11C-methionine PET improves the target volume delineation of meningiomas treated with stereotactic fractionated radiotherapy

Int J Radiat Oncol Biol Phys. 2006 Oct 1;66(2):339-44. doi: 10.1016/j.ijrobp.2006.02.047. Epub 2006 Jun 9.

Abstract

Purpose: To evaluate the role of 11C-methionine positron emission tomography (MET-PET) in target volume delineation for meningiomas and to determine the interobserver variability.

Methods and materials: Two independent observers performed treatment planning in 10 patients according to a prospective written protocol. In the first step, they used coregistered computed tomography (CT) and magnetic resonance imaging (MRI). In the second step, MET-PET was added to CT/MRI (image fusion based on mutual information).

Results: The correlation between gross tumor volume (GTVs) delineated by the two observers based on CT/MRI was r=0.855 (Spearman's correlation coefficient, p=0.002) and r=0.988 (p=0.000) when MET-PET/CT/MRI were used. The number of patients with agreement in more then 80% of the outlined volume increased with the availability of MET-PET from 1 in 10 to 5 in 10. The median volume of intersection between the regions delineated by two observers increased significantly from 69% (from the composite volume) to 79%, by the addition of MET-PET (p=0.005). The information of MET-PET was useful to delineate GTV in the area of cavernous sinus, orbit, and base of the skull.

Conclusions: The hypothesis-generating findings of potential normal tissue sparing and reduced interobserver variability provide arguments for invasive studies of the correlation between MET-PET images and histologic tumor extension and for prospective trials of target volume delineation with CT/MRI/MET-PET image fusion.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Carbon Radioisotopes*
  • Female
  • Fluorodeoxyglucose F18
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Meningeal Neoplasms / diagnostic imaging*
  • Meningeal Neoplasms / radiotherapy
  • Meningioma / diagnostic imaging*
  • Meningioma / radiotherapy
  • Methionine*
  • Middle Aged
  • Observer Variation
  • Positron-Emission Tomography / methods*
  • Radiopharmaceuticals
  • Radiosurgery / methods*
  • Tomography, X-Ray Computed

Substances

  • Carbon Radioisotopes
  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • Methionine