ORIGINAL ARTICLES   

International Angiology 1998 September;17(3):179-86

Copyright © 2000 EDIZIONI MINERVA MEDICA

lingua: Inglese

The effect of B-mode ultrasonic image standardisation on the echodensity of symptomatic and asymptomatic carotid bifurcation plaques

Elatrozy T., Nicolaides A. Tegos Th., Zarka A. Z., Griffin M., Sabetai M.

From the Irvine Laboratory for Cardiovascular Investigation and Research Academic Surgical Unit, Imperial College School of Medicine, St. Mary’s Hospital, London, UK

Background. To devel­op a meth­od that ­allows B-mode ultra­son­ic imag­es of carot­id ­plaques to be stan­dar­dised so that meas­ure­ments of ­plaque ech­o­den­sity ­become com­par­able and clin­i­cal­ly use­ful.
Methods. Design. Cross sec­tion­al study. Setting. Teaching hos­pi­tal, England. Patients: a ran­dom con­sec­u­tive ­series of 23 ­patients in part1, 19 in part II and 77 in part III. Measures. Part I: twenty-three imag­es of carot­id bifur­ca­tion ­plaques from 2 ­duplex scan­ners were dig­it­ised. Images were stan­dar­dised by 4 observ­ers so that the grey scale ­median (GSM) would be 0-5 for blood and 185-195 for adven­ti­tia. Part II: the ­effect of three dif­fer­ent record­ing media: video, mag­ne­to-opti­cal disk (MOD) and ther­mal paper on the ech­o­den­sity of 19 ­plaques’ imag­es was deter­mined. Part III: the ech­o­den­sity of 91 carot­id bifur­ca­tion ­plaques with great­er than 50% sten­o­sis was cor­re­lat­ed to the pres­ence or ­absence of ipsi­lat­er­al hem­i­spher­i­cal symp­toms.
Results. Part I: the coef­fi­cient of vari­a­tion (CV) among 4 observ­ers was 0.7%, 0% and 4.7% after image stan­dar­disa­tion for the adven­ti­tia, blood and ­plaques respec­tive­ly. Part II: a near per­fect agree­ment was ­obtained ­between the GSM of ­plaques from imag­es on video and MOD (r=0.97) after stan­dar­disa­tion. Part III: after stan­dar­disa­tion, the GSM of symp­to­mat­ic ­plaques was lower (21±14.8) than in asymp­to­mat­ic ­plaques (38±26) p=0.002. Plaque echol­u­cen­cy was more like­ly to be asso­ciat­ed with symp­toms (rel­a­tive risk 4.1 90% CI 1.8-9.4). Conclusions. Images from dif­fer­ent scan­ners by dif­fer­ent ultra­so­nog­ra­phers and ­through dif­fer­ent periph­er­als can be stan­dar­dised so that meas­ure­ments of ­plaque ech­o­den­sity may ­become com­par­able. The meth­od is rec­om­mend­ed for use in ­future nat­u­ral his­to­ry stud­ies on carot­id ­plaques where ­stroke is the end­-point.