title: Spontaneous modifications of contrast enhancement in childhood non-cerebellar pilocytic astrocytomas.
abstract: BACKGROUND
  Pilocytic astrocytoma (PA) is classified by the World Health Organization as a grade I tumor. Magnetic resonance imaging (MRI) is the gold standard in the diagnosis and follow-up of this neoplasm, and assessment of contrast enhancement (CE) pattern is essential. The purpose of this study was to investigate CE changes of non-cerebellar PA (n-C PA) stable in size with serial MRI.
  
  
  METHODS
  Nine hundred and twelve MRI exams of 140 children with histologically proven PA were retrospectively reviewed. Patients were chosen for study inclusion if they were off therapy, without neurofibromatosis type 1, and without dimensional changes of tumor/residual tumor. In patients with CE changes, tumor size and CE size were calculated with a cross product. Descriptive statistics were calculated for continuous variables; effects of possible factors influencing changes of contrast-enhanced areas were tested.
  
  
  RESULTS
  Of 39 n-C PA satisfying the inclusion criteria, 12 showed CE changes in terms of appearance/increase or disappearance/decrease of CE areas. Three of these 12 PA were infratentorial and nine supratentorial. There were no significant correlations between age, gender, tumor localization, tumor size, and modification of CE areas.
  
  
  CONCLUSIONS
  In our experience, n-C PA may show variable CE over time in the absence of tumor/residual tumor dimension change. We recommend that CE fluctuations alone cannot be considered an indicator of tumor progression/regression.
authors.affiliation: Department of Bioimaging and Radiological Sciences, Catholic University, Pol. A. Gemelli, L.go A. Gemelli 8, 000168 Rome, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Gaudino
authors.forename: Francesca
authors.initials: F
authors.lastname: Quaglio
authors.forename: Chiara
authors.initials: C
authors.lastname: Schiarelli
authors.forename: Matia
authors.initials: M
authors.lastname: Martucci
authors.forename: Tommaso
authors.initials: T
authors.lastname: Tartaglione
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Gualano
authors.forename: Giuseppe Maria
authors.initials: GM
authors.lastname: Di Lella
authors.forename: Cesare
authors.initials: C
authors.lastname: Colosimo
mesh_terms: D000293:Adolescent; D001254:Astrocytoma / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA