INTER INTRAOBSERVER VARIABILITY OF CAROTID AND FEMORAL BIFURCATION INTIMA-MEDIA THICKNESS MEASUREMENTS

Arterial wall thickening may be quantitatively assessed by measuring t he intima-media thickness (IMT) with high resolution ultrasound. Previ ous studies have shown a good inter/intraobserver variability of IMT m easurements in the common carotid. In this study we evaluated the inte r/intraobserver variability of IMT measurements in 10 randomly selecte d asymptomatic subjects (age 55.4 +/- 6). Two carotids and two femoral s were studied in each subject. IMT for each patient was the average o f five IMT measurements at the artery bifurcation. Three observers rep eated the scanning and the measurements twice with no knowledge of the previous readings. The between observer coefficient of variation (CV) was 8.45%; the intraobserver CV (mean of carotids and femorals) varie d from 4.4 to 5.1% for the three observers who measured IMT three time s. The mean absolute difference between the first and the third measur ement was 0.0738 mm. In conclusion IMT measurement variability is most ly due to differences between observers. The intraobserver variability is very small. IMT measurements at the carotid and femoral bifurcatio ns have a low variability and are a good expression of atherosclerosis as they consider early lesions at the bifurcation level which may not be observed in the common carotid.