Functional brain MR imaging based on bolus tracking with a fast T2∗-sensitized gradient-echo method

Moonen, Chrit; Barrios, Fernando A.; Zigun, Jeffrey R.; Gillen, Joseph; Li, Guoying; Sobering, Geoffrey; Sexton, Roy H.; Woo, John; Frank, Joseph A.; Weinberger, Daniel R.

doi:10.1016/0730-725x(94)92530-5

Cited by 33 publications

(23 citation statements)

References 12 publications

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“…The reduced sensitivity in the mouse images can be largely explained by the difference in experimental parameters. The signal loss due to the fivefold-smaller voxel dimensions (0.040 vs. 0.195 l) is in part compensated by the reduced volume and hence the increased sensitivity of the mouse birdcage imaging probe (probe volume ϭ 31 cm 3 for the mouse as compared to 75 cm 3 for the rat head resonator). Thus, the demands for higher spatial resolution in mouse fMRI studies significantly compromises the SNR by a factor of 2.5 as compared to the rat.…”

Section: Discussionmentioning

confidence: 99%

“…fMRI has proven its utility for the noninvasive mapping of brain function with high temporal and spatial resolution. Depending on the method applied, image contrast in fMRI is determined either by the oxygenation state of hemoglobin (BOLD) (1) or by changes in cerebral hemodynamics, i.e., cerebral blood flow (CBF) (2,3) and CBV (4). Using superparamagnetic iron-oxide nanoparticles as a blood-pool contrast agent, a local CBV rel increase is reflected by an increase in the amount of magnetite nanoparticles in the activated tissue and, correspondingly, by a decrease in the signal intensities in T 2 -weighted images.…”

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confidence: 99%

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Bicuculline‐induced brain activation in mice detected by functional magnetic resonance imaging

Mueggler

Baumann

Rausch

et al. 2001

Magnetic Resonance in Med

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Key words: functional magnetic resonance imaging; relative cerebral blood volume; bicuculline; pharmacological stimulation; mouse; iron-oxide nanoparticles; transcutaneous blood gas monitoring Genetic engineering and transgenic technology have led to advances in the generation of animal models that develop aspects of various brain pathologies, and have emphasized the need to develop accurate methods when phenotyping these animals. Such models would benefit from the development of noninvasive methods to study disease progression while allowing for a correlation with behavioral studies. The purpose of the present study was to assess the feasibility of functional magnetic resonance imaging (fMRI) in mice by monitoring changes in local relative cerebral blood volume (CBV rel ) during pharmacological stimulation under controlled physiological conditions, and hence to assess the potential of pharmacological fMRI as a noninvasive method to characterize transgenic and knock-out mice models. fMRI has proven its utility for the noninvasive mapping of brain function with high temporal and spatial resolution. Depending on the method applied, image contrast in fMRI is determined either by the oxygenation state of hemoglobin (BOLD) (1) or by changes in cerebral hemodynamics, i.e., cerebral blood flow (CBF) (2,3) and CBV (4). Using superparamagnetic iron-oxide nanoparticles as a blood-pool contrast agent, a local CBV rel increase is reflected by an increase in the amount of magnetite nanoparticles in the activated tissue and, correspondingly, by a decrease in the signal intensities in T 2 -weighted images. High-resolution CBV rel maps can be derived from the signal attenuation once the tracer has reached a steady-state blood concentration. Applying this CBV rel -fMRI method, activation in the rat sensory cortex caused by electrical stimulation of the forepaw was demonstrated (5,6). Hemodynamic changes associated with a pharmacological stimulation paradigm have been demonstrated in rats, and could be used to study drugs at the specific receptor level. Systemic infusion of the GABA A antagonist bicuculline led to an alteration in neuronal activity in cortical and subcortical brain structures. Dose-dependent CBV rel increases have been measured in various brain structures (e.g., the cortex, thalamus, and caudate putamen) in the rat (7).It is well known that physiological parameters, such as body temperature and blood gases, will affect CBV values. Mandeville et al. (6) reported CBV rel increases on the order of 50% in rats during hypercarbia by increasing arterial CO 2 tension (PaCO 2 ) from 25-55 mmHg. Although reports on the quantitative relationship between changes in CBV rel and PaCO 2 differ considerably, it is obvious that control and continuous monitoring of blood CO 2 and blood oxygenation are critical for detecting small alterations of cerebrovascular parameters in the mouse. Although larger animals can sustain frequent blood samplings, noninvasive monitoring of blood gases has been found to be essential when studying m...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Bicuculline‐induced brain activation in mice detected by functional magnetic resonance imaging

Mueggler

Baumann

Rausch

et al. 2001

Magnetic Resonance in Med

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“…Figure 1 shows a schematic representation of the 3D-PRESTO sequence as implemented in our imager. Its characteristics are reduced sensitivity to field inhomogeneities as compared with conventional EPI readout, and reduction of acquisition time by shifting the gradient echo over one or more repetition times (TR) (15,16). The 3D-PRESTO sequence has been validated in numerous fMRI studies (17)(18)(19).…”

Section: For Review)mentioning

confidence: 99%

PRESTO-SENSE: An ultrafast whole-brain fMRI technique

et al. 2000

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“…The idea of extending the echo time while maintaining efficient sampling was firstly introduced in Moonen et al (1992). Since then, echo shifting has found different applications -for example, in the field of T * 2 weighted bolus tracking (Moonen et al, 1994) and diffusion weighted images (DWI) (Delalande et al, 1999). Another popular sequence that implements echo shifting is the PRESTO sequence (Liu et al, 1993).…”

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An exploration of task based fMRI in neonates using echo-shifting to allow acquisition at longer T without loss of temporal efficiency

et al. 2016

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Optimal Contrast to Noise Ratio of the BOLD signal in neonatal and fetal fMRI has been hard to achieve because of the much longer T * 2 values in developing brain tissue in comparison to those in the mature adult brain. The conventional approach of optimizing fMRI sequences would suggest matching the echo time (T E ) and the T * 2 of the neonatal and fetal brain. However, the use of a long echo time would typically increase the minimum repetition time (T R ) resulting in inefficient sampling. Here we apply the concept of echo shifting to task based neonatal fMRI in order to achieve an improved Contrast to Noise Ratio and efficient data sampling at the same time. Echo shifted EPI (es-EPI) is a modification of a standard 2D-EPI sequence which enables echo times longer than the time * Corresponding author Email address: giulio.ferrazzi@kcl.ac.uk (Giulio Ferrazzi) 1 Contributed equally to the paper Preprint submitted to NeuroImage January 18, 2016, where N S is the number of acquired slices and T S the inter-slice repetition time). The proposed method was tested on neonatal subjects using a passive sensori-motor task paradigm. Dual echo EPI datasets with an identical readout structure to es-EPI were also acquired and used as control data to assess BOLD activation. From the results of the latter analysis, an average increase of 78 ± 41 % in Contrast to Noise Ratio was observable when comparing late to short echoes. Furthermore, es-EPI allowed the acquisition of data with an identical contrast to the late echo, but more efficiently since a higher number of slices could be acquired in the same amount of time.

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Functional brain MR imaging based on bolus tracking with a fast T2∗-sensitized gradient-echo method

Cited by 33 publications

References 12 publications

Bicuculline‐induced brain activation in mice detected by functional magnetic resonance imaging

Bicuculline‐induced brain activation in mice detected by functional magnetic resonance imaging

PRESTO-SENSE: An ultrafast whole-brain fMRI technique

An exploration of task based fMRI in neonates using echo-shifting to allow acquisition at longer T without loss of temporal efficiency

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