title: Functional analysis of the common carotid artery: relative distension differences over the vessel wall measured in vivo.
abstract: OBJECTIVE
  Absolute (DeltaD) and relative (DeltaD/D) arterial diameter distension, parameters related to the elasticity of the vessel, can be measured in superficial arteries using ultrasound-based vessel "wall tracking" techniques. Currently available systems (e.g. the Wall Track System; WTS) measure the displacement of the media-adventitia transition (outer wall). We hypothesize that, given volume incompressibility of the vessel wall, DeltaD and DeltaD/D measured at the outer wall, significantly underestimate vessel distension at the lumen-intima interface (inner wall).
  
  
  METHODS
  We measured DeltaD and DeltaD/D at both the inner and outer wall of the common carotid artery in 39 subjects (aged 18-83 years) using a new prototype "wall tracking" system based on the Vivid-7 scanner (GE Vingmed Ultrasound, Horten, Norway). In addition, DeltaD and DeltaD/D were also measured using WTS.
  
  
  RESULTS
  As anticipated, tracking the inner wall yielded lower diastolic diameters than when tracking the outer wall (Ddia = 5.70 +/- 0.80 and 6.91+/- 0.98 mm, respectively, P < 0.0001). DeltaD (0.54+/- 0.16 versus 0.49 +/- 0.16 mm; P < 0.0001) and DeltaD/D (0.096+/- 0.030 versus 0.071+/- 0.026, P < 0.0001) were indeed larger at the inner than at the outer wall. For WTS, Ddia, DeltaD and DeltaD/D were 7.04 +/- 1.02 mm, 0.45 +/- 0.14 mm and 0.066 +/- 0.022, respectively.
  
  
  CONCLUSIONS
  On average, DeltaD and DeltaD/D are 10 and 25% higher on the inner than on the outer wall, respectively. Follow-up studies in larger cohort trials are mandatory to assess whether tracking the inner wall yields arterial function parameters with a higher cardiovascular prognostic potential.
authors.affiliation: Hydraulics Laboratory, Institute of Biomedical Technology, Ghent University, Sint-Pietersnieuwstraat 41, 9000 Gent, Belgium. patrick.segers@ugent.be
authors.forename: Patrick
authors.initials: P
authors.lastname: Segers
authors.forename: Stein Inge
authors.initials: SI
authors.lastname: Rabben
authors.forename: Julie
authors.initials: J
authors.lastname: De Backer
authors.forename: Johan
authors.initials: J
authors.lastname: De Sutter
authors.forename: Thierry C
authors.initials: TC
authors.lastname: Gillebert
authors.forename: Luc
authors.initials: L
authors.lastname: Van Bortel
authors.forename: Pascal
authors.initials: P
authors.lastname: Verdonck
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging* / Q000502:physiology*; D004548:Elasticity; D005260:Female; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods / Q000592:standards