Classification of biopsy-confirmed brain tumors using single-voxel MR spectroscopy

BACKGROUND AND PURPOSE: Our purpose was to develop a classification scheme and method of presentation of in vivo single-voxel proton spectroscopic dat a from astrocytomas that most closely match the classification scheme deter mined from biopsy specimens. Since in vivo proton spectroscopy is noninvasi ve, it may be an attractive alternative to intracranial biopsy. METHODS: Single-voxel spectra were acquired using the point-resolved spectr oscopic pulse sequence as part of the Probe spectroscopy package on a G.E. 1.5-T Signa scanner. Subjects consisted of 27 patients with biopsy-confirme d brain tumors (13 with glioblastoma multiforme, six with anaplastic astroc ytoma, and eight with low-grade astrocytoma). The patients were divided int o groups based on the histologic subtype of their tumor for different treat ment protocols, RESULTS: Metabolic peak areas were normalized for each metabolite (choline, creatine, N-acetylaspartate, lactate) to the area of the unsuppressed wate r peak and to the area of the creatine peak, Kruskal-Wallis nonparametric a nalysis of variance (ANOVA) tests showed statistically significant differen ces among the tumor groups for all the area ratios, The lactate/water ratio could be used to distinguished all three tumor groups, whereas the choline /water ratio distinguished low-grade astrocytomas from the two high-grade g roups, Both the choline and lactate ratios could be used to separate the hi gh-grade from the low-grade tumors, CONCLUSION: Specific relative metabolic peak area ratios acquired from regi ons of contrast-enhancing brain tumor can be used to classify astrocytomas as to histopathologic grade.