title: Long-term evaluation of the effect of hypofractionated high-energy proton treatment of benign meningiomas by means of (11)C-L-methionine positron emission tomography.
abstract: OBJECTIVE
  To determine if (11)C-L-methionine PET is a useful tool in the evaluation of the long-term effect of proton beam treatment in patients with meningioma remnant.
  
  
  METHODS
  Included in the study were 19 patients (4 men, 15 women) with intracranial meningioma remnants who received hypofractionated high-energy proton beam treatment. Patients were examined with (11)C-L-methionine PET and MRI prior to treatment and after 6 months, and 1, 2, 3, 5, 7 and 10 years. Temporal changes in methionine uptake ratio, meningioma volume, meningioma regrowth and clinical symptoms throughout the follow-up period were evaluated.
  
  
  RESULTS
  In 17 patients the tumour volume was unchanged throughout the follow-up. The methionine uptake ratio on PET decreased over the years in most patients. In two patients the tumour remnant showed progression on MRI. In these patients, prior to the volume increase on MRI, the methionine uptake ratio increased. One patient experienced transient clinical symptoms and showed radiological evidence of a radiation-induced reaction close to the irradiated field.
  
  
  CONCLUSIONS
  Proton beam treatment is a safe and effective treatment for achieving long-term growth arrest in meningioma remnants. Follow-up with (11)C-L-methionine PET may be a valuable adjunct to, but not a replacement for, standard radiological follow-up.
authors.affiliation: Department of Neuroscience, Neurosurgery, Uppsala University, Uppsala University Hospital, 751 85, Uppsala, Sweden. Mats.Ryttlefors@Neuro.uu.se.
authors.forename: Mats
authors.identifier: http://orcid.org/0000-0003-2869-2873
authors.initials: M
authors.lastname: Ryttlefors
authors.affiliation: Department of Surgical Sciences, Radiology, Uppsala University, Uppsala University Hospital, 751 85, Uppsala, Sweden.
authors.forename: Torsten
authors.initials: T
authors.lastname: Danfors
authors.affiliation: Department of Neuroscience, Neurosurgery, Uppsala University, Uppsala University Hospital, 751 85, Uppsala, Sweden.
authors.forename: Francesco
authors.initials: F
authors.lastname: Latini
authors.affiliation: Department of Immunology, Genetics and Pathology, Medical Radiation Science, Uppsala University Hospital, 751 85, Uppsala, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Montelius
authors.affiliation: Department of Immunology, Genetics and Pathology, Experimental and Clinical Oncology, Clinical oncology, Uppsala University, Uppsala University Hospital, 751 85, Uppsala, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Blomquist
authors.affiliation: Department of Neuroscience, Neurosurgery, Uppsala University, Uppsala University Hospital, 751 85, Uppsala, Sweden.
authors.forename: Olafur
authors.initials: O
authors.lastname: Gudjonsson
mesh_terms: D000328:Adult; D000359:Aftercare; D002250:Carbon Radioisotopes; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008579:Meningioma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008715:Methionine; D008875:Middle Aged; D049268:Positron-Emission Tomography; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D002250:Carbon Radioisotopes; D008715:Methionine
keywords: 11C-L-Methionine; Meningioma; Positron emission tomography; Proton beam treatment; Stereotactic irradiation
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