The feasibility of the 3rd generation low-dose dual-source CT virtual colonscopy in the diagnosis of colorectal cancer

HUANG Tianjiao; SHI Xuesen; SUN Kai; HAN Yang; XIA Liping

doi:10.19300/j.2018.L5103

Abstract：Objective To investigate the accuracy of colonoscopy in screening of the early-stage colorectal cancer and the feasibility of the 3rd generation dual source CT virtual colonoscopy with Turbo Flash mode in the diagnosis of colorectal cancer. Method A total of 230 patients with suspected colorectal cancer were enrolled from January 2016 to March 2017 in Baotou Tumour Hospital.Among them,29 male cases and 27 female cases (age range from 38 to 83 years,average age 64±11 years)who had undergone CT virtual colonoscopy (CVTC)examination and colonoscopy and pathological biopsy were included in final analysis. Pathological result was used as gold standard. The sensitivity, specificity, positive predictive value,and negative predictive value of CTVC in diagnosis of colorectal cancer were calculated.The CTVC image quality was evaluated by two associate chief physicians. The CTVC image quality was evaluated by comparing objective evaluation indexes and radiation dose using independent sample t test,and subjective scores using Wilcoxon test.The area under receiver operating characteristic curve(AUC)of combination of CTVC examination and faecal occult blood test(FOBT) for colorectal cancer was calculated.Results The objective image quality was not statistically significant between low-dose and conventional CTVC (P>0.05).The image subjective quality scores were≥3,the images were clear enough to meet the diagnostic requirement. The average radiation dose of CTVC in CT Turbo Flash mode was 2.07 ±0.30 mSv, which was significantly lower than that of routine scanning of 4.04 ±0.66 mSv (t=-14.612,P<0.001). The sensitivity of CTVC in the diagnosis of colorectal cancer was 97.30%, specificity was 89.47%, positive predictive value was 94.74%, and negative predictive value was 94.44%. Compared with using CTVC and FOBT in the diagnosis of colorectal cancer alone, the combination of CTVC and FOBT had a higher effectiveness (AUC=0.964,95% CI: 0.900-1.000). Conclusions CTVC colorectal cancer screening has the characteristics of low radiation dose and clear image, and has high sensitivity and specificity, which can be used as an accurate method jointing with FOBT for screening high risk population of colorectal cancer.