Evaluation of the reproducibility of intrarenal R*2 and ΔR*2 measurements following administration of furosemide and during waterload

Purpose: To estimate the reproducibility of BOLD MRI measurements in the evaluation of intrarenal oxygenation levels. Materials and Methods: In this study, the reproducibility of semiquantitative BOLD MRI measurements performed on a 1.5 T scanner with a multiple gradient-echo sequence in the renal medulla and cortex, and their response to furosemide and waterload, were assessed in eight healthy young subjects (25.6 +/- 4.1 years). Each subject underwent an identical experimental procedure on two separate days. Results: Renal R-2* measurements were shown to be reproducible within similar to12% from day to day based on a coefficient of variance (CV) analysis. The changes in R-2* (DeltaR(2)*) following administration of furosemide were statistically significant, as shown by ANOVA and a paired Student's t-test, and were deemed reliable based on the reliable change index (RCI). However, DeltaR(2)* values following waterload were not statistically significant, and were not deemed reliable. Conclusion: R2* measurements were reproducible over 270 days within 12%. Furosemide produced a significant and reliable change (similar to30%), and the magnitude of change (5.7 s(-1)) was reproducible and consistent with our previous data. The response to waterload, however, did not reach statistical significance, and the magnitude did not reach the level that we had previously reported.