CT colonography: over two decades from discovery to practice

Colonic lipomas revisited on CT colonography

PURPOSE

CT colonography (CTC) is growing in its utilization as a nationally approved colorectal cancer screening test. After colonic polyps, lipomas are the second most common colonic lesions and their accurate and rapid recognition are important.

METHODS

This retrospective Institutional Review Board approved study was performed at two large academic university-based institutions. 1044 patients underwent CTC at Institution A from 2010 to 2018 and 1094 patients underwent CTC at Institution B from 2003 to 2015. All CTC examinations with at least one colonic lipoma in their report were evaluated by a fellowship-trained abdominal imaging radiologist. 47 CTC examinations containing 59 colonic lipomas were detected and included. Segmental location, sessile versus pedunculated morphology, multiplicity, average attenuation, and largest lesion diameter were evaluated. A review of the current literature on colonic lipomas is entailed.

RESULTS

The overall incidence of colonic lipoma was 2.2% in women and 2.3% in men. Mean age for detection of colonic lipomas on CTC was 66.9 years. Segmental locations of colonic lipomas include ascending colon (39%), transverse colon (19%), ileocecal valve (12%), cecum (12%), descending colon (10%), and rectosigmoid (8%). 9% of colonic lipomas were multiple, 42% were pedunculated, and 58% were sessile. The mean (range) size of detected lipomas was 19 (6-59) mm. The mean (range) attenuation was - 132 (- 41 to - 258) HU.

CONCLUSION

Most colonic lipomas are located in the ascending colon. Although they are typically solitary, just under 10% are multiple, and although they are most often sessile, slightly under half are pedunculated mimicking polyps. CTC detects smaller lipomas than optical colonoscopy.

Value of multi-slice spiral computerized tomography for diagnosis of synchronous colorectal carcinoma: a retrospective study

Objective

To compare the accuracy of multi-slice spiral computerized tomography (MSCT) with colonoscopy for diagnosing synchronous colorectal carcinoma (SCC).

Methods

We retrospectively analyzed all consecutive patients admitted to our institution with colorectal carcinoma between 19 September 2014 and 31 January 2020. Data on SCC patients who had undergone MSCT and colonoscopy were analyzed. Information on tumor location, tumor size, missed diagnosis by MSCT or colonoscopy, T stage, pathological type, and reasons for missed diagnosis was recorded and used to assess the diagnostic accuracies of MSCT and colonoscopy.

Results

Twenty-three cases met the inclusion criteria. MSCT plus colonoscopy had a significantly higher diagnostic accuracy (93.5%) than colonoscopy alone. There were significant differences in missed diagnosis rates of proximal cancer (34.8%) and distal cancer (4.3%) by colonoscopy. For MSCT, the missed diagnosis rate for tumors with a median long diameter of 1.25 cm (interquartile range 0.80, 1.50) was significantly lower than that for larger tumors (long diameter 4.00 cm; 3.00, 6.00).

Conclusions

MSCT is a valuable diagnostic tool for SCC that can effectively minimize the missed diagnosis rate of primary tumors when combined with colonoscopy.

Multicentre, prospective, randomised study comparing the diagnostic yield of colon capsule endoscopy versus CT colonography in a screening population (the TOPAZ study)

OBJECTIVE

Colon capsule endoscopy (CCE) has shown promise for colorectal neoplasia detection compared with optical colonoscopy (OC), but has not been compared with other screening tests in average risk screening patients.

DESIGN

Patients 50 to 75 years of age (African Americans, 45-75 years) were randomised to CCE or CT colonography (CTC) and subsequent blinded OC. The primary endpoint was diagnostic yield of polyps ≥6 mm with CCE or CTC. Secondary endpoints included accuracy for size and histology, examination completeness, number/proportion of subjects with polyps and adenomas ≥6 mm and ≥10 mm, subject satisfaction and safety.

RESULTS

From 320 enrolled subjects, data from 286 (89.4%) were evaluable. The proportion of subjects with any polyp ≥6 mm confirmed by OC was 31.6% for CCE versus 8.6% for CTC (pPr non-inferiority and superiority=0.999). The diagnostic yield of polyps ≥10 mm was 13.5% with CCE versus 6.3% with CTC (pPr non-inferiority=0.9954). The sensitivity and specificity of CCE for polyps ≥6 mm was 79.2% and 96.3% while that of CTC was 26.8% and 98.9%. The sensitivity and specificity of CCE for polyps ≥10 mm was 85.7% and 98.2% compared with 50% and 99.1% for CTC. Both tests were well tolerated/safe.

