How bold is blood oxygenation level‐dependent (BOLD) magnetic resonance imaging of the kidney? Opportunities, challenges and future directions. (30th September 2014)

• Record Type: Journal Article
• Authors: Niendorf, T.; Pohlmann, A.; Arakelyan, K.; Flemming, B.; Cantow, K.; Hentschel, J.; Grosenick, D.; Ladwig, M.; Reimann, H.; Klix, S.; Waiczies, S.; Seeliger, E.
• Is Part Of: Acta physiologica. Volume 213:Number 1(2015:Jan.)
• Page Start: 19
• Page End: 38
• Publication Date: 2014-09-30
• Subjects: Physiology -- Periodicals; Physiology -- Research -- Periodicals; 612
• DOI: 10.1111/apha.12393
• Languages: English
• ISSNs: 1748-1708

Abstract

<abstract abstract-type="main" id="apha12393-abs-0001"> <title>Abstract</title> <p>Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. Yet, <italic>in vivo</italic> assessment of renal haemodynamics and tissue oxygenation remains a challenge. Many of the established approaches are invasive, hence not applicable in humans. Blood oxygenation level‐dependent (BOLD) magnetic resonance imaging (MRI) offers an alternative. BOLD‐MRI is non‐invasive and indicative of renal tissue oxygenation. Nonetheless, recent (pre‐) clinical studies revived the question as to how bold renal BOLD‐MRI really is. This review aimed to deliver some answers. It is designed to inspire the renal physiology, nephrology and imaging communities to foster explorations into the assessment of renal oxygenation and haemodynamics by exploiting the powers of MRI. For this purpose, the specifics of renal oxygenation and perfusion are outlined. The fundamentals of BOLD‐MRI are summarized. The link between tissue oxygenation and the oxygenation‐sensitive MR biomarker <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2t23t6zd" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:17481708:media:apha12393:apha12393-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi mathvariant="normal">T</mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msubsup></mml:math></alternatives></inline-formula> is outlined. The merits and limitations of renal BOLD‐MRI in animal and human studies are surveyed together with their clinical implications. Explorations into detailing the relation between renal <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2t23t72k" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:17481708:media:apha12393:apha12393-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi mathvariant="normal">T</mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msubsup></mml:math></alternatives></inline-formula> and renal tissue partial pressure of oxygen (pO<sub>2</sub>) are discussed with a focus on factors confounding the <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2t23t711" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:17481708:media:apha12393:apha12393-math-0003" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi mathvariant="normal">T</mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msubsup></mml:math></alternatives></inline-formula> vs. tissue pO<sub>2</sub> relation. Multi‐modality <italic>in vivo</italic> approaches suitable for detailing the role of the confounding factors that govern <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2t23t6r3" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:17481708:media:apha12393:apha12393-math-0004" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi mathvariant="normal">T</mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msubsup></mml:math></alternatives></inline-formula> are considered. A schematic approach describing the link between renal perfusion, oxygenation, tissue compartments and renal <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2t23t6nf" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:17481708:media:apha12393:apha12393-math-0005" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi mathvariant="normal">T</mml:mi><mml:mn>2</mml:mn><mml:mrow><mml:mrow /><mml:mo>∗</mml:mo></mml:mrow></mml:msubsup></mml:math></alternatives></inline-formula> is proposed. Future directions of MRI assessment of renal oxygenation and perfusion are explored.</p> </abstract>