What is the CT, or Hounsfield, number for fat?

The correct Hounsfield unit for fat is typically around -100. Hounsfield units are a scale for measuring radiodensity, which is the ability of a substance to attenuate X-rays. On this scale, air is represented as -1000, water is 0, and fat, being less dense than water, appears as a negative number.

Fat has a lower density compared to water, which is why it is a negative value on the Hounsfield scale. It is important to understand that these values help in differentiating various tissues and substances during CT imaging. The value of around -100 provides a specific reference point for radiologists when interpreting scans, allowing for accurate assessments of body composition and identifying pathological conditions.