Detection of brain activation using oxygenation sensitive functional spectroscopy

Hennig, Juergen; Ernst, Thomas; Speck, Oliver; Deuschl, Günther; Feifel, E.

doi:10.1002/mrm.1910310115

Cited by 66 publications

(35 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…3. Curve fitting of the multiecho data corresponds to the minimization of: [17] where f describes the curve fit (e.g., a monoexponential decay), which is dependent on time and a set of parameters x ជ ϭ (x 1 , x 2 , . .…”

Section: Sensitivity Optimizationmentioning

confidence: 99%

“…Recent advances in characterizing the BOLD-contrast mechanism and the spatial localization of functional signal changes during neuronal activation were made possible by acquisition techniques that sample multiple time points of the water relaxation decay (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Furthermore, distinction of T 2 *-relaxation and other factors (e.g., inflow, hardware instabilities) can be achieved (9).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Enhancement of BOLD-contrast sensitivity by single-shot multi-echo functional MR imaging

et al. 1999

View full text Add to dashboard Cite

Improved data acquisition and processing strategies for blood oxygenatlon level-dependent (BOlO)-conlrast funcllona1 magnetie resonaneo imaging (fMRI), wllich enhance the functional eontrast-to-nolse ratio (CNR) by sampllng multiple echo limes In a single shot, are descrlbed. The dependence of Ihe CNR on Ti, Ihe image encoding time, and Ihe number of samplod oeho titnes are Investigated for exponentia1 fitting, echo summation, welghled echo summation, and averaglng of corrolalion maps oblainod at different echo limes. The mothod is validated In vlvo using visual stimulation and turbo proton echoplanar speelroseopie imaging (turbo-PEPSI), a new single-shot multi-slice MR spoclroscoplc Imaging teehnlque, whlch acqulres up 10 12 consocutive ochoplanar images wlth echo limes ranging from 1210213 msec. Quantitative Ti-mapplng slgnificanUy increasos Ihe measured extent of aetivatJon and the mean correlalion coefficient compared wilh convenlional echoplanar imaging. The sensltlvity gain with echo summation, wllicll is compulationally efficiet:'lt provides similar sensitivity as fitting. For all data processing methods sensltivlty is optimum wh on echo limes IIp 10 3.2 T 2 are sampled. This molhodology has implications for comparing functional sonsitivity at different magnetie field strengths and between braln regions with different magnetic field inhomogeneitics.

show abstract

Section: Sensitivity Optimizationmentioning

confidence: 99%

mentioning

confidence: 99%

Enhancement of BOLD-contrast sensitivity by single-shot multi-echo functional MR imaging

et al. 1999

View full text Add to dashboard Cite

show abstract

“…The BOLD effect related to the water T 2 /T * 2 change can be detected by either the fMRI technique or the functional MRS (fMRS) technique by utilizing a localized spin-echo 1 H spectroscopy without water suppression to detect the NMR signal changes in the water resonance during cortical activation (18). The fMRS technique has a much higher SNR, since its signal is acquired from a relatively large voxel.…”

Section: Theorymentioning

confidence: 99%

“…The fMRS technique has a much higher SNR, since its signal is acquired from a relatively large voxel. This sensitivity allows for the study of subtle BOLD changes in the human brain during sensory stimulation (18,19). However, there are significant differences between the NMR signal sources acquired by the spin-echo fMRS and the spin-echo fMRI.…”

Section: Theorymentioning

confidence: 99%

Observed BOLD effects on cerebral metabolite resonances in human visual cortex during visual stimulation: A functional 1H MRS study at 4 T

Zhu

Chen

2001

Magn. Reson. Med.

