Effect of 11C-methionine-positron emission tomography on gross tumor volume delineation in stereotactic radiotherapy of skull base meningiomas

Int J Radiat Oncol Biol Phys. 2008 Nov 15;72(4):1161-7. doi: 10.1016/j.ijrobp.2008.02.058. Epub 2008 Apr 25.


Purpose: To evaluate the effect of trimodal image fusion using computed tomography (CT), magnetic resonance imaging (MRI) and (11)C-methionine positron emission tomography (MET-PET) for gross tumor volume delineation in fractionated stereotactic radiotherapy of skull base meningiomas.

Patients and methods: In 32 patients with skull base meningiomas, the gross tumor volume (GTV) was outlined on CT scans fused to contrast-enhanced MRI (GTV-MRI/CT). A second GTV, encompassing the MET-PET positive region only (GTV-PET), was generated. The additional information obtained by MET-PET concerning the GTV delineation was evaluated using the PET/CT/MRI co-registered images. The sizes of the overlapping regions of GTV-MRI/CT and GTV-PET were calculated and the amounts of additional volumes added by the complementing modality determined.

Results: The addition of MET-PET was beneficial for GTV delineation in all but 3 patients. MET-PET detected small tumor portions with a mean volume of 1.6 +/- 1.7 cm(3) that were not identified by CT or MRI. The mean percentage of enlargement of the GTV using MET-PET as an additional imaging method was 9.4% +/- 10.7%.

Conclusions: Our data have demonstrated that integration of MET-PET in radiotherapy planning of skull base meningiomas can influence the GTV, possibly resulting in an increase, as well as in a decrease.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Carbon Isotopes
  • Female
  • Humans
  • Imaging, Three-Dimensional / methods
  • Male
  • Meningeal Neoplasms / diagnostic imaging*
  • Meningeal Neoplasms / surgery*
  • Meningioma
  • Methionine*
  • Middle Aged
  • Positron-Emission Tomography / methods*
  • Radiopharmaceuticals
  • Radiosurgery / methods*
  • Skull Base Neoplasms / diagnostic imaging*
  • Skull Base Neoplasms / surgery*
  • Surgery, Computer-Assisted / methods*
  • Treatment Outcome


  • Carbon Isotopes
  • Radiopharmaceuticals
  • Methionine