Search

INTRODUCTION: To report the potential value of pre-operative (18)F-FDOPA PET and anatomic MRI in diagnosis and prognosis of glioma patients. METHODS: Forty-five patients with a pathological diagnosis of glioma with pre-operative (18)F-FDOPA PET and anatomic MRI were retrospectively examined. The volume of contrast enhancement and T2 hyperintensity on MRI images along with the ratio of maximum (18)F-FDOPA SUV in tumor to normal tissue (T/N SUV(max)) were measured and used to predict tumor grade, molecular status, and overall survival (OS). RESULTS: A significant correlation was observed between WHO grade and: the volume of contrast enhancement (r=0.67), volume of T2 hyperintensity (r=0.42), and (18)F-FDOPA uptake (r=0.60)(P < 0.01 for each correlation). The volume of contrast enhancement and (18)F-FDOPA T/N SUV(max) were significantly higher in glioblastoma (WHO IV) compared with lower grade gliomas (WHO I–III), as well as for high-grade gliomas (WHO III–IV) compared with low-grade gliomas (WHO I–II). Receiver-operator characteristic (ROC) analyses confirmed the volume of contrast enhancement and (18)F-FDOPA T/N SUV(max) could each differentiate patient groups. No significant differences in (18)F-FDOPA uptake were observed by IDH or MGMT status. Multivariable Cox regression suggested age (HR = 1.16, P = 0.0001) and continuous measures of (18)F-FDOPA PET T/N SUV(max) (HR = 4.43, P = 0.016) were significant prognostic factors for OS in WHO I–IV gliomas. CONCLUSIONS: Current findings suggest a potential role for the use of pre-operative (18)F-FDOPA PET in suspected glioma. Increased (18)F-FDOPA uptake may not only predict higher glioma grade, but also worse OS.

PURPOSE: The aims of this study were to determine whether quantifying the amount of 18F-DOPA uptake in newly-diagnosed gliomas predicted tumor grade and was more accurate than qualitative reporting. METHODS: A retrospective study was performed at UCLA Medical Center to identify patients with pathology-proven glioma who underwent 18F-DOPA PET scanning ≤6 weeks prior to biopsy/resection. Tumor grade was obtained by standard pathology assays. 18F-DOPA uptake was quantified by determining maximum standardized uptake value (SUVmax) based on the injected radiotracer dose per patient's body weight in the region corresponding to the MRI-based lesion (tumor SUVmax). Tumor-to-normal-brain tissue (T/N) ratio was defined as dividing the tumor SUVmax by the SUVmax of the contralateral normal tissue at the level of the centrum semiovale, and tumor-to-basal ganglia (T/BG) ratio was also determined. Patient demographics, tumor grade, and imaging metrics were tabulated and analyzed. RESULTS: 982 18F-DOPA PET scans from January 2003 through February 2015 in 523 individual patients were reviewed, and scans in 23 patients (n = 9 female, n = 14 male with age 46.3 ± 16.4 years; n = 9 grade II, n = 7 grade III, n = 7 grade IV) were eligible for study. T/N ratio was 1.5 ± 0.6, 1.8 ± 0.4, and 3.0 ± 1.0 for grade II, III, and IV gliomas, respectively. Grade IV T/N ratio was significantly greater than that in grade II (p = 0.008) and grade III (p = 0.02) gliomas. Applying T/N ratio cut-offs of 1-1.69/1.7-2.39/ ≥ 2.4 for grade II/III/IV gliomas, the respective sensitivity/specificity were 88.9%/100%, 85.7%/87.5%, and 71.4%/93.8%. This is in contrast to the diagnostic accuracy (based on the qualitative report in the chart) of 66.7%, 85.7%, and 100%, respectively. CONCLUSIONS: The results demonstrate the utility of quantitative T/N ratio cut-offs in predicting glioma grade. Additionally, a population of grade II/III gliomas that was not diagnosed based on the qualitative report was identified. Future work will correlate 18F-DOPA uptake with survival and tumor molecular profile.