Figure 1.

Multiparametric MRI for monitoring cancer immunotherapy. (A) Schematic diagram of the multiparametric MRI approach used for investigating changes in tumor volume (T₂-weighted MRI), vascular permeability (DCE-MRI), tumor cellularity and heterogeneity (DKI) in patients with metastatic melanoma receiving immune checkpoint inhibitors. (B) Intertumoral differences in treatment response, vascular permeability, and cellularity were detected in a patient with metastatic melanoma during the first 12 weeks of treatment with nivolumab. Quantitative maps of tumor vascular permeability (K^trans ) and tumor cellularity (D_app ) were shown with corresponding changes in tumor volume measured on T₂-weighted MRI. Images reproduced with permission from Lau et al.5 D_app, apparent diffusivity; DCE, dynamic contrast-enhanced; DKI, diffusion kurtosis imaging; K^trans, the volume transfer constant from the blood plasma to the extravascular tumor interstitial space.