BOLD-MRI assessment of intrarenal oxygenation and oxidative stress in patients with chronic kidney allograft dysfunction

Abstract

Blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) uses deoxyhemoglobin as an endogenous contrast agent for the noninvasive assessment of tissue oxygen bioavailability. We hypothesized that intrarenal oxygenation was impaired in patients with chronic allograft nephropathy (CAN). Ten kidney-transplant recipients with CAN and nine healthy volunteers underwent BOLD-MRI. Medullary R2* (MR2*) and cortical R2* (CR2*) levels (measures directly proportional to tissue deoxyhemoglobin levels) were determined alongside urine and serum markers of oxidative stress (OS): hydrogen peroxide (H(2)O(2)), F(2)-isoprostanes, total nitric oxide (NO), heat shock protein 27 (HSP27), and total antioxidant property (TAOP). Mean MR2* and CR2* levels were significantly decreased in CAN (increased local oxyhemoglobin concentration) compared with healthy volunteers (20.7 +/- 1.6 vs. 23.1 +/- 1.8/s, P = 0.03 and 15.9 +/- 1.9 vs. 13.6 +/- 2.3/s, P = 0.05, respectively). There was a significant increase in serum and urine levels of H(2)O(2) and serum HSP27 levels in patients with CAN. Conversely, urine NO levels and TAOP were significantly increased in healthy volunteers. Multiple linear regression analyses showed a significant association between MR2* and CR2* levels and serum/urine biomarkers of OS. BOLD-MRI demonstrated significant changes in medullary and cortical oxygen bioavailability in allografts with CAN. These correlated with serum/urine biomarkers of OS, suggesting an association between intrarenal oxygenation and OS.

Blood oxygenation level-dependent MRI for assessment of renal oxygenation

“…36 In healthy subjects (n=9) studied 2 hours after administration of an angiotensin receptor antagonist, cortical but not medullary oxygenation increased. 37 In another group of healthy subjects (n=5), no change in oxygenation of the renal cortex or medulla was observed after chronic treatment with a direct renin inhibitor or after acute administration of an angiotensin-converting enzyme inhibitor. 38 Similarly, no change in cortical oxygenation was observed after acute administration of an angiotensin receptor antagonist in healthy subjects.…”

Kidney transplantation: Structural and functional evaluation using MR Nephro‐Urography

“…Blood oxygen level dependant (BOLD) MRI has the ability to detect changes in hemoglobin oxygenation due to the dephasing effects of deoxyhemoglobin (26,27). This allows for a noninvasive measure of renal tissue oxygenation (28), and has been advocated for use in differentiating ATN and rejection in the transplant kidney (29). Diffusion-weighted imaging and renal elastography are additional methods of interest (25,30) that have been used experimentally to evaluate the kidney, but have not yet shown utility for quantitative determination of renal function.…”

Protective Effect of Hydrogen-rich Water against Gentamicin-induced Nephrotoxicity in Rats using Blood Oxygenation Level-dependent MR Imaging

“…[15][16][17][18][19] As previously described, BOLD MRI can provide images of renal function with high spatial resolution without the use of ionizing radiation and injection of contrast agents that may aggravate acute renal failure. 21 Furthermore, BOLD MRI allows repeated measurements in a single animal and simultaneous evaluation of individual renal morphology and …”

“…Blood oxygenation level-dependent magnetic resonance imaging (BOLD MRI) provides images of renal function that are useful for evaluating in- trarenal oxygenation, [15][16][17][18][19] an important factor responsible for the onset and progression of renal failure. 17,19 To the best of our knowledge, no reports have investigated intrarenal oxygenation in GM-induced nephrotoxicity and the protective eŠect of HW against this nephrotoxicity, so we undertook this investigation in rats using BOLD MRI.…”