Exploration of Differences in Metabolite Concentrations by 7Teslas NMR Spectroscopy in Striatum and Subthalamic Nuclei in de Novo Parkinsonian Patients and Control Subjects

Summary

Initially, the exploration of brain metabolism by Nuclear Magnetic Resonance Spectroscopy (MRS) of the high magnetic field proton (1H) (11.7T) applied to acute and chronic animal models of Parkinson's disease (PD) showed glutamatergic hyperactivity within the striatum, one of the components of the basal ganglia. Interestingly, acute administration of L-dopa and acute, subchronic and chronic deep brain stimulation of the subthalamic nucleus (STN) normalizes these neurochemical profiles. Investigators also show an increase in glutamate levels in the STN ipsilateral to the substantia nigra pars compacta (SNpc) damaged by the neurotoxin, expected phenomenon, but also and surprisingly in the STN controlateral to the lesion. A degeneration of dopaminergic neurons is also observed in the controlateral SNpc at the lesion suggesting that the hyperglutamatergy of the controlateral STN to the lesion could promote neuronal death in the SNpc and thus participate in the progression and lateralization of the PD.

Using 3T MRS in PD patients, as in other studies in humans, investigators do not see changes in glutamate and glutamine levels in the putamen of Parkinsonian patients. This difference between animal and human studies can be explained:

1. by the different rate of progression between PD in humans and animal models with plasticity phenomena limiting glutamatergic hyperactivity,
2. by the effect of treatment in PD masking changes in glutamate metabolism,
3. by limiting sensitivity in the detection of metabolites (Glutamate, glutamine, GABA) at 3T.

The 7T 1H MRS improves the dispersion of chemical shifts of the metabolites studied, increases the sensitivity of the measurement, makes it possible to select regions of interest of smaller volumes (1 cm3) and thus limits the magnetic susceptibility effects that degrade the quality of the measured signal. This makes it possible to reliably separate glutamate and glutamine peaks.

In this context, investigators propose to study the metabolic changes in a homogeneous group of de novo Parkinsonian patients, naive to any treatment intended to replace the missing dopamine. The gain in spatial resolution, contrast and signal will allow better characterization of localized anomalies in small-volume structures such as basal ganglia, putamen and STN.

Conditions

• Parkinson's Disease

Interventions

OTHER

specific MRI Acquisition (NMR spectroscopy) at 7T

The MRI protocol will be performed at 7T on a Siemens NMR imaging system (Magnetom Terra, Siemens Healthcare, Erlangen, Germany), the radio frequency emission and signal reception will be done through a head quadrature resonator (64-channel phase-array coil). To avoid motion-related artifacts, the patient will be seated in a supine position, with the arms along the body and the head immobilized using a suitable head restraint. The MR protocol will take place in two phases: * Acquisition of 3D multi-slice T1 and T2-weighted morphological images to identify areas of interest; * Acquisition of 1D RMN spectra in the right and left putamen and STN. Spectra will be acquired in volumes of interest of 15mmx15mmx15mm using a localized spectroscopy sequence with and without suppression of the water signal. Main parameters are: TR (repetition time)=3000ms; TE (echo time)=20 ms; number of repetitions=128; scan time 6min).

Sponsors & Collaborators

• University Hospital, Clermont-Ferrand

  lead OTHER

Principal Investigators

• Ana Rachel MARQUES · University Hospital, Clermont-Ferrand

Study Design

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

75 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2022-04-07

Primary Completion

2029-08-31

Completion

2029-08-31

Countries

• France

Study Locations