Use of phased array coils for a determination of absolute metabolite concentrations

This work describes the use of phased array coils for a quantification of absolute metabolite concentrations. The method is demonstrated for single‐voxel localized proton MRS of human brain with an eight‐element receive‐only head coil. It is based on the transmitter reference amplitude of the body coil used for RF transmission. A relative sensitivity of every element of the phased array coil is derived from a combination of two reference scans without water suppression that correspond to either the body coil in transmit‐receive mode or the phased array coil in conjunction with body coil excitation. Experimental results were obtained at 2.9 T for both phantoms and 12 human subjects in different locations of gray and white matter. The data demonstrate that the procedure is technically robust and without a penalty in measuring time. Moreover, it takes full advantage of the signal‐to‐noise gain for quantitative proton MRS and may be extended to other phased array coils without the need for a recalibration. Magn Reson Med 53:3–8, 2005. © 2004 Wiley‐Liss, Inc.