期刊
MAGNETIC RESONANCE IN MEDICINE
卷 60, 期 2, 页码 364-372出版社
JOHN WILEY & SONS INC
DOI: 10.1002/mrm.21686
关键词
TRUST; brain; fMRI; blood oxygenation; basal state
资金
- NIMH NIH HHS [R01 MH084021] Funding Source: Medline
- NINDS NIH HHS [R21 NS054916, R01 NS039135-07, R01 NS039135, R21 NS054916-02] Funding Source: Medline
Although BOLD functional MRI (fMRI) provides a useful tool for probing neuronal activities, large intersubject variations in signal amplitude are commonly observed. Understanding the physiologic basis for these variations will have a significant impact on many fMRI studies. First, the physiologic modulator can be used as a regressor to reduce variations across subjects, thereby improving statistical power for detecting group differences. Second, if a pathologic condition or a drug treatment is shown to change fMRI responses, monitoring this modulatory parameter is useful in correctly interpreting the fMRI changes to neuronal deficits/recruitments. Here we present evidence that the task-evoked fMRI signals are modulated by baseline blood oxygenation. To measure global blood oxygenation, we used a recently developed technique, T-2 relaxation under spin-tagging (TRUST) MRI, which yielded baseline oxygenation of 63.7% +/- 7.2% in the sagittal sinus with an estimation error of 1.3%. It was found that individuals with higher baseline oxygenation tend to have a smaller fMRI signal, and vice versa. For every 10% difference in baseline oxygenation across subjects, BOLD and cerebral blood flow (CBF) signals differ by -0.4% and -30.0%, respectively, when using visual stimulation. TRUST MRI is a useful measurement for fMRI studies to control for the modulatory effects of baseline oxygenation that are unique to each subject.
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