Grading internal carotid artery stenosis using B-mode ultrasound (in vivo study).

OBJECTIVE

to determine the value of percentage area and diameter reduction in grading ICA stenosis using colour-coded B-mode transverse ultrasonic images.

MATERIALS AND METHODS

measurement of the percentage area and diameter reduction of the common carotid, external carotid and internal carotid (at the point of maximum stenosis) were performed, using duplex scanning with colour-flow imaging preoperatively, in 33 patients (six patients were excluded). The duplex measurements were compared to the percentage area and diameter reduction from transverse section of the specimens. Peak systolic (PSV) and end-diastolic velocities (EDV) were measured at the proximal CCA and ICA within the jet of turbulence. A mm scale was placed next to the specimen block, which was captured by video. The area reduction was measured by playing the video and using the same duplex software.

RESULTS

linear-regression analysis of the percentage area reduction of the in vivo against the specimen measurements showed a good linear relationship (r=0.9047). The in vivo duplex measurements had 95% confidence interval (CI) of 8% (95% CI of diameter reduction 5%).

CONCLUSION

using the gold standard of fixed histological endarterectomy specimen, the results indicate that transverse image obtained with colour B-mode imaging is more appropriate in determining the degree of stenosis.