THE RELEVANCE OF DETECTING CAROTID-ARTERY CALCIFICATION ON PLAIN RADIOGRAPH

Background and Purpose: The aim of this study was to determine the pot ential value of carotid artery calcification observed on plain radiogr aphs in patients referred for carotid angiogram in the diagnosis of ca rotid artery stenosis. Methods: One hundred sixty consecutive patients with suspected carotid artery stenosis underwent both plain radiograp hs of the carotid arteries and digital subtraction angiography of the same vessels. In addition, 108 of these patients also had duplex ultra sound of the same vascular area. The clinical usefulness of the caroti d artery calcification was assessed by calculating the likelihood rati os for different test results against results of angiography and duple x ultrasound. Results: There is a statistically significant associatio n between the degrees of calcification and carotid disease as demonstr ated by angiography (P=.0001), although positive correlation of the de grees of stenosis and calcification was only fair (Spearman correlatio n coefficient r=.4). The sensitivity of carotid calcification in detec ting clinically significant stenosis assuming any calcification is abn ormal was 89% with a specificity of 46%. The likelihood ratios for 50% stenosis by angiography varied from 0.24 (no calcification) to 3.41 ( level III) and for 50% stenosis by duplex ultrasound varied from 0.21 (no calcification) to more than 5.87 (level III). Assessments of the d egree of calcification based on plain radiographs had excellent reprod ucibility (all intraclass correlation coefficients were greater than . 9). Conclusions: In this population with a high prevalence of carotid artery disease, there is an association between the presence of caroti d calcification and atheromatous disease. If subsequent studies were t o show this to apply in the general population, this could be of value in identifying asymptomatic patients at increased risk.