Evidence for Two T2 Components of N-Acetyl-Aspartate (NAA) In Healthy White Matter

摘要: N-acetyl-aspartate (NAA) is commonly referred to as an ‘axonal marker’but recent electron microscopy evidence demonstrates higher levels of NAA in myelin than in neurons. Given the multi-exponential T 2 nature of water in white matter (WM), we sought to determine if there are similarly two pools of NAA in WM. We performed multi-echo magnetic resonance spectroscopy in the WM of 5 healthy volunteers at 3T with TE from 10-800ms and observed a short T 2 component between 13-40ms arising from 16-20% of the total signal. These preliminary results encourage further research into the bi-exponential nature of NAA in WM.