The Information Content of B-Scan Anomalies

Abstract

The immense improvement in ultrasonic B-scan picture quality over the last decade has been matched by the ever finer degree of clinical interpretation placed upon these pictures. Present day resolution capabilities have enabled the clinician to visualise anatomical structure of the order of a few wavelengths (typically λ = 0.5 mm for abdominal B-scanners). Since the information is of such a highly detailed character it is imperative that a greater understanding of the interaction of ultrasound and human soft tissues should be attempted. Typical sector B-scan pictures (see figure 1) often depict more than just a simple map of the anatomical placement of tissue structures. These ‘extra’ information, best described as B-scan anomalies, are often classed as unwanted ‘artefacts’ and disregarded when evaluating the information content of the picture. Although this is often justified, useful diagnostic information occasionally can be gained by a more rigorous appraisal of the anomalies.