR images, were retrospectively enrolled at 7 centers in the USA. Images were prospectively reviewed by three blinded, independent neuroradiologists in terms of qualitative (delineation of lesion border, visualization of internal morphology, contrast enhancement of lesions; 4-point scales from 1=poor to 4=excellent) and quantitative (lesion-to-brain ratio, contrast-to-noise ratio) endpoints. The non-inferiority of the 0.05 mmol/kg dose was determined for each visualization endpoint based on the lower limit of the 95% confidence interval for the difference in pre + postdose means between the 0.05 and 0.1 mmol/kg doses. A non-inferiority margin of -0.4 was defined.

Results:
181 (109M/72F) patients received 0.05 mmol/kg gadobenate and 171 (79/92F) received 0.1 mmol/kg gadobenate. The mean change in visualization endpoint from predose to pre+postdose was in all cases significant (p<0.0001). Readers 1, 2 and 3 evaluated 163, 165 and 164 patients and 304, 225 and 249 lesions in the 0.05 mmol/kg group, and 158, 161, and 160 patients and 382, 309 and 298 lesions in the 0.1 mmol/kg group. The lower limit of the 95% confidence interval for the difference in pre + postdose means was above the non-inferiority margin of -0.4 for all comparisons confirming that 0.05 mmol/kg gadobenate was non-inferior to 0.1 mmol/kg gadobenate for lesion visualization. This was true for sub-analyses of patients with extra-axial lesions imaged at 1.5T and patients with any CNS disease imaged at 3T. Quantitative analysis confirmed significantly higher LBRs and CNRs with the higher dose.

Conclusion:
A gadobenate dose of 0.05 mmol/kg is non-inferior to 0.1 mmol/kg gadobenate for lesion visualization and may be considered appropriate if Gd dose reduction is a priority.