الفهرس 
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Abstract
In conclusion, from the previously mentioned studies we can say that Diffusion Weighted Imaging and Apparent Diffusion Co-officiant provide a great help with promising improvement in the following situation:
• DWI can differentiate between benign and malignant neck masses with high ADC of the benign masses and low ADC in malignant masses.
• DWI has a great rule in post-operative and post-irradiated neck differentiating between the post-operative granulation tissue and post-irradiation changes and tumor recurrence as tumor recurrence has low ADC in comparison with post-operative and post-irradiation changes which have high ADC.
• In evaluation of neck lymph nodes in a metastatic disease, long before the architectural changes are apparent with anatomic imaging, nodes, even normal-sized ones, show metastatic foci that manifest as decreased ADC and can be measured on DW imaging.
• DW imaging shows promise in monitoring tumors during the course of chemoradiotherapy as the responding tumors show a continuous increase of the ADC with therapy.
• A significant difference in the ADC values of benign and malignant thyroid nodules has been reported, with all benign thyroid nodules having higher mean ADC values compared with malignant nodules.
• Differentiating paragngliomas from other lesion which appear similar to it, The ADC of the paraganglioma is higher because the mobility of water protons is relatively more free in the vascular architecture.
• DWI has a high diagnostic value in differentiating cysts from abscesses as abscesses show restricted diffusion while cysts show free diffusion.
Lastly, Diffusion imaging has passed out of its infancy andchildhood into its adolescence. Although manytechnical problems remain, the fundamentaltechnologies that will resolve those problems arealready in place and merely need refinement. Thepotential applications ofDWimaging are numerousand increasing.