fMRI at 1.5, 3 and 7 T: Characterising BOLD signal changes

Zwaag, Wietske van der; Francis, Susan T.; Head, Kevin; Peters, Andrew M.; Gowland, Penny A.; Morris, Peter G.; Bowtell, Richard

doi:10.1016/j.neuroimage.2009.05.015

Cited by 254 publications

(209 citation statements)

References 36 publications

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“…Activation-induced changes in the transverse relaxation rate R2* (¼1/T2*) were found to scale linearly to hyperlinearly with respect to B 0 (10)(11)(12)(13). Comparison of skeletal muscle BOLD studies conducted at different field strengths also implies a particular dependence of the muscle BOLD effect on B 0 (2,3,14,15).…”

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confidence: 87%

“…Functional MR studies of the human brain have demonstrated that high field strengths of the static magnetic field (B 0 ) lead to higher signal-to-noise ratios and increased BOLD signal changes in activated brain areas (10)(11)(12)(13). Activation-induced changes in the transverse relaxation rate R2* (¼1/T2*) were found to scale linearly to hyperlinearly with respect to B 0 (10)(11)(12)(13).…”

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confidence: 99%

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Blood oxygenation level‐dependent (BOLD) MRI of human skeletal muscle at 1.5 and 3 T

Partovi¹,

Schulte²,

Jacobi

et al. 2012

Magnetic Resonance Imaging

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Purpose: To evaluate the dependence of skeletal muscle blood oxygenation level-dependent (BOLD) effect and time course characteristics on magnetic field strength in healthy volunteers using an ischemia/reactive hyperemia paradigm.Materials and Methods: Two consecutive skeletal muscle BOLD magnetic resonance imaging (MRI) measurements in eight healthy volunteers were performed on 1.5 T and 3.0 T whole-body MRI scanners. For both measurements a fat-saturated multi-shot multiecho gradient-echo EPI sequence was applied. Temporary vascular occlusion was induced by suprasystolic cuff compression of the thigh. T2* time courses were obtained from two different calf muscles and characterized by typical curve parameters. Ischemia-and hyperemia-induced changes in R2* (DR2*) were calculated for both muscles in each volunteer at the two field strengths.Results: Skeletal muscle BOLD changes are dependent on magnetic field strength as the ratio DR2*(3.0 T)/ DR2*(1.5 T) was found to range between 1.6 and 2.2. Regarding time course characteristics, significantly higher relative T2* changes were found in both muscles at 3.0 T.Conclusion: The present study shows an approximately linear field strength dependence of DR2* in the skeletal muscle in response to ischemia and reactive hyperemia. Using higher magnetic fields is advisable for future BOLD imaging studies of peripheral limb pathologies.

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confidence: 87%

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confidence: 99%

Blood oxygenation level‐dependent (BOLD) MRI of human skeletal muscle at 1.5 and 3 T

Partovi¹,

Schulte²,

Jacobi

et al. 2012

Magnetic Resonance Imaging

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“…Simultaneous acquisitions also avoid differences in spurious stimuli (Novitski et al, 2003), training or habituation effects (Debener et al, 2002) and other differences in subject performance (Boly et al, 2007). Considering fMRI, it is well known that a stronger static field B 0 results both in increased magnetization and in an accentuated BOLD effect, leading to super-linear gains in functional sensitivity (Turner et al, 1993;van der Zwaag et al, 2009). As a result, in recent years, fMRI studies conducted at ultra-high field have achieved sub-millimeter spatial resolution (Yacoub et al, 2008), and higher field strengths continue to be pursued (Deelchand et al, 2010;Duyn, 2012).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous EEG–fMRI at ultra-high field: Artifact prevention and safety assessment

et al. 2015

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The simultaneous recording of scalp electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) can provide unique insights into the dynamics of human brain function, and the increased functional sensitivity offered by ultra-high field fMRI opens exciting perspectives for the future of this multimodal approach. However, simultaneous recordings are susceptible to various types of artifacts, many of which scale with magnetic field strength and can seriously compromise both EEG and fMRI data quality in recordings above 3 T. The aim of the present study was to implement and characterize an optimized setup for simultaneous EEG-fMRI in humans at 7 T. The effects of EEG cable length and geometry for signal transmission between the cap and amplifiers were assessed in a phantom model, with specific attention to noise contributions from the MR scanner coldheads. Cable shortening (down to 12 cm from cap to amplifiers) and bundling effectively reduced environment noise by up to 84% in average power and 91% in inter-channel power variability. Subject safety was assessed and confirmed via numerical simulations of RF power distribution and temperature measurements on a phantom model, building on the limited existing literature at ultra-high field. MRI data degradation effects due to the EEG system were characterized via B 0 and B 1 + field mapping on a human volunteer, demonstrating important, although not prohibitive, B 1 disruption effects. With the optimized setup, simultaneous EEG-fMRI acquisitions were performed on 5 healthy volunteers undergoing two visual paradigms: an eyes-open/eyes-closed task, and a visual evoked potential (VEP) paradigm using reversing-checkerboard stimulation. EEG data exhibited clear occipital alpha modulation and average VEPs, respectively, with concomitant BOLD signal changes. On a single-trial level, alpha power variations could be observed with relative confidence on all trials; VEP detection was more limited, although statistically significant responses could be detected in more than 50% of trials for every subject. Overall, we conclude that the proposed setup is well suited for simultaneous EEG-fMRI at 7 T.

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“…Because of its relatively small size and fine-scale anatomical structure, compared to the cerebrum, cerebellar fMRI benefits strongly from high spatial resolution, both during acquisition [1,2] and in data post-processing strategies used in fMRI [3,4]. High spatial resolution in fMRI is most easily achieved at high field strengths, where fMRI benefits from increased signal-tonoise ratio (SNR), increased blood oxygen level-dependent (BOLD) signal [5,6] and increased spatial specificity of the BOLD responses [7,8].…”

Section: Introductionmentioning

confidence: 99%