Real-time spatial compound imaging improves reproducibility in the evaluation of atherosclerotic carotid plaques

compared to conventional, single-angle imaging. We investigated intra- and interobserver agreement of 38 outlines of carotid artery plaque images acqu ired by these techniques, by measuring the overlapping area after repeated outlines. In general, both techniques showed good agreement. When consideri ng the images with poorest overlap, compound imaging had a significant adva ntage over conventional imaging regarding both intra- and interobserver agr eement. The interobserver variation for the overlapping area after two outl ines was 20% for conventional technique and 10% for compound. The interobse rver variation of the gray scale median value (GSM) for conventional techni que ranged from -32 to +20 and from -6 to +6 for compound. Likewise, the co efficient of repeatability for the GSM value was 13 for conventional imagin g and three for compound imaging, and interobserver variation for the GSM v alue for the overlapping area was 34% and 9% for conventional and compound technique. In conclusion, compound imaging improves intra- and interobserve r agreement and reduces interobserver variation in the GSM value in a clini cal setting. (C) 2001 World Federation for Ultrasound in Medicine & Biology .