Use of Stereotactic PET Images in Dosimetry Planning of Radiosurgery for Brain Tumors: Clinical Experience and Proposed Classification
- Marc Levivier, MD, PhD1,
- Nicolas Massager, MD1,
- David Wikler, MS2,
- José Lorenzoni, MD1,
- Salvador Ruiz, MD1,
- Daniel Devriendt, MD3,
- Philippe David, MD4,
- Françoise Desmedt, MS3,
- Stéphane Simon, MS3,
- Paul Van Houtte, MD3,
- Jacques Brotchi, MD1 and
- Serge Goldman, MD2
- 1Department of Neurosurgery and Centre Gamma Knife, Hôpital Erasme and Université Libre de Bruxelles, Brussels, Belgium
- 2PET/Biomedical Cyclotron Unit, Hôpital Erasme, Brussels, Belgium
- 3Department of Radiation Therapy and Laboratory of Physics, Institut Jules Bordet, Brussels, Belgium
- 4Department of Radiology, Hôpital Erasme, Brussels, Belgium
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FIGURE 1.Acrylic dedicated PET indicator box is attached to base ring of stereotactic Leksell G frame, which is secured in customized head holder during PET acquisition.
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FIGURE 2.Proposed classification. Left column represents description of relative location of tumor volumes, as defined on basis of PET (purple) and MRI (light blue). Right column illustrates choice made to define final target volume (dark blue line). In classes I, II, and III, subclasses A, B, and C are defined (only PET-, only MRI-, and PET- and MRI-target volume definition).
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FIGURE 3.(A) Distribution of clinical indications for which PET was used for dosimetry planning of radiosurgery. (B) Distribution of relative use of 18F-FDG and 11C-methionine for data acquisition in low-grade and high-grade brain tumors.
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FIGURE 4.Example of LGK radiosurgical planning using combined PET (with 18F-FDG) and MRI in patient with recurrent anaplastic oligoastrocytoma, after surgeries, radiation therapy, and chemotherapy. Tumor volume is defined separately on PET (purple line, left images) and MRI (light blue line, right images): the 2 volumes project partially in different areas (class II). Final target volume includes both PET and MRI volumes (class IIB). Yellow line represents prescription isodose and encompasses the target volume.
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FIGURE 5.Example of LGK radiosurgical planning using combined PET (with 11C-methionine) and MRI in patient with recurrent adrenocorticotrophic hormone–secreting pituitary adenoma after transphenoidal surgery. Tumor volume cannot be clearly defined on MRI; therefore, only tumor volume defined on PET (purple line, left images) is used as final target volume (class V). Yellow line represents prescription isodose and encompasses target volume.
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FIGURE 6.Example of LGK radiosurgical planning using combined PET (11C-methionine) and MRI in patient with local recurrence of metastasis, previously treated with radiosurgery. Tumor volume is defined separately on PET (purple line, left images) and MRI (light blue line, right images): the 2 volumes project partially in different areas (class II). Final target volume (dark blue line) includes entirely both PET and MRI volumes (class IIB). Yellow line represents prescription isodose and encompasses target volume.
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FIGURE 7.Distribution of 72 lesions according to proposed classification. (A) Contribution of PET findings for definition of final target volume is presented for each class. (B) Diagram illustrates how positive PET findings were used to define final target volume for radiosurgical treatment of brain tumors.
