title: Differentiation of Brain Tumor Recurrence from Post-Radiotherapy Necrosis with 11C-Methionine PET: Visual Assessment versus Quantitative Assessment.
abstract: OBJECTIVE
  The aim of this multi-center study was to assess the diagnostic capability of visual assessment in L-methyl-11C-methionine positron emission tomography (MET-PET) for differentiating a recurrent brain tumor from radiation-induced necrosis after radiotherapy, and to compare it to the accuracy of quantitative analysis.
  
  
  METHODS
  A total of 73 brain lesions (glioma: 31, brain metastasis: 42) in 70 patients who underwent MET-PET were included in this study. Visual analysis was performed by comparison of MET uptake in the brain lesion with MET uptake in one of four regions (around the lesion, contralateral frontal lobe, contralateral area, and contralateral cerebellar cortex). The concordance rate and logistic regression analysis were used to evaluate the diagnostic ability of visual assessment. Receiver-operating characteristic curve analysis was used to compare visual assessment with quantitative assessment based on the lesion-to-normal (L/N) ratio of MET uptake.
  
  
  RESULTS
  Interobserver and intraobserver κ-values were highest at 0.657 and 0.714, respectively, when assessing MET uptake in the lesion compared to that in the contralateral cerebellar cortex. Logistic regression analysis showed that assessing MET uptake in the contralateral cerebellar cortex with brain metastasis was significantly related to the final result. The highest area under the receiver-operating characteristic curve (AUC) with visual assessment for brain metastasis was 0.85, showing no statistically significant difference with L/Nmax of the contralateral brain (AUC = 0.89) or with L/Nmean of the contralateral cerebellar cortex (AUC = 0.89), which were the areas that were the highest in the quantitative assessment. For evaluation of gliomas, no specific candidate was confirmed among the four areas used in visual assessment, and no significant difference was seen between visual assessment and quantitative assessment.
  
  
  CONCLUSIONS
  The visual assessment showed no significant difference from quantitative assessment of MET-PET with a relevant cut-off value for the differentiation of recurrent brain tumors from radiation-induced necrosis.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Ryogo
authors.initials: R
authors.lastname: Minamimoto
authors.affiliation: Departments of Radiology, Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, Fukushima, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Saginoya
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Chisato
authors.initials: C
authors.lastname: Kondo
authors.affiliation: Departments of Radiology, Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, Fukushima, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Tomura
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Kimiteru
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Matsuo
authors.affiliation: Department of Neurosurgery, Yokohama Rosai Hospital, Yokohama, Kanagawa, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Matsunaga
authors.affiliation: Department of Neurosurgery, Yokohama Rosai Hospital, Yokohama, Kanagawa, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Shuto
authors.affiliation: Department of Neurosurgery, NTT Medical Center Tokyo, Tokyo, Japan.
authors.forename: Atsuya
authors.initials: A
authors.lastname: Akabane
authors.affiliation: Department of Radiology, National Center for Global Health and Medicine Kohnodai Hospital, Chiba, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Miyata
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Sakai
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kubota
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D002250:Carbon Radioisotopes / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D006801:Humans; D008297:Male; D008715:Methionine / Q000378:metabolism; D008875:Middle Aged; D009336:Necrosis; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D059906:Neuroimaging; D015588:Observer Variation; D049268:Positron-Emission Tomography / Q000379:methods*; D012189:Retrospective Studies
chemical_list: D002250:Carbon Radioisotopes; D008715:Methionine