Comparison of 18F-FET and 18F-FDG PET in brain tumors

doi:10.1016/j.nucmedbio.2009.05.005

Nuclear Medicine and Biology

Volume 36, Issue 7, October 2009, Pages 779-787

https://doi.org/10.1016/j.nucmedbio.2009.05.005 Get rights and content

Abstract

The purpose of this study was to compare the diagnostic value of positron emission tomography (PET) using [¹⁸F]-fluorodeoxyglucose (¹⁸F-FDG) and O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (¹⁸F-FET) in patients with brain lesions suspicious of cerebral gliomas.

Methods

Fifty-two patients with suspicion of cerebral glioma were included in this study. From 30 to 50 min after injection of 180 MBq ¹⁸F-FET, a first PET scan (¹⁸F-FET scan) was performed. Thereafter, 240 MBq ¹⁸F-FDG was injected and a second PET scan was acquired from 30 to 60 min after the second injection (¹⁸F-FET/¹⁸F-FDG scan). The cerebral accumulation of ¹⁸F-FDG was calculated by decay corrected subtraction of the ¹⁸F-FET scan from the ¹⁸F-FET/¹⁸F-FDG scan. Tracer uptake was evaluated by visual scoring and by lesion-to-background (L/B) ratios. The imaging results were compared with the histological results and prognosis.

Results

Histology revealed 24 low-grade gliomas (LGG) of World Health Organization (WHO) Grade II and 19 high-grade gliomas (HGG) of WHO Grade III or IV, as well as nine others, mainly benign histologies. The gliomas showed increased ¹⁸F-FET uptake (>normal brain) in 86% and increased ¹⁸F-FDG uptake (>white matter) in 35%. ¹⁸F-FET PET provided diagnostically useful delineation of tumor extent while this was impractical with ¹⁸F-FDG due to high tracer uptake in the gray matter. A local maximum in the tumor area for biopsy guidance could be identified with ¹⁸F-FET in 76% and with ¹⁸F-FDG in 28%. The L/B ratios showed significant differences between LGG and HGG for both tracers but considerable overlap so that reliable preoperative grading was not possible. A significant correlation of tracer uptake with overall survival was found with ¹⁸F-FDG only. In some benign lesions like abscesses, increased uptake was observed for both tracers indicating a limited specificity of both techniques.

Conclusions

¹⁸F-FET PET is superior to ¹⁸F-FDG for biopsy guidance and treatment planning of cerebral gliomas. The uptake of ¹⁸F-FDG is associated with prognosis, but the predictive value is limited and a histological evaluation of tumor tissue remains necessary. Therefore, amino acids like ¹⁸F-FET are the preferred PET tracers for the clinical management of cerebral gliomas.

Introduction

Today, magnetic resonance imaging (MRI) is the method of choice for the diagnosis of brain tumors, but positron emission tomography (PET) may provide significant additional clinical information in many circumstances [1]. The most widely used PET tracer is [¹⁸F]-fluorodeoxyglucose (¹⁸F-FDG) that has been applied successfully for tumor grading of cerebral gliomas, as a prognostic parameter, to guide biopsy and to differentiate tumor recurrence from radionecrosis [2], [3], [4]. The specificity of ¹⁸F-FDG for tumor tissue, however, is limited owing to high uptake in inflammatory tissue and clinical usefulness of ¹⁸F-FDG for the diagnosis of tumor recurrence is controversial [1], [4]. Another problem for brain tumor imaging is the high uptake of ¹⁸F-FDG in the normal brain tissue, which prohibits the definition of tumor extent. In contrast to ¹⁸F-FDG, the uptake of radiolabelled amino acids in the normal brain is low and brain tumors are delineated from normal brain tissue with a high tumor-to-brain contrast. Numerous studies have demonstrated that brain tumor imaging using amino acids such as ¹¹C-methionine (¹¹C-MET) are especially useful to determine the extent of cerebral gliomas for treatment planning and for biopsy guidance [5]. The role of amino acid imaging for grading and prognosis of cerebral gliomas is controversial [5]. In spite of convincing clinical results, the use of ¹¹C-MET remains restricted to a few centers with an on-site cyclotron due to the short-lived ¹¹C (20-min half-life versus 109 min for ¹⁸F). In recent years some ¹⁸F-labelled amino acids have been developed that allow a more widespread use of amino acid imaging. One of the most promising tracers is O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (¹⁸F-FET) that can be produced in large amounts for clinical purposes like ¹⁸F-FDG [6], [7]. A number of studies have proven the clinical value of ¹⁸F-FET PET to determine the extent of cerebral gliomas for treatment planning and biopsy guidance, the detection of tumor recurrences and prognosis especially in low-grade gliomas (LGG) [8], [9], [10], [11], [12]. Some studies have compared the diagnostic potential of ¹⁸F-FDG PET in brain tumors to that of ¹¹C-MET [2], [3], [13], [14], [15] and to that of SPECT using ¹²³I-iodo-alpha-l-methyl-tyrosine (¹²³I-IMT) [16], [17], [18]. A comparison of ¹⁸F-FET PET and ¹⁸F-FDG PET is not yet available. In this prospective study, we compared PET imaging with ¹⁸F-FDG and ¹⁸F-FET and clinical follow-up in patients who were admitted between 2004 and 2005 with the clinical suspicion of a brain tumor.

