Previous studies showed that fast‐growing tumors showed higher vascular permeability and capillary density on MRI and histopathology, respectively, compared to the slow‐growing tumor model,(18) because highly vascularized tumors have increased levels of vascular endothelial growth factor (VEGF).(19) Although both kep and Ktrans reflected vascular permeability, kep was presently more sensitive than Ktrans in distinguishing MO cancers from MV cancers. The gene discussed is VEGFA; the disease is cancer.