Jaroszynski Kathryn M, Lee Hyunyeol, Langham Michael C, Wehrli Felix W
Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
NMR Biomed. 2025 Sep;38(9):e70120. doi: 10.1002/nbm.70120.
The measurement of cerebral oxygen metabolism is important to understand and treat many disorders. Constrained quantitative BOLD (qBOLD) MRI is a calibration-free method for 3D voxel-wise whole-brain mapping of brain oxygen metabolism. This study aimed to evaluate the agreement between constrained qBOLD and global oximetry methods both at baseline and in response to a caffeine stimulus. Healthy volunteers (N = 10, age 30 ± 8 years) were imaged with constrained qBOLD, MOTIVE (metabolism of oxygen via T and interleaved velocity encoding), dual-slice (DS), and single-slice (SS) OxFlow. Subjects were then given a 200 mg caffeine pill and imaged at 2-s temporal resolution immediately thereafter for 30 min by SS-OxFlow. After 30 min, the baseline protocol was repeated. Constrained qBOLD uses prior constraints to the QSM + qBOLD model to solve for voxel-wise oxygen extraction fraction (OEF). Quantification of cerebral blood flow (CBF) was accomplished for qBOLD from a separate measurement via pseudo-continuous arterial spin labeling (pCASL) to yield CMRO. Constrained qBOLD measured OEF (31 ± 5% gray matter [GM], 31 ± 6% white matter [WM] at baseline; 36 ± 7 GM, 35 ± 8 WM post-caffeine) was in good agreement with global oximetry methods DS-OxFlow (30 ± 4, 37 ± 5), SS-OxFlow (31 ± 4, 37 ± 4), and MOTIVE (32 ± 5, 39 ± 5). Temporal data showed a gradual increase in OEF with a commensurate reduction in CBF while the caffeine was taking effect. No significant change in CMRO was noted with any of the techniques. Regional analysis of the basal ganglia, hippocampus, and thalamus found there was a significant increase in OEF post caffeine. The results indicate constrained qBOLD to yield OEF with negligible bias to global oximetry methods, both at baseline and post caffeine. The results also suggest that constrained qBOLD has the sensitivity to detect changes in oxygen metabolism due to a vasoconstrictive stimulus.
脑氧代谢的测量对于理解和治疗多种疾病至关重要。受限定量血氧水平依赖（qBOLD）磁共振成像（MRI）是一种无需校准的方法，可用于对脑氧代谢进行三维体素级全脑映射。本研究旨在评估受限qBOLD与全局血氧测定法在基线状态以及对咖啡因刺激反应时的一致性。10名健康志愿者（年龄30±8岁）接受了受限qBOLD、MOTIVE（通过T和交错速度编码进行氧代谢）、双切片（DS）和单切片（SS）氧通量成像。然后给受试者服用200毫克咖啡因片，并在此后立即以2秒的时间分辨率通过SS - 氧通量成像30分钟。30分钟后，重复基线检查方案。受限qBOLD利用对QSM + qBOLD模型的先验约束来求解体素级氧摄取分数（OEF）。通过伪连续动脉自旋标记（pCASL）从单独测量中完成qBOLD的脑血流量（CBF）定量，以得出脑氧代谢率（CMRO）。受限qBOLD测量的OEF（基线时灰质[GM]为31±5%，白质[WM]为31±6%；咖啡因刺激后GM为36±7%，WM为35±8%）与全局血氧测定法DS - 氧通量（30±4%，37±5%）、SS - 氧通量（31±4%，37±4%）和MOTIVE（32±5%，39±5%）高度一致。时间数据显示，在咖啡因起作用时，OEF逐渐增加，同时CBF相应减少。使用任何一种技术均未发现CMRO有显著变化。对基底神经节、海马体和丘脑的区域分析发现，咖啡因刺激后OEF显著增加。结果表明，受限qBOLD在基线和咖啡因刺激后产生的OEF与全局血氧测定法相比偏差可忽略不计。结果还表明，受限qBOLD具有检测血管收缩刺激引起的氧代谢变化的敏感性。
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