Subsequent Optical Colonoscopy Research Articles

Comment on "Artificial intelligence in gastroenterology: A state-of-the-art review".

Colon capsule endoscopy (CCE) was introduced nearly two decades ago. Initially, it was limited by poor image quality and short battery time, but due to technical improvements, it has become an equal diagnostic alternative to optical colonoscopy (OC). Hastened by the coronavirus disease 2019 pandemic, CCE has been introduced in clinical practice to relieve overburdened endoscopy units and move investigations to out-patient clinics. A wider adoption of CCE would be bolstered by positive patient experience, as it offers a diagnostic investigation that is not inferior to other modalities. The shortcomings of CCE include its inability to differentiate adenomatous polyps from hyperplastic polyps. Solving this issue would improve the stratification of patients for polyp removal. Artificial intelligence (AI) has shown promising results in polyp detection and characterization to minimize incomplete CCEs and avoid needless examinations. Onboard AI appears to be a needed application to enable near-real-time decision-making in order to diminish patient waiting times and avoid superfluous subsequent OCs. With this letter, we discuss the potential and role of AI in CCE as a diagnostic tool for the large bowel.

Diagnostic Performance of Multitarget Stool DNA and CT Colonography for Noninvasive Colorectal Cancer Screening.

BackgroundMultitarget stool DNA (mt-sDNA) screening has increased rapidly since simultaneous approval by the U.S. Food and Drug Administration and Centers for Medicare and Medicaid Services in 2014, whereas CT colonography screening remains underused and is not covered by Centers for Medicare and Medicaid Services.PurposeTo report postapproval clinical experience with mt-sDNA screening for colorectal cancer (CRC) and compare results with CT colonography screening at the same center.Materials and MethodsIn this retrospective cohort study, asymptomatic adults underwent clinical mt-sDNA screening during a 5-year interval (2014-2019). Electronic medical records were searched to verify test results and document subsequent optical colonoscopy and histopathologic findings. A similar analysis was performed for CT colonography screening during a 15-year interval (2004-2019), with consideration of thresholds for positivity of both 6-mm and 10-mm polyp sizes. χ2 or two-sample t tests were used for group comparisons.ResultsA total of 3987 asymptomatic adult patients (mean age, 64 years ± 9 [standard deviation]; 2567 women) underwent mt-sDNA screening and 9656 patients (mean age, 57 years ± 8; 5200 women) underwent CT colonography. Test-positive rates for mt-sDNA and for 6-mm- and 10-mm-threshold CT colonography were 15.2%, 16.4%, and 6.7%, respectively. Optical colonoscopy follow-up rates for positive results of mt-sDNA and 6-mm- and 10-mm-threshold CT colonography were 13.1%, 12.3%, and 5.9%, respectively. Positive predictive values (PPVs) for any neoplasm 6 mm or greater, advanced neoplasia, and CRC for mt-sDNA were 54.2%, 22.7%, and 1.9% respectively; for 6-mm-threshold CT colonography, PPVs were 76.8%, 44.3%, and 2.7%; for 10-mm-threshold CT colonography, PPVs were 84.5%, 75.2%, and 5.2%, respectively (P < .001 for mt-sDNA vs CT colonography for all except 6-mm CRC at CT colonography). For mt-sDNA versus 6-mm-threshold CT colonography, overall detection rates for advanced neoplasia were 2.7% and 5.0%, respectively (P < .001); corresponding detection rates for CRC were 0.23% and 0.31%, respectively (P = .43).ConclusionThe detection rates of advanced neoplasia at CT colonography screening were greater than those of multitarget stool DNA. Detection rates were similar for colorectal cancer.© RSNA, 2020See also the editorial by Yee in this issue.