Section snippets

Patient population

Within a 2-year period from 2004 to 2005, a group of 59 consecutive adult patients admitted with suspicion of a cerebral glioma or a recurrence of a previously operated glioma was investigated by ¹⁸F-FET and ¹⁸F-FDG PET. The study was approved by the university ethics committee and federal authorities. All subjects gave written informed consent for their participation in the study. Seven patients with suspicion of a LGG or a benign lesion had to be excluded from further evaluation because they

Results

A total of 52 patients who had ¹⁸F-FET and ¹⁸F-FDG PET scans prior to histological diagnosis were analyzed. Forty-three patients had diffuse cerebral gliomas, of whom 33 had primary tumors and 10 recurrences. Twenty-two patients had LGG corresponding to WHO Grade II, 13 patients had anaplastic gliomas of WHO Grade III and 11 patients had glioblastomas of WHO Grade IV. One patient turned out to carry an intracerebral malignant lymphoma; one patient had a giant, invasive pituitary adenoma and

Discussion

The purpose of this study was to compare the diagnostic value of ¹⁸F-FET and ¹⁸F-FDG PET in patients with brain lesions suspicious of cerebral gliomas because which of the two tracers should be preferred for brain tumor imaging is still under discussion. A number of studies have already compared the potential of PET imaging with radiolabeled amino acids to that of ¹⁸F-FDG and reported concordantly that diagnostics using amino acids is more helpful for the clinical management of glioma patients

Conclusion

¹⁸F-FET PET is superior to ¹⁸F-FDG for biopsy guidance and treatment planning of cerebral gliomas. The uptake of ¹⁸F-FDG correlates with prognosis but the predictive value is limited and histological evaluation of tumor tissue remains necessary. Therefore, amino acids like ¹⁸F-FET are the preferred PET tracers for the clinical management of cerebral gliomas.

Acknowledgment

The authors wish to thank Suzanne Schaden, Elisabeth Theelen and Barbara Elghahwagi for assistance in the patient studies, and Silke Grafmüller, Erika Wabbals and Sascha Rehbein for radiosynthesis of ¹⁸F-FET. This work was supported by the Brain Imaging Center West (BICW) and a grant from the Deutsche Krebshilfe to G.R. (70-3088-Sa I). The facility for magnetic resonance imaging at the Institute of Neuroscience and Medicine-Forschungszentrum was supported by the Bundesministerium für Bildung

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Comparison of 18F-FET and 18F-FDG PET in brain tumors

Abstract

Methods

Results

Conclusions

Introduction

Section snippets

Patient population

Results

Discussion

Conclusion

Acknowledgment

Appl Radiat Isot

Nucl Med Biol

Int J Radiat Oncol Biol Phys

Nucl Med Biol

Clinical applications of PET in brain tumors

J Nucl Med

Preoperative evaluation of 54 gliomas by PET with fluorine-18-fluorodeoxyglucose and/or carbon-11-methionine

J Nucl Med

Regional methionine and glucose uptake in high-grade gliomas: a comparative study on PET-guided stereotactic biopsy

J Nucl Med

PET in differentiation of recurrent brain tumor from radiation injury

J Nucl Med

Radiolabeled amino acids: basic aspects and clinical applications in oncology

J Nucl Med

Synthesis and radiopharmacology of O-(2-[18F]fluoroethyl)-l-tyrosine for tumor imaging

J Nucl Med

O-(2-[18F]fluoroethyl)-l-tyrosine PET combined with magnetic resonance imaging improves the diagnostic assessment of cerebral gliomas

Brain

Value of O-(2-[18F]fluoroethyl)-l-tyrosine PET for the diagnosis of recurrent glioma

Eur J Nucl Med Mol Imaging

Positron emission tomography with O-(2-[18F]fluoroethyl)-l-tyrosine versus magnetic resonance imaging in the diagnosis of recurrent gliomas

Neurosurgery

Prognostic value of O-(2-18F-fluoroethyl)-l-tyrosine PET and MRI in low-grade glioma

J Nucl Med

Usefulness of 11C-methionine PET in the evaluation of brain lesions that are hypo- or isometabolic on 18F-FDG PET

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O-(2-[¹⁸F]fluoroethyl)-l-tyrosine PET combined with magnetic resonance imaging improves the diagnostic assessment of cerebral gliomas

Value of O-(2-[¹⁸F]fluoroethyl)-l-tyrosine PET for the diagnosis of recurrent glioma

Positron emission tomography with O-(2-[¹⁸F]fluoroethyl)-l-tyrosine versus magnetic resonance imaging in the diagnosis of recurrent gliomas

Prognostic value of O-(2-¹⁸F-fluoroethyl)-l-tyrosine PET and MRI in low-grade glioma

Comparison of ¹⁸F-FDG and ¹¹C-methionine for PET-guided stereotactic brain biopsy of gliomas

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