The biological meaning of MRI-based biomarkers of cancer can be studied using spatially matched histologically stained tumor sections. However, correlations are often weak or contradictory, possibly due to confounding necrosis that models fail to describe. In this work, we demonstrate the potential of using VERDICT MRI model parameters to separate necrosis from viable tumor tissue non-invasively. Radiation treated tumors demonstrating large necrotic and viable regions are imaged, excised and stained using immunohistochemical methods. Correlations between spatially matched VERDICT and immunohistochemical maps reveal that VERDICT clearly separates necrosis from viable tumor.