Intercaudate distance to inner table width ratio
Intercaudate distance to inner table width ratio (CC/IT) is used in assessing patients with neurodegenerative diseases that affect the caudate nuclei. It is best known for assessing individuals with suspected Huntington disease but is in no way specific for the diagnosis, also seen in other less common diseases (e.g. Nasu Hakola disease). An alternative measurement is the frontal horn width to intercaudate distance ratio (FH/CC).
On the same axial plane obtained on the ACPC (anterior commissure and posterior commissure) line, the ratio between the distance between the caudate heads (where they are closest) and the distance between inner table of the skull (measured along the same line as the intercaudate distance) is obtained.
The normal CC/IT ratio range is 0.09 to 0.12. As the caudate heads reduce in size, the CC distance will increase and as such, the CC/IT ratio will increase.