sth about DIXON

[aelster]

Dear Fungfung310,
Your statements about the Dixon method and india ink artifact are all correct. Phase cancellation only occurs in voxels that contain both water and fat when the echo time is appropriate for the OOP condition to occur. Voxels containing pure water or pure fat are not affected.
In the human body there are many areas containing pure water -- the cerebral ventricles containing CSF and bladder containing urine are obvious candidates. Many tissues like the brain are predominantly water but contain fat in the form of phospholipids and sphingolipids (myelin). These lipids have very short T2 values and are not visualized on conventional MR pulse sequences, so the brain may be considered to be pure water. Finding pure fat is difficult -- Adipose tissue is predominantly lipid but also contains blood vessels and lymphatics with some water in it.
Hope this helps.
ADE