Combining sodium MRI, proton MR spectroscopic imaging, and intracerebral EEG in epilepsy. Issue 2 (11th October 2022)

• Record Type: Journal Article
• Authors: Azilinon, Mikhael; Makhalova, Julia; Zaaraoui, Wafaa; Medina Villalon, Samuel; Viout, Patrick; Roussel, Tangi; El Mendili, Mohamed M.; Ridley, Ben; Ranjeva, Jean‐Philippe; Bartolomei, Fabrice; Jirsa, Viktor; Guye, Maxime
• Is Part Of: Human brain mapping. Volume 44:Issue 2(2023)
• Page Start: 825
• Page End: 840
• Publication Date: 2022-10-11
• Subjects: 1H‐spectroscopic imaging -- 7 T MRI -- epilepsy -- intracranial EEG -- multimodal imaging -- sodium MRI; Brain mapping -- Periodicals; 611.81
• DOI: 10.1002/hbm.26102
• Languages: English
• ISSNs: 1065-9471

Abstract

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 drug‐resistant 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 T2 * 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 non‐involved 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 in PZ and in NIZ but not in EZ. Our results are in agreement with the energetic failure hypothesis in epileptic regions associated with widespread tissue reorganization. Abstract : We combined sodium MRI, MR spectroscopic imaging, and stereoelectroencephalography to study epileptic and nonepileptic regions in vivo in patients suffering from focal epilepsy. Increased sodium and decreased N‐acetyl aspartate concentrations, potentially linked to energetic failures, were found in the epileptogenic zones (EZs), while homeostatic and structural alterations were found outside the EZs.