Poster Presentation Australian & New Zealand Society of Magnetic Resonance Conference 2017

Diurnal effects on brain MRI volume and 1D MR neurospectroscopy (#92)

Oun Al-iedani 1 , Karen Ribbons 2 , Jameen ARM 3 , Jeannette Lechner-Scott 2 3 4 , Saadallah Ramadan 1
  1. School of Health Sciences, University of Newcastle , Newcastle, NSW, Australia
  2. Department of Neurology , John Hunter Hospital, Newcastle, NSW, Australia
  3. Hunter Medical Research Institute, Newcastle, NSW, Australia
  4. School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia

Background and Aims: Novel MRI techniques have recently been developed to increase our understanding underlying pathophysiology in a number of neurological diseases including multiple sclerosis(MS). 1H Magnetic Resonance Spectroscopy(1H-MRS) is a non-invasive technique that evaluates neurometabolite levels1. MR-based total brain volume(TBV) changes (atrophy) have been associated with MS progression2. One possible factor that needs to be considered in longitudinal studies is the potential impact of diurnal effects on brain volume3 and neurometabolite levels4. Repeated 3D-MPRAGE and 1H-MRS were undertaken over a 10-hour period in healthy controls(HCs) to determine diurnal changes in TBV and neurometabolite profiles in the posterior cingulate gyrus(PCG).

Methods: 10 HCs, 5 males and 5 females (36.1±7.7 years) were scanned at 07:00(T1), 12:00 (T2) and 17:00(T3) on the same day using a 3T MRI scanner (Prisma, Siemens), equipped with a 64-channel head coil. Isotropic MPRAGE(1mm3) was acquired at each time point. Volumetric analysis was carried out using the scanner’s auto-segmentation software (MorphoBox)5. 1H-MRS(PRESS) was acquired with TR/TE:2000/30ms and voxel size of (30x30x30mm3). Spectroscopic data were analysed by LCModel6. Repeated measures ANOVAs were used to evaluate the effect of time on outcomes.

Results &Discussion: Similar to other studies3, the average TBV across all subjects decreased from T1 to T3 by (3.62±3.9) ml which is a variation of -0.25%, however, there was no statistically significant effect of time of day or gender on TBV(P=0.4, F=2.78). Statistically significant diurnal effects were only seen for glycerophosphocholine (GPC, +13%, P=0.007) and total choline levels (tCho=GPC+PCh, +1.4%, P=0.02), both of which increased at T2 compared to T1. Sex did not impact on neurometabolite levels. Increase in GPC may be associated with physiological variations throughout the day in response to osmotic regulation7.

Conclusion: Our results suggest that there are no statistically significant differences in TBV and neurometabolites, except for choline-containing compounds, at different times of the day.

References

  1. Evans CJ, McGonigle DJ, and Edden RA. Diurnal stability of gamma-aminobutyric acid concentration in visual and sensorimotor cortex. J Magn Reson Imaging. 2010; 31(1): 204-9.
  2. Sormani MP, Arnold DL, and De Stefano N. Treatment effect on brain atrophy correlates with treatment effect on disability in multiple sclerosis. Ann Neurol. 2014; 75(1): 43-9.
  3. Nakamura K, Brown RA, Narayanan S, et al. Diurnal fluctuations in brain volume: Statistical analyses of MRI from large populations. Neuroimage. 2015; 118(126-32.
  4. Soreni N, Noseworthy MD, Cormier T, et al. Intraindividual variability of striatal (1)H-MRS brain metabolite measurements at 3 T. Magn Reson Imaging. 2006; 24(2): 187-94.
  5. Schmitter D, Roche A, Marechal B, et al. An evaluation of volume-based morphometry for prediction of mild cognitive impairment and Alzheimer's disease. Neuroimage Clin. 2015; 7(7-17.
  6. Provencher S. LCModel1 & LCMgui User’s Manual. 2012;
  7. Stefan B and Ashok P. MR Spectroscopy of Pediatric Brain Disorders: Springer Science & Business Media; 2012. 402 p