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

 Mapping Differential Metabolic Regions in the MS brain using fast Spiral MRSI (#91)

Oun Al-iedani 1 , Karen Ribbons 2 , Rodney Lea 3 , Jeannette Lechner-Scott 2 3 4 , Ovidiu Andronesi 5 , 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
  5. Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA

Background and Aims: Multiple Sclerosis (MS), is a chronic neurodegenerative disease that relies heavily on the use of MRI in disease diagnosis and management, however, reliable markers of disease progression are still needed. Here, we applied non-invasive fast spiral 1H Magnetic Resonance Spectroscopic Imaging(1H-MRSI)[1] to identify differential metabolic regions(DMRs) in the whole brain of stable/medicated relapsing remitting MS(RRMS) patients.

Methods: Brain MRSI data for major neurometabolites were acquired from 16 RRMS patients and 9 age-and-sex matched healthy controls (HCs). Evaluated neurometabolites included N-acetylaspartate(NAA), glutamine+glutamate(Glx) and glycerophosphorylcholine (GPC) - as a ratio to total creatine (tCr).  MRSI data (1x1x1cm3, TE30ms) was acquired using a 3T Prisma MRI (Siemens) with a 64-channel head coil with VOI(AP-RL-HF):10x8x4cm starting ~1cm above corpus callosum. LCModel(v6.2-2B)[2] was used for metabolite quantification. Comparisons of mean metabolite ratios between groups for each voxel were undertaken using T-tests. A DMR was defined as a cluster of 3 or more adjacent voxels all having statistically significant metabolic differences between RRMS and HCs (P<0.05).

Results and Discussion: Results revealed 3 separate DMRs exhibiting a reduction in NAA/tCr (9-23%). Of these, one DMR, located within deep cortical white matter in posterior parietal lobes at post-central gyrus, also displayed an increase in Glx/tCr and GPC/tCr (5‑29%). Additional morphological and structural mapping is needed to fully appreciate the clinical significance of this finding. Reduction in NAA/tCr is suggestive of axonal loss in MS, as shown by others applying conventional MRSI [3]. Elevated GPC is often associated with abnormal membrane turnover and myelin breakdown, while elevated Glx has been  associated with oligodendrocyte destruction; suggesting a connection to MS progression [4, 5] .

Conclusions: Whole-brain fast MRSI can be used to assess neurometabolites at short TE and 3T. Mapping DMRs for neurometabolites in the MS brain using this technique may enhance clinical monitoring of MS patients.