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

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 alpha-particle-emitting actinium-225 radiolabeled antibody. We compared the mean T2 values of different renal compartments between control and external beam radiotherapy or alpha-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.