الفهرس 
Gross anatomy of the human brainOnly 14 pages are availabe for public view
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Abstract
Multiple sclerosis (MS) is a condition marked by an extensive spectrum
of neurologic signs and symptoms, and is believed to be caused by an
autoimmune attack on the myelin and axons of the central nervous system. It
is the most common cause of nontraumatic disability in individuals of young
and middle age. The clinical course of the disease can be highly variable
depending on the number and severity of relapses and degree of progression.
It can present in different forms, such as, relapsing remitting (RRMS),
secondary progressive (SPMS), primary progressive (PPMS) and progressive
relapsing (PRMS). Diagnosis is made from clinical signs and symptoms
referable to discrete areas of the central nervous system that are disseminated
in time and space , supported by paraclinical laboratory and radiological, in
particular MRI, findings.
MRI, in addition to advanced approaches, including PET scanning, can
detect a broad range of brain and spinal cord abnormalities from discreet
lesions to subtle changes in normal appearing white matter (NAWM) and
normal appearing gray matter (NAGM). Although these techniques cannot
stand alone in making the diagnosis of MS, they are key contributors to early
detection and an understanding of the pathogenesis of the disease.
Furthermore, it may be argued that neuroimaging plays the most important
role in evaluating disease progression and the effects of various therapies by
providing an ongoing measure of burden of disease (eg, number of lesions
and degree of brain atrophy).
Currently, conventional MRI, with and without Gd, is useful for the
routine diagnosis and evaluation of MS. It is highly sensitive to
inflammation, although its specificity has limitations. Conventional MRI
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(including T2-weighted images, T-1weighted images with and without
gadolinium enhancement and fluid attenuated inversion recovery (FLAIR) is
the gold standard imaging technique for identification of demyelinating
lesions and it provide several markers of disease activity and evolution
including the number of gadolinium enhancing and new T2-hyperintense and
T1-hypointense lesions. Lesions may be observed anywhere in the CNS
white matter including the brain supratentorium and infratentorium, the brain
stem and the spinal cord. However more typical locations include corpus
callosum and periventricular white matter. Typical MS lesions appear as T2
and FLAIR hyperintesities, they have ovoid appearance with their largest
axis oriented perpendicular to the ventricular surface and several arise from
the corpus callosum, this characteristic configuration has been demonstrated
in the pathologic specimen and sometimes is referred to as “Dawson
fingers”. Also gray matter is known to be involved in MS but its
involvement has been hard to evaluate using c-MRI because lesion contrast
in gray matter is less dramatic than in white matter. One goal for future
applications of conventional MRI is an improved capability to detect lesions
in gray matter.
Although lesion number and location add sensitivity and specificity to
the diagnosis of MS, both subclinical disease activity (measured as new
lesions on MRI in the absence of signs or symptoms) and non-radiologic
disease progression (clinical progression in the absence of new MRI lesions)
are not uncommon. This phenomenon has become known as the ”clinicalimaging
paradox” of MS. Furthermore, pathologic studies have clearly
identified significant cortical demyelination and tissue injury, although
conventional imaging studies have not demonstrated these abnormalities.
These observations have led to the development of several advanced MRI
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measures to identify better imaging correlates of MS disease-related injury
and progression.
Advanced MRI methodologies, such as MT, MRS and DTI provide
further insight into tissue integrity and its disruption in MS; MTI and DTI
reveal injury to NAWM. Continued perfection of these techniques as well as
volumetric MRI may provide a practical means of monitoring the efficacy of
various disease-modifying therapies for individual patients and in clinical
trials. Finally, MRS and PET scanning, though dramatically different
techniques, provide insights into the biochemistry of the nervous system and
what goes wrong by tracking the behavior of various metabolites in the CNS.
Finally Conventional magnetic resonance imaging techniques is highly
sensitive in detecting multiple sclerosis plaques and provide a quantitative
assessment of inflammatory activity and lesion load. However, there is a
persisting mismatch between clinical and magnetic resonance imaging
efficacy, Advanced MRI sequences such as Proton Magnetic Resonance
Spectroscopy (1HMRS), Magnetization transfer imaging (MTI), Diffusionweighted
imaging (DWI), Diffusion Tensor-MRI, Fiber Tractography &
other are a non-invasive techniques that have improved our ability to
quantify the pathological changes in MS, they also helps in:
-Monitoring the Disability
-Evaluating Occult Disease
-Establishing a Prognosis
-Monitoring the effects of Therapies.