Fully automatic measurement of the carotid intima thickness in ultrasound images using extinction values

Atherosclerotic cardiovascular disease is the leading cause of death in the world. Ultrasound evaluation of carotid intima-media thickness (cIMT) is a fast and non-invasive approach widely used to estimate cardiovascular risk. However, evaluation of the faint carotid intima sublayer thickness (cIT) is reported to be a better marker of atherosclerosis and adverse cardiovascular risk than cIMT. To date, evaluation of cIT is achieved by manual measures of carotid wall images usually derived from transducers set at high frequency (22 MHz-25 MHz). Based on mathematical morphology techniques, we developed a fully automated method for measuring the thickness of cIT. The numbers generated by the automatic method were compared to the average values generated by manual measurements performed by two specialists evaluating 120 high-resolution carotid images from 80 individuals. Carotid images were obtained with an ultrasound transducer set at 10 MHz, which is easily available in clinical practice. The cIT measurements obtained by the automatic and manual methods showed a particularly good correlation (r = 0.82). This result is quite significant, considering the complexity of extracting such a faint measure in ultrasound images that may be easily obtained in routine clinical settings.