OBJECTIVETo explore the value of computed tomography colonography with low radiation dose combined with the enhanced scanning in the diagnosis of colorectal carcinoma.

METHODSA total of 120 patients with clinical suspected colorectal carcinoma undergoing CT colonography and enhanced scanning were randomly divided into routine dose group and low dose group. Conventional colonoscopy and/or surgical pathology were used as the gold standard. Sensitivity, specificity and Youden's index of colorectal cancer TNM staging accuracy were calculated in two groups. The radiation dose of two groups was compared.

RESULTSFor conventional dose and low dose group, in the diagnosis of colorectal cancer (including cancer and adenoma), the sensitivity was 100% (45/45 and 44/44), specificity was 93.3%(14/15) and 87.5%(14/16), the Youden's index was 0.93 and 0.88. There were no significant differences between two groups in T, N and M staging accuracy preoperatively (P>0.05). The effective radiation dose of low dose group was significantly lower than that of conventional dose group [(15.9 ± 4.3) mSv vs. (21.4 ± 5.5) mSv, P<0.01].

CONCLUSIONLow dose CTC combined with enhanced scanning not only reduces the radiation dose of patients, but can possesses similar value of conventional dose CTC in the early diagnosis and preoperative pathological staging of colorectal cancer.