Positron emission tomography with injection of methionine as a prognostic factor in glioma.

Object. Positron emission tomography with l-[methyl-11C]methionine (MET-PET) provides information on the metabolism of gliomas. The aim of this study was to determine the predictive value of MET-PET in the treatment of patients with gliomas. Methods. Since 1992, 85 patients with a World Health Organization (WHO) classification—verified glioma underwent PET studies in which MET was injected before (74 cases) or after treatment (11 cases). Analysis of PET data was conducted by the same investigator using two scales: a qualitative visual grading scale and a quantitative scale (ratio between tumor uptake and normal brain uptake, classified on a seven-level scale). Uptake of MET was present in 98% of gliomas. The investigator judged this uptake to be moderate to very high based on visual inspection (qualitative scale). For all grades of gliomas, a visual grade of 3 was statistically associated with a shorter patient survival period (p < 0.005). The tumor/normal brain uptake ratio was significantly influenced b...