These include any enhancement observed with gadolinium in MRI scans, the proliferation rate indicated by the Ki-67/MIB-1 index, a high uptake value from 18F-fluoroethyl-tyrosine (FET) positron emission tomography (PET) scans, and the indirect measurement of tumor cell density through apparent diffusion coefficient imaging [17]. The gene discussed is MKI67; the disease is neoplasm.