title: Follow-up MR findings of spinal foraminal nerve sheath tumors after stereotactic irradiation.
abstract: OBJECTIVE
  The purpose of this study was to investigate follow-up MR findings of spinal foraminal nerve sheath tumors after stereotactic irradiation.
  
  
  METHODS
  Thirty-five foraminal nerve sheath tumors in 28 patients who underwent stereotactic radiosurgery (SRS) (n = 28) or stereotactic radiotherapy (SRT) (n = 7) were included. The MR images were reviewed to identify serial changes in tumor volume and intratumoral necrosis. Growth and shrinkage were defined as volume changes of ±19.7 % or more; stability was within ±19.7 %. Transient swelling was defined as shrinkage preceded by significant growth. A tumor with shrinkage or stability was regarded as tumor control.
  
  
  RESULTS
  Of 35 tumors, 16 (46 %) were stable, 14 (40 %) shrunk, and 5 (14 %) grew. Transient swelling was seen for 13 (37 %) lesions. Newly developed intratumoral necrosis was observed for 19 (54 %) of 35 tumors and was significantly associated with transient swelling (p = 0.039) and with tumor control (p = 0.017). SRS was not significantly associated with transient swelling.
  
  
  CONCLUSIONS
  In follow-up MR images of spinal foraminal nerve sheath tumors after stereotactic irradiation, newly developed intratumoral necrosis and transient swelling were often seen. Intratumoral necrosis was associated with transient swelling and tumor control.
authors.affiliation: Department of Radiology, Inje University Ilsan Paik Hospital, College of Medicine, 2240, Daehwa-dong, Ilsanseo-gu, Goyang-si, Gyeonggi-do 411-706, Korea.
authors.forename: Hyo Jin
authors.initials: HJ
authors.lastname: Kang
authors.forename: Yoon Joon
authors.initials: YJ
authors.lastname: Hwang
authors.forename: Yong Hoon
authors.initials: YH
authors.lastname: Kim
authors.forename: Su Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Byung Hoon
authors.initials: BH
authors.lastname: Lee
authors.forename: Moon-Jun
authors.initials: MJ
authors.lastname: Sohn
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D018317:Nerve Sheath Neoplasms / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D047368:Tumor Burden