Evaluation of pressure-driven brain infusions in nonhuman primates by intra-operative 7 tesla MRI

Purpose: To characterize the effects of pressure‐driven brain infusions using high field intra‐operative MRI. Understanding these effects is critical for upcoming neurodegeneration and oncology trials using convection‐enhanced delivery (CED) to achieve large drug distributions with minimal off‐target exposure. Materials and Methods: High‐resolution T2‐weighted and diffusion‐tensor images were acquired serially on a 7 Tesla MRI scanner during six CED infusions in nonhuman primates. The images were used to evaluate the size, distribution, diffusivity, and temporal dynamics of the infusions. Results: The infusion distribution had high contrast in the T2‐weighted images. Diffusion tensor images showed the infusion increased diffusivity, reduced tortuosity, and reduced anisotropy. These results suggested CED caused an increase in the extracellular space. Conclusion: High‐field intra‐operative MRI can be used to monitor the distribution of infusate and changes in the geometry of the brain's porous matrix. These techniques could be used to optimize the effectiveness of pressure‐driven drug delivery to the brain. J. Magn. Reson. Imaging 2012; 36:1339–1346. © 2012 Wiley Periodicals, Inc.