“…PPs, especially K trans , show a strong correlation with glioma grade [ 4 ]. However, there are different opinions on the reliability of using PPs in isolation for PCNSL, and most investigators are interested in enhancing the tumor parenchyma and not the peritumoral parenchyma [ [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] ]( Table 1 ). Theoretically, in GBM and PCNSL, abnormal peritumoral parenchyma signals are caused not only by changes in interstitial water but also by scattered tumor cell infiltration.…”