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65th Annual Meeting of the German Society of Neurosurgery (DGNC)

German Society of Neurosurgery (DGNC)

11 - 14 May 2014, Dresden

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Differentiation of local recurrent brain metastasis from radiation-induced changes using [18F]Fluoroethyl-L-Tyrosine PET

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  • Maximilian I. Ruge - Department for Stereotaxy and Functional Neurosurgery, Center of Neurosurgery, University of Cologne, Germany; Center of Integrated Oncology (CIO), University of Cologne, Cologne, Germany
  • Christina Hamisch - Department of Neurosurgery, University of Cologne, Center of Neurosurgery, Cologne, Germany
  • Gabriele Stoffels - Institute of Neuroscience and Medicine, Forschungszentrum Jülich, Jülich, Germany
  • Michael Sabel - Department of Neurosurgery, University of Düsseldorf, Düsseldorf, Germany
  • Karl-Josef Langen - Institute of Neuroscience and Medicine, Forschungszentrum Jülich, Jülich, Germany; Department of Nuclear Medicine, RWTH Aachen University Hospital, Aachen, Germany
  • Norbert Galldiks - Institute of Neuroscience and Medicine, Forschungszentrum Jülich, Jülich, Germany; Department of Neurology, University of Cologne, Cologne, Germany; Center of Integrated Oncology (CIO), University of Cologne, Cologne, Germany

Deutsche Gesellschaft für Neurochirurgie. 65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Dresden, 11.-14.05.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocDI.02.06

doi: 10.3205/14dgnc123, urn:nbn:de:0183-14dgnc1237

Published: May 13, 2014

© 2014 Ruge et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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Objective: The aim of this study was to investigate the potential of [18F]fluoroethyl-L-tyrosine (18F-FET) PET for differentiating local recurrent brain metastasis from radiation-induced changes after radiation therapy since the use of contrast-enhanced MRI for this issue is often difficult.

Method: 38 patients (mean age, 54±11 y) with single or multiple contrast-enhancing brain lesions (n=49) on MRI after radiation therapy of brain metastases were investigated with dynamic 18F-FET PET. Maximum and mean tumor/brain ratios (20–40 min postinjection) (TBRmax, TBRmean) of 18F-FET uptake were determined. Time activity curves (TAC) were generated and the time-to-peak (TTP) was calculated. Furthermore, TACs of each lesion were assigned to one of the following curve patterns: (I) constantly increasing 18F-FET uptake; (II) 18F-FET uptake peaking early (TTP ≤20 min) followed by a plateau; and (III) 18F-FET uptake peaking early (TTP ≤20 min) followed by a constant descent. The diagnostic accuracy of the TBRmax and TBRmean of 18F-FET uptake and the curve patterns for the correct identification of recurrent brain metastasis was evaluated by receiver-operating-characteristic (ROC) analyses using subsequent histological analysis (17 lesions in 16 patients) or clinical course and MR imaging findings (32 lesions in 22 patients) as reference.

Results: Both TBRmax and TBRmean were significantly higher in patients with recurrent metastasis (n=25) than in patients with radiation-induced changes (n=24) (TBRmax 3.3±1.0 vs. 2.3±0.4, P<0.001; TBRmean 2.2±0.4 vs. 1.7±0.1, P<0.001). The sensitivity/specificity of 18F-FET PET for the correct identification of recurrent brain metastases was 84/79% using TBRmax (AUC 0.851±0.06, cut-off 2.6; P<0.001), 92/83% using TBRmean (AUC 0.901±0.05, cut-off 1.9; P<0.001), and 84/100% for curve patterns II and III vs. curve pattern I (P<0.001). Highest sensitivity/specificity (96/88%) to diagnose local recurrent metastasis was obtained when both a TBRmean ≥1.9 and curve pattern II or III were present (AUC 0.963±0.03; P<0.001).

Conclusions: Our findings suggest that the combined evaluation of the TBRmean of 18F-FET uptake and the pattern of TAC can differentiate local brain metastasis recurrence from radiation-induced changes with high accuracy. 18F-FET PET may thus contribute significantly to the management of patients with brain metastases.