What is the Hounsfield Unit (HU) value for cerebrospinal fluid (CSF)?

Cerebrospinal fluid (CSF) typically has a Hounsfield Unit (HU) value that is very close to 0. In CT imaging, the Hounsfield scale is used to quantify radiodensity, where air is defined as -1000 HU, water is defined as 0 HU, and dense structures like bone can have values well over +1000 HU.

CSF, being a clear fluid with a density similar to water, is usually assigned a value of 0 HU, which reflects its low density compared to other substances. This characteristic allows radiologists and technicians to distinguish CSF from other tissues in the brain and spinal cord during CT examinations.

Values higher than 0 HU indicate denser materials, such as fat or various tissues in the brain, while a value lower than 0 HU would indicate substances like air or fat. Thus, the correct representation of CSF on the Hounsfield scale aligns with a value of 0 HU, as this accurately reflects its density and allows for proper interpretation in the context of CT imaging.