Estimation of Kidney Oxygenation by Blood Oxygenation Level Dependent Magnetic Resonance Imaging

Li, Luping; Prasad, Pottumarthi V.

doi:10.1007/978-1-60761-857-7_30

Cited by 1 publication

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“…Renal blood oxygenation level-dependent (BOLD) magnetic resonance imaging is currently the only known non-invasive method that can be used to evaluate renal oxygenation in humans 3,4 . Extensive research has shown that this technique has the ability to detect intra-subject changes following various interventions 3,5–7 .…”

Section: Introductionmentioning

confidence: 99%

Renal Blood Oxygenation Level-Dependent Magnetic Resonance Imaging

Thacker¹,

Li²,

Li³

et al. 2015

Investigative Radiology

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Objectives To determine a robust (sensitive and objective) method for analyzing renal blood oxygenation level-dependent (BOLD) MRI data. Materials and Methods 47 subjects (30 with Chronic Kidney Disease and 17 controls) were imaged at baseline and following furosemide with a multi-echo gradient recalled echo sequence. Conventional analysis consisted of regional segmentation (small-cortex, large-cortex and medulla), followed by computing the mean of each region. Additionally, we segmented the entire parenchyma and computed the mean (μ1) plus higher moments (μ2, μ3, and μ4). Two raters performed each of the segmentation steps and agreement was assessed with intra-class correlation coefficients (ICC). We used a measure of effect size (Cohen’s d value), in addition to the usual measure of statistical significance, p-values, for determining significant results. Results The mean of the renal parenchyma showed the highest agreement between raters (ICC=0.99), and the higher parenchyma moments were on par with large cortical ROI ICC. The renal parenchymal mean also exhibited significant sensitivity to changes post-furosemide in healthy subjects (p=0.002, d=0.84); in agreement with medullary ROIs (p=0.002, d=1.59). When comparing controls and subjects with CKD at baseline, cortical ROI showed a significant difference (p=0.015, d=−0.69) while the parenchyma ROI did not (p=0.152, d=0.39). Post-furosemide data in all regions resulted in a significant difference (large-cortex: p=0.026, d=−0.51; medulla: p=0.019, d=−0.61) with the renal parenchyma ROI resulting in the largest effect size (p=0.003, d=−0.75). Higher moments of the renal parenchyma showed similar significant differences as well. Conclusions Overall, our data support the use of the entire parenchyma to evaluate changes in the medulla following administration of furosemide, a widely used pharmacological maneuver. Changes in higher moments indicate that there is more than just a shift in the mean renal R2* and may provide clinically relevant information without the need for subjective regional segmentation. For evaluating differences between controls and subjects with CKD at baseline; large cortical ROI provided the highest sensitivity and objectivity. A combination of renal parenchyma assessment and large cortical ROI may provide the most robust method of evaluating renal BOLD MRI data.

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