Jean-Noël Hyacinthe

Haute école de santé Genève · Radiologic Technology

Dissolution Dynamic Nuclear Polarization (dDNP) is the most versatile hyperpolarization technique to enhance NMR sensitivity in the liquid state. The unprecedented signal enhancement is the key for a large range of applications spanning from fast chemical reaction monitoring to metabolism investigation in real time. Unfortunately, this exceptional...

Dissolution Dynamic Nuclear Polarization (dDNP) was invented almost twenty years ago. Ever since, hardware advancement has observed 2 trends: the quest for DNP at higher field and, more recently, the development of cryogen free polarizers. Despite the DNP community is slowly migrating towards “dry” systems, many “wet” polarizers are still in use. T...

Cerebral metabolism, which can be monitored by magnetic resonance spectroscopy (MRS), changes rapidly after brain ischaemic injury. Hyperpolarisation techniques boost 13C MRS sensitivity by several orders of magnitude, thereby enabling in vivo monitoring of biochemical transformations of hyperpolarised (HP) 13C-labelled precursors with a time resol...

The purpose of this study was to develop micron-sized droplet emulsions able to increase the heat deposition of high intensity focused ultrasound (HIFU), aiming to accelerate the tumour ablation in highly perfused organs with reduced side effects. The investigated droplets consisted of a perfluorooctyl bromide (PFOB) core coated with a biocompatibl...

Objective: Perfluorocarbon nano- and micron-sized emulsions are a new field of investigation in cancer treatment due to their ability to be used as imaging contrast agents, or as delivery vectors for pharmaceuticals. They also demonstrated capability to enhance the efficiency of high intensity focused ultrasound thermo-therapy. In the context of n...

Purpose: Treatments using high-intensity focused ultrasound (HIFU) in the abdominal region remain challenging as a result of respiratory organ motion. A novel method is described here to achieve 3D motion-compensated ultrasound (US) MR-guided HIFU therapy using simultaneous ultrasound and MRI. Methods: A truly hybrid US-MR-guided HIFU method was...

A fast positioning method for brain tumor microbeam irradiations for preclinical studies at third-generation X-ray sources is described. The three-dimensional alignment of the animals relative to the X-ray beam was based on the X-ray tomography multi-slices after iodine infusion. This method used pink-beam imaging produced by the ID17 wiggler. A gr...

Hyperpolarization via dissolution dynamic nuclear polarization (DNP) is a versatile method to dramatically enhance the liquid-state NMR signal of X-nuclei and can be used for performing metabolic and molecular imaging. It was recently demonstrated that instead of incorporating persistent radicals as source of unpaired electron spins, required for D...

In addition to the dedicated spin exchange optical pumping (SEOP) technique, an alternative method to produce hyperpolarizedxenon gasusing dynamic nuclear polarization (DNP) followed by a sublimation procedure was proposed. The challenge associated with sublimation DNP is to obtain solid-state samples with the required homogeneity following the inc...

Hyperpolarization via dissolution dynamic nuclear polarization (DNP) is a versatile method to dramatically enhance the liquid-state NMR signal of X-nuclei and can be used for performing metabolic and molecular imaging. It was recently demonstrated that instead of incorporating persistent radicals as source of unpaired electron spins, required for D...

Significance Hyperpolarization is a significant development in MRI because it allows for imaging different metabolites in real time in vivo. There are no fundamental obstacles to rapid translation of this technique. Yet, to date, it has been necessary to use persistent radicals that need to be filtered out before injection and require pharmacologic...

In a method and an apparatus for magnetic resonance guided high intensity focused ultrasound (HIFU), precise localization of the focal point of the HIFU is determined by imaging an examination subject in parallel with GRE sequences that respectively include a positive monopolar gradient pulse and a negative monopolar gradient pulse, that respective...

Human bone blood flow, mean blood speed and the number of moving red blood cells were assessed (in arbitrary units), as a function of time, during one cardiac cycle. The measurements were obtained non-invasively on five volunteers by laser-Doppler flowmetry at large interoptode spacing. The investigated bones included: patella, clavicle, tibial dia...

MR acoustic radiation force imaging (ARFI) is an elegant adjunct to MR-guided high intensity focused ultrasound for treatment planning and optimization, permitting in situ assessment of the focusing and targeting quality. The thermal effect of high intensity focused ultrasound pulses associated with ARFI measurements is recommended to be monitored...

Using a small, but very instructive experiment, it is demonstrated that laser-Doppler flowmetry (LDF) at large interoptode spacing represents a unique tool for new investigations of thermoregulatory processes modulating the blood flow of small muscle masses in humans. It is shown on five healthy subjects that steady-state values of blood flow (perf...

To define the relationship between regional coronary vasodilator capacity and myocardial circumferential strain at rest in normal weight, overweight, and obese individuals with normal global left-ventricular function. Myocardial blood flow at rest and during pharmacologic vasodilation was measured with (13)N-ammonia PET/CT in mL/g/minute in normal...

Manganese (Mn(2+)) is considered as a specific MRI contrast agent that enters viable cardiomyocytes through calcium pathways. Compared to extracellular gadolinium based contrast agents, it has the potential to assess cell viability. To date, only information from the washout phase after recirculation has been used for the detection and characteriza...

Accurate assessment of mice cardiac function with magnetic resonance imaging is essential for longitudinal studies and for drug development related to cardiovascular diseases. Whereas dedicated small animal MR scanners are not readily available, it would be a great advantage to be able to perform cardiac assessment on clinical systems, in particula...

