Publication
Simultaneous 68Ga-DOTATOC-PET/MRI for IMRT treatment planning for meningioma: first experience
Journal Paper/Review - Feb 6, 2011
Thorwarth Daniela, Henke Guido, Müller Arndt-Christian, Reimold Matthias, Beyer Thomas, Boss Andreas, Kolb Armin, Pichler Bernd, Pfannenberg Christina
Units
PubMed
Doi
Citation
Type
Journal
Publication Date
Issn Electronic
Pages
Brief description/objective
PURPOSE
To evaluate intensity-modulated radiotherapy (IMRT) treatment planning based on simultaneous positron-emission tomography and magnetic resonance imaging (PET/MRI) of meningioma.
METHODS AND MATERIALS
A meningioma patient was examined prior to radiotherapy with dedicated planning computed tomography (CT), MRI, PET/CT with gallium-68-labeled DOTATOC (68Ga-DOTATOC), and simultaneous 68Ga-DOTATOC-PET/MRI. The first gross target volume (GTV) was defined based on a combination of separate MR and 68Ga-DOTATOC-PET/CT imaging (GTVPET/CT+MR). Then, the simultaneous PET/MR images were used to delineate a second GTV (GTVPET/MR) by following exactly the same delineation strategy. After an isotropic expansion of those volumes by a 4-mm safety margin, the resulting planning target volumes (PTVs) were compared by calculating the intersection volume and the relative complements. A cross-evaluation of IMRT plans was performed, where the treatment plan created for the PTVPET/CT+MR was applied to the PET/MR-based PTVPET/MR.
RESULTS
Generally, target volumes for IMRT treatment planning did not differ between MRI plus 68Ga-DOTATOC-PET/CT and simultaneous PET/MR imaging. Only in certain regions of the GTV were differences observed. The overall volume of the PET/MR-based PTV was approximately the same as that obtained from PET/CT data. A small region of infiltrative tumor growth next to the main tumor mass was better visualized with combined PET/MR due to smaller PET voxel sizes and improved recovery. An IMRT treatment plan was optimized for the PTVPET/CT+MR. The evaluation of this plan with respect to the PTVPET/MR showed parts of the target volume that would not have received the full radiation dose after delineation of the tumor, based on simultaneous PET/MR.
CONCLUSION
This case showed that differences in target volumes delineated on the basis of separate MR and PET/CT and simultaneous PET/MR may be observed that can have significant consequences for an effectively applied radiotherapy treatment plan.