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Theories of perception have proposed a basic distinction between parallel pre-attentive and serial attentive modes of processing. However, chronometric measures are often ambiguous in separating parallel and serial processes. We have used the activity of attention-related regions of the human brain, measured with functional magnetic resonance imaging, to(More)
In the present work, the NMR properties of perfluorooctylbromide are revisited to derive a high-sensitivity fluorine MRI strategy. It is shown that the harmful effects of J-coupling can be eliminated by carefully choosing the bandwidth of the 180 degrees pulses in a spin-echo sequence. The T(2) of the CF(3) resonance of the molecule is measured using a(More)
We detected glutamate C4 and C3 labeling in the monkey brain during an infusion of [U-13C6]glucose, using a simple 1H PRESS sequence without 13C editing or decoupling. Point-resolved spectroscopy (PRESS) spectra revealed decreases in 12C-bonded protons, and increases in 13C-bonded protons of glutamate. To take full advantage of the simultaneous detection of(More)
One of the promises of Ultra High Field (UHF) MRI scanners is to bring finer spatial resolution in the human brain images due to an increased signal to noise ratio. However, at such field strengths, the spatial non-uniformity of the Radio Frequency (RF) transmit profiles challenges the applicability of most MRI sequences, where the signal and contrast(More)
Transmit arrays have been developed to compensate for radiofrequency inhomogeneities in high-field MRI using different excitation schemes. They can be classified into static or dynamic shimmings depending on the target: homogenizing the radiofrequency field directly or homogenizing the flip angle distribution using the Bloch equation. We have developed an(More)
An MR thermometry method is proposed for measuring in vivo small temperature changes engendered by external RF heat sources. The method relies on reproducible and stable respiration and therefore currently applies to ventilated animals whose breathing is carefully controlled. It first consists in characterizing the stability of the main magnetic field as(More)
The in vivo determination of peripheral vascular resistances (VR) is crucial for the assessment of arteriolar function. It requires simultaneous determination of organ perfusion (F) and arterial blood pressure (BP). A fully non-invasive method was developed to measure systolic and diastolic BP in the caudal artery of rats based on dynamic NMR angiography. A(More)
Parallel transmission is a very promising method to tackle B1+ field inhomogeneities at ultrahigh field in magnetic resonant imaging (MRI). This technique is however limited by the mutual coupling between the radiating elements. Here we propose to solve this problem by designing a passive magneto-electric resonator that we here refer to as stacked magnetic(More)
Lithium is the first-line mood stabilizer for the treatment of patients with bipolar disorder. However, its mechanisms of action and transport across the blood-brain barrier remain poorly understood. The contribution of lithium-7 magnetic resonance imaging (7 Li MRI) to investigate brain lithium distribution remains limited because of the modest sensitivity(More)
OBJECTIVE To determine whether left ventricular hypertrophy can be correctly evaluated in hypertensive rats with a new nuclear magnetic resonance (NMR) imaging modality that is relatively simple to operate and provides results of constant quality while offering a high signal-to-noise ratio. DESIGN Left ventricular mass as calculated from the NMR imaging(More)
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