الفهرس 
Cerebrospinal fluid (CSF)Only 14 pages are availabe for public view
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Abstract
The main benefit of diffusion is its ability to identify cellular damage earlier and with more specificity than other MRI techniques, even where subtle pathological damage disrupts the tissue architecture, the increased mobility of water molecules is detected by DWI. This provides identification of pathology that could be missed by conventional MRI. In patients with hydrocephalus and acutely increased cerebral pressure, DWI showed a significantly higher ADC values in the periventricular region even without periventricular hyperintensity on conventional MR sequences. Therefore, increased ADC values in the periventricular white matter may be a clinically useful sign of hydrocephalus, and it may prove useful in cases with equivocal clinical or imaging findings. Measurements of ADC values may be valuable in assessing the treatment response in these patients because the ADC values in the periventricular white matter usually decrease towards normal levels with successful treatment. Though extracellular edema leading to increased ADC values seen in the early stages of hydrocephalus, the decrease in ADC values of the brain parenchyma may indicate tissue damage and metabolic compromise in persistent hydrocephalus. Also the ADC values for hydrocephalus CSF was decreased by 10% compared with normal CSF and increased by an average of 10.5% after treatment. Decreased CSF ADC value ( together with increased ADC value of periventricular region) may be a clinically useful sign of hydrocephalus, while their change after treatment may be valuable in assessing the treatment response because CSF pressure and intra cerebral pressure usually decrease towards normal levels with successful treatment. The frontal to occipital horn ratio value was decreased by 4.3% after treatment. This indicates that the change in CSF ADC value may provide more sensitive response from treatment than ventricular size change. This suggests CSF ADC value may be important prognostic factor when assessing treatment outcome of hydrocephalus. With more advanced diffusion MRI imaging techniques, DTI can distinguish the compression characteristics of white matter before and after surgery in patients with acute hydrocephalus. The demonstration that DTI can quantify changes before and after surgery might give the radiologist a tool with which to estimate tissue recovery. Also it can give the neurosurgeon an indicator, in addition to clinical improvement, of the effectiveness of surgery, especially in patients in whom there is a decrease in intracranial pressure with no evident decrease in the size of the ventricles. In patients with NPH, pre and postoperative ADC values in periventricular white matter hyperintensities and in normal appearing periventricular tissue was more valuable than perfusion studies. Although both good and poor postoperative outcome patient groups had reduced rCBV in the periventricular tissues, the good outcome group was characterized by a normal ADC and the poor outcome group by an elevated ADC which may be a reflection of the degree of damage. As regarding cerebral atrophy and Alzheimer’s disease which enter in the differential diagnosis of NPH, patients with enlarged ventricles due to cerebral atrophy have normal diffusion values, while patients with enlarged ventricles due to NPH tend to have abnormal or high diffusion values. Thus helps in the differentiation between both conditions. Also there was a statistically significant increase of diffusion values in patients with NPH, ranging from 5-10% above that of Alzheimer’s patients. This may improve the detection and differential diagnosis of NPH.