title: Dynamic characterization of the CT angiographic 'spot sign'.
abstract: OBJECTIVE
  Standard (static) CT angiography is used to identify the intracerebral hemorrhage (ICH) spot sign. We used dynamic CT-angiography to describe spot sign characteristics and measurement parameters over 60-seconds of image acquisition.
  
  
  METHODS
  We prospectively identified consecutive patients presenting with acute ICH within 4.5 hours of symptom onset, and collected whole brain dynamic CT-angiography (dCTA). Spot parameters (earliest appearance, duration, maximum Hounsfield unit (HU), time to maximum HU, time to spot diagnostic definition, spot volume and hematoma volumes) were measured using volumetric analysis software.
  
  
  RESULTS
  We enrolled 34 patients: three were excluded due to secondary causes of ICH. Of the remaining 31 patients there were 18 females (58%) with median age 70 (range 47-86) and baseline hematoma volume 33 ml (range 0.7-103 ml). Positive dCTA spot sign was present in 13 patients (42%) visualized as an expanding 3-dimensional structure temporally evolving its morphology over the scan period. Median time to spot appearance was 21 s (range 15-35 seconds). This method allowed tracking of spots evolution until the end of venous phase (active extravasation) with median duration of 39 s (range 25-45 seconds). The average density and time to maximum density was 204HU and 30.8 s (range 23-31 s) respectively. Median time to spot diagnosis was 20.8 s using either 100 or 120HU definitions.
  
  
  CONCLUSIONS
  Dynamic CTA allows a 3-dimensional assessment of spot sign formation during acute ICH, and captured higher spot sign prevalence than previously reported. This is the first study to describe and quantify spot sign characteristics using dCTA; these can be used in ongoing and upcoming ICH studies.
authors.affiliation: Division of Neuroradiology, Department of Medical Imaging, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada.
authors.forename: Santanu
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Department of Medicine, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada; Department of Neurology, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Alhazzaa
authors.affiliation: Department of Pathology, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada.
authors.forename: Jason K
authors.initials: JK
authors.lastname: Wasserman
authors.affiliation: Department of Medicine, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada.
authors.forename: Yang Yang
authors.initials: YY
authors.lastname: Sun
authors.affiliation: Department of Medicine, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada.
authors.forename: Grant
authors.initials: G
authors.lastname: Stotts
authors.affiliation: Department of Medicine, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada.
authors.forename: Mathew J
authors.initials: MJ
authors.lastname: Hogan
authors.affiliation: Department of Clinical Neurosciences, Foothills Medical Centre, Calgary Health Region, Calgary, Alberta, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Demchuk
authors.affiliation: Division of Neuroradiology and Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Richard I
authors.initials: RI
authors.lastname: Aviv
authors.affiliation: Department of Medicine, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada; Department of Epidemiology and Community Medicine, Ottawa Hospital Research Institute and University of Ottawa, Ontario, Canada.
authors.forename: Dar
authors.initials: D
authors.lastname: Dowlatshahi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002533:Cerebral Angiography / Q000379:methods*; D002543:Cerebral Hemorrhage / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D054893:Cone-Beam Computed Tomography / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009864:Ontario; D011446:Prospective Studies