Proton magnetic resonance spectroscopy in patients with glial tumors: a multicenter study

Abstract

The authors represent a cooperative group of 15 institutions that examined the feasibility of using metabolic fea tures observed in vivo with 'H-magnetic resonance (MR) spectroscopy to characterize brain tumors of the glial type.The institutions provided blinded, centralized MR spectroscopy data processing along with independent central review of MR spectroscopy voxel placement, composition and contamination by brain, histopathological typing using current World Health Organization criteria, and clinical data, Proton 'H-MR spectroscopy was performed using a spin-echo technique to obtain spectra from 8-cc voxels in the tumor and when feasible in the contralateral brain. Eighty-six cases were assessable, 41 of which had contralateral brain spectra. Glial tumors had significantly elevated intensities of choline signals, decreased intensities of creatine signals, and decreased intensities of N-acetyl asp art ate compared to brain. Choline signal intensities were highest in astrocytomas and anaplastic astrocytomas, and creatine signal intensi ties were lowest in glioblastomas. However, whether expressed relative to brain or as intratumoral ratios, these meta bolic characteristics exhibited large variations within each subtype of glial tumor. The resulting overlaps precluded diagnostic accuracy in the distinction of low-and high-grade tumors. Although the extent of contamination of the ]H-MR spectroscopy voxel by brain had a marked effect on metabolite concentrations and ratios, selection of cases with minimal contamination did not reduce these overlaps. Thus, each type and grade of tumor is a metabolically hetero geneous group. Lactate occurred infrequently and in all grades. Mobile lipids, on the other hand, occurred in 41% of high-grade tumors with higher mean amounts found in glioblastomas. This result, coupled with the recent demonstra tion that intratumoral mobile lipids correlate with microscopic tumor cell necrosis, leads to the hypothesis that mobile lipids observed in vivo in E H-MR spectroscopy may correlate independently with prognosis of individual patients. W. G. Negendank, et ciL rylcholine), one primarily from creatines (creatine and phosphocreatine), and one primarily from acetyl aspar tate (NAA), In disease, signals from lactate and mobile lipids may also be observed.Studies of extracts of surgical specimens of human as trocytic tum ors using ]H -N M R spectroscopy indicated an increase in the ratio o f cholines to creatines, and a decrease in the ratio of N A A to creatines, with increas ing histopathological grades of m alignancy.16,45'61 Studies in patients using !H-N M R spectroscopy, referred to as MR spectroscopy, indicated sim ilar correlations betw een m etabolic features in vivo and the histopathological grades of astrocytic tum ors. 4'11'14'21,32,43'57'58'61 Other MR spectroscopy studies indicated that lactate is more likely to be present in high-than in low-grade tumors4, 14,15'20'21 and that the am ount of lactate may correlate with the extent of hyperm etabolic glucose consumption sho...

Spectroscopic increase in choline signal is a nonspecific marker for differentiation of infective/inflammatory from neoplastic lesions of the brain

“…Choline has been found to be higher in high-grade gliomas than in low-grade gliomas, probably reflecting the increased turnover of the membranes and increased cellularity (3). There has been an inconsistency in the spectral profile of malignant tumors of brain reported in the literature (4,15). Some of the glioblastoma multiforme have been reported to show low choline, suggestive of inclusion of necrotic areas within the volume of interest, reflecting the low cellular concentration in the region.…”

Common processing of in vivo MR spectra

“…This may be sufficient for some purposes: in clinical diagnosis it may be useful to consider only signal ratios such as those of the methyl proton spins of N-acetylaspartate, creatine and choline in 1 H MR spectra of the brain to assess the presence of pathological tissue, for instance tumor tissue e.g. 57,58 For general clinical purposes a local reference data set with normal ratios for healthy tissue is often required. In focal pathologies, this reference spectrum can be acquired from the patient, e.g.…”

“…[70][71][72] Multi-center trials, such as those on brain tumors, e.g. 58,73 can provide large data sets to explore the features necessary for a proper classification of these kinds of spectra.…”

Supervised pattern recognition for the prediction of contrast-enhancement appearance in brain tumors from multivariate magnetic resonance imaging and spectroscopy

“…Features derived from diffusion images are thought to provide information on cellular density and the nature of local edema [1,2], while perfusion imaging yields information about cerebral vasculature [3][4][5]. Proton spectroscopy can be used to measure levels of cerebral metabolites that may be indicative of metabolically active tumor, necrosis and regions with compromised energetics [6][7][8].…”