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PT  - JOURNAL ARTICLE
AU  - Biller, A.
AU  - Reuter, M.
AU  - Patenaude, B.
AU  - Homola, G.A.
AU  - Breuer, F.
AU  - Bendszus, M.
AU  - Bartsch, A.J.
TI  - Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by &lt;sup&gt;1&lt;/sup&gt;H-MR Imaging and Spectroscopy
AID  - 10.3174/ajnr.A4508
DP  - 2015 Dec 01
TA  - American Journal of Neuroradiology
PG  - 2277--2284
VI  - 36
IP  - 12
4099  - http://www.ajnr.org/content/36/12/2277.short
4100  - http://www.ajnr.org/content/36/12/2277.full
SO  - Am. J. Neuroradiol.2015 Dec 01; 36
AB  - BACKGROUND AND PURPOSE: As yet, there are no in vivo data on tissue water changes and associated morphometric changes involved in the osmo-adaptation of normal brains. Our aim was to evaluate osmoadaptive responses of the healthy human brain to osmotic challenges of de- and rehydration by serial measurements of brain volume, tissue fluid, and metabolites.MATERIALS AND METHODS: Serial T1-weighted and 1H-MR spectroscopy data were acquired in 15 healthy individuals at normohydration, on 12 hours of dehydration, and during 1 hour of oral rehydration. Osmotic challenges were monitored by serum measures, including osmolality and hematocrit. MR imaging data were analyzed by using FreeSurfer and LCModel.RESULTS: On dehydration, serum osmolality increased by 0.67% and brain tissue fluid decreased by 1.63%, on average. MR imaging morphometry demonstrated corresponding decreases of cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus. These changes reversed during rehydration. Continuous fluid ingestion of 1 L of water for 1 hour within the scanner lowered serum osmolality by 0.96% and increased brain tissue fluid by 0.43%, on average. Concomitantly, cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus increased. Changes in brain tissue fluid were related to volume changes of the whole brain, the white matter, and hypothalamus/thalamus. Only volume changes of the hypothalamus/thalamus significantly correlated with serum osmolality.CONCLUSIONS: This is the first study simultaneously evaluating changes in brain tissue fluid, metabolites, volume, and cortical thickness. Our results reflect cellular volume regulatory mechanisms at a macroscopic level and emphasize that it is essential to control for hydration levels in studies on brain morphometry and metabolism in order to avoid confounding the findings.HCThematocritOSMserumserum osmolality