Role of 18F-FDG PET-CT in prediction of survival in recurrent glioma patients

Objectives Purpose of this study was to evaluate the role of ¹⁸F-FDG PET-CT in prediction of survival in recurrent glioma patients.

Methods Eighty patients with clinical suspicion of recurrent glioma underwent FDG PET-CT scan. In all positive cases, tumor to gray mater (T/G) and tumor to white mater (T/W) uptake ratio calculated. Patients were followed up clinically with (Temozolamide in 32, reoperation in 5, radiotherapy in 2) or without treatment (41). Univariate and multivariate analyses were done to see the association of survival with different factors like age, sex, size and grade, previous treatment, clinical symptoms, treatment for recurrence, T/G and T/W ratios. Kaplan Meier survival estimates were done using FDG PET-CT findings.

Results FDG PET/CT scan was positive in 43 while negative in 37 patients. 17 FDG positive and 2 FDG negative patients were died in median follow up period of 342 days (12days -783 days). In univriate analysis, significant association was found with size, T/G ratio, T/W ratio, pretreatment and treatment of recurrence. In multivariate analysis, T/G ratio(p=0.000), T/W ratio(p=0.023) and treatment of recurrence with Temozolamide (p=0.002) had only significance. In Kaplan Meier estimates, FDG positive patients had poorer prognosis than negative patients(p=0.001) and T/G >1had poorer prognosis than T/G <1(p=0.000).

Conclusions FDG PET/CT is a strong predictor of survival in the patients of recurrent glioma. Both the uptake ratios (T/G and T/W) are independent predictor, but strongest association found with T/G ratio.