Assessment of Tumor Volumes in Skull Base Glomus Tumors Using Gluc-Lys[{sup 18}F]-TOCA Positron Emission Tomography

Journal Article · Sun Mar 15 00:00:00 EDT 2009 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2008.05.037· OSTI ID:21172676

Astner, Sabrina T ^[1]; Bundschuh, Ralph A; Beer, Ambros J; Ziegler, Sibylle I; Krause, Bernd J; Schwaiger, Markus ^[2]; Molls, Michael ^[1]; Grosu, Anca L ^[3]; Essler, Markus ^[2]

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1. Klinik fuer Strahlentherapie und Radiologische Onkologie, Klinikum rechts der Isar der Technischen Universitaet Muenchen, Munich (Germany)
2. Klinik und Poliklinik fuer Nuklearmedizin, Klinikum rechts der Isar der Technischen Universitaet Muenchen, Munich (Germany)
3. Klinik fuer Strahlenheilkunde, Universitaet Freiburg, Freiburg (Germany)

Purpose: To assess a threshold for Gluc-Lys[{sup 18}F]-TOCA positron emission tomography (PET) in target volume delineation of glomus tumors in the skull base and to compare with MRI-based target volume delineation. Methods and Materials: The threshold for volume segmentation in the PET images was determined by a phantom study. Nine patients with a total of 11 glomus tumors underwent PET either with Gluc-Lys[{sup 18}F]-TOCA or with {sup 68}Ga-DOTATOC (in 1 case). All patients were additionally scanned by MRI. Positron emission tomography and MR images were transferred to a treatment-planning system; MR images were analyzed for lesion volume by two observers, and PET images were analyzed by a semiautomated thresholding algorithm. Results: Our phantom study revealed that 32% of the maximum standardized uptake value is an appropriate threshold for tumor segmentation in PET-based target volume delineation of gross tumors. Target volume delineation by MRI was characterized by high interobserver variability. In contrast, interobserver variability was minimal if fused PET/MRI images were used. The gross tumor volumes (GTVs) determined by PET (GTV-PET) showed a statistically significant correlation with the GTVs determined by MRI (GTV-MRI) in primary tumors; in recurrent tumors higher differences were found. The mean GTV-MRI was significantly higher than mean GTV-PET. The increase added by MRI to the common volume was due to scar tissue with strong signal enhancement on MRI. Conclusions: In patients with glomus tumors, Gluc-Lys[{sup 18}F]-TOCA PET helps to reduce interobserver variability if an appropriate threshold for tumor segmentation has been determined for institutional conditions. Especially in patients with recurrent tumors after surgery, Gluc-Lys[{sup 18}F]-TOCA PET improves the accuracy of GTV delineation.

• OSTI ID: 21172676
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 73; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ACCURACY
ALGORITHMS
CARCINOMAS
FLUORINE 18
GALLIUM 68
IMAGES
NMR IMAGING
PATIENTS
PHANTOMS
POSITRON COMPUTED TOMOGRAPHY
SKULL
SURGERY