USA: In a new study conducted by Haley K.Perlow and team it was shown that 68Ga-DOTATATE PET imaging may assist radiation oncologists in creating more accurate radiation therapy volumes by detecting undiagnosed regions of illness that are not seen on MRI. The findings of this study were published in the International Journal of Radiation Oncology, Biology, Physics.
MRI contrast augmented images have typically been used to determine residual tumors in radiation therapy planning for meningiomas. However, for individuals with a meningioma at the skull base, sagittal sinus, or after resection, determining the gross tumor volume may be challenging. In certain cases, advanced PET imaging with 68Ga-DOTATATE PET, which has been demonstrated to be more precise than MRI imaging, can be employed for target volume delineation. The researchers believe that the 68Ga-DOTATATE PET scan-based therapeutic approach will result in lesser radiation volumes and will detect more regions of illness than conventional MRI alone.

This study's data evaluated de-identified, retrospective, and blinded gross tumor volume (GTV) contour delineation with seven central nervous system (CNS) specialists for 25 meningioma patients who received both a 68Ga-DOTATATE PET and an MRI for radiation treatment planning. Each physician contoured the MRI and PET in a non-sequential manner for each patient.
The findings of this study were as follows:
1. Each physician's median MRI volume varied from 16.94 to 25.53 ccs.
2. Each physician's median PET volume varied from 2.09 to 8.36 ccs.
3. Each physician had a lower median PET volume.
4. Furthermore, 7/25 (28%) patients had novel non-adjacent regions contoured on PET by at least 6 of the 7 doctors that were not contoured by these doctors on the accompanying MRI.
5. These additional locations would not have been included in the standard MRI-based volumes.
In conclusion, this work suggests that Ga-68 DOTATATE PET imaging may aid radiation oncologists in creating more accurate radiation therapy volumes by detecting unsuspected regions of illness not seen on MRI, and that 68Ga-DOTATATE PET guided treatment planning should be investigated prospectively.
Reference:
Perlow, H. K., Siedow, M., Gokun, Y., McElroy, J., Matsui, J., Zoller, W., Beyer, S., Arnett, A., Blakaj, D., Boulter, D., Fritz, J., Miller, E., Raval, R., Kleefisch, C., Bovi, J., & Palmer, J. D. (2022). 68Ga-DOTATATE PET-based Radiation Contouring Creates More Precise Radiation Volumes for Meningioma Patients. In International Journal of Radiation Oncology*Biology*Physics. Elsevier BV. https://doi.org/10.1016/j.ijrobp.2022.04.009