Incidental Discovery of Early Strongyloides stercoralis Colitis in an Active Duty Service Member

Strongyloides stercoralis is a potentially lethal parasitic infection with a broad range of clinical and endoscopic manifestations. While hyperinfection can result in dramatic colonoscopic findings that mimic ulcerative colitis, asymptomatic patients may exhibit more subtle findings such as erythema or nonspecific white lesions. A 43-year-old Nigerian born woman was referred to the gastroenterology clinic for workup of longstanding constipation. She reported onset related to her uncomplicated spontaneous vaginal deliveries. Varied laxative use yielded no improvement. The patient denied weight loss, fatigue, tenesmus, urgency, or incomplete evacuation. Travel history was remarkable for recent travel to Nigeria and annual vacations in Belize. Abdominal exam was unremarkable. A rectal exam revealed a palpable mass in the left lateral rectal wall. Laboratory evaluation was notable for a mild normocytic anemia and peripheral eosinophilia. Computed tomography of the pelvis with contrast revealed retroversion of the uterus with suggestion of mass effect on the rectum and sigmoid colon. Defacography confirmed mild uterine prolapse and a small rectocele. A subsequent optical colonoscopy revealed grossly normal colonic mucosa, with exception of external hemorrhoids and punctate white papules in the proximal right colon. Biopsy and histologic examination of the lesions revealed colonic mucosa with eosinophilic infiltrate and filariform S. stercoralis larva. The patient was subsequently treated with ivermectin, and referred to urogynecology for pelvic floor physical therapy. This case illustrates subtle colonoscopic findings of S. stercoralis colitis. Endoscopy in foreign born patients with a history of exotic travel requires a high index of suspicion for diagnosis of parasitic infections. In this case, the burden of parasitic disease was unlikely a prime contributor to her presenting symptom profile; however, the biopsy of suspicious lesions led to an early diagnosis of a potentially life threatening infection. Recognition of the more subtle colonoscopic findings is key to early diagnosis and treatment to prevent significant morbidity and mortality.Figure

Computer-Aided Detection of Colorectal Polyps at CT Colonography: Prospective Clinical Performance and Third-Party Reimbursement.

We assessed the initial clinical performance and third-party reimbursement rates of supplementary computer-aided detection (CAD) at CT colonography (CTC) for detecting colorectal polyps 6 mm or larger in routine clinical practice. We retrospectively assessed the prospective clinical performance of a U.S. Food and Drug Administration-approved CAD system in second-reader mode in 347 consecutive adults (mean age, 57.6 years; 205 women, 142 men) undergoing CTC evaluation over a 5-month period. The reference standard consisted of the prospective interpretation by experienced CTC radiologists combined with subsequent optical colonoscopy (OC), if performed. We also assessed third-party reimbursement for CAD for studies performed over an 18-month period. In all, 69 patients (mean [± SD] age, 59.0 ± 7.7 years; 32 men, 37 women) had 129 polyps ≥ 6 mm. Per-patient CAD sensitivity was 91.3% (63 of 69). Per-polyp CAD-alone sensitivity was 88.4% (114 of 129), including 88.3% (83 of 94) for 6- to 9-mm polyps and 88.6% (31 of 35) for polyps 10 mm or larger. On retrospective review, three additional polyps 6 mm or larger were seen at OC and marked by CAD but dismissed as CAD false-positives at CTC. The mean number of false-positive CAD marks was 4.4 ± 3.1 per series. Of 1225 CTC cases reviewed for reimbursement, 31.0% of the total charges for CAD interpretation had been recovered from a variety of third-party payers. In our routine clinical practice, CAD showed good sensitivity for detecting colorectal polyps 6 mm or larger, with an acceptable number of false-positive marks. Importantly, CAD is already being reimbursed by some third-party payers in our clinical CTC practice.

Accuracy of Detecting Colorectal Polyps Utilizing Colon Capsule Endoscopy 2: A Meta-analysis

