title: Comparison of 1- and 2-marker techniques for calculating system magnification factor for angiographic measurement of intracranial vessels.
abstract: OBJECTIVE
  Accurate estimation of an intracranial vessel size is crucial during a diagnostic or therapeutic angiography procedure. The use of 1 or 2 external markers of known size is previously proposed to manually estimate the magnification factor (MF) of an intracranial vessel. The authors evaluated the use of different external marker techniques commonly used during angiographic measurements.
  
  
  METHODS
  Forty-three intracranial vessels in 17 patients were measured using 1-and 2-marker techniques. To obtain the MF, 2 metallic markers were attached to the frontal-temporal regions. The MFs for the targeted vessels were obtained from the x-ray films by measuring the image sizes of the markers and their positions with respect to the target vessel.
  
  
  RESULTS
  Using a phantom, the errors resulted from (a) linear interpolation of MFs, (b) linear interpolation of inverse MFs, and (c) using the MFs of 1 marker, which were 1.23% to 2.23%, 0.8% to 1.55%, and 3.85% to 14.62%, respectively. A similar trend was observed for the measurement of cerebral arteries.
  
  
  CONCLUSIONS
  The use of 2 markers can result in a more accurate estimation of the vessel size. The use of only 1 external marker can lead to substantial error based on the location of the target vessel. Optimizing image acquisition is also crucial for accurate determination of vessel size.
authors.affiliation: Imaging Core Laboratory; Zeenat Qureshi Stroke Research Center, UMDNJ-New Jersey Medical School, Medical Science Building-H 506, 185 South Orange Avenue, Newark, NJ 07103, USA. divaniaa@umdnj.edu
authors.forename: A A
authors.initials: AA
authors.lastname: Divani
authors.forename: C R
authors.initials: CR
authors.lastname: Tholany
authors.forename: A U
authors.initials: AU
authors.lastname: Siddiqui
authors.forename: A
authors.initials: A
authors.lastname: AlKawi
authors.forename: M S
authors.initials: MS
authors.lastname: Hussain
authors.forename: J F
authors.initials: JF
authors.lastname: Kirmani
authors.forename: A I
authors.initials: AI
authors.lastname: Qureshi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002533:Cerebral Angiography / Q000379:methods*; D002536:Cerebral Arteries / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging