Untersuchung neuer computertomographischer Kriterien

Abstract

50 symptomatic atherosclerotic stenoses of an extracranial carotid artery were examined using new CT-criteria and the results compared to findings from Doppler-ultrasonography (Doppler) and digital subtraction angiography (DSA). The degree of carotid stenosis was ?50%. Besides determination of the established measures for the degree of stenosis according to the ECST-, CC- and NASCET-methods using residual luminal diameter and area, a further characterisation of the atherosclerotic stenosis through CT-angiography (CTA) was considered.Doppler-grading of stenoses was carried out as part of the routine clinical work-up after stroke under supervision of an experienced neurologist. In 22 cases, degrees of stenoses were available from a parallel study using formal catheter-based angiography. For the degree of stenosis and residual luminal area three established methods of measurement were employed: ECST, NASCT, CC. The surface of a stenosing plaque was characterised further by stratifying it through simple visual inspection: smooth/ulcerated, centric/eccentric, soft/calcified/mixed. The amount of calcified plaque was determined by measurement on contiguous cross-sectional image slices. Clinical details were obtained from the case notes. Data was subjected to appropriate statistical analyses.The study showed that results from CTA and Doppler are comparable in the examination of internal carotid artery stenoses of ?50%. Of the three measures, the CC- and ECST-methods are to be preferred when compared to Doppler and DSA since the NASCET-method tended to underestimate the degree of stenosis. The CTA-measurement of residual cross-sectional luminal area was more consistent than the diameter-measurement of a stenosis for stenoses of 70-99% when compared to DSA and Doppler. Consideration of cross-sectional area was preferable to diameter of stenosis for the determination of plaque surface. No correlation was found between the amount of calcified plaque and the degree of stenosis. However, expectedly, longer stenoses were found to have a higher calcium load. Eccentric and smooth stenoses were more common than ulcerated, centric ones, in line with published data. No significant relation could be established between plaque surface characteristics and calcium load but centric stenoses tended to be of a higher grade. The study sample's age and sex distribution was typical of the atherosclerotic aetiology.CTA has been shown to be a valid since comparable tool when estimating carotid stenoses and may be employed as a second line investigation. When determining the degree of stenosis, measurement according to ECST-criteria is most suitable. Measurement of cross-sectional residual luminal area may, in future, play a significant role, since it allows a more precise characterisation of surface characteristics of a given stenosis which aids risk stratification.