INTRACRANIAL TUMORS IN CHILDREN - SMALL SINGLE-VOXEL PROTON MR SPECTROSCOPY USING SHORT-ECHO AND LONG-ECHO SEQUENCES

We report preliminary experience using single-voxel, proton MR spectro scopy (MRS) employing small voxels of interest, in combination with sh ort and long echo-time protocols, for the assess ment of primary intra cranial tumors in children. We examined 23 children with primary intra cranial tumors detected by MRI, and 32 controls with similar ages, usi ng MRS on a 1.5 T system. Localized single-voxel (3.7 +/- 1.3 cc) prot on spectra were obtained with short-echo (2,000/18),stimulated-echo (S TEAM) and long-echo (2,000/270) spin-echo (PRESS) protocols. All spect ra were evaluated qualitatively; 10 tumor and 19 control spectra were processed for peak area quantification. Small voxels of interest were able to account for tissue heterogeneity. Combined acquisition of shor t- and long-echo spectra increased the number of detectable metabolite s, The solid portion of all tumors exhibited reduced N-acetyl-aspartat e (NAA), strong contribution from cholines (Cho) and inositols or glyc ine, minimal presence of total creatine (tCr), enhanced broad mobile l ipid resonances and accumulated lactate. Calculated selected metabolit e ratios of Cho/tCr and Cho/NAA were substantially increased from cont rol values. The cystic portions of the masses showed only lipid and la ctate peaks.