The case of the missing glutamine

A theoretical study was performed to determine the accuracy and repeatability of multiple one‐dimensional pulse sequences in the quantification of glutamine concentration at 3 T. Variable repeatability (12% to > 50%) and significant absolute error (?50% to +70%) were noted for the eight pulse sequences considered. Data acquired in vivo using three of the pulse sequences used for simulation matched the predicted repeatability well; among the pulse sequences considered, point‐resolved spectroscopy (TE = 80 ms) offered minimal error and acceptable repeatability (12%) for brain glutamine measurements. Following correction for the expected bias of each pulse sequence, consistent glutamine measurements, in the 1‐mM range, were reported with the three sequences. An explanation for the mismatch between in vivo ¹H MRS and in vitro ¹³C/¹H MRS at high field was attempted. Copyright © 2011 John Wiley & Sons, Ltd.