Quality assessment of localization technique performance in small volume in vivo H-1 MR spectroscopy

A new phantom and evaluation method for experimental evaluation of H-1-magn etic resonance spectroscopy single volume localization techniques regarding signal contamination (C), defined as the part of the signal originating ou tside the volume of interest, is presented. The quality assessment method i s based on a spherical phantom with an oil/water interface in order to redu ce susceptibility effects, and applied for stimulated-echo acquisition meth od (STEAM) and spin-echo (SE) sequences, echo times of 270, 135, and 10 ms, and cubic volumes of interest (VOI) of 1(3), 1.5(3), 2(3), 2.5(3), and 3(3 ) cm(3), To be able to mimic measurements of the contamination in three dim ensions the physical gradients representing the three orthogonal directions for slice selection were shifted in the pulse sequences. Contamination val ues in one dimension differed between 6.5% and 8.4% in SE sequences, and be tween 0.7% and 13.8% in STEAM sequences; In STEAM sequences a decrease of C with increasing VOI size was observed while SE sequences showed comparable C values for the different VOI sizes tested. The total contamination in th ree dimensions were 19% and 18% in SE and STEAM sequences with a TE of 270 ms, and 7% in a STEAM sequence with a TE of 10 ms, respectively; The presen ted evaluation method is easily applied to the new phantom and showed high reproducibility, (C) 1999 Elsevier Science Inc.