Jean-Louis Leviel

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Tissue samples were obtained by serial stereotactic biopsies in 32 patients with glial brain tumors localized by CT. On each sample, several tissue parameters, such as water content, specific gravity of the dry and wet tissue, electrical impedance, histopathological and cytological examinations, as well as nuclear magnetic resonance (NMR) relaxation times(More)
Hyperpolarized (129)Xe dissolved in a lipid emulsion constitutes an NMR tracer that can be injected into the blood stream, enabling blood-flow measurement and perfusion imaging. A small volume (0.15 ml) of this tracer was injected in 1.5 s in rat carotid and (129)Xe MR spectra and images were acquired at 2.35 T to evaluate the potential of this approach for(More)
STUDY DESIGN This study examined the effect of radio-frequency thermocoagulation on cadaveric disc material. Radio-frequency lesions are induced to decompress the nerve root by coagulating the nucleus pulposus. OBJECTIVES The purpose of this study was to assess the potential of the radio-frequency lesion technique for treating lumbar disc herniation(More)
Hyperpolarized 129Xe was dissolved in a lipid emulsion and administered to anaesthetized rats by manual injections into the carotid (approximately 1-1.5 mL in a maximum time of 30 s). During injection, 129Xe NMR brain spectra at 2.35 T were recorded over 51 s, with a repetition time of 253 ms. Two peaks assigned to dissolved 129Xe were observed (the larger(More)
The magnetic polarization of the stable (129)Xe isotope may be enhanced dramatically by means of optical techniques and, in principle, hyperpolarized (129)Xe MRI should allow quantitative mapping of cerebral blood flow with better spatial resolution than scintigraphic techniques. A parameter necessary for this quantitation, and not previously known, is the(More)
The delay in the appearance and the extent of a lesion induced by gamma-irradiation, in rabbit iliospinalis muscles, have been evaluated in vivo by MRI. The left side rabbit muscle was irradiated with an 192Ir sealed source at two skin surface doses: 40 Gy and 80 Gy. The progress of the lesion was followed on a long-term basis (12 months) by using T2(More)
Chronic implantation of surface coils on the skull has been developed to record 31P NMR spectra of the brain in unanesthetized rats. Intraperitoneal sublethal potassium cyanide doses induce strong and reversible changes in high-energy phosphate compounds in the brain, similar in part to those induced by ischemia. These effects are dose-dependent as far as(More)
The purpose of this study was to evaluate the recently proposed technique of 3He prepolarization at low temperature and high field (Kober et al. Magn Reson Med 1999; 41:1084-1087) for fast imaging of the lung. Helium-3 was cooled to 2.4 K in a magnetic field of 8 Tesla to obtain a polarization of 0.26%. The polarized 3He was warmed up to room temperature(More)
The first 3He nuclear magnetic resonance (NMR) experiments using low-temperature prepolarization are presented. 3He cells were polarized at 4.2 K and 4.7 T, transported to another magnet, heated to room temperature, and used for NMR experiments at 2.35 T. Cells with and without a rubidium coating were tested. In both cases, the NMR signal was greater than(More)