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Eur J Nucl Med Mol Imaging. 2006 Jul;33(7):792-800. Epub 2006 Mar 21.

Serial O-(2-[(18)F]fluoroethyl)-L: -tyrosine PET for monitoring the effects of intracavitary radioimmunotherapy in patients with malignant glioma.

Author information

1
Department of Nuclear Medicine, Klinikum Grosshadern, University of Munich, Marchioninistrasse 15, 81377 Munich, Germany. Gabriele.Poepperl@med.uni-muenchen.de

Abstract

PURPOSE:

Intracavitary radioimmunotherapy (RIT) offers an effective adjuvant therapeutic approach in patients with malignant gliomas. Since differentiation between recurrence and reactive changes following RIT has a critical impact on patient management, the aim of this study was to analyse the value of serial O-(2-[(18)F]fluoroethyl)-L: -tyrosine (FET) PET scans in monitoring the effects of this locoregional treatment.

METHODS:

Following conventional therapy, 24 glioma patients (5 WHO III, 19 WHO IV) underwent one to five RIT cycles with either (131)I-labelled (n=19) or (188)Re-labelled (n=5) anti-tenascin antibodies. Patients were monitored with serial FET PET scans (2-12 scans). For semiquantitative evaluation, maximal tumoural uptake (TU(max)) was evaluated and the ratio to background (BG) was calculated. Results of PET were correlated with histopathological findings (n=9) and long-term clinical follow-up for up to 87 months.

RESULTS:

In seven tumour-free patients, PET revealed slightly increasing but homogeneous FET uptake surrounding the resection cavity with a peak up to 18 months following RIT (TU(max)/BG 2.07+/-0.25) but stable or decreasing values during further follow-up (last follow-up: TU(max)/BG 1.63+/-0.22). Seventeen patients developed regrowth of residual tumour/tumour recurrence showing additional nodular FET uptake (TU(max)/BG 2.79+/-0.53). A threshold value of 2.4 (TU(max)/BG) allowed best differentiation between recurrence and reactive changes (sensitivity 82%, specificity 100%).

CONCLUSION:

FET PET is a sensitive tool for monitoring the effects of locoregional RIT. Homogeneous, slightly increasing FET uptake around the tumour cavity with a peak up to 18 months after RIT, followed by stable or decreasing uptake, points to benign, therapy-related changes. In contrast, nodular uptake is a reliable indicator of recurrence.

PMID:
16550381
PMCID:
PMC1998889
DOI:
10.1007/s00259-005-0053-7
[Indexed for MEDLINE]
Free PMC Article

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