Introduction: Colorectal cancer (CRC) is the 3rd most commonly diagnosed cancer in USA. Optical colonoscopy (OC) is considered the gold standard for CRC screening but is invasive with inherent complications, requires sedation and has poor patient compliance. Colon Capsule Endoscopy (CCE) was first introduced back in 2006 (Given Imaging, Israel) as an alternative to OC; however, sensitivity of 1st generation colon capsule endoscopy (CCE1) was suboptimal. So a 2nd generation colon capsule endoscopy (CCE2) was developed. The role of CCE in CRC screening has been studied with variable results. The aim of this study is to assess sensitivity and specificity of CCE2 in comparison to OC. Methods: Literature from 2006 to May 2015 was reviewed using PUBMED and COCHRANE databases. Studies reporting per patient analysis for detection of colorectal polyps by CCE2 confirmed by OC were included. One abstract from Gastrointestinal endoscopy was also included. Microsoft Excel was utilized for data entry and statistical analysis. Two independent reviewers reviewed the data and conflicts were resolved by discussion. Results: Our search strategy yielded 4 studies with sample size of 1127 patients. Mean age of study population was 56.5yrs. Pooled data for polyps >6mm showed per patient CCE2 sensitivity and specificity with 95% CI of 85.8% (81.2 to 89.6) and 90.6% (88.5 to 92.5), respectively. Pooled data for polyps >10mm showed per patient CCE2 sensitivity and specificity of 85.9% (78.8 to 91.3) and 96.5% (95.2 to 97.6), respectively. Colon cleansing rate for CCE 2 was 81.9%. CCE2 excretion rate within 10hrs in 902 patients was 86.9%. No adverse events related to CCE2 were reported. Conclusion: Our study showed that CCE2 is safe and effective at detecting colorectal polyps. CCE2 has a sensitivity (85%) significantly higher than CCE1 (71%). CCE could be a novel modality for CRC screening as the procedure is minimally invasive, safe, does not require sedation or air insufflation and is well accepted by patients. Since CCE could be done in outpatient setting this would make it more cost effective than OC. CCE has 2 important limitations. First, it still requires same level of bowel preparation as OC and more importantly when polyps are identified by CCE, patients will need subsequent OC for polyp removal. More robust studies are needed to validate CCE as a screening tool, but for now CCE could be used as an alternative approach in patients whose OC is contraindicated or incomplete.Figure 1Figure 2

Adverse events following computed tomographic colonography compared to optical colonoscopy in the elderly

ObjectiveTo evaluate gastrointestinal and cardiovascular adverse event risks associated with optical colonoscopy (OC) among Medicare outpatients who received computed tomography colonography (CTC) as their initial method of colorectal evaluation. MethodsMedicare claims were compared between 6114 outpatients ≥66years who received initial CTC and 149,202 outpatients who received initial OC between January 2007 and December 2008. OC patients were matched on county of residence and year of evaluation. Outcomes included lower gastrointestinal bleeding, gastrointestinal perforation, other gastrointestinal events and cardiovascular events resulting in an emergency department visit or hospitalization within 30days. ResultsAmong 1000 outpatients undergoing initial CTC, 12.4 experienced lower gastrointestinal bleeding, 0.7 perforation, 18.0 other gastrointestinal events and 45.5 cardiovascular events within 30days. After multivariate adjustment, risks of lower gastrointestinal bleeding, other gastrointestinal events and cardiovascular events were higher with initial OC than CTC, with or without subsequent OC (Odds Ratio 1.91 95 Confidence Interval [1.47,2.49], Odds Ratio 1.35 95 Confidence Interval [1.07,1.69] and Odds Ratio 1.38 95 Confidence Interval [1.18,1.62], respectively); however, perforation risk did not differ (p=0.10). This pattern is similar in older and symptomatic populations. ConclusionRates of gastrointestinal bleeding, other gastrointestinal events and cardiovascular events are lower following initial CTC than OC, but rates of perforation do not differ.

Correlation of Abnormal CT Findings of Lower GI Tract with Subsequent Colonoscopy

Purpose: To ascertain the significance of abnormal findings on CT scan related to lower GI tract with a subsequent optical colonoscopy in an outpatient setting. Methods: All patients that underwent an optical colonoscopy for evaluation of abnormal CT findings at an outpatient endoscopy center were reviewed. Findings on colonoscopy and biopsies were compared with the original findings on CT scan that necessitated the subsequent colonoscopy. Results: A total of 102 patients over a 10-year period (2003 to 2013) were reviewed. Age of patients ranged from 21-90 years. Fifty seven (56%) were females, 45 (44%) were males. All abnormal colonoscopic findings were biopsied and verified with pathology. CT had revealed colon wall thickening in 47 (46%), diverticulosis in 17 (16%), diverticulosis and colon wall thickening in 10 (10%). Twenty eight (28%) had other findings, including colon mass. Conclusion: Two-thirds of patients that had a demonstrable abnormality of lower GI tract on CT scan had significant relevant colonoscopy findings. A majority of lower GI findings on CT scans can be attributed to diverticulosis, colitis, and polyps. In six out of seven cases, a colonic mass was subsequently confirmed to be adenocarcinoma on colonoscopy. Therefore, all abnormal CTs warrant further investigation with colonoscopy.Table: Table. CT findings and Colonoscopy resultsTable: Table. Colonoscopic findings of “other findings” on CT scan

