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Etemadifar et al. Imaging of demyelinated corpus callosum

and also to illustrate possible prognostic criteria in much more heterogeneous than in MS. [36]
imaging aspect of such diseases. In some studies, it
has been suggested that diffusion weighted imaging Functional MRI
(DWI) of CC may not be helpful in determination of As we previously pointed out, functional MRI and DTI
prognosis in patients of ADEM, on the other hand, method of imaging are more helpful in exploration of
Donmez et al. suggested that brainstem involvement microstructural and functional changes, especially in
[51]
in ADEM disease may have an influence on the NAWM in demyelinating disorders from the aspects of
prognosis of the disorder, correspondent to the studies discrimination and diagnosis. According to the study
showing beneficial use of ADC parameters in prediction by Kimura et al. [58] in patients with NMO, damage
of motor disabilities. Combined use of clinical and to extensive regions of NAWM has been observed.
radiologic findings are needed to predict the chance of To investigate this possibility that microstructural
relapse in patients suffering from ADEM. Patients with alterations are present in these WM tracts, DTI should
large demyelinating lesions may have more degree be applied. According to this study findings FA was
of disabilities evaluated by EDSS but they have an decreased in splenium of CC and left optic radiate.
excellent response to therapy. It was showed that size In another study focused on DTI features of NAWM in
[59]
of the lesions is not a direct indicator of poor prognosis. NMO patients which was performed by Jeantroux et al.,
According to what we found in different studies on it was showed that ADC was increased and FA was
“ADEM prognosis” there is no certainty on how useful decreased in NMO patients in posterior limb of internal
are MRI features to predict outcome of ADEM and there capsule and optic radiation and spinal cord NAWM.
are yet more studies to explore this area of research. FA had the best correlation with EDSS. FA was
lower in spinal cord lesions. In contrast there was no
CC IN DEVIC’S NEUROMYELITIS OPTICA difference between two groups, neither in the anterior
limb of internal capsule nor in the CC. These results
MRI suggest that NAWM outside the tracts mentioned
Neuromyelitis optica is a CNS demyelinating disease above remained normal, showing that infralesional
causing acute transverse myelitis with bilateral optic abnormality is not usually seen in NMO in contrast to
neuropathy. Paraplegia and blindness are possible the MS disease. [59] These findings are consistent with
complications. There is no definite imaging criteria to the findings by Sun et al., [60] in which they found the
distinguish NMO from other demyelinating disorders similar results suggesting that DTI parameters (mean
such as MS and ADEM. [54,55] Irrelative of what is found diffusivity and lambda1) were unchanged in CC
in CC that will be discussed further in this article general region. This field of study needs further investigations
distinguishing findings of MRI in such diseases are: yet to determine the distinguishing patterns and
midbrain lesions in the ventral part with poorly defined parameters in NAWM, especially callosal region in
margins for ADEM vs. Medulla lesions in the dorsal part NMO patients. [61,62]
with poorly defined shape for NMO, and pons lesions
with well-defined shape for MS (as the most common CC as a prognosis indicator
sites of involvement). CC involvement is more common A combination of biomarkers, neuroimaging data
in MS in comparison to NMO but there are also some and clinical symptoms are needed to predict
involvement pattern differences to be pointed out. CC prognosis of NMO. It is difficult to consider
lesions in NMO are mostly evident in acute phase callosal tract features of neuroimaging as the only
of disease and they have generally some similar indicator of disease outcome. In many studies DTI
characteristics. They are usually multiple, edematous parameters, especially FA, showed to have the
and heterogeneous in intensity, while in chronic stage, closest correlation with EDSS. As a result, it can be
lesions shrink and disappear. In MS, lesions are small, helpful in measuring disease outcome and disability.
non-edematous, and the intensity is homogenous in He et al. [63] showed decreased FA and increased
the acute phase and they are more commonly located ADC of CC, especially during the acute phase of the
at lower margin of CC. [56-59] As Chen et al. showed in disease, plays an important role in the anticipation
[6]
their study, subcallosal dash dot sign was helpful as it of cognitive dysfunction and clinical outcome. The
was more common in patient with MS than in the NMO. researchers have compared regional measures of
In another study by Makino et al., it was showed that patients with stable and acute NMO with healthy
[36]
involvement of splenium of CC in NMO patients was patients. Both acute and stable NMO patients had
more common than the involvement of the same area a higher average FA in regions of interest of the
in patients with MS (57% vs. 27%). The lesions in NMO thalamus and putamen. Acute NMO patients had
also tended to spread from the lower to upper parts significantly higher average MDs than controls in the
of CC. They also found out that lesions in NMO were genu of the CC and optic radiation, and significantly
Neuroimmunology and Neuroinflammation ¦ Volume 4 ¦ April 27, 2017 73