Prognositic value of proton MR spectroscopy of cerebral hemisphere tumors in children

We studied 14 young people with newly diagnosed hemisphere tumors, aged from 3 to 20 years (average 10 years). All underwent surgery following MR imaging (MRI) and spectroscopy (MRS). The tumors studied were three glioblastomas, one each of ganglio-glioblastoma, primitive neuroectodermal tumor (PNET), rhabdoid teratoid tumor, pilocytic astrocytoma, ependymoma, anaplastic ependymoma, and gliomatosis cerebri, and four gangliogliomas. Four patients died; ten patients are alive (five with stable residual tumor, five with no evident tumor). Images and spectra were acquired on a 1.5-T imager. Proton MRS was performed before gadolinium injection in all but one case. Single-voxel techniques were utilized in all cases, using a spin-echo or STEAM sequence with a long echo time (135 or 270 ms). Peak areas of N-acetyl aspartate (NAA), choline (Cho), and creatine and phosphocreatine (Cr) were assessed. The NAA/Cho peak-area ratio was very low in the patients who died (mean ± s.d. 0.20 ± 0.14), and higher in the patients who are alive (0.74 ± 0.47; P = 0.007 two-tailed t-test). The Cr/Cho peak-area ratio also followed a similar trend for the two groups (mean ± s.d. 0.17 ± 0.07 and 0.49 ± 0.30, respectively; P = 0.01 by two-tailed t-test).