Correlation of 6-18F-fluoro-L-dopa PET uptake with proliferation and tumor grade in newly diagnosed and recurrent gliomas.
ABSTRACT 6-(18)F-fluoro-l-dopa ((18)F-FDOPA) measured with PET as a biomarker of amino acid uptake has been investigated in brain tumor imaging. The aims of the current study were to determine whether the degree of (18)F-FDOPA uptake in brain tumors predicted tumor grade and was associated with tumor proliferative activity in newly diagnosed and recurrent gliomas.
Fifty-nine patients (40 men, 19 women; mean age ± SD, 44.4 ± 12.3 y) with newly diagnosed (n = 22) or recurrent (n = 37) gliomas underwent (18)F-FDOPA PET perioperatively. Tumor tissue was obtained by resection or biopsy in all patients. The tumor grade and Ki-67 proliferation index were obtained by standard pathology assays. Tumor (18)F-FDOPA uptake was quantified by determining various standardized uptake value (SUV) parameters (mean SUV, maximum SUV [SUVmax], mean values of voxels with top 20% SUVs, and tumor-to-normal-brain tissue ratios) that were then correlated with histopathologic grade and Ki-67 proliferation index.
Fifty-nine lesions in 59 patients were analyzed. (18)F-FDOPA uptake was significantly higher in high-grade than in low-grade tumors for newly diagnosed tumors (SUVmax, 4.22 ± 1.30 vs. 2.34 ± 1.35, P = 0.005) but not for recurrent tumors that had gone through treatment previously (SUVmax, 3.36 ± 1.26 vs. 2.67 ± 1.18, P = 0.22). An SUVmax threshold of 2.72 differentiated low-grade from high-grade tumors, with a sensitivity and specificity of 85% and 89%, respectively, using receiver-operating-characteristic curve analysis (area under the curve, 0.86). (18)F-FDOPA PET uptake correlated significantly with Ki-67 tumor proliferation index in newly diagnosed tumors (r = 0.66, P = 0.001) but not in recurrent tumors (r = 0.14, P = 0.41).
(18)F-FDOPA uptake is significantly higher in high-grade than in low-grade tumors in newly diagnosed but not recurrent tumors that had been treated previously. A significant correlation between (18)F-FDOPA uptake and tumor proliferation in newly diagnosed tumors was observed, whereas this correlation was not identified for recurrent tumors. Thus, (18)F-FDOPA PET might serve as a noninvasive marker of tumor grading and might provide a useful surrogate of tumor proliferative activity in newly diagnosed gliomas.
- SourceAvailable from: Sellam Karunanithi[show abstract] [hide abstract]
ABSTRACT: Purpose Differentiation between recurrence and radiation necrosis in patients with glioma is crucial, since the two entities have completely different management and prognosis. The purpose of the present study was to compare the efficacies of 18F-FDG PET/CT and 3,4-dihydroxy-6-[18F] fluoro-phenylalanine (18F-FDOPA) PET/CT in detection of recurrent gliomas. Methods A total of 28 patients (age 38.82±1.25 years; 85. 7 % men) with histopathologically proven glioma with clinical/imaging suspicion of recurrence were evaluated using 18F-FDG PET/CT and 18F-FDOPA PET/CT. 18FFDG PET/CT and 18F-FDOPA PET/CT images were evaluated qualitatively and semiquantitatively. The combination of clinical follow-up, repeat imaging and/or biopsy (when available) was taken as the reference standard. Results Based on the reference standard, 21 patients were positive and 7 were negative for tumour recurrence. The sensitivity, specificity and accuracy of 18FFDG PET/CT were 47.6 %, 100 % and 60.7 %, respectively, and those of 18F-FDOPA PET/CT were 100 %, 85.7 % and 96.4 %, respectively. The results of 18FFDG PET/CT and 18F-FDOPA PET/CT were concordant in 57.1 % of patients (16 of 28) and discordant in 42. 9 % (12 of 28). The difference in the findings between 18F-FDG PET/CT and 18F-FDOPA PET/CT was significant (P=0.0005, McNemar’s test). The difference was significant for low-grade tumours (P=0.0039) but not for high-grade tumours (P=0.250). Conclusion 18F-FDOPA PET/CT is highly sensitive and specific for detection of recurrence in glioma patients. It is superior to 18F-FDG PET/CT for this purpose and is especially advantageous in patients with low-grade gliomas.European journal of nuclear medicine and molecular imaging 03/2013; · 5.11 Impact Factor