Predicting Polyp Location on Optical Colonoscopy From CT Colonography by Minimal-Energy Curve Modeling of the Colonoscope Path

The ability to accurately locate a polyp found on computed tomographic colonography (CTC) at subsequent optical colonoscopy (OC) is an important task in colorectal cancer screening. We present a method to more accurately match polyp locations at CTC and OC. A colonoscope was modeled as a flexible tube with negligible stretch and minimal strain. The path of the colonoscope was estimated using a minimal-energy curve method. The energy function was defined and optimized by a subdivision scheme. The prediction of polyp locations at OC from CTC was converted to an optimization problem. The prediction performance was evaluated on 134 polyps by comparing the predicted with the true polyp locations at OC. The method can accurately predict polyp locations at OC to within ±0.5 colonoscope mark (5cm) for more than 58% of polyps and to within ±1 colonoscope mark (10cm) for more than 96% of polyps, significantly improving upon previously published methods. This method can be easily incorporated into routine OC practice and allow the colonoscopist to begin the examination by targeting locations of potential polyps found at CTC.

Normalized Distance Along the Colon Centerline: A Method for Correlating Polyp Location On CT Colonography and Optical Colonoscopy

OBJECTIVE. The ability to accurately locate a polyp found on CT colonography (CTC) at subsequent optical colonoscopy (OC) is an important part of the successful implementation of CTC for colorectal cancer screening. The purpose of this study was to determine whether a polyp's normalized distance along the colon centerline derived from CTC data can accurately predict its location on OC.MATERIALS AND METHODS. The polyp population consisted of 152 polyps in 121 patients. CTC polyp findings were verified by same-day segmentally-unblinded OC. Each polyp's normalized distance along the colon centerline was computed by dividing its distance from the anorectal junction measured along the colon centerline by the length of the colon at CTC. The predicted polyp location at OC was computed by multiplying the normalized distance along the colon centerline by the colon length at OC (i.e., the distance to the cecum as determined at full colonoscope insertion). The differences between the true and predicted polyp locatio...

CT colonography polyp matching: differences between experienced readers

The purpose of this study was to investigate if experienced readers differ when matching polyps shown by both CT colonography (CTC) and optical colonoscopy (OC) and to explore the reasons for discrepancy. Twenty-eight CTC cases with corresponding OC were presented to eight experienced CTC readers. Cases represented a broad spectrum of findings, not completely fulfilling typical matching criteria. In 21 cases there was a single polyp on CTC and OC; in seven there were multiple polyps. Agreement between readers for matching was analyzed. For the 21 single-polyp cases, the number of correct matches per reader varied from 13 to 19. Almost complete agreement between readers was observed in 15 cases (71%), but substantial discrepancy was found for the remaining six (29%) probably due to large perceived differences in polyp size between CT and OC. Readers were able to match between 27 (71%) and 35 (92%) of the 38 CTC detected polyps in the seven cases with multiple polyps. Experienced CTC readers agree to a considerable extent when matching polyps between CTC and subsequent OC, but non-negligible disagreement exists.

