A NEW AUTOMATED COMPUTERIZED ANALYZING SYSTEM SIMPLIFIES READINGS ANDREDUCES THE VARIABILITY IN ULTRASOUND MEASUREMENT OF INTIMA-MEDIA THICKNESS

Background and Purpose A computerized analyzing system with manual tra cing of echo interfaces for measurement of intima-media thickness and lumen diameter in carotid and femoral arteries was previously develope d by our research group and has been used for many years in several la boratories. However, manual measurements are not only time consuming, but the results from these readings are also dependent on training and subjective judgement. A further problem is the observed drift in meas urements over time. A new computerized technique for automatic detecti on of echo interfaces was therefore developed. The aim of this study w as to evaluate the new automated computerized analyzing system. Method s The new system is based on dynamic programming and includes optional interactive modification by the human operator. Local measurements of vessel echo intensity, intensity gradient, and boundary continuity ar e extracted by image analysis techniques and included as weighed terms in a cost function. The dynamic programming procedure is used for det ermining the optimal location of the vessel interfaces in a way that t he cost function is minimized. Results With the new automated computer ized analyzing system the measurement results were less dependent on t he reader's experience, and the variability between readers was less c ompared with the old manual analyzing system. The measurements were al so less time consuming. Conclusions The new automated analyzing system will not only greatly increase the speed of measurements but also red uce the variability between readers. It should also reduce the variabi lity between different laboratories if the same analyzing program is u sed. Furthermore, the new system will probably prevent the problem wit h drift in measurements over time.