title: New indices of arterial stiffness measured from longitudinal motion of common carotid artery in relation to reference methods, a pilot study.
abstract: BACKGROUND
  Longitudinal wall motion of carotid artery is a useful but challenging parameter to measure. In this study, we tested our previously published motion tracking algorithm and validated our method against applanation tonometry measurements.
  
  
  RESULTS
  We measured the two-dimensional carotid artery wall motion from 19 healthy subjects and, as a reference, performed applanation tonometry measurements in parallel with the ultrasound study. The results show that peak velocities (R = -0·484; P<0·05) and accelerations (R = -0·524; P<0·05) of the longitudinal motion between intima and adventitia layers exhibit a greater correlation with the arterial stiffness parameters, for example the augmentation index than the corresponding amplitude of the longitudinal motion (R = -0·132; P>0·05). The amplitudes of the longitudinal motion, between intima and adventitia, are related more to the physical size of the subject, as they correlated significantly with the height (R = 0·597; P<0·01) and weight (R = 0·562; P<0·05) of the subject as well as the cross-sectional dimension of the measured artery (R = 0·611; P<0·01). Furthermore, two new indices have been introduced, Polydeg and RAlength, with which to study the shape of the longitudinal motion curve; both parameters displayed significant correlation with arterial stiffness, for example augmentation index (R = 0·468; P<0·05 and R = 0·609; P<0·01, respectively).
  
  
  CONCLUSIONS
  The new longitudinal motion parameters presented here displayed clear potential to be used as novel stiffness indices.
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Yli-Ollila
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland.|Department of Clinical Physiology and Nuclear Medicine, University of Eastern Finland, Kuopio, Finland.
authors.forename: Tomi
authors.initials: T
authors.lastname: Laitinen
authors.affiliation: Department of Physics, Biophysics, University of Oulu, Oulu, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Weckström
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Tiina M
authors.initials: TM
authors.lastname: Laitinen
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D062186:Arterial Pressure; D001783:Blood Flow Velocity; D001795:Blood Pressure Determination; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging* / Q000502:physiology; D055119:Elastic Modulus; D004562:Electrocardiography; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000592:standards*; D008297:Male; D008365:Manometry; D008875:Middle Aged; D008955:Models, Cardiovascular; D010865:Pilot Projects; D011237:Predictive Value of Tests; D012016:Reference Values; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000592:standards*; D059289:Vascular Stiffness; D055815:Young Adult
keywords: applanation tonometry; arterial elasticity; longitudinal distension; radial distension; ultrasound