Screening CT Colonography in an Asymptomatic Average-Risk Asian Population: A 2-Year Experience in a Single Institution

The purpose of our study was to report the results of screening CT colonography (CTC) in an asymptomatic average-risk Asian population. In 2005 and 2006, 1,015 Korean adults (609 men and 406 women; mean age, 51 years) underwent screening CTC using a 16-MDCT scanner and an automated CO2 delivery system. During the study period, the protocols were changed to use less vigorous purgation and lower radiation doses; fecal tagging (n = 890) and primary 3D interpretation (n = 966) were generally used. CTC results were categorized as C0, inadequate; C1, no significant polyp; C2, one or two 6- to 9-mm polyps; C3, polyps > or = 10 mm or > or = three 6- to 9-mm polyps; and C4, mass. Patients with positive CTC results were referred to gastroenterologists for follow-up or management planning. Categories C0-C4 were assigned to 21 (2.1%), 916 (90.2%), 54 (5.3%), 23 (2.3%), and one (0.1%) patients, respectively. Fifty-four patients with C4 (n = 1), C3 (n = 20), or C2 (n = 33) underwent subsequent optical colonoscopy: complete (n = 53) and incomplete (n = 1). Per-patient positive predictive values (PPVs) for categories C3-C4 and C2-C4 were 90% (18/20) and 74% (39/53), respectively. Per-polyp PPVs at 10- and 6-mm thresholds were 92% (22/24) and 69% (45/65), respectively. The diagnostic yield for advanced neoplasm was 1.5% (15/1,015). Our results seem comparable to Western experiences, showing that a successful screening CTC program can be reproduced in an Asian population.

Findings on Optical Colonoscopy After Positive CT Colonography Exam

The aim of this study is to evaluate the findings on optical colonoscopy (OC) after a positive CT colonography (CTC) exam and characterize the type of polyps seen on OC but not reported by CTC. Over an 18-month period a total of 159 asymptomatic adults had polyps seen on computed tomography colonography examination and subsequently underwent planned therapeutic optical colonoscopy. The colonoscopists were aware of the findings on CT colonography prior to further evaluation of the colon. Characteristics of polyps and adenomas seen on subsequent optical colonoscopy but not seen or reported on CT colonography were examined. The adenoma miss rate for CT colonography overall was 18.9% (25/132) including 6.2% (4/65) for polyps >9 mm and 18.2% (8/44) for polyps 6-9 mm. Three of the adenomas >9 mm not seen on CTC were sessile, and two were found in patients with technically difficult CT colonography studies due to poor colonic distention. No adenomas with advanced pathology <6 mm were found on optical colonoscopy but not reported on CT colonography. False-positive CTC referral where no polyp was seen on colonoscopy was 5.0%. CT colonography has adenoma miss rates similar to miss rates historically found with optical colonoscopy, with most missed adenomas being <10 mm and sessile in shape.

Screening for Colorectal Neoplasia with CT Colonography: Initial Experience from the 1st Year of Coverage by Third-Party Payers

To evaluate our experience in the 1st year of computed tomographic (CT) colonography screening since the initiation of local third-party payer coverage. This HIPAA-compliant study was approved by the institutional review board, and informed consent was waived. Over a 1-year period that ended on April 27, 2005, 1110 consecutive adults (585 women, 525 men; mean age, 58.1 years) underwent primary CT colonography screening. More than 99% were covered by managed care agreements. CT colonographic interpretation was performed with primary three-dimensional polyp detection, and the final results were issued within 2 hours. Patients with large (> or =10-mm) polyps were referred for same-day optical colonoscopy, and patients with medium-sized (6-9-mm) lesions had the option of immediate optical colonoscopy or short-term CT colonography surveillance. Large colorectal polyps were identified at CT colonography in 43 (3.9%) of 1110 patients. Medium-sized lesions were identified in 77 (6.9%) patients, 31 (40%) of whom chose optical colonoscopy and 46 (60%) of whom chose CT colonography surveillance. Concordant lesions were identified in 65 of 71 patients who underwent subsequent optical colonoscopy (positive predictive value, 91.5%). Sixty-one (86%) of 71 optical colonoscopic procedures were performed on the same day as CT colonography, thereby avoiding the need for repeat bowel preparation. The actual endoscopic referral rate for positive findings at CT colonography was 6.4% (71 of 1110 patients). The demand for CT colonography screening from primary care physicians and their patients increased throughout the study period. As a primary colorectal screening tool, CT colonography covered by third-party payers has an acceptably low endoscopic referral rate and a high concordance of positive findings at optical colonoscopy.