title: "Occult" post-contrast signal enhancement in pediatric diffuse intrinsic pontine glioma is the MRI marker of angiogenesis?
abstract: BACKGROUND
  In diffuse intrinsic pontine gliomas (DIPG), subtracting pre-contrast from post-contrast T1-weighted images (T1WI) occasionally reveals subtle, "occult" enhancement. We hypothesized that this represents intravascular enhancement related to angiogenesis and hence that these tumors should have greater blood volume fractions than do non-enhancing tumors.
  
  
  METHODS
  We retrospectively screened MR images of 66 patients initially diagnosed with DIPG and analyzed pretreatment conventional and dynamic susceptibility contrast (DSC) perfusion MRI studies of 61 patients. To determine the incidence of occult enhancement, cerebral blood volume (CBV) values were compared in areas of occult enhancement (OcE), no enhancement (NE), and normal-appearing deep cerebellar white matter (DCWM).
  
  
  RESULTS
  Tumors of 10 patients (16.4 %) had occult enhancement; those of 6 patients (9.8 %) had no enhancement at all. The average CBV in areas of occult enhancement was significantly higher than that in non-enhancing areas of the same tumor (P = .03), within DCWM in the same patient (P = .03), and when compared to anatomically paired/similar regions of interest (ROI) in patients with non-enhancing tumors (P = .005).
  
  
  CONCLUSIONS
  Areas of OcE correspond to areas of higher CBV in DIPG, which may be an MRI marker for angiogenesis, but larger scale studies may be needed to determine its potential relevance to grading by imaging, treatment stratification, biopsy guidance, and evaluation of response to targeted therapy.
authors.affiliation: Department of Radiological Sciences, St. Jude Children's Research Hospital, MS220, 262 Danny Thomas Place, Memphis, TN, 38105, USA.
authors.forename: Ashley E
authors.initials: AE
authors.lastname: Conway
authors.forename: Wilburn E
authors.initials: WE
authors.lastname: Reddick
authors.forename: Yimei
authors.initials: Y
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Yuan
authors.forename: John O
authors.initials: JO
authors.lastname: Glass
authors.forename: Justin N
authors.initials: JN
authors.lastname: Baker
authors.forename: Larry E
authors.initials: LE
authors.lastname: Kun
authors.forename: Alberto
authors.initials: A
authors.lastname: Broniscer
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Patay
mesh_terms: D000293:Adolescent; D020295:Brain Stem Neoplasms / Q000098:blood supply* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D005910:Glioma / Q000098:blood supply* / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009389:Neovascularization, Pathologic; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media