Validation of quantitative BOLD MRI measurements in kidney: Application to unilateral ureteral obstruction

Pedersen, Michael; Dissing, Thomas H.; Merkenborg, J.A.N.; Stedkilde-Jergensen, Hans; Hansen, Lars H.; Pedersen, Lars B.; Grenier, N.; Frekiaer, JeRgen

doi:10.1111/j.1523-1755.2005.00334.x

Cited by 152 publications

(161 citation statements)

References 32 publications

(22 reference statements)

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“…Therefore, the present study was designed to test the hypothesis that despite proportional changes in whole kidney O 2 delivery and consumption, acute progressive renal arterial stenosis (RAS) leads to decreases in regional renal tissue oxygenation. To test this hypothesis and determine whether stoichiometric energy requirements are altered, we assessed changes in renal O 2 consumption, arteriovenous O 2 differences, and sodium reabsorption, and we concurrently measured intrarenal tissue oxygenation directly with oxygen electrodes (17,21,25) during acute RAS.…”

mentioning

confidence: 99%

Regional decreases in renal oxygenation during graded acute renal arterial stenosis: a case for renal ischemia

Warner

Gomez

Bolterman

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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. Regional decreases in renal oxygenation during graded acute renal arterial stenosis: a case for renal ischemia. Am J Physiol Regul Integr Comp Physiol 296: R67-R71, 2009. First published October 29, 2008 doi:10.1152/ajpregu.90677.2008.-Ischemic nephropathy describes progressive renal failure, defined by significantly reduced glomerular filtration rate, and may be due to renal artery stenosis (RAS), a narrowing of the renal artery. It is unclear whether ischemia is present during RAS since a decrease in renal blood flow (RBF), O 2 delivery, and O2 consumption occurs. The present study tests the hypothesis that despite proportional changes in whole kidney O 2 delivery and consumption, acute progressive RAS leads to decreases in regional renal tissue O 2. Unilateral acute RAS was induced in eight pigs with an extravascular cuff. RBF was measured with an ultrasound flow probe. Cortical and medullary tissue oxygen ͑P t O 2 ͒ of the stenotic kidney was measured continuously with sensors during baseline, three sequentially graded decreases in RBF, and recovery. O 2 consumption decreased proportionally to O2 delivery during the graded stenosis (19 Ϯ 10.8, 48.2 Ϯ 9.1, 58.9 Ϯ 4.7 vs. 15.1 Ϯ 5, 35.4 Ϯ 3.5, 57 Ϯ 2.3%, respectively) while arterial venous O 2 differences were unchanged. Acute RAS produced a sharp reduction in O 2 efficiency for sodium reabsorption (P Ͻ 0.01). Cortical ͑P t O 2 ͒ decreases are exceeded by medullary decreases during stenosis (34.8 Ϯ 1.3%). Decreases in tissue oxygenation, more pronounced in the medulla than the cortex, occur despite proportional reductions in O 2 delivery and consumption. This demonstrates for the first time that hypoxia is present in the early stages of RAS and suggests a role for hypoxia in the pathophysiology of this disease. Furthermore, the notion that arteriovenous shunting and increased stoichiometric energy requirements are potential contributors toward ensuing hypoxia with graded and progressive acute RAS cannot be excluded.ischemia; renal tissue oxygenation; renal blood flow; pig THE TERM "ISCHEMIC NEPHROPATHY" has been used to describe progressive renal failure, defined by a significantly reduced glomerular filtration rate (GFR) or loss of renal parenchyma due to renal artery stenosis, a narrowing of one or more of the renal arteries. Ischemia, however, results from a rate of blood flow that is insufficient to satisfy metabolic demands, thereby leading to tissue hypoxia. There is little evidence to suggest that ischemic nephropathy is accompanied by renal tissue hypoxia (24). In fact, the kidney has a high blood flow relative to its weight (3), which results in very small arterial-venous differences in oxygenation, suggesting a large O 2 supply and limited O 2 consumption. Importantly, Nielsen et al. (15) found in patients with significant unilateral renal artery stenosis that O 2 consumption decreased with limited blood flow, suggesting that a decrease in O 2 supply is not enough to cause ischemic renal disease (22). Moreover, the reduced O 2 supply and demand s...

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confidence: 99%

Regional decreases in renal oxygenation during graded acute renal arterial stenosis: a case for renal ischemia

Warner

Gomez

Bolterman

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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“…It was demonstrated recently in animals that acute experimental reduction of renal perfusion pressure, with subsequent reduction of renal blood flow, diminishes the renal blood oxygenation level-dependent (BOLD) MRI signal. 7,8 BOLD MRI exploits the fact that the different magnetic susceptibilities of oxygenated and deoxygenated hemoglobin result in locally different effective transversal relaxation rates. Therefore, changes in tissue oxygenation can be detected by BOLD MRI via altered concentrations of deoxyhemoglobin.…”

