Delineating the gross tumor volume (GTV) is a core task within radiation treatment planning. GTVs must be precisely defined irrespective of the region involved, but even more so in a sensitive area such as the brain. As precision medicine cannot exist without precision imaging, the current article aims to discuss the various imaging modalities employed in the radiation treatment planning of brain tumors.
Gliomas, meningiomas, and paragangliomas are some of the most challenging tumors and the advancement in diagnostic imaging can significantly contribute to their delineation. For gliomas, irradiation based on multiparametric magnetic resonance imaging (MRI) and amino-acid positron emission tomography (PET)/computed tomography (CT) may have a higher sensitivity and specificity, which could lead to a better sparing of organs at risk and help distinguish between tumor, edema, and radiogenic alterations. Meningiomas and paragangliomas are often associated with a good prognosis. Therefore, GTV delineation according to MRI and somatostatin receptor ligand-PET/CT plays an essential role in sparing sensitive structures and maintaining a good quality of life for these patients.
The combination of multiparametric MRI and PET/CT (possibly in the form of PET/MRI) presently appears to be the optimal approach for target volume delineation. The comparative efficacy of these imaging modalities has to be further evaluated in prospective trials.
*Department of Radiation Oncology, Medical Center – University of Freiburg, Freiburg, Germany
†Department of Nuclear Medicine, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
‡Department of Radiation Oncology, Klinikum Rechts der Isar, Technical University of Munich, Germany; Institute of Innovative Radiotherapy (iRT), Department of Radiation Sciences (DRS), Helmholtz Zentrum München (HMGU), Munich, Germany
§University of Washington School of Medicine, Department of Radiology, Seattle, WA
||German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany
¶German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Address correspondence to Anca L. Grosu, MD, Department of Radiation Oncology, Medical Center – University of Freiburg, Robert-Koch Str. 3, 79106 Freiburg, Germany (e-mail: email@example.com).
IP was partially funded by the Else Kröner-Fresenius-Stiftung, Germany, within the EXCEL (Excellent Clinician Scientists in Freiburg – Education for Leadership) Programme “Immunological Causes and Therapies of Cancer.” The funding source had no involvement in the writing of the manuscript or in the decision to submit the article for publication.
The authors have no conflicts of interest to disclose.