Abstract
BACKGROUND: Brain Tumours (BTs) have been widely evaluated using the 3,4-dihydroxy-6-18 fluoro-L-phenylalanine (F-18-FDOPA) PET. The aim of the study was to evaluate the role of PET FDOPA in low grade glioma (LGG). METHODS: We enrolled all patient affected by LGG. All patients underwent FDOPA PET and MRI examination. METHODS: Both FLAIR and contrast-enhanced T1-weighted sequences were considered for the response assessment to treatment in according to RANO criteria. The PET images were interpreted as positive when the lesion definitely increased F-FDOPA accumulation taking into consideration the background and the controlateral site. The slices with a maximal F-FDOPA uptake in the ROI were chosen for quantitative measurement of metabolic activity of the tracer [standardized uptake value (SUV)]. In order to evaluate the concordance between diagnostic test 1 (MRI) and diagnostic test 2 (FDOPA) we calculated the unweighted kappa statistic and its relative 95% Confidence interval (95%CI). This value was interpreted in a qualitative manner on the basis of the Landis and Koch classification criteria. RESULTS: We enrolled 56 (35 males and 21 females) patients affected by LGG. The mean age at diagnosis was 44.5 years. Out of the 56 patients recruited for this study, 23% were a newly diagnosed, 45% in chemotherapy treatment, and 32% were untreated but had a regular follow-up. The Kappa statistic for the whole sample was equal to 0.301 (95%CIs from 0.21 to 0.40) showing a fair concordance between the two tests in terms of diagnostic capability. We found a good correlations between residual volume and SUV max (r = 0.435, p = 0.002 by Spearman Rank Correlation Coefficient), indicating that the greater the residual volume, the higher the SUV max was. Also the multivariate analysis showed that a SUV max greater than 1.65 was the only independent predictor of disease progression (HR = 4.59, 95% CIs from 0.99 to 21.31, p = 0.054). This implies that a patient with a SUV max higher than 1.65 had an almost 5-fold increased risk of disease progression, regardless of its clinical and MRI characteristics. CONCLUSION: Our results confirm that PET 18F-FDOPA may be a role diagnostic and prognostic in patients with LGG.