Relaxation and exchange dynamics of hyperpolarized 129Xe in human blood. Issue 2 (28th August 2014)

• Record Type: Journal Article
• Authors: Norquay, Graham; Leung, General; Stewart, Neil J.; Tozer, Gillian M.; Wolber, Jan; Wild, Jim M.
• Is Part Of: Magnetic resonance in medicine. Volume 74:Issue 2(2015:Aug.)
• Page Start: 303
• Page End: 311
• Publication Date: 2014-08-28
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25417
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25417-sec-0001" sec-type="section"> <title>Purpose</title> <p> <sup>129</sup>Xe‐blood NMR was performed over the full blood oxygenation range to evaluate <sup>129</sup>Xe relaxation and exchange dynamics in human blood.</p> </sec> <sec id="mrm25417-sec-0002" sec-type="section"> <title>Methods</title> <p>Hyperpolarized <sup>129</sup>Xe was equilibrated with blood and isolated plasma, and NMR was performed at 1.5 T.</p> </sec> <sec id="mrm25417-sec-0003" sec-type="section"> <title>Results</title> <p>The <sup>129</sup>Xe relaxation rate was found to increase nonlinearly with decreasing blood oxygenation. Three constants were extrapolated: <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfsg4" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>r</mml:mi><mml:mrow><mml:mi>s</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> = 11.1, a "relaxivity index" characterizing the rate of change of <sup>129</sup>Xe relaxation as a function of blood oxygenation, and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfsfk" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:msubsup><mml:mi>T</mml:mi><mml:mn>1</mml:mn><mml:mrow><mml:mi mathvariant="normal">oHb</mml:mi></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> = 0.13 s<sup>−1</sup> and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfsks" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0003" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:msubsup><mml:mi>T</mml:mi><mml:mn>1</mml:mn><mml:mrow><mml:mi mathvariant="normal">dHb</mml:mi></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> = 0.42 s<sup>−1</sup>, the <sup>129</sup>Xe relaxation rates in oxygenated blood and deoxygenated blood, respectively. In addition, rate constants, <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfshp" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0004" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mi mathvariant="normal">a</mml:mi></mml:msub><mml:mo> </mml:mo><mml:mo>=</mml:mo><mml:mo> </mml:mo></mml:mrow></mml:math></alternatives></inline-formula> 0.022 ms<sup>−1</sup> and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfs8t" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0005" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mi mathvariant="normal">b</mml:mi></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> = 0.062 ms<sup>−1</sup>, were determined for xenon diffusing between red blood cells (RBCs) and plasma (hematocrit = 48%). The <sup>129</sup>Xe‐O<sub>2</sub> relaxivity in plasma, <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfs4m" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0006" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>r</mml:mi><mml:mrow><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> = 0.075 s<sup>−1</sup> mM<sup>−1</sup>, and the <sup>129</sup>Xe relaxation rate in isolated plasma (without dissolved O<sub>2</sub>), <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfsd1" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0007" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant="normal">1, b</mml:mi></mml:mrow><mml:mn>0</mml:mn></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> = 0.046 s<sup>−1</sup>, were also calculated. Finally, intrinsic <sup>129</sup>Xe‐RBC relaxation rates, <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfsbx" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0008" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>, </mml:mo><mml:mi mathvariant="normal">a</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">oHb</mml:mi></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> = 0.19 s<sup>−1</sup> and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj23trfs32" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25417:mrm25417-math-0009" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:msubsup><mml:mi>T</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>, </mml:mo><mml:mi mathvariant="normal">a</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">dHb</mml:mi></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> = 0.84 s<sup>−1</sup>, in oxygenated blood and deoxygenated blood, respectively, were calculated.</p> </sec> <sec id="mrm25417-sec-0004" sec-type="section"> <title>Conclusion</title> <p>The relaxation and exchange analysis performed in this study should provide a sound experimental basis upon which to design future MR experiments for dissolved xenon transport from the lungs to distal tissues. Magn Reson Med 74:303–311, 2015. © 2014 Wiley Periodicals, Inc.</p> </sec> </abstract>