The Usefulness of Dynamic O-(2-18F-Fluoroethyl)-L-Tyrosine PET in the Clinical Evaluation of Brain Tumors in Children and Adolescents

Experience regarding O-(2-F-18-fluoroethyl)-L-tyrosine (F-18-FET) PET in children and adolescents with brain tumors is limited. Methods: Sixty-nine F-18-FET PET scans of 48 children and adolescents (median age, 13 y; range, 1-18 y) were analyzed retrospectively. Twenty-six scans to assess newly diagnosed cerebral lesions, 24 scans for diagnosing tumor progression or recurrence, 8 scans for monitoring of chemotherapy effects, and 11 scans for the detection of residual tumor after resection were obtained. Maximum and mean tumor-tobrain ratios (TBRs) were determined at 20-40 min after injection, and time-activity curves of F-18-FET uptake were assigned to 3 different patterns: constant increase; peak at greater than 20-40 min after injection, followed by a plateau; and early peak (<= 20 min), followed by a constant descent. The diagnostic accuracy of F-18-FET PET was assessed by receiver-operating-characteristic curve analyses using histology or clinical course as a reference. Results: In patients with newly diagnosed cerebral lesions, the highest accuracy (77%) to detect neoplastic tissue (19/26 patients) was obtained when the maximum TBR was 1.7 or greater (area under the curve, 0.80 +/- 0.09; sensitivity, 79%; specificity, 71%; positive predictive value, 88%; P = 0.02). For diagnosing tumor progression or recurrence, the highest accuracy (82%) was obtained when curve patterns 2 or 3 were present (area under the curve, 0.80 +/- 0.11; sensitivity, 75%; specificity, 90%; positive predictive value, 90%; P = 0.02). During chemotherapy, a decrease of TBRs was associated with a stable clinical course, and in 2 patients PET detected residual tumor after presumably complete tumor resection. Conclusion: Our findings suggest that F-18-FET PET can add valuable information for clinical decision making in pediatric brain tumor patients.