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Zhao et al. Developments in auxiliary examination of CJD

and that of 14-3-3 protein was 70.4%. The similar the average diffusion of water molecules from all
[24]
DWI signal can also be observed in patients affected directions-the greater MD measured, the more water
by mitochondrial encephalomyopathy and toxic molecules unrestricted in the tissue. When there is
encephalopathy such as mercury poisoning. fiber loss causing the increase in extracellular space,
MD increases. When there is microstructural pathology
The majority of sCJD patients (80-90%) have like myelination defects in the fiber, FA decreases. DTI
cortical abnormal hyperintensities on DWI, and the can reflect dynamic microstructural changing in brain
percentage of basal ganglia alterations is about 50- tissue. Previously, DTI was used to study pathology
[47]
69%. [19,42] Other studies on DWI showed a fewer in neurodegenerative diseases such as Alzheimer’s
detection of increased signal in the thalamus of CJD disease and dementia with Lewy bodies. [48,49] Recently,
patients. Thalamus involvement is more frequent in advances have been made in DTI for CJD diagnosis.
vCJD and VV2 subtype of sCJD patients. GSS is For instance, significant decreases have been
rarely abnormal in DWI. A quantitative analysis of observed in MD, but not FA, in the caudate and pulvinar
[5]
apparent diffusion coefficient(ADC) value can display of sCJD patients compared to other rapidly progressive
slight changes in the thalamus of sCJD patients dementia patients and normal controls. Some studies
although abnormal signal may not be found visually. hypothesized that the spongiform changes in CJD
The DWI scan sequence of MRI shows high sensitivity could restrict water molecule diffusion and lead to
for the abnormal hyperintensities in cerebral cortex decreased MD and a relative preservation of FA. [50,51]
and basal ganglia, but none of the standard MRI Along with the changing of DWI hyperintensity in the
sequences reveal abnormal signal in cerebellum or disease course of CJD, MD decreases in the early
brain stem of CJD patients. DWI appears sensitive stage of disease and tends to be normal or increase
to the restricted diffusion of water in cortex and in the terminal stage. The increasing MD is associated
basal ganglia but not in the cerebellum and brain with more significant loss of function. Neuronal loss
stem. The abnormal regions may be unilateral at increases water diffusion and augmentation of MD
the disease onset then bilateral with time. In some measurement in the late stages of CJD. In addition,
cases the signal intensity decreases as the disease the increased size of micro-vacuolation and their
progresses. [40,43] Hyperintensities can be observed on coalescence in end-stage of CJD might cause an
DWI in early stage of sCJD when 14-3-3 protein and increased free water flow. The DTI test is highly
[52]
PSWCs are still negative. Recent study proposed that sensitive, but not very specific. Therefore, DTI is an
the patients with abnormal DWI hyperintensities in important tool for diagnosis, but alone is not sufficient
basal ganglia lesion had shorter disease duration and for a CJD diagnosis.
higher incidence of myoclonus. The lower apparent
diffusion coefficient in basal ganglia indicated the Magnetic resonance spectroscopy
faster presence of akinetic mutism and a shorter Magnetic resonance spectroscopy (MRS) is a
disease course. [44] However, others have not obtained noninvasive examination that can quantitatively
the same results. Contrary to other rapid dementias, analyze specific atomic nucleus and their chemical
sCJD patients manifest wider range of hyperintensity components based on MRI technique and chemical
on DWI than on FLAIR sequence. [41] The area of shift. MRS displays the metabolism and biochemistry
abnormal DWI hyperintensities are in accordance with of pathological tissue in the form of spectrum. Proton
clinical manifestation and the area of PSWCs. With the magnetic resonance spectroscopy ( H-MRS) is the
1
thorough researches on DWI, CJD diagnostic criteria most widely applied MRS technique, which can
are continuously updated. The abnormal signal of detect the resonance peak of more than twelve brain
DWI was described as one of the diagnosis standards metabolite and neurotransmitter like N-acetyl-aspartate
officially in 2009 (Zerr et al. [18] ); Vitali et al. [41] and (NAA), creatine (Cr), myo-inositol (mI), and choline.
Meissner et al. [45] described the DWI hyperintensities Currently, H-MRS is mainly used to study metabolic
1
in detail and proposed the MRI diagnostic criteria of disorders of the CNS, tumors, and dementia disease.
CJD in 2009 and 2011, respectively. There have been very few studies on CJD although
MRS provides information on chemical metabolism.
Diffusion tensor imaging
Diffusion tensor imaging (DTI) is a relatively new MRI In one case report of sCJD, MRS detected marked
scan technique that reflects the diffusion anisotropy extensive decreased NAA, and displayed increased
of water in cerebral white matter and the integrity of myo-inositol/creatine ratio in basal ganglia and the
white matter fiber tracts. The fractional anisotropy insular cortex, along with slightly reduced choline/
[46]
(FA) image of DTI can visually display the structure creatine ratio. Similarly, other case studies
[53]
of white matter fiber. Mean diffusivity (MD) reflects revealed decreased NAA in basal ganglia, thalamus
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