Magnetization transfer effect on human brain metabolites and macromolecules

• Published in: Magnetic resonance in medicine 2005-11, Vol.54 (5), p.1281-1285
• Main Authors: McLean, Mary A., Simister, Robert J., Barker, Gareth J., Duncan, John S.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; brain; Brain - metabolism; Brain - radiation effects; Electromagnetic Fields; Energy Transfer - radiation effects; Female; Humans; Macromolecular Substances - metabolism; Macromolecular Substances - radiation effects; macromolecules; magnetic resonance spectroscopy; Magnetic Resonance Spectroscopy - methods; magnetization transfer; Male; metabolites; Middle Aged; Neurotransmitter Agents - metabolism; Neurotransmitter Agents - radiation effects; Radiation Dosage; Water - metabolism
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.20665

A pulse sequence was implemented to observe the magnetization transfer (MT) effect on metabolites, water, and macromolecules in human frontal lobes in vivo at 1.5 Tesla. Signals were compared following the application of three hard pulses of 0.745 μT amplitude, applied at frequency offsets of either 2500 Hz or 30 kHz, preceding a conventional point‐resolved spectroscopy (PRESS)‐localized acquisition with an echo time (TE) of 30 ms and repetition time (TR) of 3 s. This gave an MT effect on water in vivo of 46%, while direct saturation by the MT pulses at 2.5 kHz offset was confirmed to be under 4% for all metabolites. We observed significant MT saturation in vivo for N‐acetylated compounds, choline (Cho), myo‐inositol, and lactate (Lac); a trend of an effect on glutamate + glutamine (Glx); and the typically observed effect on creatine (Cr). No significant MT effect was seen on the macromolecule signal, which was observed using metabolite nulling. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.