Evaluation of intrarenal oxygenation by BOLD MRI at 3.0T

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Abstract
Purpose To examine the benefit of using higher field strengths for BOLD MRI to detect changes in renal medullary oxygenation following pharmacological maneuvers. Materials and Methods Renal BOLD MRI, primarily at 1.5T, has been shown to be useful for monitoring changes in medullary oxygenation status. We performed the present studies on a 3.0T scanner using a multiple gradient‐echo (mGRE) sequence with a multicoil array to acquire 16 T2*‐weighted images within a single breath‐hold. Data were obtained before and after administration of furosemide (20 mg iv). Results The baseline renal R2* (mean ± SE) at 3.0T was 37.4±1.2 Hz in the medulla, and 21.8 ± 1.2 Hz in the cortex. The BOLD response to furosemide (ΔR2*) at 3.0T was 11.8 ± 1.1 Hz in the medulla, and 3.0 ± 0.5 Hz in the cortex. Conclusion Higher magnetic field strength is beneficial for renal BOLD MRI studies. The cortico‐medullary contrast on the R2* map was significantly improved at 3.0T, with no evidence of increased bulk susceptibility artifacts. Baseline R2* and ΔR2* in the renal medulla at 3.0T were both significantly higher compared to our previously reported data obtained at 1.5T. J. Magn. Reson. Imaging 2004;20:901–904.