Semi-quantitative assessment for pre-post comparison method. (A) Enhancement distribution at range of 20%-100% defined with muscle ROI. (B) Brain masking: CSF – blue, grey matter – red, white matter – green. (C) Permeable pixels at region defined by total brain region mask. (D) Permeable pixels at region defined by brain tissue mask, excluding pixels relating to ventricles and subarachnoid space appearing in C. (E) Clustering procedure applied to D. Single pixels and regions smaller than minimal size of 10 pixels were removed.