by Jonathan Lin, MD and Cheryce Fischer, MD
According to the ACR BI-RADS (Breast Imaging-Reporting and Data System) atlas, a mass is 3-dimensional lesion that occupies space. Masses on ultrasound should be seen and evaluated in three planes. There are 5 morphologic descriptors used when reporting a mass seen on ultrasound. These descriptors include: shape, orientation, margin, echo pattern and posterior features.
Orientation: Orientation is defined with reference to the skin line. Parallel or “wider-than-tall” orientation is often a characteristic of benign masses; however, it should not be the sole feature when assessing for likelihood of malignancy.
Margin: The margin is the edge or border of the lesion.
Echo pattern: The echogenicity of masses is described relative to the mammary fat.
Posterior features: Posterior features represent the attenuation characteristics of a mass in respect to its acoustic transmission.