Positron emission tomography with O-(2-[18F]fluoroethyl)-l-tyrosine versus magnetic resonance imaging in the diagnosis of recurrent gliomas.
OBJECTIVE
New treatment modalities are available for patients with glioma, which may lead to unspecific changes in posttherapeutic magnetic resonance imaging (MRI) findings. Differentiation between tumor- and therapy-associated contrast enhancement on MRI scans after treatment may be difficult. The aim of this study was to analyze the diagnostic value of O-(2-[F]fluoroethyl)-l-tyrosine (FET)-positron emission tomography (PET) and MRI in the detection of tumor recurrence in patients with glioma after radiotherapy, radiosurgery, or multimodal treatment.


METHODS
The study included 36 patients with gliomas and neuroradiological diagnosis of tumor recurrence and 9 patients who had undergone radioimmunotherapy. Patients were consecutively treated between September 2001 and May 2003. A contemporary FET-PET investigation was performed in all patients. A tissue diagnosis was made for comparative analysis in all patients with progressive neuroradiological or clinical findings (32 of 45 patients). In patients with transient neuroradiological or clinical deterioration (13 of 45 patients), clinical follow-up was used to support or contradict the imaging-based diagnosis.


RESULTS
Tumor recurrence was documented in 31 of 45 patients, and 14 of 45 patients were tumor free. FET-PET and MRI revealed a correct diagnosis in 44 and 36 patients, respectively. The difference was statistically significant (P < 0.01). Concordant findings after MRI and FET-PET were documented in 37 patients and discordant findings in 8 patients. The difference was statistically significant (P < 0.01). Specificity of FET-PET was 92.9%, and sensitivity was 100% (in patients suspected of having recurrent tumor as revealed by MRI). Sensitivity of MRI was 93.5%, and specificity was 50% (P < 0.05).


CONCLUSIONS
For patients with gliomas undergoing multimodal treatment or various forms of irradiation, conventional follow-up with MRI is insufficient to distinguish between benign side effects of therapy and tumor recurrence. FET-PET is a powerful tool to improve the differential diagnosis in these patients.
Rachinger
Walter
W
Department of Neurosurgery, University of Munich, Munich, Germany. walter.rachinger@med.uni-muenchen.de
Goetz
Claudia
C
Pöpperl
Gabriele
G
Gildehaus
Franz Josef
FJ
Kreth
Friedrich Wilhelm
FW
Holtmannspötter
Markus
M
Herms
Jochen
J
Koch
Walter
W
Tatsch
Klaus
K
Tonn
Jörg-Christian
JC
D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D005910:Glioma / Q000175:diagnosis*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D012008:Recurrence; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18