A fast, reliable, automatic shimming procedure using 1H chemical-shift-imaging spectroscopy.
The importance and the difficulty of achieving good B0 homogeneity over the volume of interest in in vivo NMR spectroscopy are well known. A fast, reliable, versatile, and fully automatic shimming procedure has been developed, using 3D chemical-shift imaging to measure the field distribution using only the water peak in the sample of interest. The procedure minimizes the mean-square error in the field distribution with respect to a constant field where the signal exists (e.g., the head). This produces a set of linear equations that can be solved by standard matrix methods. The procedure has been applied on a commercial imager producing water linewidths from the entire head as low as 8 Hz at 1.5 T. The mean linewidth and standard deviation from 94 head studies were 11.7 +/- 1.9 Hz.
Hu
J
J
Department of NMR and Medical Spectroscopy, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Javaid
T
T
Arias-Mendoza
F
F
Liu
Z
Z
McNamara
R
R
Brown
T R
TR
D000465:Algorithms; D001331:Automation; D001834:Body Water / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D006801:Humans; D006859:Hydrogen; D007089:Image Enhancement / Q000379:methods*; D016014:Linear Models; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D018482:Muscle, Skeletal / Q000378:metabolism; D015203:Reproducibility of Results; D014867:Water / Q000737:chemistry
D014867:Water; D006859:Hydrogen