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High temporal resolution parametric MRI monitoring of the initial ischemia/reperfusion phase in experimental acute kidney injury.

Pohlmann A, Hentschel J, Fechner M, Hoff U, Bubalo G, Arakelyan K, Cantow K, Seeliger E, Flemming B, Waiczies H, Waiczies S, Schunck WH, Dragun D, Niendorf T - PLoS ONE (2013)

Bottom Line: There is an unmet need to better understand the mechanisms operative during the initial phase of ischemic AKI.Our study demonstrated for the first time that continuous and high temporal resolution parametric MRI is feasible for in-vivo monitoring and characterization of I/R induced AKI in rats.This technique may help in the identification of the timeline of key events responsible for development of renal damage in hypoperfusion-induced AKI.

View Article: PubMed Central - PubMed

Affiliation: Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine, Berlin, Germany. andreas.pohlmann@mdc-berlin.de

ABSTRACT
Ischemia/reperfusion (I/R) injury, a consequence of kidney hypoperfusion or temporary interruption of blood flow is a common cause of acute kidney injury (AKI). There is an unmet need to better understand the mechanisms operative during the initial phase of ischemic AKI. Non-invasive in vivo parametric magnetic resonance imaging (MRI) may elucidate spatio-temporal pathophysiological changes in the kidney by monitoring the MR relaxation parameters T2* and T2, which are known to be sensitive to blood oxygenation. The aim of our study was to establish the technical feasibility of fast continuous T2*/T2 mapping throughout renal I/R. MRI was combined with a remotely controlled I/R model and a segmentation model based semi-automated quantitative analysis. This technique enabled the detailed assessment of in vivo changes in all kidney regions during ischemia and early reperfusion. Significant changes in T2* and T2 were observed shortly after induction of renal ischemia and during the initial reperfusion phase. Our study demonstrated for the first time that continuous and high temporal resolution parametric MRI is feasible for in-vivo monitoring and characterization of I/R induced AKI in rats. This technique may help in the identification of the timeline of key events responsible for development of renal damage in hypoperfusion-induced AKI.

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Ischemia reperfusion experiments: T2*-weighted (MGE acquisition) and T2-weighted MR images (MSME acquisition) shown in gray scale together with color-coded T2* and T2 parameter maps.Alternating T2* and T2 measurements (MGE and MSME scans) were repeated continuously throughout the entire experiment (55 time points). Images and maps are shown for six time points: last baseline, onset of ischemia and end of ischemia after 45 minutes, onset of reperfusion, and 12 minutes and 100 minutes after onset of reperfusion. All parameter maps are shown in Figure S2.
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pone-0057411-g004: Ischemia reperfusion experiments: T2*-weighted (MGE acquisition) and T2-weighted MR images (MSME acquisition) shown in gray scale together with color-coded T2* and T2 parameter maps.Alternating T2* and T2 measurements (MGE and MSME scans) were repeated continuously throughout the entire experiment (55 time points). Images and maps are shown for six time points: last baseline, onset of ischemia and end of ischemia after 45 minutes, onset of reperfusion, and 12 minutes and 100 minutes after onset of reperfusion. All parameter maps are shown in Figure S2.

Mentions: Directly following surgery the animal was transferred to the warmed MRI animal bed. For the remainder of the experiment T2* and T2 were continuously monitored by interleaved T2*/T2 mapping with a temporal resolution of ∼3 minutes. After a baseline of five T2*/T2 measurements the hydraulic occluder around the aorta was temporarily closed and a vehicle (100 µl of saline containing 1% DMSO) administered. Thereafter, ischemia was induced by closing the hydraulic occluder around the renal artery and vein for 45 minutes, followed by a reperfusion phase of ∼100 minutes. Renal blood flow during the three phases of the I/R experiment was monitored by time-of-flight (TOF) MR angiographies of the kidney, acquired prior and immediately after ischemia induction, as well as after onset of reperfusion. The absence of the flow-dependent intra-vascular signal during ischemia served to confirm complete occlusion of the renal artery and vein. Figure 4 illustrates the experimental procedure, by showing the timeline and the corresponding T2*-weighted and T2-weighted MR images for six time points, together with T2* and T2 parameter maps.


High temporal resolution parametric MRI monitoring of the initial ischemia/reperfusion phase in experimental acute kidney injury.

Pohlmann A, Hentschel J, Fechner M, Hoff U, Bubalo G, Arakelyan K, Cantow K, Seeliger E, Flemming B, Waiczies H, Waiczies S, Schunck WH, Dragun D, Niendorf T - PLoS ONE (2013)

Ischemia reperfusion experiments: T2*-weighted (MGE acquisition) and T2-weighted MR images (MSME acquisition) shown in gray scale together with color-coded T2* and T2 parameter maps.Alternating T2* and T2 measurements (MGE and MSME scans) were repeated continuously throughout the entire experiment (55 time points). Images and maps are shown for six time points: last baseline, onset of ischemia and end of ischemia after 45 minutes, onset of reperfusion, and 12 minutes and 100 minutes after onset of reperfusion. All parameter maps are shown in Figure S2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585384&req=5

pone-0057411-g004: Ischemia reperfusion experiments: T2*-weighted (MGE acquisition) and T2-weighted MR images (MSME acquisition) shown in gray scale together with color-coded T2* and T2 parameter maps.Alternating T2* and T2 measurements (MGE and MSME scans) were repeated continuously throughout the entire experiment (55 time points). Images and maps are shown for six time points: last baseline, onset of ischemia and end of ischemia after 45 minutes, onset of reperfusion, and 12 minutes and 100 minutes after onset of reperfusion. All parameter maps are shown in Figure S2.
Mentions: Directly following surgery the animal was transferred to the warmed MRI animal bed. For the remainder of the experiment T2* and T2 were continuously monitored by interleaved T2*/T2 mapping with a temporal resolution of ∼3 minutes. After a baseline of five T2*/T2 measurements the hydraulic occluder around the aorta was temporarily closed and a vehicle (100 µl of saline containing 1% DMSO) administered. Thereafter, ischemia was induced by closing the hydraulic occluder around the renal artery and vein for 45 minutes, followed by a reperfusion phase of ∼100 minutes. Renal blood flow during the three phases of the I/R experiment was monitored by time-of-flight (TOF) MR angiographies of the kidney, acquired prior and immediately after ischemia induction, as well as after onset of reperfusion. The absence of the flow-dependent intra-vascular signal during ischemia served to confirm complete occlusion of the renal artery and vein. Figure 4 illustrates the experimental procedure, by showing the timeline and the corresponding T2*-weighted and T2-weighted MR images for six time points, together with T2* and T2 parameter maps.

Bottom Line: There is an unmet need to better understand the mechanisms operative during the initial phase of ischemic AKI.Our study demonstrated for the first time that continuous and high temporal resolution parametric MRI is feasible for in-vivo monitoring and characterization of I/R induced AKI in rats.This technique may help in the identification of the timeline of key events responsible for development of renal damage in hypoperfusion-induced AKI.

View Article: PubMed Central - PubMed

Affiliation: Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine, Berlin, Germany. andreas.pohlmann@mdc-berlin.de

ABSTRACT
Ischemia/reperfusion (I/R) injury, a consequence of kidney hypoperfusion or temporary interruption of blood flow is a common cause of acute kidney injury (AKI). There is an unmet need to better understand the mechanisms operative during the initial phase of ischemic AKI. Non-invasive in vivo parametric magnetic resonance imaging (MRI) may elucidate spatio-temporal pathophysiological changes in the kidney by monitoring the MR relaxation parameters T2* and T2, which are known to be sensitive to blood oxygenation. The aim of our study was to establish the technical feasibility of fast continuous T2*/T2 mapping throughout renal I/R. MRI was combined with a remotely controlled I/R model and a segmentation model based semi-automated quantitative analysis. This technique enabled the detailed assessment of in vivo changes in all kidney regions during ischemia and early reperfusion. Significant changes in T2* and T2 were observed shortly after induction of renal ischemia and during the initial reperfusion phase. Our study demonstrated for the first time that continuous and high temporal resolution parametric MRI is feasible for in-vivo monitoring and characterization of I/R induced AKI in rats. This technique may help in the identification of the timeline of key events responsible for development of renal damage in hypoperfusion-induced AKI.

Show MeSH
Related in: MedlinePlus