Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Radio-Diagnosis

Background: The most effective treatment for Ewing Sarcoma is neo-adjuvant chemotherapy along with surgical resection of the tumor.The prognosis significantly correlates with the degree of tumor necrosis following preoperative chemotherapy.The tumor necrosis will result in loss of the cell membrane integrity and expansion of the extracellular diffusion space which can be detected as an increase in the mean ADC value. Material and methods: This is a retrospective analytic study including (40) patients referred to radiology department from the surgical or clinical oncology department who are primary diagnosed to have Ewing's sarcoma referred to the radiology department for initial & post chemotherapy follow up MRI.The patients had Multiplanar MR imaging sequences with contrast including T1 and T2 WI with fat-suppressed images utilizing 1.5 T scanner.Diffusion-weighted sequence with multiple b-values (b-0, 50, 400 &800). ADC maps were calculated from the diffusion-weighted images utilizing specific software at the work station. Results: Regarding the quantitative analysis of DWI, we generated the ADC map, and then we selected the ROI manually.The ADC value was automatically calculated on the workstation to get minimum and mean ADC values (x 10-3 mm). -Measurements were recorded as a representative value for each case. Initial and follow-up images were matched and ADC calculations were performed on follow-up MRI. -ROC curve was constructed with area under curve analysis performed to detect best cut off value of ADC .79 for detection of good response. P- values less than 0.05 were considered as statistically significant and in the study it is 0.025. Conclusion: Quantitative DW imaging with ADC mapping & ADC percentage after neo-adjuvant chemotherapy allows detailed analysis of the treatment response in Ewing{u2019}s sarcoma

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