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confidence: 99%

Angiotensin II Decreases the Renal MRI Blood Oxygenation Level–Dependent Signal

et al. 2006

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Abstract-Acute experimental reduction of renal blood flow decreases the renal blood oxygenation level-dependent (BOLD) MRI signal in animals. Angiotensin II also reduces renal blood flow, but the ability of BOLD MRI to dynamically detect this response has not yet been investigated in humans. Six healthy male volunteers underwent an individual dose-finding study to identify the intravenous doses of angiotensin II, norepinephrine, and sodium nitroprusside necessary to induce a 15-mm Hg peak mean arterial blood pressure change. MRI studies followed within 3 weeks, when angiotensin II (8.8Ϯ1.4 ng/kg), norepinephrine (52Ϯ12 ng/kg), and sodium nitroprusside (2.0Ϯ0.3 g/kg) were given twice in an unblocked, randomized sequence while imaging experiments were performed on a 1.5-T Siemens Sonata. A multiecho echo-planar imaging sequence was used to acquire T2* maps with a temporal resolution of 1 respiratory cycle. Averaged over a renal cortex dominated region of interest, angiotensin II caused a shortening of T2* between 6% and 10%. Sodium nitroprusside and norepinephrine, although of equal potency concerning blood pressure responses, did not alter the renal BOLD signal. The renal BOLD response to angiotensin II appeared with short onset latency (as early as 10 seconds after peripheral intravenous angiotensin II bolus administration) suggesting that this response is a consequence of altered perfusion rather than increased renal oxygen consumption. This effect is likely mediated by the kidneys. 3,4 A2 affects a variety of kidney functions potentially influencing long-term BP control, such as renal handling of sodium 5 and renal hemodynamics. 6 Clearance techniques may be applied in humans to study such effects but are time consuming. Alternative noninvasive techniques are warranted. It was demonstrated recently in animals that acute experimental reduction of renal perfusion pressure, with subsequent reduction of renal blood flow, diminishes the renal blood oxygenation level-dependent (BOLD) MRI signal. 7,8 BOLD MRI exploits the fact that the different magnetic susceptibilities of oxygenated and deoxygenated hemoglobin result in locally different effective transversal relaxation rates. Therefore, changes in tissue oxygenation can be detected by BOLD MRI via altered concentrations of deoxyhemoglobin. Because A2 reduces renal blood flow, 6,9 we hypothesized that A2 reduces the renal BOLD MRI signal, as well. Norepinephrine (NE) and sodium nitroprusside (SNP) are potent vasoactive substances with excellent dose-response characteristics. They may be administered in individually adjusted doses as to affect arterial BP and renal perfusion pressure at the same extend as does A2. Previous research indicated NE 10,11 and SNP 12,13 to have little or no impact on renal perfusion because of renal autoregulation. Thus, we hypothesized that NE and SNP also have no effect on the BOLD MRI signal and used these substances as control interventions. MethodsSix healthy male volunteers (mean age, 26; range, 22 to 29 years; body weight, 71.2; ra...

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“…The validity of the BOLD signal for monitoring of renal oxygenation has been investigated in animal studies: Renal BOLD MRI was demonstrated to reflect oxygen consumption in pigs by comparison with oxygen partial pressure (p O 2 ) measurements performed with oxygen-sensitive microelectrodes [31].…”

Section: Applicationsmentioning

confidence: 99%

“…Pedersen et al [31] DWI diffusion-weighted imaging, DTI diffusion tensor imaging, ASL arterial spin labeling, BOLD blood oxygen level dependent…”

Section: Animal Study Dwi/ Dtimentioning

confidence: 99%

Clinical Functional MRI of the kidneys

2013

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In functional renal magnetic resonance imaging (MRI), advanced techniques are applied to obtain information on a functional and molecular level from the kidney tissue beyond pure morphology. Techniques such as diffusion-weighted and diffusion tensor imaging, arterial spin labelling, and blood oxygenation level-dependent imaging provide potential biomarkers of organ function. Moreover, dynamic contrast-enhanced techniques after the intravenous injection of gadolinium-chelates may be used to assess glomerular filtration and urinary excretion. This review summarizes recent developments of contrast-and non-contrast-enhanced MRI techniques for assessment of renal function in a clinical setting. The physiological background and the sequence techniques are described in detail. Potential clinical applications of the different techniques are discussed regarding their potential usefulness in the assessment of parenchymal diseases, urinary tract anomalies, transplant kidney function, and renal masses.

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Validation of quantitative BOLD MRI measurements in kidney: Application to unilateral ureteral obstruction

Abstract: BOLD MRI provides noninvasive estimates of regional renal oxygen content and our study demonstrates that this technique may provide a useful tool in UUO which is associated with altered renal oxygen consumption.

Cited by 152 publications

References 32 publications

Regional decreases in renal oxygenation during graded acute renal arterial stenosis: a case for renal ischemia

Regional decreases in renal oxygenation during graded acute renal arterial stenosis: a case for renal ischemia

Angiotensin II Decreases the Renal MRI Blood Oxygenation Level–Dependent Signal

Clinical Functional MRI of the kidneys

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