ANALYSIS OF MACROMOLECULE RESONANCES IN H-1-NMR SPECTRA OF HUMAN BRAIN

Macromolecule resonances underlying metabolites in H-1 NMR spectra were investigated in temporal lobe biopsy tissue from epilepsy patients and from localized H-1 spectra of the brains of healthy volunteers. The 1(H) NMR spectrum of brain tissue was compared with that of cytosol and dialyzed cytosol after removal of low molecular weight molecules (<3500 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 (delta J) and connectivities determined from 2D experiments in vitro. Two prominent connectivities associated with macromolecules in vitro (0.93-2.05 delta and 1.6-3.00 delta) were also detected in vivo by the J-editing method. Advantage was taken of the large difference in measured T-1 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.