Tissue echogenicity

Ultrasound image of a silicone granuloma in the breast

The amplitude od the detected ultrasound wave represents the degree of ultrasound refelction in the volume element (voxel) tissue and determines the degree of brightness of the image point (pixel). According to the size of the reflection and the resulting brightness, we determine the so-called echogenicity (reflectivity) of individual structures.

We distinguish:

• Hyperechoic structures: Show strong ultrasound reflections and are shown as bright/white pixels. E.g. bones, calcifications, concretions, etc.
• Hypoechoic structures: Show weak ultrasound reflections and are shown as dark/gray pixels. E.g. soft tissues, pathological deposits, etc.
• Anechoic structures: They are shown without brightness/black pixels. E.g. homogeneous structures, liquids, etc.
• Isoechoic structures: There are different structures that are characterized by the same echogenicity (brightness).

The echogenicity of the tissue can be increased using contrast agents. These are typically microbubbles of gas (e.g. air, volatile hydrocarbons) that are introduced into the body. Microbubbles can be free or so-called encapsulated, i.e. enclosed in a suitable cover, most often made of biopolymer.

Links

Used literature

• SEDLÁŘ, Martin – STAFFA, Erik – MORNSTEIN, Vojtěch. Zobrazovací metody využívající neionizující záření [online]. Brno : Institute of Biophysics, Faculty of Medicine, Masaryk University in Brno, 2013, Available from <http://www.med.muni.cz/biofyz/zobrazovacimetody/files/zobrazovaci_metody.pdf>.