In vivo mapping of brain myo-inositol

Mohammad Haris, Kejia Cai, Anup Singh, Hari Hariharan, Ravinder Reddy

Research output: Contribution to journalArticle

125 Citations (Scopus)

Abstract

Myo-Inositol (MI) is one of the most abundant metabolites in the human brain located mainly in glial cells and functions as an osmolyte. The concentration of MI is altered in many brain disorders including Alzheimer's disease and brain tumors. Currently available magnetic resonance spectroscopy (MRS) methods for measuring MI are limited to low spatial resolution. Here, we demonstrate that the hydroxyl protons on MI exhibit chemical exchange with bulk water and saturation of these protons leads to reduction in bulk water signal through a mechanism known as chemical exchange saturation transfer (CEST). The hydroxyl proton exchange rate (k=600s-1) is determined to be in the slow to intermediate exchange regime on the NMR time scale (chemical shift (Δω)>k), suggesting that the CEST effect of MI (MICEST) can be imaged at high fields such as 7T (Δω=1.2×103rad/s) and 9.4T (Δω=1.6×103rad/s). Using optimized imaging parameters, concentration dependent broad CEST asymmetry between ~0.2 and 1.5ppm with a peak at ~0.6ppm from bulk water was observed. Further, it is demonstrated that MICEST detection is feasible in the human brain at ultra high fields (7T) without exceeding the allowed limits on radiofrequency specific absorption rate. Results from healthy human volunteers (N=5) showed significantly higher (p=0.03) MICEST effect from white matter (5.2±0.5%) compared to gray matter (4.3±0.5%). The mean coefficient of variations for intra-subject MICEST contrast in WM and GM were 0.49 and 0.58 respectively. Potential overlap of CEST signals from other brain metabolites with the observed MICEST map is discussed. This noninvasive approach potentially opens the way to image MI in vivo and to monitor its alteration in many disease conditions.

Original languageEnglish
Pages (from-to)2079-2085
Number of pages7
JournalNeuroImage
Volume54
Issue number3
DOIs
Publication statusPublished - 1 Feb 2011
Externally publishedYes

Fingerprint

Brain Mapping
Inositol
Protons
Hydroxyl Radical
Water
Brain
Brain Diseases
Brain Neoplasms
Neuroglia
Healthy Volunteers
Alzheimer Disease
Magnetic Resonance Spectroscopy

Keywords

  • Brain
  • Chemical exchange saturation transfer
  • Exchange rate
  • Myo-inositol

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Neurology

Cite this

Haris, M., Cai, K., Singh, A., Hariharan, H., & Reddy, R. (2011). In vivo mapping of brain myo-inositol. NeuroImage, 54(3), 2079-2085. https://doi.org/10.1016/j.neuroimage.2010.10.017

In vivo mapping of brain myo-inositol. / Haris, Mohammad; Cai, Kejia; Singh, Anup; Hariharan, Hari; Reddy, Ravinder.

In: NeuroImage, Vol. 54, No. 3, 01.02.2011, p. 2079-2085.

Research output: Contribution to journalArticle

Haris, M, Cai, K, Singh, A, Hariharan, H & Reddy, R 2011, 'In vivo mapping of brain myo-inositol', NeuroImage, vol. 54, no. 3, pp. 2079-2085. https://doi.org/10.1016/j.neuroimage.2010.10.017
Haris M, Cai K, Singh A, Hariharan H, Reddy R. In vivo mapping of brain myo-inositol. NeuroImage. 2011 Feb 1;54(3):2079-2085. https://doi.org/10.1016/j.neuroimage.2010.10.017
Haris, Mohammad ; Cai, Kejia ; Singh, Anup ; Hariharan, Hari ; Reddy, Ravinder. / In vivo mapping of brain myo-inositol. In: NeuroImage. 2011 ; Vol. 54, No. 3. pp. 2079-2085.
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