The Metabolic Epicenter of Supratentorial Gliomas: A¹H-MRSI Study

Abstract

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...

Using ex vivo proton magnetic resonance spectroscopy to reveal associations between biochemical and biological features of meningiomas

“…An extrapolation from this work is the use of ex vivo or in vivo MR spectroscopy to monitor brain tumor metabolism under treatment and to observe shifts in tumor activity with progression or regression. 49,50 Meningiomas, however, will be challenging to assess with regard to how and whether such metabolic information will affect treatment planning. These tumors may be aggressive or slow growing, may become quiescent, and are significantly affected by extent of resection and by sampling, and by interpretation of variability and bias with regard to "recurrence" and "invasion" of the arachnoidal membrane.…”