<i>In vivo</i> measurement of changes in venous blood‐oxygenation with high resolution functional MRI at 0.95 Tesla by measuring changes in susceptibility and velocity

Hoogenraad, F.; Reichenbach, Jürgen R.; Haacke, E. Mark; Lai, Song; Kuppusamy, K.; Sprenger, M.

doi:10.1002/mrm.1910390116

Cited by 77 publications

(72 citation statements)

References 24 publications

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“…The resulting Y values were not significantly different from the corresponding measured values (P = 0.48). We further noted that although we adopted the group mean arterial oxygenation of 98% for these calculations, coinciding with commonly assumed values (Hoogenraad et al, 1998), our observations were robust against physiologically plausible variations in arterial oxygenation. For Y a varying between 96 and 100%, the resultant fractional uncertainties DCMRO 2 and C were both within B10%.…”

Section: Resultssupporting

confidence: 67%

Global Cerebral Oxidative Metabolism during Hypercapnia and Hypocapnia in Humans: Implications for BOLD fMRI

Chen

Pike

2010

J Cereb Blood Flow Metab

155

145

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The effect of carbon dioxide (CO 2 ) on cerebral metabolism is of tremendous interest to functional imaging. In particular, mild-to-moderate hypercapnia is routinely used in calibrated blood oxygenlevel dependent (BOLD)-functional magnetic resonance imaging (fMRI)-based quantification of cerebral oxidative metabolism changes (DCMRO 2 ), and relies on the assumption of a stable CMRO 2 during CO 2 challenges. However, this assumption has been challenged by certain animal studies, necessitating its verification in humans and under conditions customary to fMRI. We report, for the first time, on global DCMRO 2 measurements made noninvasively in humans during graded hypercapnia and hypocapnia. We used computerized end-tidal CO 2 modulation to minimize undesired concurrent changes in oxygen pressure, and our findings suggest that no significant change in global CMRO 2 is expected at the levels of end-tidal CO 2 changes customary to calibrated BOLD.

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Section: Resultssupporting

confidence: 67%

Global Cerebral Oxidative Metabolism during Hypercapnia and Hypocapnia in Humans: Implications for BOLD fMRI

Chen

Pike

2010

J Cereb Blood Flow Metab

155

145

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“…and Ref. 13). This time-dependent intravascular phase term (⌿ iv ) will cause a beat between the intravascular NMR signal (S iv ) and the extravascular NMR signal (S ev ), causing the magnetization in the voxel to vary in amplitude (S) and phase (⌽).…”

Section: Vector Model Of the Bold Signalmentioning

confidence: 87%

“…The major contributors to the BOLD signal that have been discussed are represented in vector form in Fig. 2a, adapted from the work of Hoogenraad et al (13). Because of the symmetry of the extravascular magnetic field perturbation (cos2 term in Eq.…”

Section: Vector Model Of the Bold Signalmentioning

confidence: 99%

“…This time-dependent intravascular phase term (⌿ iv ) will cause a beat between the intravascular NMR signal (S iv ) and the extravascular NMR signal (S ev ), causing the magnetization in the voxel to vary in amplitude (S) and phase (⌽). Previous reports have considered the MRI signal properties of the intravascular compartment as a significant part of the voxel volume (2,13). One can go beyond this by looking for very subtle effects which cannot be seen in single images, but which can be revealed because of the statistical power realized through the repetitive nature of the fMRI technique.…”

Section: Vector Model Of the Bold Signalmentioning

confidence: 99%

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Postacquisition suppression of large‐vessel BOLD signals in high‐resolution fMRI

