TheRelevance ofDetecting Carotid Artery Calcification on PlainRadiograph

Background andPurpose: Theaimofthisstudy was todetermine thepotential value ofcarotid artery calcification observed on plain radiographs inpatients referred forcarotid angiogram inthediagnosis of carotid artery stenosis. Methods: Onehundredsixty consecutive patients withsuspected carotid artery stenosis underwent both plain radiographs ofthecarotid arteries anddigital subtraction angiography ofthesame vessels. In addition, 108ofthesepatients alsohadduplexultrasound ofthesame vascular area.Theclinical usefulness ofthecarotid artery calcification was assessed bycalculating thelikelihood ratios fordifferent test results against results ofangiography andduplex ultrasound. Results: Thereisa statistically significant association between thedegrees ofcalcification andcarotid disease as demonstrated byangiography (P=.0001), although positive correlation ofthedegrees of stenosis andcalcification was onlyfair(Spearman correlation coefficient r=.4). Thesensitivity ofcarotid calcification indetecting clinically significant stenosis assuming anycalcification isabnormal was 89% witha specificity of46%.Thelikelihood ratios for50ostenosis byangiography varied from0.24(no calcification) to3.41(level III)andfor50% stenosis byduplexultrasound variedfrom0.21(no calcification) tomore than5.87(level III). Assessments ofthedegree ofcalcification basedon plain radiographs hadexcellent reproducibility (all intraclass correlation coefficients weregreater than.9). Conclusions: Inthispopulation witha highprevalence ofcarotid artery disease, there isan association between thepresenceofcarotid calcification andatheromatous disease. Ifsubsequent studies weretoshow thistoapplyinthegeneral population, thiscouldbeofvalueinidentifying asymptomatic patients at increased risk. (Stroke. 1993;24:1330-1334.)