TMEM97 and neoplasm: In this work, the sigma-2 receptor ligand 2-(2-[18F]fluoroethoxy)-N-(4-(3,4-dihydro-6,7-dimethoxyisoquinolin-2(1H)-yl)butyl)-5-methylbenzamide, [18F]ISO-1 [16], was used to assess two clinically-relevant properties of breast tumors: a) measurement of the proliferative status of the tumor; and, b) prediction of the volumetric change associated with tumor growth.