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Genitourinary Imaging |
1 From the Department of Radiology, Neuroradiology and Nuclear Medicine (H.C.T., S.S.), Department of Urology (T.M.K., U.E.S.), Department of Nephrology and Hypertension (M.M.), and Department of Clinical Research (P.V.), University Hospital of Bern, Inselspital, Freiburgstrasse 10, CH-3010 Bern, Switzerland; and Department of Radiology, University Hospitals of Leuven, Leuven, Belgium (F.D.K.). Received May 22, 2007; revision requested July 24; revision received August 17; accepted September 12; final version accepted November 1. H.C.T. supported by a research grant from the Swiss National Foundation, National Center of Competence in Research, "Computer-aided and image-guided medical interventions," NCCR CO-ME, and a grant from the H.E.M. Foundation, Liechtenstein. Address correspondence to H.C.T. (e-mail: Harriet.Thoeny{at}insel.ch).
Purpose: To prospectively determine if changes in intrarenal oxygenation during acute unilateral ureteral obstruction can be depicted with blood oxygen level–dependent (BOLD) magnetic resonance (MR) imaging.
Materials and Methods: The study was approved by the local ethics committee, and written informed consent was obtained from all patients. BOLD MR imaging was performed in 10 male patients (mean age, 45 years ± 17 [standard deviation]; range, 20–73 years) with a distal unilateral ureteral calculus and in 10 healthy age-matched male volunteers to estimate R2*, which is inversely related to tissue Po2. R2* values were determined in the cortex and medulla of the obstructed and the contralateral nonobstructed kidneys. To reduce external effects on R2*, the R2* ratio between the medulla and cortex was also analyzed. Statistical analysis was performed with nonparametric rank tests. P < .05 was considered to indicate a significant difference.
Results: All patients had significantly lower medullary and cortical R2* values in the obstructed kidney (median R2* in medulla, 10.9 sec–1 [range, 9.1–14.3 sec–1]; median R2* in cortex, 10.4 sec–1 [range, 9.7–11.3 sec–1]) than in the nonobstructed kidney (median R2* in medulla, 17.2 sec–1 [range, 14.6–23.2 sec–1], P = .005; median R2* in cortex, 11.7 sec–1 [range, 11.0–14.0 sec–1], P = .005); values in the obstructed kidneys were also significantly lower than values in the kidneys of healthy control subjects (median R2* in medulla, 16.1 sec–1 [range, 13.9–18.1 sec–1], P < .001; median R2* in cortex, 11.6 sec–1 [range, 10.5–12.9 sec–1], P < .001). R2* ratios in the obstructed kidneys (median, 1.06; range, 0.85–1.27) were significantly lower than those in the nonobstructed kidneys (median, 1.49; range, 1.26–1.71; P = .005) and those in the kidneys of healthy control subjects (median, 1.38; range, 1.23–1.47; P < .001). In contrast, R2* ratios in the nonobstructed kidneys of patients were significantly higher than those in kidneys of healthy control subjects (P = .01).
Conclusion: Increased oxygen content in the renal cortex and medulla occurs with acute unilateral ureteral obstruction, suggesting reduced function of the affected kidney.
© RSNA, 2008
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Radiology 2008 247: 595-596.
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  Z. J. Wang and B. M. Yeh Is Assessing Renal Oxygenation by Using Blood Oxygen Level-Dependent MR Imaging a Clinical Reality? Radiology, June 1, 2008; 247(3): 595 - 596. [Full Text] [PDF]
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