Baseline blood oxygenation modulates response amplitude: Physiologic basis for intersubject variations in functional MRI signals

Hanzhang Lu, Chenguang Zhao, Yulin Ge, Kelly Lewis-Amezcua

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

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.

Original languageEnglish (US)
Pages (from-to)364-372
Number of pages9
JournalMagnetic Resonance in Medicine
Volume60
Issue number2
DOIs
StatePublished - Aug 2008

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Magnetic Resonance Imaging
Cerebrovascular Circulation
Photic Stimulation
Pharmaceutical Preparations

Keywords

  • Basal state
  • Blood oxygenation
  • Brain
  • fMRI
  • TRUST

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

Baseline blood oxygenation modulates response amplitude : Physiologic basis for intersubject variations in functional MRI signals. / Lu, Hanzhang; Zhao, Chenguang; Ge, Yulin; Lewis-Amezcua, Kelly.

In: Magnetic Resonance in Medicine, Vol. 60, No. 2, 08.2008, p. 364-372.

Research output: Contribution to journalArticle

Lu, Hanzhang ; Zhao, Chenguang ; Ge, Yulin ; Lewis-Amezcua, Kelly. / Baseline blood oxygenation modulates response amplitude : Physiologic basis for intersubject variations in functional MRI signals. In: Magnetic Resonance in Medicine. 2008 ; Vol. 60, No. 2. pp. 364-372.
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