title: High accuracy of arterial spin labeling perfusion imaging in differentiation of pilomyxoid from pilocytic astrocytoma.
abstract: BACKGROUND
  Pilomyxoid astrocytoma (PMA) is a relatively new tumor entity which has been added to the 2007 WHO Classification of tumors of the central nervous system. The goal of this study is to utilize arterial spin labeling (ASL) perfusion imaging to differentiate PMA from pilocytic astrocytoma (PA).
  
  
  METHODS
  Pulsed ASL and conventional MRI sequences of patients with PMA and PA in the past 5 years were retrospectively evaluated. Patients with history of radiation or treatment with anti-angiogenic drugs were excluded.
  
  
  RESULTS
  A total of 24 patients (9 PMA, 15 PA) were included. There were statistically significant differences between PMA and PA in mean tumor/gray matter (GM) cerebral blood flow (CBF) ratios (1.3 vs 0.4, p < 0.001) and maximum tumor/GM CBF ratio (2.3 vs 1, p < 0.001). Area under the receiver operating characteristic (ROC) curves for differentiation of PMA from PA was 0.91 using mean tumor CBF, 0.95 using mean tumor/GM CBF ratios, and 0.89 using maximum tumor/GM CBF. Using a threshold value of 0.91, the mean tumor/GM CBF ratio was able to diagnose PMA with 77 % sensitivity, 100 % specificity, and a threshold value of 0.7, provided 88 % sensitivity and 86 % specificity. There was no statistically significant difference between the two tumors in enhancement pattern (p = 0.33), internal architecture (p = 0.15), or apparent diffusion coefficient (ADC) values (p = 0.07).
  
  
  CONCLUSIONS
  ASL imaging has high accuracy in differentiating PMA from PA. The result of this study may have important applications in prognostication and treatment planning especially in patients with less accessible tumors such as hypothalamic-chiasmatic gliomas.
authors: Department of Radiology, Children's Hospital of Philadelphia, Perelman School of Medicine of the University of Pennsylvania, 324S 34th Street - Wood 2115, Philadelphia, PA, 19104, USA, seyedali.nabavizadeh@uphs.upenn.edu.
authors: S A
authors: SA
authors: Nabavizadeh
authors: R
authors: R
authors: Assadsangabi
authors: M
authors: M
authors: Hajmomenian
authors: M
authors: M
authors: Santi
authors: A
authors: A
authors: Vossough
mesh_terms: D001254:Astrocytoma / Q000098:blood supply / Q000473:pathology*; D001932:Brain Neoplasms / Q000098:blood supply / Q000473:pathology*; D002560:Cerebrovascular Circulation; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D013113:Spin Labels