Quantitative mapping of cerebral oxygen metabolism using breath-hold calibrated fMRI
Quantitative mapping of cerebral oxygen metabolism using breath-hold calibrated fMRI
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DOI：
10.1101/2021.04.08.438939
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发表时间：
2021-04
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影响因子：
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通讯作者：
M. Germuska;RC Stickland;AM Chiarelli;H. Chandler;R. Wise
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作者：
M. Germuska;RC Stickland;AM Chiarelli;H. Chandler;R. Wise
磁共振成像（MRI）提供了非侵入性绘制脑代谢耗氧率（CMRO 2）的可能性，这对于了解和监测健康和疾病中的神经功能至关重要。基于动脉自旋标记（ASL）和血氧水平依赖（BOLD）信号的呼吸调制的映射CMRO2的现有方法需要冗长的采集和动脉氧和二氧化碳水平两者的独立调制。在这里，我们提出了一种新的简化方法，可以使用一个简单的屏气范例映射脑氧代谢率。该方法结合了氧气运输和生理约束的流动扩散建模，以创建最大BOLD信号M、基线血流量（CBF0）和CMRO2之间的非线性映射。梯度提升决策树用于直接从模拟MRI数据学习该映射。建模研究表明，所提出的方法是强大的大脑生理和代谢的变化。这种新的无气体方法为现有的双校准方法提供了一种快速实用的替代方案，消除了对专业呼吸设备和长采集时间的需求。体内测试的方法，使用8分钟45秒的协议，重复屏气，进行了15名健康志愿者，产生定量地图的脑血流量（CBF），氧提取分数（OEF），和CMRO2。
Magnetic resonance imaging (MRI) offers the possibility to non-invasively map the rate of cerebral metabolic oxygen consumption (CMRO2), which is essential for understanding and monitoring neural function in both health and disease. Existing methods of mapping CMRO2, based on respiratory modulation of arterial spin labelling (ASL) and blood oxygen level dependent (BOLD) signals, require lengthy acquisitions and independent modulation of both arterial oxygen and carbon dioxide levels. Here, we present a new simplified method for mapping the rate of cerebral oxygen metabolism that can be performed using a simple breath-holding paradigm. The method incorporates flow-diffusion modelling of oxygen transport and physiological constraints to create a non-linear mapping between the maximum BOLD signal, M, baseline blood flow (CBF0), and CMRO2. A gradient boosted decision tree is used to learn this mapping directly from simulated MRI data. Modelling studies demonstrate that the proposed method is robust to variation in cerebral physiology and metabolism. This new gas-free methodology offers a rapid and pragmatic alternative to existing dual-calibrated methods, removing the need for specialist respiratory equipment and long acquisition times. In-vivo testing of the method, using an 8-minute 45 second protocol of repeated breath-holding, was performed on 15 healthy volunteers, producing quantitative maps of cerebral blood flow (CBF), oxygen extraction fraction (OEF), and CMRO2.