Tozer D J, Davies G R, Altmann D R, Miller D H, Tofts P S
NMR Research Unit, Department of Neuroinflammation, Institute of Neurology, University College London, London WC1N 3BG, UK.
Magn Reson Med. 2005 Jun;53(6):1415-22. doi: 10.1002/mrm.20479.
Two relatively new techniques purport to give measures of the myelin content of brain tissue. These measures are the myelin water fraction from multicompartmental T(2) analysis, and the semisolid proton fraction from analysis of magnetization transfer (MT). The myelin water fraction is the fraction of signal with a T(2) of less than 50 ms measured from a 32-echo sequence. It is believed to originate from water trapped between the myelin bilayers. The semisolid proton fraction is thought to include protons within phospholipid bilayers and macromolecular protons, and may also be a measure of myelin content. Multicompartmental T(2) and MT imaging were carried out on controls and patients with multiple sclerosis (MS), and estimates of the semisolid proton and myelin water fractions were obtained from white matter (WM), gray matter (GM), and MS lesions. These were then correlated for each tissue and subject group. Positive correlations were seen for MS lesions (r approximately 0.2) and in WM in patients (r = 0.6). A negative correlation (r approximately -0.3) was seen for GM. These results indicate that the two techniques measure, to some extent, the same thing (most likely myelin content), but that other factors, such as inflammation, mean they may provide complementary information.
有两种相对较新的技术旨在测量脑组织的髓磷脂含量。这些测量方法分别是通过多室T(2)分析得到的髓磷脂水分数，以及通过磁化转移（MT）分析得到的半固体质子分数。髓磷脂水分数是从32回波序列测量得到的T(2)小于50毫秒的信号分数。据信它源自被困在髓磷脂双层之间的水。半固体质子分数被认为包括磷脂双层内的质子和大分子质子，也可能是髓磷脂含量的一种测量方法。对对照组和多发性硬化症（MS）患者进行了多室T(2)和MT成像，并从白质（WM）、灰质（GM）和MS病变中获得了半固体质子分数和髓磷脂水分数的估计值。然后对每个组织和受试者组进行相关性分析。在MS病变中观察到正相关（r约为0.2），在患者的白质中也观察到正相关（r = 0.6）。在灰质中观察到负相关（r约为 -0.3）。这些结果表明，这两种技术在一定程度上测量的是同一种东西（很可能是髓磷脂含量），但其他因素，如炎症，意味着它们可能提供互补信息。
