title: Extracranial internal carotid artery stenosis in children with sickle cell disease - Which transducer, what measurement?
abstract: BACKGROUND
  Transcranial Doppler ultrasound is used to screen and assess the intracranial arteries of children with sickle cell disease. Recent findings suggest that extracranial internal carotid artery (eICA) stenosis is also a contributing factor to silent cerebral infarction. Stenosis has been measured using phased array transducers with no beam/flow angle correction and linear arrays with angle correction.
  
  
  METHODS
  A total of 124 children undergoing TCD assessment were investigated for eICA velocities. Manual measurements of peak systolic velocity and TCD mean velocity were made with phased and linear array transducers.
  
  
  RESULTS
  Peak systolic velocities ranged from 60 to 534 cm/s (median 126 cm/s) using the linear array and 53 to 394 cm/s (median 115 cm/s) using the phased array transducers. TCD mean ranged from 39 to 419 cm/s (median 81 cm/s) using the linear array and 34 to 295 cm/s (median 72 cm/s) using the phased array transducers.
  
  
  CONCLUSIONS
  There are advantages and disadvantages of each method, but stenoses were readily identified as focal velocity increases. We suggest thresholds for each transducer and recommend that imaging of the eICA forms part of screening for this group of children.
authors.affiliation: Department of Medical Engineering and Physics, King's College Hospital NHS Foundation Trust, London, UK.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Deane
authors.affiliation: Department of Medical Engineering and Physics, King's College Hospital NHS Foundation Trust, London, UK.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Freedman
authors.affiliation: Department of Paediatric Haematology, King's College Hospital NHS Foundation Trust, London, UK.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Height
authors.affiliation: Department of Paediatric Haematology, King's College Hospital NHS Foundation Trust, London, UK.
authors.forename: David C
authors.initials: DC
authors.lastname: Rees
keywords: Doppler ultrasound; Sickle cell disease; cerebrovascular disease