Combining sodium MRI, proton MR spectroscopic imaging, and intracerebral EEG in epilepsy
Abstract
Whole brain ionic and metabolic imaging has potential as a powerful tool for the characterization of brain diseases. We combined sodium MRI (23 Na MRI) and 1 H-MR Spectroscopic Imaging (1 H-MRSI), assessing changes within epileptogenic networks in comparison with electrophysiologically normal networks as defined by stereotactic EEG (SEEG) recordings analysis. We applied a multi-echo density adapted 3D projection reconstruction pulse sequence at 7 T (23 Na-MRI) and a 3D echo-planar spectroscopic imaging sequence at 3 T (1 H-MRSI) in 19 patients suffering from drugresistant focal epilepsy who underwent presurgical SEEG. We investigated 23 Na MRI parameters including total sodium concentration (TSC) and the sodium signal fraction associated with the short component of T 2 * decay (f), alongside the level of metabolites N-acetyl aspartate (NAA), choline compounds (Cho), and total creatine (tCr). All measures were extracted from spherical regions of interest (ROIs) centered between two adjacent SEEG electrode contacts and z-scored against the same ROI in controls. Group comparison showed a significant increase in f only in the epileptogenic zone (EZ) compared to controls and compared to patients' propagation zone (PZ) and noninvolved zone (NIZ). TSC was significantly increased in all patients' regions compared to controls. Conversely, NAA levels were significantly lower in patients compared to controls, and lower in the EZ compared to PZ and NIZ. Multiple regression analyzing the relationship between sodium and metabolites levels revealed significant relations
Keywords
ultrashort echo time
voltage-gated sodium channel
fluorodeoxyglucose PET
hydrogen
sodium
anterior commissure-posterior commissure
achieved significance level
choline compounds
CRLB
Cramer-Rao lower bound
DNET
dysembryoplastic neuroepithelial tumor
EAAT
glutamate transporter
extracellular volume
Epileptogenicity Index
EPSI
echoplanar spectroscopic imaging
epileptogenic zone
fraction of sodium signal with short T 2 * decays
focal cortical dysplasia
FDR
false discovery rate
FOV
field of view
GRAPPA
GeneRalized Autocalibrating Partial Parallel Acquisition
HC
healthy control
MIDAS
Metabolite Imaging and Data Analyses System
MNI
Montreal Neurological Institute
MP2RAGE
magnetization prepared 2 rapid acquisition gradient echo
MPRAGE
magnetization prepared rapid acquisition gradient echo
Na+/K+ pump
sodium potassium pump
N-acetyl aspartate
apparent concentrations of sodium with long T2* decays
apparent concentrations of sodium with short apparent T2* decay
bicarbonate sodium cotransporter
sodium calcium exchanger
sodium hydrogen antiporter
noninvolved zone
sodium potassium chloride cotransporter
pH
potential of hydrogen
propagation zone
region of interest
stereotactic EEG
sodium longT 2 * relaxation time
sodium short T 2 * relaxation time
total creatine
echo time
inversion time
repetition time
total sodium concentration
Domains
Imaging
Origin : Files produced by the author(s)