MRI detects tubulointerstitial changes in mouse models of radiation‐induced nephropathy

Abstract Purpose We hypothesized that radiation‐induced tubulointerstitial changes in the kidney can be assessed using MRI‐based T 2 relaxation time measurements. Methods We performed MRI, histology, and serum biochemistry in two mouse models of radiation nephropathy: one involving external beam radiotherapy and the other using internal irradiation with an α‐particle‐emitting actinium‐225 radiolabeled antibody. We compared the mean T 2 values of different renal compartments between control and external beam radiotherapy or α‐particle‐emitting actinium‐225 radiolabeled antibody–treated groups and between the two radiation‐treated groups using a Wilcoxon rank‐sum test. Results Significantly higher T 2 values were found in the cortex and outer stripe of the outer medulla in all treated animals compared with the control group ( p  < 0.05). In addition, these changes in T 2 were observed before any changes in serum parameters, animal body weight, and kidney volume occurred. Conclusion T 2 mapping is sensitive to radiation‐induced tubulointerstitial changes in the kidney.