RT Journal Article SR Electronic T1 Diagnostic Performance of 18F-FET PET in Newly Diagnosed Cerebral Lesions Suggestive of Glioma JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 229 OP 235 DO 10.2967/jnumed.112.109603 VO 54 IS 2 A1 Marion Rapp A1 Alexander Heinzel A1 Norbert Galldiks A1 Gabriele Stoffels A1 Jörg Felsberg A1 Christian Ewelt A1 Michael Sabel A1 Hans J. Steiger A1 Guido Reifenberger A1 Thomas Beez A1 Heinz H. Coenen A1 Frank W. Floeth A1 Karl-Josef Langen YR 2013 UL http://jnm.snmjournals.org/content/54/2/229.abstract AB The aim of this study was to assess the clinical value of O-(2-18F-fluoroethyl)-l-tyrosine (18F-FET) PET in the initial diagnosis of cerebral lesions suggestive of glioma. Methods: In a retrospective study, we analyzed the clinical, radiologic, and neuropathologic data of 174 patients (77 women and 97 men; mean age, 45 ± 15 y) who had been referred for neurosurgical assessment of unclear brain lesions and had undergone 18F-FET PET. Initial histology (n = 168, confirmed after surgery or biopsy) and the clinical course and follow-up MR imaging in 2 patients revealed 66 high-grade gliomas (HGG), 77 low-grade gliomas (LGG), 2 lymphomas, and 25 nonneoplastic lesions (NNL). In a further 4 patients, initial histology was unspecific, but during the course of the disease all patients developed an HGG. The diagnostic value of maximum and mean tumor-to-brain ratios (TBRmax/TBRmean) of 18F-FET uptake was assessed using receiver-operating-characteristic (ROC) curve analyses to differentiate between neoplastic lesions and NNL, between HGG and LGG, and between high-grade tumor (HGG or lymphoma) and LGG or NNL. Results: Neoplastic lesions showed significantly higher 18F-FET uptake than NNL (TBRmax, 3.0 ± 1.3 vs. 1.8 ± 0.5; P < 0.001). ROC analysis yielded an optimal cutoff of 2.5 for TBRmax to differentiate between neoplastic lesions and NNLs (sensitivity, 57%; specificity, 92%; accuracy, 62%; area under the curve [AUC], 0.76; 95% confidence interval [CI], 0.68–0.84). The positive predictive value (PPV) was 98%, and the negative predictive value (NPV) was 27%. ROC analysis for differentiation between HGG and LGG (TBRmax, 3.6 ± 1.4 vs. 2.4 ± 1.0; P < 0.001) yielded an optimal cutoff of 2.5 for TBRmax (sensitivity, 80%; specificity, 65%; accuracy, 72%; AUC, 0.77; PPV, 66%; NPV, 79%; 95% CI, 0.68–0.84). Best differentiation between high-grade tumors (HGG or lymphoma) and both NNL and LGG was achieved with a TBRmax cutoff of 2.5 (sensitivity, 79%; specificity, 72%; accuracy, 75%; AUC, 0.79; PPV, 65%; NPV, 84%; 95% CI, 0.71–0.86). The results for TBRmean were similar with a cutoff of 1.9. Conclusion: 18F-FET uptake ratios provide valuable additional information for the differentiation of cerebral lesions and the grading of gliomas. TBRmax of 18F-FET uptake beyond the threshold of 2.5 has a high PPV for detection of a neoplastic lesion and supports the necessity of an invasive procedure, for example, biopsy or surgical resection. Low 18F-FET uptake (TBRmax < 2.5) excludes a high-grade tumor with high probability.