What does a high hounsfield unit indicate?

A high Hounsfield unit (HU) on a CT scan indicates denser tissues or materials. The Hounsfield scale measures radiodensity, where air is represented by a value of -1000 HU, water is 0 HU, and denser substances like bone can have values exceeding +1000 HU. As the density of a substance increases, it absorbs more X-rays, resulting in a higher Hounsfield unit value.

For instance, dense structures such as bones exhibit high Hounsfield unit values compared to less dense tissues like fat, which has lower values. This principle allows radiologists and medical professionals to differentiate between various types of tissues and substances within the body, aiding in diagnosis and treatment planning. Thus, high Hounsfield units are clinically significant for identifying and characterizing dense tissues or materials, such as tumors, calcifications, or bone.