CONCLUSION

CCE was superior to CTC for detection of polyps ≥6 mm and non-inferior for identification of polyps ≥10 mm. CCE should be considered comparable or superior to CTC as a colorectal neoplasia screening test, although neither test is as effective as OC.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov no: NCT02754661.

Splenic Injury After a Colonoscopy: Threading the Scope Carefully in Heritable Connective Tissue Disorders

Colonoscopies have reduced colorectal cancer (CRC) burden in the United States, and their utility has expanded to include various diagnostic and therapeutic indications. Complications are seen in up to 1% and increase with age and polypectomy. As colonoscopies become widespread, specific populations seem to be at a much higher risk; notably patients with heritable connective tissue disorders (HCTD). As life expectancy increases, these patients undergo routine screenings and require careful peri-endoscopic care to reduce adverse outcomes. Amongst HCTD, Ehlers-Danlos syndrome (EDS) is commonly implicated, however, no reports of Marfan syndrome (MS) exist. We present a unique case of splenic injury after colonoscopy in a patient with MS. Successful outcomes require early suspicion and emergent surgical evaluation in patients with hemodynamic instability after a colonoscopy. Increased ligament laxity and bowel fragility are the most likely mechanisms. Alternative CRC strategies like fecal immunochemical test (FIT), fecal occult, Cologuard, or virtual colonography can be considered.

Computed tomography colonography and radiation risk: How low can we go?

Computed tomography colonography (CTC) has become a key examination in detecting colonic polyps and colorectal carcinoma (CRC). It is particularly useful after incomplete optical colonoscopy (OC) for patients with sedation risks and patients anxious about the risks or potential discomfort associated with OC. CTC's main advantages compared with OC are its non-invasive nature, better patient compliance, and the ability to assess the extracolonic disease. Despite these advantages, ionizing radiation remains the most significant burden of CTC. This opinion review comprehensively addresses the radiation risk of CTC, incorporating imaging technology refinements such as automatic tube current modulation, filtered back projections, lowering the tube voltage, and iterative reconstructions as tools for optimizing low and ultra-low dose protocols of CTC. Future perspectives arise from integrating artificial intelligence in computed tomography machines for the screening of CRC.

Colon Capsule Endoscopy vs. CT Colonography Following Incomplete Colonoscopy: A Systematic Review with Meta-Analysis

Following incomplete colonoscopy (IC) patients often undergo computed tomography colonography (CTC), but colon capsule endoscopy (CCE) may be an alternative. We compared the completion rate, sensitivity and diagnostic yield for polyp detection from CCE and CTC following IC. A systematic literature search resulted in twenty-six studies. Extracted data included inter alia, complete/incomplete investigations and polyp findings. Pooled estimates of completion rates of CCE and CTC and complete colonic view rates (CCE reaching the most proximal point of IC) of CCE were calculated. Per patient diagnostic yields of CCE and CTC were calculated stratified by polyp sizes. CCE completion rate and complete colonic view rate were 76% (CI 95% 68-84%) and 90% (CI 95% 83-95%). CTC completion rate was 98% (CI 95% 96-100%). Diagnostic yields of CTC and CCE were 10% (CI 95% 7-15%) and 37% (CI 95% 30-43%) for any size, 13% (CI 95% 9-18%) and 21% (CI 95% 12-32%) for >5-mm and 4% (CI 95% 2-7%) and 9% (CI 95% 3-17%) for >9-mm polyps. No study performed a reference standard follow-up after CCE/CTC in individuals without findings, rendering sensitivity calculations unfeasible. The increased diagnostic yield of CCE could outweigh its slightly lower complete colonic view rate compared to the superior CTC completion rate. Hence, CCE following IC appears feasible for an introduction to clinical practice. Therefore, randomized studies investigating CCE and/or CTC following incomplete colonoscopy with a golden standard reference for the entire population enabling estimates for sensitivity and specificity are needed.

