EP646 - Practice Patterns Associated with CT Colonography

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Purpose/Background: It is well-documented that computed tomography colonography (CTC) is an effective method of colorectal cancer (CRC) screening, as its accuracy is comparable to that of optical colonoscopy for the detection of cancer and polyps greater than 6mm in size. CTC is useful in patients with medical comorbidities precluding anesthesia administration or for patients who have not successfully completed a colonoscopy. Despite these indications, the actual practice patterns and impact of CTC on treatment have not been well established. CTC is expected to gain relevance and popularity in 2025, as the U.S. Centers for Medicare and Medicaid Services (CMS) begin to offer reimbursement for CTC for CRC screening. This study sought to better characterize real-world use of CTC in clinical practice and describe its impact on management.

Methods/Interventions: In this single institution, retrospective observational study, we included all patients who underwent CTC from 2013-2023 at our urban, academic medical center. We collected demographic data as well as relevant clinical variables such as the indication for CTC, results of the CTC, referral to surgery and subsequent interventions. Descriptive statistics were used to report outcomes.

Results/Outcomes: A total of 131 patients were included in the study. Median age was 63 (range, 35-90) and 65% (n=85) were female. Patient race was 52% white (n=68), 34% Black and (n=44), and 8% Asian (n=11). 11% of these patients (n=13) identified as Hispanic. Most had not undergone prior abdominal or pelvic surgery (n=102, 78%). Common indications for colonic evaluation included screening (n=81, 62%), melena or hematochezia (n=16, 12%), prior episode of diverticulitis (n=11, 8%) and polyp or cancer surveillance (n=8, 6%). Patients most frequently underwent CTC because of failed or incomplete colonoscopy (n=110, 87%). Colonoscopy most often failed due to restricted mobility of the colon (n=23, 21%), a tortuous colon (n=19, 17%), excessive looping of the colonoscope (n=14, 13%), stricture (n=12, 11%) or obstructing mass (n=6, 5%). 71 of the CTCs were normal (54%), 50 had at least one abnormal finding (38%) and 10 were nondiagnostic, usually due to under-distention of the colon (8%). Of the abnormal studies, 18 revealed polyps (36%), 7 revealed a colonic mass (14%), 6 revealed diverticula (12%), and 4 revealed extracolonic masses for which patients were referred to specialists (1%). After CTC, 39 patients were referred to GI (30%) and 10 to colorectal surgeons (8%). 42 patients underwent future colonoscopy successfully (32%). Average follow-up was 5.4 years.

Conclusion/Discussion: Our study describes current practice patterns patients undergoing CTC in a single center over the past decade. Patients generally underwent CTC after technically challenging and incomplete optical colonoscopy secondary to restricted mobility, looping, or a tortuous colon. Our results indicate that currently CTC is used as an adjunct to colonoscopy rather than a screening test, which may change in 2025 when CMS reimburses for CTC for CRC screening. Given the demands on endoscopists, the lower age threshold for colonoscopy screening, and patient preference, CTC may change the landscape of CRC screening in the US. More research is needed to determine the target patient population who should be referred directly to CTC, such as comorbid patients who may not tolerate anesthesia and those who have undergone pelvic radiation or surgery.