Abstract
Echographic diagnosis of breast cancer has been used in clinical medicine for the past several years. Echographic findings and characteristics suggesting differentiation between malignant and benign tumors have been reported by various investigators. These signs are analyzed in correlation with histological findings, especially cancerous connective tissue and nonconnective tissue and retrotumorous shadow patterns in clinical echograms of various breast cancers. Special reference is made to ultrasound attenuation related to bioacoustical tissue characteristics. This causal mechanism provides a stepping-stone for further improvements in ultrasound apparatus designed for clinical diagnosis of breast cancer. Furthermore, it may stimulate basic research on the bioacoustical properties of ultrasound reflection, absorption, and velocity.