Anatomical understanding of the breast and practical aspects of ultrasound diagnosis

Abstract

The mammary gland is located close to the body surface, allowing high-resolution morphological assessment using high-frequency ultrasound probes, which is valuable for the detailed evaluation and diagnosis of lesions. However, breast composition varies considerably with age and between individuals, and distinguishing normal structures from pathological findings can be challenging. This review provides an overview of the anatomy and ultrasound features of the subcutaneous tissue, Cooper’s ligaments, lobular and lobule structures, and terminal duct lobular units (TDLUs). Variations in normal anatomy, age-related changes, and key points for differentiating these from abnormalities are described. The stroma surrounding ducts and lobules appears as a hypoechoic area on ultrasound, referred to as the glandular tissue component (GTC). Previous reports have suggested an association between GTC and breast cancer risk, and a high GTC is often associated with mammographically dense breasts, indicating its potential utility in risk-stratified breast cancer screening. Because high-frequency ultrasound is subject to considerable signal attenuation, scanning techniques have a substantial impact on diagnostic outcomes. This review discusses technical considerations to enhance diagnostic accuracy, including optimal patient positioning, probe handling and compression, scanning range and speed, use of dynamic assessment, and precautions when employing vascular imaging and elastography. Accurate diagnosis and avoidance of unnecessary further examinations require a thorough understanding of the detailed anatomy and physiological changes of the breast, as well as their correlation with ultrasound appearances. This review aims to support such understanding in routine clinical practice.