title: Assessment of 3D T2-weighted high-sampling-efficiency technique (SPACE) for detection of cerebellar tonsillar motion: new useful sign for Chiari I malformation.
abstract: OBJECTIVE
  To describe tonsillar blackout sign (TBS) on three-dimensional (3D)-SPACE, evaluate its performance in identifying Chiari malformation (CM1) as diagnostic marker, and investigate its role in differentiation of symptomatic and asymptomatic CM1.
  
  
  METHODS
  One-hundred fifty-six patients were divided into two groups based on caudal displacement of cerebellar tonsils: CM1 (Group I) and non-CM1 (Group II). Group I was subclassified as symptomatic and asymptomatic by a neurosurgeon. Two radiologists evaluated TBS and cerebrospinal fluid flow abnormality.
  
  
  RESULTS
  All subjects presenting TBS had CM1. Difference in presence of TBS between Group I and Group II was highly significant (P<.001).Grading of TBS in symptomatic patients was significantly higher than that in asymptomatic patients (P<.001).
  
  
  CONCLUSIONS
  TBS is highly suggestive of CM1 and potentially useful in differentiation of symptomatic and asymptomatic CM1.
authors.affiliation: Department of Radiology, School of Medicine, Gazi University Ankara, Turkey. Electronic address: drucar@yahoo.com.
authors.forename: Murat
authors.initials: M
authors.lastname: Ucar
authors.affiliation: Department of Radiology, School of Medicine, Gazi University Ankara, Turkey.
authors.forename: Nil
authors.initials: N
authors.lastname: Tokgoz
authors.affiliation: Department of Radiology, School of Medicine, Gazi University Ankara, Turkey.
authors.forename: Ali Murat
authors.initials: AM
authors.lastname: Koc
authors.affiliation: Department of Radiology, School of Medicine, Gazi University Ankara, Turkey.
authors.forename: Koray
authors.initials: K
authors.lastname: Kilic
authors.affiliation: Department of Neurosurgery, School of Medicine, Gazi University Ankara, Turkey.
authors.forename: Alp Ozgun
authors.initials: AO
authors.lastname: Borcek
authors.affiliation: Department of Radiology, School of Medicine, Gazi University Ankara, Turkey.
authors.forename: Ali Yusuf
authors.initials: AY
authors.lastname: Oner
authors.affiliation: Department of Radiology, School of Medicine, Gazi University Ankara, Turkey.
authors.forename: Gokalp
authors.initials: G
authors.lastname: Kalkan
authors.affiliation: Department of Radiology, School of Medicine, Gazi University Ankara, Turkey.
authors.forename: Koray
authors.initials: K
authors.lastname: Akkan
mesh_terms: D000328:Adult; D001139:Arnold-Chiari Malformation / Q000175:diagnosis*; D002531:Cerebellum / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: 3D T2-weighted high-sampling-efficiency technique (SPACE); CSF flow MR imaging; Chiari I malformation; Tonsillar motion