Noninvasive characterization of plaque morphology using helical computed tomography.
BACKGROUND
Evidence suggests that atherosclerotic plaque composition and morphology are more important predictors of plaque stability and clinical behavior than the degree of vessel stenosis. Unfortunately, noninvasive methods of plaque characterization in situ using duplex ultrasound have been largely unsuccessful. We investigated the accuracy of helical computed tomography (HCT) in defining plaque morphology in patients undergoing carotid endarterectomy.


METHODS
Candidates for endarterectomy were enrolled prospectively and underwent HCT with intravenous contrast injection. The attenuation values (in Hounsfield Units) of plaque features such as calcium, fibrous tissue, and lipid were measured and correlated with the tissue types seen on microscopic examination. Percent luminal stenosis derived from transverse HCT images was also compared to values obtained from duplex ultrasound.


METHODS
Ambulatory patients referred to a tertiary, metropolitan medical center.


RESULTS
A total of 21 out of 22 cases were suitable for comparison. Qualitatively, HCT accurately defined plaque features containing calcium, fibrous stroma, and lipid. Using tissue attenuation values (Hounsfield Units - H), HCT distinguished between lipid and fibrous stroma (means 39+/-12 H and 90+/-24 H, respectively, p<0.001). HCT-derived calculations of percent stenosis also correlated with the ultrasound data (p<0.001).


CONCLUSIONS
HCT is an accurate, noninvasive means for studying detailed plaque morphology and composition. This technique provides the basis for further studies correlating plaque anatomy with clinical behavior.
Estes
J M
JM
Department of Surgery, New England Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA.
Quist
W C
WC
Lo Gerfo
F W
FW
Costello
P
P
D000368:Aged; D000369:Aged, 80 and over; D001161:Arteriosclerosis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D003287:Contrast Media / Q000008:administration & dosage; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007479:Iopamidol / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D018616:Ultrasonography, Doppler, Duplex
D003287:Contrast Media; D007479:Iopamidol