Menon

2001

Magnetic Resonance in Med

205

229

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Large-vessel BOLD contamination is a serious impediment to localization of neural activity in high-resolution fMRI studies. A new method is presented which estimates and removes the fraction of BOLD signal that arises from oriented vessels, such as cerebral and pial veins in a voxel, by measuring their influence on the phase angle of the complex valued fMRI time series. A maximum likelihood estimator based on a linear leastsquares fit of the BOLD signal phase to the BOLD signal magnitude in a voxel is shown to efficiently suppress the BOLD effect from these larger veins, whose activation is not well colocalized with the neural response. In high-resolution in vivo fMRI data at 4 T, it is estimated that the method is sensitive to the phase changes in the cerebral, larger intracortical, and pial veins. The technique requires no special pulse sequence modifications or acquisition strategies, and is computationally fast and intrinsically robust. At field strengths of 0.5-7 Tesla (1-5), the intensity changes in MRI observed during functional activation using gradient-echo EPI are dominated by the intravascular BOLD changes in the cortical cerebral veins and larger pial veins (macrovascular BOLD). This increases the effective point spread function of the fMRI technique in high-resolution imaging studies (6,7), since these larger veins can extend from several to tens of millimeters from the site of neuronal activity (8). Even at lower resolutions, larger veins can give rise to uncertainty in localization. For example, the presence of a draining vein in the central sulcus (2,8) makes distinguishing pre-from postcentral gyrus activity in the cortex extremely difficult, with obvious implications for other applications, such as presurgical planning in the motor cortex. While many clever techniques, such as spin-echo EPI, spiral, diffusion-weighted EPI, and perfusion-weighted methodologies, have been proposed to suppress the macrovascular BOLD effect, the use of gradient-echo EPI has been virtually ubiquitous in BOLD applications over the past decade because of its speed, multislice capability, ease of acquisition, and robust signal.The objection to the use of the macrovascular BOLD signal in certain brain mapping applications is based on the inhomogeneous distribution of veins in the brain (Ref. 8 and references therein). Cortical cerebral veins can range from 0.5-2.5 mm in radius and are typically found every 5-30 mm along the cortical surface. Because of the folded nature of the cortex, some of these veins can be found in sulci while yet others cross sulci on their way to venous sinuses. The cerebral veins collect deoxygenated blood received from the pial vein network, a dense, branching collection of 25-250-m-radius vessels located every 0.2-3 mm along the cortical surface. The smallest pial veins are formed from the right-angle emergence of an intracortical vein (10 -60 m radius) that penetrates the cortex tangential to the surface. These tangential penetrations occur every 0.25-1.5 mm on the cortical surface, and with ...

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“…Yet, in voxels embedded in vascular compartments, and , where act indicates "on activation", rest indicates "on rest", is the susceptibility difference between fully oxygenated and deoxygenated blood and Hct is the fractional hematocrit in the vein. The latter relation was used for the estimation of functional oxygenation changes in large veins of the visual cortex and in pial veins of the motor cortex in humans (Haacke et al, 1997;Haacke et al, 1995;Hoogenraad et al, 1998). The 2013 study was performed at 2.5 mm isotropic resolution, and involved removal of non-local phase effects.…”

Section: Potentials and Pitfallsmentioning

confidence: 99%

Functional quantitative susceptibility mapping (fQSM)

et al. 2014

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Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is a powerful technique, typically based on the statistical analysis of the magnitude component of the complex time-series. Here, we additionally interrogated the phase data of the fMRI time-series and used quantitative susceptibility mapping (QSM) in order to investigate the potential of functional QSM (fQSM) relative to standard magnitude BOLD fMRI. High spatial resolution data (1 mm isotropic) were acquired every 3 seconds using zoomed multi-slice gradient-echo EPI collected at 7 T in single orientation (SO) and multiple orientation (MO) experiments, the latter involving 4 repetitions with the subject's head rotated relative to B0. Statistical parametric maps (SPM) were reconstructed for magnitude, phase and QSM time-series and each was subjected to detailed analysis. Several fQSM pipelines were evaluated and compared based on the relative number of voxels that were coincidentally found to be significant in QSM and magnitude SPMs (common voxels). We found that sensitivity and spatial reliability of fQSM relative to the magnitude data depended strongly on the arbitrary significance threshold defining "activated" voxels in SPMs, and on the efficiency of spatiotemporal filtering of the phase time-series. Sensitivity and spatial reliability depended slightly on whether MO or SO fQSM was performed and on the QSM calculation approach used for SO data. Our results present the potential of fQSM as a quantitative method of mapping BOLD changes. We also critically discuss the technical challenges and issues linked to this intriguing new technique. seconds using zoomed multi-slice gradient-echo EPI collected at 7 T in single orientation (SO) and multiple orientation (MO) experiments, the latter involving 4 repetitions with the subject's head rotated relative to B 0 . Statistical parametric maps (SPM) were reconstructed for magnitude, phase and QSM timeseries and each was subjected to detailed analysis. Several fQSM pipelines were evaluated and compared based on the relative number of voxels that were coincidentally found to be significant in QSM and magnitude SPMs (common voxels). We found that sensitivity and spatial reliability of fQSM relative to the magnitude data depended strongly on the arbitrary significance threshold defining "activated" voxels in SPMs, and on the efficiency of spatio-temporal filtering of the phase time-series. Sensitivity and spatial reliability depended slightly on whether MO or SO fQSM was performed and on the QSM calculation approach used for SO data.

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In vivo measurement of changes in venous blood‐oxygenation with high resolution functional MRI at 0.95 Tesla by measuring changes in susceptibility and velocity

Cited by 77 publications

References 24 publications

Global Cerebral Oxidative Metabolism during Hypercapnia and Hypocapnia in Humans: Implications for BOLD fMRI

Global Cerebral Oxidative Metabolism during Hypercapnia and Hypocapnia in Humans: Implications for BOLD fMRI

Postacquisition suppression of large‐vessel BOLD signals in high‐resolution fMRI

Functional quantitative susceptibility mapping (fQSM)

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