Abstract: Objective: To discuss the value of the open lower magnetic resonance(MR) scanner in detecting rectal cancer,and to analyze the signs.Materials and methods: We have collected sixteen cases of rectal cancer diagnosed by our pathology examination.The sixteen patients would cooperate throughout the entire scanning process and they didn’t have serious diseases in the heart,liver,lung or kidney.The intestinal tract was prepared on the previous day.Spasmolysant was given to the patients fifteen minutes before scanning,after that,about 1000ml of normal saline was inpoured through the cannula inside of the anus,followed by about 1000ml of air to expand the intestinal canal as large as possible.Inpouring was stopped when the patients experienced discomfort.Before the examination,the patients were trained to inhale and exhale calmly and to diminish their breath extent to the limit.Patients used supine and prone positions while being examined.Result: The main MR manifestations of rectal cancer were local or diffuse thickening of the intestinal walls and forming of lumps,which appears as a middle-to-low-signal-intensity in T1 MR imaging with distinct border and a relative higher-signal-intensity in T2 MR imaging.The cancer was shown as irregular strengthening images by Gd-DTPA.The surrounding organs such as the uterus,urinary bladder,prostate gland and pelvic cavity wall could be well displayed by MR.Conclusion: The open-configuration lower strength MR scanner is relatively easy to operate in the process of diagnosing rectal cancer and can show clearly the pathological change of rectal cancer.At the same time,it brings few sufferings and little trouble to patients.It is a new method and shows high value in assisting in the diagnosis of rectal cancer.