Real-time compound imaging obtains multiple coplanar tomographic ultrasound images and combines them into a single compound image, reducing acoustic artifacts and noise. The purpose of this study is to determine if real-time compound imaging improves evaluation of breast cancer compared to conventional sonography.

From May 2000 to July 2001, we scanned the same axial plane with conventional sonography and real-time compound imaging in 520 patients with solid breast nodules. Twenty-eight cancers in 25 patients which were confirmed pathologically were included in this study. Twenty-five of 28 cases were invasive ductal carcinoma and the remaining three were ductal carcinoma in situ. Each image pair consisted of a conventional ultrasound and a real-time compound image with a stationary probe, to maintain an identical projection. The evaluating points were 1) contrast between cancer and normal breast tissue, 2) depiction of margin, 3) clarity of internal echotexture, 4) clarity of posterior echo pattern, and 5) clarity of internal microcalcification. Two radiologists graded for quality of images on a 5-point scale and in a blinded fashion and Wilcoxon rank test was used for comparison between conventional and real-time compound images.

For reviewer 1/reviewer 2, compound image showed grade improvements in 1) contrast (1.4±0.5/1.4±0.7), 2) margin (1.4±0.5/1.8±0.4), 3) internal echotexture (1.0±0.5/1.4±0.7), 4) posterior echo pattern (-0.9±0.7/-0.8±0.7), and 5) internal microcalcification (1.8±0.5/1.8±0.5). In all evaluating points, there was statistically significant difference between conventional and compound images (P<0.05).

Real-time compound imaging improves contrast, depiction of margin, and clarity of internal echotexture and internal microcalcification of the breast cancer. But compound image is not effective to evaluate posterior echo pattern of the breast cancer.