Dependence of blood T2 on oxygenation at 7 T: In vitro calibration and in vivo application. Issue 6 (10th July 2013)

• Record Type: Journal Article
• Authors: Krishnamurthy, Lisa C.; Liu, Peiying; Xu, Feng; Uh, Jinsoo; Dimitrov, Ivan; Lu, Hanzhang
• Is Part Of: Magnetic resonance in medicine. Volume 71:Issue 6(2014:Jun.)
• Page Start: 2035
• Page End: 2042
• Publication Date: 2013-07-10
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.24868
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm24868-sec-0001" sec-type="section"> <title>Purpose</title> <p>The calibratable relationship between blood oxygenation (<italic>Y</italic>) and <italic>T</italic><sub>2</sub> allows quantification of cerebral venous oxygenation. We aim to establish a calibration plot between blood <italic>T</italic><sub>2</sub>, <italic>Y</italic>, and hematocrit at 7 T, and using <italic>T</italic><sub>2</sub>‐relaxation‐under‐spin‐tagging MRI, determine human venous blood oxygenation in vivo.</p> </sec> <sec id="mrm24868-sec-0002" sec-type="section"> <title>Methods</title> <p>In vitro experiments were performed at 7 T on bovine blood samples using a Carr‐Purcell‐Meiboom‐Gill‐<italic>T</italic><sub>2</sub> sequence, from which we characterized the relationship among <italic>T</italic><sub>2</sub>, <italic>Y</italic>, and hematocrit. T<sub>2</sub>‐relaxation‐under‐spin‐tagging MRI was implemented at 7 T to measure venous blood <italic>T</italic><sub>2</sub> in vivo, from which oxygenation was estimated using the in vitro calibration plot. Hyperoxia was performed to test the sensitivity of the method to oxygenation changes, and the 7 T results were compared with those at 3 T.</p> </sec> <sec id="mrm24868-sec-0003" sec-type="section"> <title>Results</title> <p>In vitro data showed that arterial and venous <italic>T</italic><sub>2</sub> at 7 T are 68 and 20 ms, respectively, at a typical hematocrit of 0.42. In vivo measurement showed a cerebral venous oxygenation of 64.7 ± 5.0% and a test‐retest coefficient‐of‐variation of 3.6 ± 2.4%. Hyperoxia increased <italic>Y</italic><sub>v</sub> by 9.0 ± 1.4% (<italic>P</italic> = 0.001) and the 3 and 7 T results showed a strong correlation (<italic>R</italic> = 0.95) across individuals.</p> </sec> <sec id="mrm24868-sec-0004" sec-type="section"> <title>Conclusion</title> <p>We provided an in vitro calibration plot for conversion of blood <italic>T</italic><sub>2</sub> to oxygenation at 7 T and demonstrated its utility in vivo. Magn Reson Med 71:2035–2042, 2014. © 2013 Wiley Periodicals, Inc.</p> </sec> </abstract>