Abnormalities in the Macroscopically Normal White Matter in Cases of Mild or Spinal Multiple Sclerosis (MS)

Magnetization transfer can predict clinical evolution in patients with multiple sclerosis

“…The cerebral NAWM changes in MS include diffuse gliosis and diffuse inflammatory activity [1,2], small foci of demyelination [1] and axon alterations [33,36]. The presence in MS of widespread brain pathology heavily involving the NAWM is in agreement with the strong correlation found in several studies between clinical disability and MR markers of axonal damage [12] or tissue destruction [15,[51][52][53] in NAWM.…”

“…This may be due to the lower pathological specificity of conventional MRI markers that are not able to differentiate multiple pathological changes affecting water relaxation (inflammation or demyelination) coexisting in MS lesions. Furthermore, there is pathologic evidence [1,2] that there can be focal microscopic changes and diffuse molecular pathology of myelin outside the macroscopic lesions of MS visible on MRI.…”

Water content and myelin water fraction in multiple sclerosis

“…This 4.2 % increase in NAWM water content is only slightly higher than our result. Inflammation in the NAWM of patients with MS has also been observed, as well as other abnormalities such as microglial activation, increased astrocyte proliferation and presence of myelin breakdown products [1][2][3]. We found that, on average, MS lesions had a 6.3 % higher water content relative to cNAWM.…”

“…Relative water content for NAWM and NAGM was estimated from the ratio of signal (extrapolated to TE = 0ms) in the chosen region of interest to that in an internal grey matter standard (putamen). Relative water content for lesions was calculated two ways: [1] for 85 lesions from the 18 MS patients imaged through the base of the genu and splenium, relative water content was the ratio of signal in the lesion to putamen intensity; and [2] for all 189 lesions from 33 patients relative water content was the ratio of signal in the lesion to cNAWM. Myelin water fraction was defined as the signal with T 2 below 50 ms divided by the total signal in the T 2 distribution.…”

T 2 : The Transverse Relaxation Time

“…This further explains why the correlation between clinical and radiological findings is, at best, moderate. Quantitative ROIbased studies of T 2 -relaxation times in NAWM have shown relaxation times to be prolonged by an average of approximately 5-10 % compared with control subjects (Figure 6.26;Stevenson et al, 2000;Miller et al, 1989;Rumbach et al, 1991;Armspach et al, 1991;Barbosa et al, 1994;Kesselring et al, 1989;Haughton et al, 1992), consistent with the occurrence of diffuse demyelination (Larsson et al, 1988), diffuse astrocytic hyperplasia (Allen et al, 1981), vasogenic oedema , perivascular infiltration or scattered products of disintegrated myelin (Ormerod et al, 1987). Histopathological studies have reported microscopic abnormalities in 72 % of samples of macroscopically normal white matter from patients with MS (Allen and McKeown, 1979).…”