{"title":"Improving quantitative BOLD-based measures of oxygen extraction fraction using hyperoxia BOLD-derived measures of blood volume.","authors":"Alan J Stone, Nicholas P Blockley","doi":"10.1002/mrm.30559","DOIUrl":null,"url":null,"abstract":"<p><strong>Purpose: </strong>Streamlined quantitative BOLD (sqBOLD) is a refinement of the quantitative BOLD (qBOLD) technique capable of producing noninvasive and quantitative maps of oxygen extraction fraction (OEF) in a clinically feasible scan time. However, sqBOLD measurements of OEF have been reported as being systematically lower than expected in healthy brain. Because the qBOLD framework infers OEF from the ratio of the reversible transverse relaxation rate ( <math> <semantics> <mrow><msubsup><mi>R</mi> <mn>2</mn> <mo>'</mo></msubsup> </mrow> <annotation>$$ {\\mathrm{R}}_2^{\\prime } $$</annotation></semantics> </math> ) and deoxygenated blood volume (DBV), this underestimation has been attributed the overestimation of DBV. Therefore, this study proposes the use of an independent measure of DBV using hyperoxia BOLD and investigates whether this results in improved estimates of OEF.</p><p><strong>Methods: </strong>Monte Carlo simulations were used to simulate the qBOLD and hyperoxia-BOLD signals and to compare the systematic and noise-related errors of sqBOLD and the new hyperoxia-qBOLD (hqBOLD) technique. Experimentally, sqBOLD and hqBOLD measurements were performed and compared with TRUST (T<sub>2</sub> relaxation under spin tagging)-based oximetry in the sagittal sinus.</p><p><strong>Results: </strong>Simulations showed a large improvement in the uncertainty of DBV measurements, leading to a much improved dynamic range for OEF measurements with hqBOLD. In a group of 10 healthy volunteers, hqBOLD produced measurements of OEF in cortical gray matter (OEF<sub>hqBOLD</sub> = 38.1 ± 10.1%) that were not significantly different from TRUST oximetry measures (OEF<sub>TRUST</sub> = 40.4 ± 7.7%), whereas sqBOLD-derived measures (OEF<sub>sqBOLD</sub> = 16.1 ± 3.1%) were found to be significantly different.</p><p><strong>Conclusion: </strong>The simulations and experiments in this study demonstrate that an independent measure of DBV provides improved estimates of OEF.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0000,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Magnetic Resonance in Medicine","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1002/mrm.30559","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING","Score":null,"Total":0}
引用次数: 0
Abstract
Purpose: Streamlined quantitative BOLD (sqBOLD) is a refinement of the quantitative BOLD (qBOLD) technique capable of producing noninvasive and quantitative maps of oxygen extraction fraction (OEF) in a clinically feasible scan time. However, sqBOLD measurements of OEF have been reported as being systematically lower than expected in healthy brain. Because the qBOLD framework infers OEF from the ratio of the reversible transverse relaxation rate ( ) and deoxygenated blood volume (DBV), this underestimation has been attributed the overestimation of DBV. Therefore, this study proposes the use of an independent measure of DBV using hyperoxia BOLD and investigates whether this results in improved estimates of OEF.
Methods: Monte Carlo simulations were used to simulate the qBOLD and hyperoxia-BOLD signals and to compare the systematic and noise-related errors of sqBOLD and the new hyperoxia-qBOLD (hqBOLD) technique. Experimentally, sqBOLD and hqBOLD measurements were performed and compared with TRUST (T2 relaxation under spin tagging)-based oximetry in the sagittal sinus.
Results: Simulations showed a large improvement in the uncertainty of DBV measurements, leading to a much improved dynamic range for OEF measurements with hqBOLD. In a group of 10 healthy volunteers, hqBOLD produced measurements of OEF in cortical gray matter (OEFhqBOLD = 38.1 ± 10.1%) that were not significantly different from TRUST oximetry measures (OEFTRUST = 40.4 ± 7.7%), whereas sqBOLD-derived measures (OEFsqBOLD = 16.1 ± 3.1%) were found to be significantly different.
Conclusion: The simulations and experiments in this study demonstrate that an independent measure of DBV provides improved estimates of OEF.
目的：流线型定量BOLD （sqBOLD）是对定量BOLD （qBOLD）技术的改进，能够在临床可行的扫描时间内产生无创的氧提取分数（OEF）定量图。然而，据报道，sqBOLD测量的OEF在健康大脑中系统性地低于预期。由于qBOLD框架从可逆横向松弛率（r2 ' $$ {\mathrm{R}}_2^{\prime } $$）和脱氧血容量（DBV）的比值推断出OEF，因此这种低估被归因于对DBV的高估。因此，本研究建议使用高氧BOLD来独立测量DBV，并研究这是否会改善OEF的估计。方法：采用蒙特卡罗模拟方法对qBOLD和hyperxia - bold信号进行模拟，比较sqBOLD和新的hyperxia -qBOLD （hqBOLD）技术的系统误差和噪声误差。实验中，我们进行了sqBOLD和hqBOLD测量，并与基于TRUST（自旋标记下T2松弛）的矢状窦血氧测定进行了比较。结果：模拟显示DBV测量的不确定性有很大的改善，导致hqBOLD测量OEF的动态范围有很大的改善。在10名健康志愿者中，hqBOLD测量了皮质灰质的OEF （OEFhqBOLD = 38.1±10.1）%) that were not significantly different from TRUST oximetry measures (OEFTRUST = 40.4 ± 7.7%), whereas sqBOLD-derived measures (OEFsqBOLD = 16.1 ± 3.1%) were found to be significantly different.Conclusion: The simulations and experiments in this study demonstrate that an independent measure of DBV provides improved estimates of OEF.
期刊介绍：
Magnetic Resonance in Medicine (Magn Reson Med) is an international journal devoted to the publication of original investigations concerned with all aspects of the development and use of nuclear magnetic resonance and electron paramagnetic resonance techniques for medical applications. Reports of original investigations in the areas of mathematics, computing, engineering, physics, biophysics, chemistry, biochemistry, and physiology directly relevant to magnetic resonance will be accepted, as well as methodology-oriented clinical studies.
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