MRI of renal oxygenation and function after normothermic ischemia–reperfusion injury

Abstract

The in vivo assessment of renal damage after ischemia-reperfusion injury, such as in sepsis, hypovolemic shock or after transplantation, is a major challenge. This injury often results in temporary or permanent nonfunction. In order to improve the clinical outcome of the kidneys, novel therapies are currently being developed that limit renal ischemia-reperfusion injury. However, to fully address their therapeutic potential, noninvasive imaging methods are required which allow the in vivo visualization of different renal compartments and the evaluation of kidney function. In this study, MRI was applied to study kidney oxygenation and function in a murine model of renal ischemia-reperfusion injury at 7 T. During ischemia, there was a strongly decreased oxygenation, as measured using blood oxygen level-dependent MRI, compared with the contralateral control, which persisted after reperfusion. Moreover, it was possible to visualize differences in oxygenation between the different functional regions of the injured kidney. Dynamic contrast-enhanced MRI revealed a significantly reduced renal function, comprising perfusion and filtration, at 24 h after reperfusion. In conclusion, MRI is suitable for the noninvasive evaluation of renal oxygenation and function. Blood oxygen level-dependent or dynamic contrast-enhanced MRI may allow the early detection of renal pathology in patients with ischemia-reperfusion injury, such as in sepsis, hypovolemic shock or after transplantation, and consequently may lead to an earlier intervention or change of therapy to minimize kidney damage.

Blood oxygenation level-dependent MRI for assessment of renal oxygenation

“…In mice studied with BOLD MRI 1 hour and 24 hours after reperfusion, cortical oxygenation was increased, whereas outer medullary hypoxia persisted. 53 After longer periods of reperfusion in the rat (3 days), medullary oxygenation was increased despite a reduction in medullary blood flow, with no change in cortical pO 2 . 54 Hyperoxia after ischemia/ reperfusion injury may be explained if reduced oxygen consumption due to reduced Cortex Epstein et al 33 Wang et al 50 Economides et al 34 Pruijm et al 26 …”

High-resolution renal perfusion mapping using contrast-enhanced ultrasonography in ischemia-reperfusion injury monitors changes in renal microperfusion

“…The post-ischemia perfusion to the outer medulla is decreased disproportionately to the reduction in total kidney perfusion (3-6)) and likely in patients following ischemic injury (7). The local perfusion in the outer medulla can be reduced due to arteriolar vasoconstriction, endothelial injury, and local interstitial edema secondary to increased capillary permeability.…”

Magnetic Resonance Spectroscopy (MRS) in Kidney Transplantation: Interest and Perspectives

“…In a murine model, BOLD MRI of a clamped kidney showed the decreased oxygenation of all regions. 24 hours after reperfusion, a lower reoxygenation of the outer medulla than control was found, and a higher reoxygenation of the cortex and an identical reoxygenation of the inner medulla were determined (Oostendorp et al, 2011). These results highlighted the potential of BOLD MRI for the detection of change in kidney tissue oxygenation.…”