Differences between carotid wall morphological phenotypes measured by ultrasound in one, two and three dimensions.
Ultrasound measurements are both surrogate markers and risk factors for atherosclerosis end points. Carotid intima-media thickness (IMT) is most commonly used, but ultrasound can also define structures in higher spatial dimensions, such as total plaque area (TPA) and total plaque volume (TPV). Because there are minimal data regarding the relationship between IMT, TPA and TPV, we measured these variables in 272 Oji-Cree subjects. We found pairwise correlations for IMT:TPA, IMT:TPV and TPA:TPV of 0.507, 0.588 and 0.846, respectively (transformed variables, all P <0.0001). In a subset of 168 subjects with complete cardiovascular risk factor data, we performed multivariate regression analysis to identify sources of variation for IMT, TPA and TPV. We found that the ultrasound traits showed different correlations with individual cardiovascular risk factors. In particular, IMT was significantly associated with hypertension, TPA with smoking and plasma cholesterol, and TPV with diabetes. Therefore, these ultrasound measures of carotid artery morphology, while somewhat correlated, likely represent distinctive quantitative traits with different biological determinants, as underscored by different risk factor associations in the multivariate regression analysis. Because the measurements have different implications and determinants, investigators might need to be selective about the particular measurements they choose for specific applications.
Al-Shali
Khalid
K
Blackburn Cardiovascular Genetics Laboratory, Robarts Research Institute, 406-100 Perth Drive, London, Ont., Canada N6A 5K8.
House
Andrew A
AA
Hanley
Anthony J G
AJ
Khan
Hafiz M R
HM
Harris
Stewart B
SB
Mamakeesick
Mary
M
Zinman
Bernard
B
Fenster
Aaron
A
Spence
J David
JD
Hegele
Robert A
RA
D000328:Adult; D001161:Arteriosclerosis / Q000000981:diagnostic imaging*; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000473:pathology*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007198:Indians, North American; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010641:Phenotype; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D017539:Tunica Intima / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000473:pathology*; D014463:Ultrasonography