[Determination of intima-media thickness of the carotid artery: influences of methods, proband and examination variables]

Abstract

Aim: Comparison of two different methods for the measurement of the common carotid artery intima-media thickness (IMT) regarding results and reproducibility, and investigation of the influence of the subjects' characteristics on the results.

Method: 20 healthy subjects were studied (6 men, 14 women, mean age 27.4 +/- 4.4 years). B-Mode pictures were taken of the carotid arteries on both sides (longitudinal sections from ventral and lateral) and stored for measurement either in systole or in diastole. Maximum IMT was measured conventionally by manual setting of calipers (method 1), the mean IMT over a length of 1 cm was calculated from the area of the intima plus media by means of a computer (method 2). 10 subjects were studied twice for the evaluation of intra- and interobserver variability.

Results: Mean IMT was between 0.48 +/- 0.07 mm (method 1/observer 1) and 0.55 +/- 0.07 mm (method 2/observer 2). IMT values resulting from method 2 had a better correlation in repeated measurements (coefficient 0.84/0.93 for inter-/intraobserver comparison) than those resulting from method 1 (0.79/0.67). Age and height were significantly correlated with IMT (coefficients 0.53 and 0.52 for method 2), no correlation was found for body weight, BMI, sex or years of smoking. There was a significant inverse correlation between blood pressure and IMT (-0.21 to -0.32).

Conclusion: In younger healthy subjects, the results of IMT measurement are influenced by age, height and actual blood pressure. The values resulting from both methods are comparable, whereas method 2 has a better reproducibility.