Uptake and tracer kinetics of O-(2-18F-fluoroethyl)-L-tyrosine in meningiomas: preliminary results

Jan F. Cornelius, Gabriele Stoffels, Christian Filß, Norbert Galldiks, Philipp Slotty, Marcel Kamp, Mustafa el Khatib, Daniel Hänggi, Michael Sabel, Jörg Felsberg, Hans Jakob Steiger, Heinz H. Coenen, Nadim J. Shah, Karl Josef Langen

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Abstract

Purpose: O-(2-[18F]Fluoroethyl)-l-tyrosine (18F-FET) is a well-established PET tracer for the imaging of cerebral gliomas, but little is known about 18F-FET uptake in meningiomas. The aim of this study was to explore 18F-FET kinetics and tumour-to-background contrast in meningiomas of various histologies.

Methods: A group of 24 patients with suspected cerebral meningioma on MRI/CT had an additional dynamic 18F-FET PET scan prior to surgery. Time–activity curves (TAC) of 18F-FET uptake in the tumours and tumour-to-brain ratios (TBR) for early (3 – 14 min after injection) and late 18F-FET uptake (20 – 40 min after injection) were analysed and compared with histological subtypes and WHO grade. 18F-FET uptake in critical structures in the skull base was also evaluated in terms of tumour-to-tissue (T/Tis) ratio.

Results: TBR of 18F-FET uptake in meningiomas was significantly higher in the early phase than in the late phase (3.5 ± 0.8 vs. 2.2 ± 0.3; P < 0.001). The difference in TBR between low-grade meningiomas (WHO grade I, 18 patients) and high-grade meningiomas (WHO grade II or III, 6 patients) was significant in the late phase of 18F-FET uptake (2.1 ± 0.2 vs. 2.5 ± 0.2, P = 0.003) while there was no significant difference in the early phase. ROC analysis showed that TBR of 18F-FET uptake in the late phase had significant power to differentiate low-grade from high-grade meningiomas (AUC 0.87 ± 0.18, sensitivity 83 %, specificity 83 %, optimal cut-off 2.3; P < 0.01). Evaluation of TAC yielded three different curve patterns of 18F-FET PET uptake. Combination of TBR (cut-off value 2.3) and TAC pattern slightly improved the differentiation of high-grade from low-grade meningiomas (accuracy 92 %; P = 0.001). Analysis of background radioactivity in the skull base indicated that 18F-FET uptake may be helpful in distinguishing meningioma tissue in the late phase. T/Tis ratios were >1.2 in all patients for the periorbita, sphenoidal sinus, pituitary gland, tentorium, bone and brain, in more than 90 % of patients for the mucosa and dura, but in only 63 % of patients for the cavernous sinus.

Conclusion: 18F-FET PET may provide additional information for noninvasive grading of meningiomas and possibly for the discrimination of tumour in critical areas of the skull base. A further evaluation of 18F-FET PET in meningiomas appears to be justified.

Original languageEnglish
Pages (from-to)459-467
Number of pages9
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Volume42
Issue number3
DOIs
Publication statusPublished - Mar 2015
Externally publishedYes

Keywords

  • <sup>18</sup>F-FET PET
  • Grading
  • Meningioma
  • Skull base

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