View full text Add to dashboard Cite

Using the localized spin-echo 1 H MRS technique, the water resonance and methyl resonance peaks of the cerebral metabolites N-acetylaspartate (NAA at 2.0 ppm) and phosphocreatine/creatine (Cr at 3.0 ppm) were studied in the human visual cortex to detect and quantify the blood oxygenation level dependent (BOLD) effect during visual stimulation at 4 T. Significant BOLD effects, which reflect the increases of spectral peak height (H) accompanied by the decreases of spectral linewidth (⌬ 1/2 ), were observed in NAA (H: 2.5%; ⌬ 1/2 : ؊1.7%) and Cr (H: 3.1%; ⌬ 1/2 : ؊1.8%) as well as in water (H: 3.1%; ⌬ 1/2 : ؊2.3%). Because NAA and Cr mainly exist in the brain cells, the BOLD effects on these cerebral metabolite resonances only measure the susceptibility component spreading into the extravascular cellular compartment. In contrast, water is affected in the intraand the extravascular compartments. Therefore, the water signal measures the BOLD effects in both compartments. BOLD responses in water were similar to those observed in metabolites. The similarity indicates that the susceptibility spreading into the extravascular parenchyma contributed significantly to the observed BOLD effects at 4 T. The functional magnetic resonance imaging (fMRI) technique based on the blood oxygenation level dependent (BOLD) contrast has become a preferred neuroimaging methodology (1-6). The magnitude of the BOLD change due to elevated neuronal activity is determined by the local susceptibility changes (7-10). These changes originate from the variations of deoxyhemoglobin content in blood and spread both in the intravascular and extravascular tissue compartments. Neuronal activity induces both metabolic and hemodynamic changes in focal areas. The neuron firing elevates cerebral blood flow (CBF) and increases the oxygen supply around the activated sites. The oxidative metabolism extracts the oxygen carried by hemoglobin in blood and utilizes it for oxidative phosphorylation. This process occurs in the mitochondria of neurons and astrocytes/glia that coincide with the site of neuronal activity. Increases in the oxygen supply through CBF change and the oxygen utilization through oxidative metabolism result in changes in the blood oxygenation level and deoxyhemoglobin content beginning in the capillary areas. Then the blood in the capillaries passes through the postcapillary venules and drains into the venous vessels, resulting in changes in the deoxyhemoglobin content in these vessels and spreading the susceptibility gradients around and away from the actual sites of neuronal activity (11). These alterations in susceptibility gradients are detectable inside the vessels (intravascular compartment) and in the tissue near the vessels (extravascular compartment) using MRI. The relative BOLD contribution from intra-and extravascular compartments depends on the vascular architectures, magnetic field strength, image acquisition methods, as well as cerebral blood volume changes induced by neuronal activity (12,13). Generally, the extravascular BOLD...

show abstract

“…For example, the single voxel methods originally developed for magnetic resonance spectroscopy (MRS) enable detailed temporal sampling of the isolated voxel within as little as a single repetition time (10). Such methods were used to probe BOLD signal biophysics in the early development of fMRI (11), although their time efficiency for real-time fMRI NF has not been explored. Intermediate between single voxel and whole-brain coverage, methods have been developed that spatially resolve multiple compartments by limited phase encoding (12), as well as various ''line-scan'' methods that involve one-dimensional frequency encoding readouts or spatial localization provided by isolating a column of voxels in space (13)(14)(15)(16).…”

mentioning

confidence: 99%

Multiecho coarse voxel acquisition for neurofeedback fMRI

Kuo

Chiew

Tam

et al. 2010

Magnetic Resonance in Med

View full text Add to dashboard Cite

''Real-time'' functional magnetic resonance imaging is starting to be used in neurofeedback applications, enabling individuals to regulate their brain activity for therapeutic purposes. These applications use two-dimensional multislice echo planar or spiral readouts to image the entire brain volume, often with a much smaller region of interest within the brain monitored for feedback purposes. Given that such brain activity should be sampled rapidly, it is worthwhile considering alternative functional magnetic resonance imaging pulse sequences that trade spatial resolution for temporal resolution. We developed a prototype sequence localizing a column of magnetization by outer volume saturation, from which densely sampled transverse relaxation time decays are obtained at coarse voxel locations using an asymmetric gradient echo train. For 5 3 20 3 20 mm 3 voxels, 256 echoes are sampled at~1 msec and then combined in weighted summation to increase functional magnetic resonance imaging signal contrast. This multiecho coarse voxel pulse sequence is shown experimentally at 1.5 T to provide the same signal contrast to noise ratio as obtained by spiral imaging for a primary motor cortex region of interest, but with potential for enhanced temporal resolution. A neurofeedback experiment also illustrates measurement and calculation of functional magnetic resonance imaging signals within 1 sec, emphasizing the future potential of the approach. Magn Reson Med 65:715-724,

show abstract

Detection of brain activation using oxygenation sensitive functional spectroscopy

Cited by 66 publications

References 8 publications

Enhancement of BOLD-contrast sensitivity by single-shot multi-echo functional MR imaging

Enhancement of BOLD-contrast sensitivity by single-shot multi-echo functional MR imaging

Observed BOLD effects on cerebral metabolite resonances in human visual cortex during visual stimulation: A functional 1H MRS study at 4 T

Multiecho coarse voxel acquisition for neurofeedback fMRI

Contact Info

Product

Resources

About