Our results suggest that appropriate analysis of (1)H-MRSI data can predict survival in patients with supratentorial gliomas at least as accurately as data derived from more invasive clinicopathological features.

Oral dyskinesias may occur spontaneously or be induced by medications such as antipsychotics and antidepressants. In this study, single voxel proton magnetic resonance spectroscopy was used to compare metabolite levels in the striatum for (1) 12 patients with drug-induced tardive dyskinesia (TD), (2) 12 patients with spontaneous oral dyskinesia (SOD), (3) 8 antidepressant-treated patients without TD, and (4) 8 control subjects. Statistically significant reductions in the choline/creatine (Cho/Cr) ratio were measured for the drug-treated patients with TD (-13%, P = 0.020) and SOD patients (-12%, P = 0.034) relative to control subjects. In comparison with antidepressant-treated patients without TD, drug-treated patients with TD showed a non statistically significant reduction in Cho/Cr (-11%, P = 0.079). All other metabolite ratios (N-acetylaspartate (NAA)/Cr, myo-inositol (mI)/Cr, glutamine + glutamate (Glx)/Cr, macromolecule + lipid (MM+Lip)/Cr, NAA/Cho) were unaffected by either type of dyskinesia. The observed Cho/Cr reduction in dyskinesia patients suggests decreased membrane phosphatidylcholine turnover, which provides free choline as precursor of molecules responsible for cellular signal transduction.

696Supratentorial gliomas are the most frequently diagnosed primary brain tumors in adults. 1 Despite representing only 1.5% of all malignancies, 2 they are a significant cause of cancerrelated death in the general population. 3 As a result, a considerable body of research has focused on identifying prognostic markers for patients with these tumors. Although no list of such markers is universally accepted, many authors consistently agree that histopathological grade, 4-7 patient age, [8][9][10][11][12] ABSTRACT: Background: Assessing the impact of glioma location on prognosis remains elusive. We approached the problem using multivoxel proton magnetic resonance spectroscopic imaging ( 1 H-MRSI) to define a tumor "metabolic epicenter", and examined the relationship of metabolic epicenter location to survival and histopathological grade. Methods: We studied 54 consecutive patients with a supratentorial glioma (astrocytoma or oligodendroglioma, WHO grades II-IV). The metabolic epicenter in each tumor was defined as the 1 H-MRSI voxel containing maximum intra-tumoral choline on preoperative imaging. Tumor location was considered the X-Y-Z coordinate position, in a standardized stereotactic space, of the metabolic epicenter. Correlation between epicenter location and survival or grade was assessed. Results: Metabolic epicenter location correlated significantly with patient survival for all tumors (r 2 = 0.30, p = 0.0002) and astrocytomas alone (r 2 = 0.32, p = 0.005). A predictive model based on both metabolic epicenter location and histopathological grade accounted for 70% of the variability in survival, substantially improving on histology alone to predict survival. Location also correlated significantly with grade (r 2 = 0.25, p = 0.001): higher grade tumors had a metabolic epicenter closer to the midpoint of the brain. Conclusions: The concept of the metabolic epicenter eliminates several problems related to existing methods of classifying glioma location. The location of the metabolic epicenter is strongly correlated with overall survival and histopathological grade, suggesting that it reflects biological factors underlying glioma growth and malignant dedifferentiation. These findings may be clinically relevant to predicting patterns of local glioma recurrence, and in planning resective surgery or radiotherapy.RÉSUMÉ: Épicentre métabolique des gliomes sustentoriels : une étude SRM 1H. Contexte : L'impact de la localisation d'un gliome sur le pronostic demeure difficile à déterminer. Nous avons abordé ce problème au moyen de l'imagerie par spectroscopie « multivoxel » par résonance magnétique de proton (SRM 1H) afin d'identifier l' « épicentre métabolique » de la tumeur et d'examiner la relation entre la localisation de l'épicentre métabolique d'une part et la survie et le grade anatomopathologique d'autre part. Méthodes : Nous avons étudié 54 patients consécutifs porteurs d'un gliome sustentoriel (astrocytome ou oligodendrogliome, grades II à IV selon la classification de l'OMS). L'épicentre métabolique de chaque...

Oral dyskinesias occur in elderly individuals in relation to drug use (tardive dyskinesia, TD) or edentulousness (edentulous orodyskinesia, EOD) but their characterization remains incomplete. Our aim was to investigate whether magnetic resonance techniques such as diffusion-weighted imaging (DWI) and magnetization transfer imaging (MTI) of the brain could be used to differentiate dyskinetic patients from control subjects. Eight drug-treated patients with TD, 12 EOD patients, 8 drug-treated patients without TD, and 10 control subjects were recruited and examined by DWI and MTI. Measurements in the caudate nucleus, putamen, and globus pallidus yielded globally different apparent diffusion coefficient (ADC) values between drug treated patients with TD and control subjects but the magnetization transfer ratios showed no significant variations. The discrimination between dyskinetic patients and control subjects offered by ADC values was however slightly poorer than the discrimination offered by the previously published choline/creatine ratios measured by MR spectroscopy in the basal ganglia. The results are consistent with the pathophysiological hypothesis of damage to cholinergic interneurons.