Proton echo-planar spectroscopic imaging of J-coupled resonances in human brain at 3 and 4 Tesla.
In this multicenter study, 2D spatial mapping of J-coupled resonances at 3T and 4T was performed using short-TE (15 ms) proton echo-planar spectroscopic imaging (PEPSI). Water-suppressed (WS) data were acquired in 8.5 min with 1-cm(3) spatial resolution from a supraventricular axial slice. Optimized outer volume suppression (OVS) enabled mapping in close proximity to peripheral scalp regions. Constrained spectral fitting in reference to a non-WS (NWS) scan was performed with LCModel using correction for relaxation attenuation and partial-volume effects. The concentrations of total choline (tCho), creatine + phosphocreatine (Cr+PCr), glutamate (Glu), glutamate + glutamine (Glu+Gln), myo-inositol (Ins), NAA, NAA+NAAG, and two macromolecular resonances at 0.9 and 2.0 ppm were mapped with mean Cramer-Rao lower bounds (CRLBs) between 6% and 18% and approximately 150-cm(3) sensitive volumes. Aspartate, GABA, glutamine (Gln), glutathione (GSH), phosphoethanolamine (PE), and macromolecules (MMs) at 1.2 ppm were also mapped, although with larger mean CRLBs between 30% and 44%. The CRLBs at 4T were 19% lower on average as compared to 3T, consistent with a higher signal-to-noise ratio (SNR) and increased spectral resolution. Metabolite concentrations were in the ranges reported in previous studies. Glu concentration was significantly higher in gray matter (GM) compared to white matter (WM), as anticipated. The short acquisition time makes this methodology suitable for clinical studies.
Posse
Stefan
S
Department of Psychiatry, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA. sposse@unm.edu
Otazo
Ricardo
R
Caprihan
Arvind
A
Bustillo
Juan
J
Chen
Hongji
H
Henry
Pierre-Gilles
PG
Marjanska
Malgorzata
M
Gasparovic
Charles
C
Zuo
Chun
C
Magnotta
Vincent
V
Mueller
Bryon
B
Mullins
Paul
P
Renshaw
Perry
P
Ugurbil
Kamil
K
Lim
Kelvin O
KO
Alger
Jeffry R
JR
D000328:Adult; D001923:Brain Chemistry; D001931:Brain Mapping / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted