Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Radio-diagnosis

Fifty patients who met the inclusion and exclusion criteria were enrolled in this prospective study, from those attending the gastroenterology clinic of the surgical department of the National Cancer Institute during the period from January 2016 till January 2018, 30 female and 20 male patients, with mean age 49.4 years ± 15.28; age ranging from (22-79 years) were pathologically proven, received neoadjuvant CRT course of 6 weeks and were assessed by T2 WI & DW-MRI pre and post-CRT.All Images were independently reviewed by two readers blinded to the results to determine the detectability of rectal cancer, and the post therapeutic response.Results:Regarding the T staging; the majority of the cases 37(74 %) were initially diagnosed as T3 stage, 8(16%) as T4 stage and 5(10%) as T2 stage, while post-CRT findings were 31(62%) T3, 10(20%) T2, 9(18%) T4. T-stage down-staging of the 5 cases from T3 to T2 is seen post- CRT with a highly significant difference P-value < 0.005 (Z= -5.536). However only one case was found to progress from T3 to T4 stage.The mean tumor size pre-CRT was 7.66 cm ± 2.76 and decreased to 6.7 cm ± 2.82 post-CRT. The decrease in size post-CRT is highly significant with a P-value =0.000 (t-value= 4.477).Regarding the pathological subtypes 38 out of 50 cases (76%) were adenocarcinoma (mostly grade 2), 8 cases (16%) mucinous adenocarcinoma, 3 cases (6%) signet ring adenocarcinoma and 1 case (2%) was gastrointestinal-stromal tumor (GIST

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