Update on Flexible Sigmoidoscopy, Computed Tomographic Colonography, and Capsule Colonoscopy

This article reviews alternative colorectal cancer (CRC) screening tests, including flexible sigmoidoscopy (FS), computed tomography (CT) colonography, and colon capsule endoscopy. FS has abundant and convincing evidence supporting its use for CRC screening and is a commonly used CRC test worldwide. CT colonography has demonstrated convincing results for CRC screening, but concerns regarding cost, accuracy for flat or sessile neoplasia, reproducibility, extracolonic findings, and lack of coverage have limited its use and development. Colon capsule endoscopy has demonstrated encouraging results for polyp detection in average-risk individuals, but is not approved for CRC screening at the current time.

Nationwide, Longitudinal Trends in CT Colonography Utilization: Cross-Sectional Survey Results From the 2010 and 2015 National Health Interview Survey

PURPOSE

Colon cancer screening reduces deaths from colorectal cancer. Screening rates have plateaued; however, studies have found that giving patients a choice between different screening tests improves adherence. CT colonography is a minimally invasive screening test with high sensitivity for colonic polyps (>1 cm). With increasing insurance coverage of CT colonography nationwide, there are limited estimates of CT colonography utilization over time. Our purpose was to estimate CT colonography utilization over time using nationally representative cross-sectional survey data.

METHODS

We utilized 2010 and 2015 National Health Interview Survey cross-sectional data. Participants between ages 50 and 75 without colorectal cancer history were included. Accounting for complex survey design elements, logistic regression analyses evaluated changes in CT colonography utilization over time, adjusted for potential confounders, and stratified by insurance and age.

RESULTS

Overall, 21,686 respondents were included (8,965 in 2010, 12,721 in 2015). Reported CT colonography utilization decreased from 1.2% to 0.9% (odds ratio [OR] 0.92, 95% confidence interval [CI] 0.86-0.98). Stratified analyses revealed no changes in utilization in patients with private insurance (P = .35) and in patients younger than 65 (P = .07). Overall awareness of CT colonography decreased from 20.5% to 15.9% (OR 0.93, 95% CI 0.91-0.95). Reported optical colonoscopy utilization increased from 57.9% to 63.6% (OR 1.03, 95% CI 1.02-1.05).

CONCLUSION

Despite increasing self-reported utilization of optical colonoscopy from 2010 to 2015, survey results suggest that CT colonography awareness (∼16%) and utilization (∼1%) remain low. Improved public awareness and coverage expansion to Medicare-aged populations will promote improved CT colonography utilization and overall colorectal cancer screening rates.

Prevalence of polyps ≥6 mm on follow-up CT colonography in a cohort with no significant colon polyps at baseline

AIM

Assess the prevalence of neoplasia ≥6 mm at repeat CT colonoscopy (CTC) in individuals with no significant lesions at baseline.

METHODS

Individuals aged ≥18 years, with/without CRC risk factors, with no polyps ≥6 mm on baseline CTC (negative baseline) who underwent repeat CTC in a large HMO from 2001 to 2011 were retrospectively identified. Studies were reviewed by board-certified radiologists with experience interpreting CTC. Demographic details, CRC risk factors, and the number, size, and location of incident lesions were noted. Findings were classified using the C-RADS scale. Lesion prevalence at CTC-2 was determined, and study interval and risk characteristics of patients with- and without findings were compared.

RESULTS

Our study included 636 individuals (369 men [58.0%]; mean age 59.9 years) with negative baseline CTC who underwent repeat CTC after a mean 4.6 year interval (SD 1.6 years). At baseline, 469/636 (73.7%) were at average risk for CRC; 418 remained at average risk for CTC-2 with 51 (8.0%) developing new risk factors in the interval between studies. At CTC-2, 47 participants (7.4%) presented 52 significant neoplasia: 35 polyps 6-9 mm, 14 polyps ≥10 mm, and 3 masses in 3/636 participants (0.47%). 2/3 masses, 6/14 polyps ≥10 mm (42.9%), and 12/25 polyps 6-9 mm (48.0%) were in individuals with risk factors for CRC. Histopathology was available for 12/52 lesions (23.1%): 8 tubular adenomas, 2 villous adenomas, 1 hamartomatous polyp, 1 case of normal tissue.

CONCLUSION

A mean 4.6 years after negative-baseline CTC, neoplasia ≥6 mm were seen in 7.4% of participants, including masses in 0.47%, supporting recommendations for a 5-year study interval.