Using computed tomography colonography in patients at high risk of colorectal cancer – a prospective study in a university hospital in South America

OBJECTIVES The purpose of our study was to report the results of the implementation of computed tomography colonography in a university hospital setting serving a Brazilian population at high risk of colorectal cancer. METHODS After creating a computed tomography colonography service in our institution, 85 patients at high risk of colorectal cancer underwent computed tomography colonography followed by a same-day optical colonoscopy from September 2010 to May 2012. The overall accuracy of computed tomography colonography in the detection of lesions ≥6 mm was compared to that of optical colonoscopy (direct comparison). All colonic segments were evaluated using quality imaging (amount of liquid and solid residual feces and luminal distension). To assess patient acceptance and preference, a questionnaire was completed before and after the computed tomography colonography and optical colonoscopy. Fisher's exact test was used to measure the correlations between colonic distension, discomfort during the exam, exam preference and interpretation confidence. RESULTS Thirteen carcinomas and twenty-two lesions ≥6 mm were characterized. The sensitivity, specificity and accuracy of computed tomography colonography were 100%, 98.2% and 98.6%, respectively. Computed tomography colonography was the preferred method of investigation for 85% of patients. The preparation was reported to cause only mild discomfort for 97.6% of patients. According to the questionnaires, there was no significant relationship between colonic distension and discomfort (p>0.05). Most patients (89%) achieved excellent bowel preparation. There was a statistically significant correlation between the confidence perceived in reading the computed tomography colonography and the quality of the preparation in each colonic segment (p≤0.001). The average effective radiation dose per exam was 7.8 mSv. CONCLUSION It was possible to institute an efficient computed tomography colonography service at a university hospital that primarily assists patients from the public health system, with high accuracy, good acceptance and effective radiation doses. Our results seem to be comparable to other centers of excellence and fall within acceptable published guidelines, showing that a successful computed tomography colonography program can be reproduced in a South American population screened in a university hospital.