Analysis of macromolecule resonances in 1H NMR spectra of human brain

Abstract

Macromolecule resonances underlying metabolites in ¹H NMR spectra were investigated in temporal lobe biopsy tissue from epilepsy patients and from localized ¹H spectra of the brains of healthy volunteers. The ¹H NMR spectrum of brain tissue was cornpared with that of cytosol and dialyzed cytosol after removal of low molecular weight molecules (4500 daltons) at 8.4 and 2.1 Tesla. The assignment of specific resonances to macromolecules in 2.1 Tesla, short‐ TE, localized human brain ¹H NMR spectra in vivo was made on the basis of a J‐editing method using the spectral parameters (δ, J) and connectivities determined from 2D experiments in vitro. Two prominent corinectivities associated with macromolecules in vitro (0.93–2.05 δ and 1.6–3.00 δ) were also detected in vivo by the J‐editing method. Advantage was taken of the large difference in measured T₁ relaxation times between macromolecule and metabolite resonances in the brain spectrum to acquire ‘metabolite‐nulled’ macromolecule spectra. These spectra appear identical to the spectra of macromolecules isolated in vitro.