Effects of calcification on the detection of internal carotid artery stenosis by peak systolic velocity

Abstract

Background and Purpose: In the diagnosis of internal carotid artery stenosis (ICS), measurement of peak systolic velocity (PSV) is useful. However, some patients with calcified lesions do not meet the diagnostic criteria. We examined the effects of calcification on the diagnosis of ICS based on PSV. Methods: The subjects were 150 consecutive patients (mean age: 73 years, male: 114) who underwent carotid CT angiography (CTA) and carotid ultrasonography from September 2014 to August 2015. Among the 300 blood vessels of the subjects, those other than carotid arteries with occlusion, post-endarterectomy or stenting were examined. Regarding calcification, the subjects were divided into the calcification group, which exhibited ≥50% perivascular calcification, and the control group, which exhibited <50% calcification, based on CT transverse images. The CTA stenosis rate based on PSV diagnosis was compared between the two groups. Results: In the analysis of 81 blood vessels in the calcification group and 166 blood vessels in the control group, the correlation coefficients of the stenosis rate and PSV were 0.81 and 0.87, respectively. The sensitivity/specificity to detect NASCET stenosis rate of 70% or more with PSV of 200 cm/sec was 90%/75% and 100%/90% in the calcification and control groups, respectively. The calcification group included false-negative subjects for whom observation of the inner cavity was difficult, and false-positive subjects who showed low stenosis rate and PSV>200 cm/sec. Conclusion: Although PSV is a useful marker, even for calcified lesions, the diagnostic accuracy may be affected by cases in which evaluation of the inner cavity is difficult and by those with increased PSV and a low stenosis rate.