Three-dimensional and quantitative analysis of atherosclerotic plaque composition by automated differential echogenicity.
OBJECTIVE
To validate automated and quantitative three-dimensional analysis of coronary plaque composition using intracoronary ultrasound (ICUS).


BACKGROUND
ICUS displays different tissue components based on their acoustic properties in 256 grey-levels. We hypothesised that computer-assisted image analysis (differential echogenicity) would permit automated quantification of several tissue components in atherosclerotic plaques.


RESULTS
Ten 40-mm-long left anterior descending specimens were excised during autopsy of which eight could be successfully imaged by ICUS. Histological sections were taken at 5 mm intervals and analyzed. Since most of the plaques were calcified and having a homogeneous appearance, one specimen with a more heterogeneous composition was further examined: at each interval of 5 mm, 15 additional sections (every 100 microm) were evaluated. Plaques were scored for echogenicity against the adventitia: brighter (hyperechogenic) or less bright (hypoechogenic). Areas of hypoechogenicity correlated with the presence of smooth muscle cells. Areas of hyperechogenicity correlated with presence of collagen, and areas of hyperechogenicity with acoustic shadowing correlated with calcium. None of these comparisons showed statistical significant differences.


CONCLUSIONS
This ex vivo feasibility study shows that automated three-dimensional differential echogenicity analysis of ICUS images allows identification of different tissue types within atherosclerotic plaques. This technology may play a role as an additional tool in longitudinal studies to trace possible changes in plaque composition.
Department of Cardiology, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands.
Nico
N
Bruining
Stefan
S
Verheye
Michiel
M
Knaapen
Pamela
P
Somers
Jos R T C
JR
Roelandt
Evelyn
E
Regar
Iddo
I
Heller
Sebstiaan
S
de Winter
Jurgen
J
Ligthart
Glenn
G
Van Langenhove
Pim J
PJ
de Feijter
Patrick W
PW
Serruys
Ronald
R
Hamers
D001331:Automation; D001344:Autopsy; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000473:pathology; D005240:Feasibility Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012107:Research Design; D041623:Tomography, Optical Coherence; D018084:Ultrasonography, Interventional