Mean Standard Uptake Values Ratios (SUVR) will be calculated with cerebellar gray matter activity as reference in volumes of interest. Voxel-wise uptake will then be divided by this reference value to get SUVR maps. PET images will be corrected for motion and partial volume effect thanks to simultaneous MRI acquisition. To analyze the longitudinal PET data, each follow-up T1-weighted MRI will be co-registered to the baseline MRI, and a within-subject template image will be calculated by averaging the coregistered T1-weighted images. This mean image will be used to calculate optimal transformation parameters to Montreal Neurological Institute (MNI) space. Next, baseline and follow-up PET images will be co-registered to the baseline MRI, spatially normalized to MNI using this optimal transformation, and scaled with cerebellar gray uptake. Individual percent annual changes maps will be then calculated. These maps will represent the voxel-wise calculation of percent metabolic change after BBB opening.