Non-invasive grading of oligodendrogliomas: correlations between in vivo metabolic pattern and histopathology

Abstract

Several studies have shown that the prognosis of oligodendrogliomas is dependent on their histological grade. In order to identify a non-invasive method for the primary diagnosis and follow-up of these tumours, we investigated the relationship between their in vivo metabolism, assessed by positron emission tomography (PET), and their histological grade assessed at the same time. Forty-seven patients with histologically confirmed oligodendrogliomas were investigated. Conventional neuroradiological assessment by computed tomography and magnetic resonance imaging (MRI) was performed in all the patients. All the histology slices were reviewed by the same pathologist after referral from various pathology laboratories. The PET investigation included a carbon-1 methionine (11C-MET) uptake study and, in the majority of cases, a fluorine-18 fluorodeoxyglucose (18F-FDG) uptake study, in order to investigate at the same time both amino acid metabolism and glycolysis. The sampled tumour region of interest (ROI) was defined from the T1-weighted 3D MR scan matched with the PET scan. Tracer concentration in each voxel of the tumour ROI was divided by the mean concentration in an ROI of the same size located in the healthy brain tissue. For each tumour and each tracer, we characterized the metabolic pattern on the basis of the mean and the maximum tumour to healthy tissue concentration ratio, and also the standard deviation and range of the ratios, which indicate the degree of metabolic heterogeneity of the tumour. The histological criteria for differentiating between high- and low-grade tumours were those of the WHO and, partially, of the Sainte-Anne-Daumas-Duport classification. Highly significant differences between high- and low-grade oligodendrogliomas (Mann-Whitney test: P<0.0001) were observed for all the assessed parameters of 11C-MET uptake. On the other hand, the pattern of 18F-FDG uptake showed only moderate differences between the two tumour groups.

In VivoUptake and Metabolism of α-[11C]Methyl-l-Tryptophan in Human Brain Tumors

“…Thus, increased AMT uptake does not appear to be the consequence of tumor-induced seizures or interictal epileptiform activity during the tracer uptake. a-[ 11 C]methyl-L-tryptophan uptake in lowgrade tumors is of particular clinical interest because accurate delineation of recurrent or residual low-grade tumors is difficult on MRI and such tumors typically show low uptake on glucose and other amino-acid PET scans (DiChiro, 1987;Kaschten et al, 1998;Derlon et al, 2000;Benard et al, 2003). a-[ 11 C]methyl-L-tryptophan appears to be a unique PET tracer by showing increased uptake in DNETs, which do not accumulate several other PET tracers (Lee et al, 2000;Richardson et al, 2001;Maehara et al, 2004;Weckesser et al, 2005).…”

Characterization of oligodendrogliomas using short echo time 1H MR spectroscopic imaging

“…1 In PET studies metabolic differences have been demonstrated between low-grade and high-grade oligodendrogliomas. 36,37 In vivo MRS has already been shown to be useful in distinguishing the grades of other brain tumors (e.g. astrocytomas 11,14,[38][39][40] ).…”

Corpus Callosal Oligodendroglioma: A Rare Entity

“…PET scan may also be useful for grading ODG's non-invasively [7]. In a different study by Derlon et al demonstrated that anaplastic ODG's exhibited a higher 18F-flurodeoxy-glucose and methionine (MET) uptake than low grade ODG's [7].…”

“…Derlon et al in his study found that both these tumor types exhibit glucose hypo-metabolism but on methionine (MET) PET imaging, the uptake of MET was high in the oligo-dendroglioma lesions and decreased, normal or only moderately increased in the astrocytoma group [6]. PET scan may also be useful for grading ODG's non-invasively [7]. In a different study by Derlon et al demonstrated that anaplastic ODG's exhibited a higher 18F-flurodeoxy-glucose and methionine (MET) uptake than low grade ODG's [7].…”