Background Obesity is associated with cardiac remodelling with increased left ventricular mass and end-diastolic volume. CMR is a unique technique to evaluate cardiac morphology and function in obese individuals. Among CMR techniques, myocardial tagging allows to quantify myocardial strain and left ventricular rotation along the RR cycle (1). The a...

The aim of the study was to evaluate the reliability and sensitivity of tagged cardiac magnetic resonance imaging (cMRI) in assessment of regional cardiac dysfunction induced by short ischemia. For clinical low dose dobutamine tests, quantitative strain analyses derived from tagged cMRI have been shown to be able to detect viable myocardium. Howev...

Background: The purpose of this study was to measure regional contractile function in the normal rat using cardiac cine and tagged cardiovascular magnetic resonance (CMR) during incremental low doses of dobutamine and at rest.

Despite intense effort, obesity is still rising throughout the world. Links between obesity and cardiovascular diseases are now well established. Most of the cardiovascular changes related to obesity can be followed by magnetic resonance imaging (MRI) or by magnetic resonance spectroscopy (MRS). In particular, we will see in this review that MRI/MR...

A high throughput method was designed to produce hyperpolarized gases by combining lowtemperature dynamic nuclear polarization with a sublimation procedure. It is illustrated by applications to 129Xe nuclear magnetic resonance in xenon gas, leading to a signal enhancement of 3 to 4 orders of magnitude compared to the room-temperature thermal equili...

Manganese (Mn(2+)) was recognized early as an efficient intracellular MR contrast agent to assess cardiomyocyte viability. It had previously been used for the assessment of myocardial infarction in various animal models from pig to mouse. However, whether Manganese-Enhanced MRI (MEMRI) is also able to assess infarction in the acute phase of a coron...

To evaluate the feasibility of loading resting monocytes/macrophages by intravenous (i.v.) injection of fluorescent iron oxide nanoparticles prior to injury and tracking of these cells in the very same animal to myocardial infarction (MI) by magnetic resonance imaging (MRI) and optical imaging. Rats were injected with fluorescent iron oxide nanopar...

Real-time cardiac MRI appears as a promising technique to evaluate the mechanical function of the heart. However, ultra-fast MRI acquisitions come with an important signal-to-noise ratio (SNR) penalty, which drastically reduces the image quality. Hence, a real-time denoising approach would be desirable for SNR amelioration. In the clinical context...

Real-time cardiac MRI appears as a promising technique to evaluate the mechanical function of the heart. However, ultra-fast MRI acquisitions come with an important signal-to-noise ratio (SNR) penalty, which drastically reduces the image quality. Hence, a real-time denoising approach would be desirable for SNR amelioration. In the clinical context...

The purpose of this study was to measure regional contractile function in the normal rat using cardiac cine and tagged cardiovascular magnetic resonance (CMR) during incremental low doses of dobutamine and at rest. Five rats were investigated for invasive left ventricle pressure measurements and five additional rats were imaged on a clinical 1.5 T...

The aim of this study was to measure the myocardial area at risk in rat, using MRI and manganese injection during a coronary occlusion/reperfusion model at 1.5T. A sequential protocol with occlusion and MnCl2 injection immediately followed by MRI was used with the assumption that MnCl2-induced contrast persistence is enough to accurately image the...

It has been shown that manganese-enhanced MRI (MEMRI) can safely depict the myocardial area at risk in models of coronary occlusion-reperfusion for at least 2 h after reperfusion. To achieve this, a solution of MnCl(2) is injected during coronary occlusion. In this model, the regional function quantification deficit of the stunning phase cannot be...

The purpose of this study was to assess the feasibility of cardiac magnetic resonance (MR) tagging in rats on a standard clinical 1.5T MR system. Small animal models have been largely used as an experimental model in cardiovascular disease studies but mainly on high field systems (>4T) dedicated to research. Given the larger availability of routine...

This work takes is part of a medical research project which intends to induce and study cardiac hibernation in rats. The underlying goal is to understand the physiology of heart disease. We present here a novel method to compute the 2D-deformation field of the heart (rat or human) from tagged MRI. Previous work is not suitable for wide clinical use...

The overall goal was to study cardiovascular function in small animals using a clinical 1.5-T MR scanner optimizing a fast gradient-echo cine sequence to obtain high spatial and temporal resolution. Normal rat hearts (n = 9) were imaged using a 1.5-T MR scanner with a spiral fast gradient-echo (fast field echo for Philips scanners) sequence, three...

We present in this paper some examples of the applications of the Nuclear Magnetic Resonance (NMR) of xenon used as a probe in the study of different chemical environments: determination of the porosity of micro- and mesoporous solids, evaluation of the concentrations and sizes of amorphous domains in solid polymers, characterization of liquid crys...

Publisher Summary This chapter examines the use of laser-polarized xenon nuclear magnetic resonance (NMR) for brain perfusion imaging. The biophysical properties of xenon make it a good candidate for NMR tissue probing or perfusion studies. Xenon is hyperpolarized by collisional spin exchange with rubidium vapor pumped optically at 795 nm. It is fo...

The purposes of this study were to assess the extent of the inflow effect on signal intensity (SI) for fast gradient-recalled-echo (GRE) sequences used to observe first-pass perfusion, and to develop and validate a correction method for this effect. A phantom experiment with a flow apparatus was performed to determine SI as a function of Gd-DTPA co...

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...

Introduction It has been shown that Manganese Enhanced Magnetic Resonance (MEMR) can be use to depict, in a non invasive way, the myocardial area at risk in models of coronary occlusion-reperfusion [1]. To this purpose MnCl 2 solution is injected during the occlusion. In such models, we cannot evaluate global and regional function before MnCl 2 inj...