title: Multivoxel proton MRS for differentiation of radiation-induced necrosis and tumor recurrence after gamma knife radiosurgery for brain metastases.
abstract: Multivoxel proton magnetic resonance spectroscopy (MRS) was used for differentiation of radiation-induced necrosis and tumor recurrence after gamma knife radiosurgery for intracranial metastases in 33 consecutive cases. All patients presented with enlargement of the treated lesion, increase of perilesional brain edema, and aggravation or appearance of neurological signs and symptoms on average 9.3 +/- 4.9 months after primary treatment. Metabolic imaging defined four types of lesions: pure tumor recurrence (11 cases), partial tumor recurrence (11 cases), radiation-induced tumor necrosis (10 cases), and radiation-induced necrosis of the peritumoral brain (1 case). In 1 patient, radiation-induced tumor necrosis was diagnosed 9 months after radiosurgery; however, partial tumor recurrence was identified 6 months later. With the exception of midline shift, which was found to be more typical for radiation-induced necrosis (P < 0.01), no one clinical, radiologic, or radiosurgical parameter either at the time of primary treatment or at the time of deterioration showed a statistically significant association with the type of the lesion. Proton MRS-based diagnosis was confirmed histologically in all surgically treated patients (7 cases) and corresponded well to the clinical course in others. In conclusion, multivoxel proton MRS is an effective diagnostic modality for identification of radiation-induced necrosis and tumor recurrence that can be used for monitoring of metabolic changes in intracranial neoplasms after radiosurgical treatment. It can be also helpful for differentiation of radiation-induced necrosis of the tumor and that of the peritumoral brain, which may have important clinical and medicolegal implications.
authors: Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo, 162-8666, Japan. m_chernov@yahoo.com
authors: Mikhail F
authors: MF
authors: Chernov
authors: Motohiro
authors: M
authors: Hayashi
authors: Masahiro
authors: M
authors: Izawa
authors: Masao
authors: M
authors: Usukura
authors: Shimetoshi
authors: S
authors: Yoshida
authors: Yuko
authors: Y
authors: Ono
authors: Yoshihiro
authors: Y
authors: Muragaki
authors: Osami
authors: O
authors: Kubo
authors: Tomokatsu
authors: T
authors: Hori
authors: Kintomo
authors: K
authors: Takakura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001923:Brain Chemistry; D001932:Brain Neoplasms / Q000473:pathology* / Q000556:secondary* / Q000601:surgery; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009336:Necrosis / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D009364:Neoplasm Recurrence, Local / Q000378:metabolism / Q000473:pathology*; D049268:Positron-Emission Tomography; D011832:Radiation Injuries / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D019275:Radiopharmaceuticals; D016634:Radiosurgery / Q000009:adverse effects*; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18