Diagnostic Performance of ¹⁸F-FET PET in Newly Diagnosed Cerebral Lesions Suggestive of Glioma

Abstract

The aim of this study was to assess the clinical value of O-(2-18 F-fluoroethyl)-L-tyrosine ( 18 F-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 6 15 y) who had been referred for neurosurgical assessment of unclear brain lesions and had undergone 18 F-FET PET. Initial histology (n 5 168, 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-tobrain ratios (TBR max/ TBR mean ) of 18 F-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 18 F-FET uptake than NNL (TBR max , 3.0 6 1.3 vs. 1.8 6 0.5; P , 0.001). ROC analysis yielded an optimal cutoff of 2.5 for TBR max 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 (TBR max , 3.6 6 1.4 vs. 2.4 6 1.0; P , 0.001) yielded an optimal cutoff of 2.5 for TBR max (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 TBR max 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 TBR mean were similar with a cutoff of 1.9. Conclusion:18 F-FET uptake ratios provide valuable additional information for the differentiation of cerebral lesions and the grading of gliomas. TBR max of 18 F-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 18 F-FET uptake (TBR max , 2.5) excludes a high-grade tumor with high probability.

Dynamic 18F‐FET PET in suspected WHO grade II gliomas defines distinct biological subgroups with different clinical courses

“…Static 18 F-FET uptake parameters such as SUV max /BG did not gain relevance in prognostic models, which is supported by recently published data. 11,42,46 As SUV max /BG values were calculated in the summed images from 20 to 40 minutes this might have underestimated the SUV max /BG values of some of the tumors.…”

“…13,39 Dynamic analysis of 18 F-FET uptake was shown to enable the differentiation between low-and highgrade gliomas and to distinguish between tumor recurrency and treatment-related effects after adjuvant treatment with high diagnostic power. [11][12][13][40][41][42] Currently, there exists no standard recommendation for initial management of suspected low-grade gliomas. The current prospective protocol represents our daily clinical practise: meticulous histological and molecular-genetic characterization of each individual tumor by MRI/ PET-guided molecular stereotactic biopsy procedures was considered the initial surgical step prior to treatment decision as advised by the interdisciplinary tumor board.…”

18F-fluoroethyl-L-tyrosine positron emission tomography for the differential diagnosis of tumefactive multiple sclerosis versus glioma: A case report

“…To explore the possibility of the coexistence of a primary brain tumor, Fig. 1F) (14). Kinetic analysis revealed a clear uptake pattern in the mean standardized uptake value, with a rapid initial increase followed by a slow further tracer accumulation (Fig.…”

“…Subsequent complete resection of the tumor provided material that allowed the diagnosis of a WHO grade III oligoastrocytoma. Following diagnosis, the patient was irradiated and consequently treated with a combination of procarbazine (100 mg daily, days [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] and lomustine (110 mg/kg, day 1) for 6 eight-week cycles. Brain MRI examination performed at the most recent follow-up in November 2015, revealed that the patient exhibited stable disease.…”

Late Pseudoprogression in Glioblastoma: Diagnostic Value of Dynamic O-(2-[18F]fluoroethyl)-L-Tyrosine PET

“…Comparing with the most known tracer, 18 F-FDG 18F-FET is considered particularly suitable for glioma research because of its low background activity (10). Also, 18 F-FET PET has been shown to be useful in treatment planning (11), detecting malignant progression in low grade glioma (12), identifying glioma in newly diagnosed cerebral lesions (13) and the diagnosis of recurrent malignant glioma (13,14). A disrupted blood-brain barrier (BBB), as indicated by contrast enhancement on MRI, per se does not lead to significant FET uptake (15).…”