Abstracts

Rationale: Recent studies suggest that increased choline levels and neuroinflammation (NI) may be biomarkers of Major Depressive Disorder (MDD). Brain temperature may be used as a proxy for NI. To date, brain temperature studies have been conducted only in healthy patients with MDD without comorbid epilepsy. We investigated brain choline levels and temperature with volumetric magnetic resonance spectroscopic imaging (MRSI) in healthy controls and in patients with temporal lobe epilepsy (TLE) with and without depression.

Methods: Twenty healthy controls (HC, 22–52 YOA) and 20 temporal lobe epilepsy (TLE, 22–71 YOA) patients completed questionnaires and underwent imaging on a 3T MRI. Volumetric MRSI data collected by whole-brain echo-planar spectroscopic imaging were reconstructed and processed within the Metabolite Imaging and Data Analysis System. This included spatial reconstruction, frequency alignment, B₀ inhomogeneity correction, lipid suppression, spectral fitting, normalization and integration with water reference data. Brain temperature was calculated by T_CRE=−102.61×Δ_H20-CRE+206.1°C. Choline (CHO) was quantified as the ratio over CRE (CHO/CRE). The Hospital Anxiety and Depression Scale (HADS) measured anxiety and depressive symptoms. The Profile of Mood States (POMS) assessed total mood disturbance (TMD) using seven subscales of negative affect. Independent samples t-tests computed group differences in mood measures. Voxelwise general linear models computed group differences in the association between mood measures and T_CRE and CHO/CRE. Significance testing was conducted with permutation-based testing with the Threshold-Free Cluster Enhancement toolbox. Logarithmically scaled p-values were considered significant at p< 0.05, with corrections for multiple comparisons using family-wise error.