Impact of [18F]-fluoro-ethyl-tyrosine PET imaging on target definition for radiation therapy of high-grade glioma.

Abstract

BACKGROUND:

We sought to assess the impact of amino-acid (18)F-fluoro-ethyl-tyrosine (FET) positron emission tomography (PET) on the volumetric target definition for radiation therapy of high-grade glioma versus the current standard using MRI alone. Specifically, we investigated the influence of tumor grade, MR-defined tumor volume, and the extent of surgical resection on PET positivity.

METHODS:

Fifty-four consecutive high-grade glioma patients (World Health Organization grades III-IV) with confirmed histology were scanned using FET-PET/CT and T1 and T2/fluid attenuated inversion recovery MRI. Gross tumor volume and clinical target volumes (CTVs) were defined in a blinded fashion based on MRI and subsequently PET, and volumetric analysis was performed. The extent of the surgical resection was reviewed using postoperative MRI.

RESULTS:

Overall, for ∼ 90% of the patients, the PET-positive volumes were encompassed by T1 MRI with contrast-defined tumor plus a 20-mm margin. The tumor volume defined by PET was larger for glioma grade IV (P < .001) and smaller for patients with more extensive surgical resection (P = .004). The margin required to be added to the MRI-defined tumor in order to fully encompass the FET-PET positive volume tended to be larger for grade IV tumors (P = .018).

CONCLUSION:

With an unchanged CTV margin and by including FET-PET for gross tumor volume definition, the CTV will increase moderately for most patients, and quite substantially for a minority of patients. Patients with grade IV glioma were found to be the primary candidates for PET-guided radiation therapy planning.

• Authors: Per Munck Af Rosenschold, Junia Costa, Svend Aage Engelholm, Michael J Lundemann, Ian Law, Lars Ohlhues, Silke Engelholm
• Journal: Neuro-oncology (Neuro Oncol) Vol. 17 Issue 5 Pg. 757-63 (May 2015) ISSN: 1523-5866 [Electronic] England
• PMID: 25537018 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: [email protected].

Chemical References

• O-(2-fluoroethyl)tyrosine
• Tyrosine

Topics

• Adult
• Aged
• Aged, 80 and over
• Brain Neoplasms (diagnostic imaging, pathology, radiotherapy)
• Glioma (diagnostic imaging, pathology, radiotherapy)
• Humans
• Magnetic Resonance Imaging
• Middle Aged
• Neoplasm Grading
• Positron-Emission Tomography
• Tyrosine (analogs & derivatives)
• Young Adult