title: Asymptomatic cystic changes in the brain of children after cranial irradiation: frequency, latency, and relationship to age.
abstract: BACKGROUND
  Although radiation therapy plays an important role in the management of children with brain tumors, radiation-induced brain damage sometimes occurs after radiation therapy. In some pediatric patients who had undergone cranial radiation therapy, we noticed cystic changes in the brain on follow-up MRI. The purpose of this study was to determine the frequency, latency, relationship with patient age, radiation dose, and serial change in the cystic changes in children after cranial irradiation.
  
  
  METHODS
  We retrospectively studied MRI in 33 children who had undergone cranial irradiation for their primary brain tumors. Postirradiation cystic change in the brain on follow-up MRI was defined as a well-demarcated, oval-shaped, CSF-like signal intensity area, and no contrast enhancement.
  
  
  RESULTS
  Of the 33 patients, 6 (18.2%) had one or more cystic lesions. The latency of the cystic changes ranged from 1.5 to 7 years (mean 2.6 years). Cystic changes were found in the subcortical, periventricular and other deep white matter and the basal ganglia. The size of the lesions ranged from 1 to 10 mm at their first appearance; eight cystic lesions increased in size. None the cystic lesions reduced in size or resolved with time and none required intervention. All patients with cystic changes had received irradiation when they were 6 years of age or younger. The cystic changes occurred within the radiation field in patients treated with a radiation dose of 36 Gy or more.
  
  
  CONCLUSIONS
  Asymptomatic brain parenchymal cystic changes appear to occur in children who have undergone cranial irradiation at 6 years of age or younger.
authors.affiliation: Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan. mkitajima@fc.kuh.kumamoto-u.ac.jp
authors.forename: Mika
authors.initials: M
authors.lastname: Kitajima
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hirai
authors.forename: Natsuki
authors.initials: N
authors.lastname: Maruyama
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamura
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Hayashida
authors.forename: Yuji
authors.initials: Y
authors.lastname: Baba
authors.forename: Ryuji
authors.initials: R
authors.lastname: Murakami
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Yukunori
authors.initials: Y
authors.lastname: Korogi
authors.forename: Hideo
authors.initials: H
authors.lastname: Nakamura
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Kuratsu
mesh_terms: D000293:Adolescent; D001921:Brain / Q000473:pathology / Q000528:radiation effects*; D001927:Brain Diseases / Q000175:diagnosis* / Q000453:epidemiology; D001932:Brain Neoplasms / Q000532:radiotherapy*; D020863:Central Nervous System Cysts / Q000175:diagnosis* / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D016371:Cranial Irradiation / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D011832:Radiation Injuries / Q000175:diagnosis* / Q000453:epidemiology; D011879:Radiotherapy Dosage