DIFUSSION MRI involves acquisition of signal of movement of water proton in cellular spaces of body (Brownian motio

 It includes qualitative method either restricted or facilitated and quantitive method which is apparent diffusion coefficient value(ADC) which is related to proportion of extracellular and intracellular components of the tissue., ADC is calculated with use of at least two b value more accurate using more DWI with different b value,ADC levels is low in increased tissue cellularity, as malignancy., ADC levels is high in non-tumoral tissue alterations such as direct endoscopy oedema, radiotherapy necrosis are expected to have minimal cellularity. ADC is most accurate in the detection of malignancy versus tissue edema or radionecrosis the aim of study to assess value of ADC as regarding measuring sensitivity and specificity and accuracy to differentiate tumor recurrence from radionecrosis.