Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults

Computed Tomography Colonography: 2025 Update

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States. Most cases arise from polyps, which can be detected and removed before becoming cancerous. Computed tomography colonography (CTC), also known as virtual colonoscopy, was first introduced in 1994 as a minimally invasive method for CRC screening and diagnosis. This 2025 update on CTC will focus on (1) techniques and dose reduction strategies, (2) image display methods, (3) reporting and classification systems, (4) tumor staging capabilities, (5) integration of advanced imaging techniques, and (6) cost-effectiveness and reimbursement.

CT Colonography for Colorectal Cancer Prevention and Detection: Integration Into Clinical Practice, From the AJR Special Series on Screening

CT colonography (CTC) is a CT examination, performed with low dose and typically without IV contrast media, optimized to detect colorectal polyps and cancer. Despite extensive supporting data, CTC has had variable acceptance and use over the past two decades, particularly for a main indication of colorectal cancer screening. CTC is now at an inflection point after the approval in 2025 by CMS for reimbursement of CTC performed for colorectal cancer screening. Widespread use of CTC for CRC screening could help increase screening adherence rates and prevent cancer incidence. Nonetheless, radiologists must incorporate emerging knowledge regarding polyps' natural history and recognition of sessile serrated lesions, to leverage the screening efficiencies of CTC-based screening. The purposes of this article are to describe the current status of CRC in the United States and United Kingdom with consideration of historical reasons that have limited the test's use along with recent events that may portend a marked change in the test's acceptance; to highlight the challenges and potential solutions toward successful widespread CTC implementation; and to present new concepts in CTC and CRC screening relevant to radiologists.

Virtual Colonoscopy: Retrospective Comparison of the Findings in Supine and Prone Positions

BACKGROUND

Early detection of colorectal cancer (CRC) is significantly associated with reduced morbidity and mortality. Virtual colonoscopy (VC) is a minimally invasive, safe and well-tolerated alternative procedure to traditional colonoscopy. Therefore, we aimed to evaluate the findings of VC particularly in supine and prone positions as well as to contribute to the practical challenges of procedure.

METHODS

Total number of 20 patients who underwent VC were included in this retrospective study. After proper bowel cleansing was achieved, intestinal dilatation was performed by injecting air into the rectum. Two different shots were performed in the supine and prone positions. Additionally, intestinal diameters were measured from the cecum to the rectum at their widest point via 2-dimensional coronal reformat.

RESULTS

Polyps were detected in 3 patients which were confirmed by optical colonoscopy. The mean cecum diameter was detected as the largest diameter in the supine and prone examinations. In both supine and prone examinations, the distal descending colon was the most challenging site. Additionally, the mean descending colon diameter calculated in the prone position (40.9 ± 6.4 mm) was found to be statistically larger than descending colon diameter calculated in the supine position (36.1 ± 5.3 mm) (P = 0.001).

CONCLUSIONS

Our findings clearly demonstrated that combination of prone and supine scanning provides clear field of vision on narrow parts of the colon which improves accurate estimation for polyp detection. Furthermore, VC appears to be more comfortable, safe, fast, and cost-efffective procedure for CRC screening with advantages of low radiation exposure, extracolonic findings and lack of sedation requirements.

Cost effectiveness analysis of three colorectal cancer screening modalities in Kuwait

Colorectal cancer (CRC) poses a significant health challenge in Kuwait, ranking as the second most common cancer with the incidence rate 13.2 cases per 100,000 people in year 2019. This study aims to determine the cost-effectiveness of three colorectal cancer (CRC) screening methods in Kuwait from the perspective of Kuwait's healthcare providers. Using a Decision Tree Analysis Model, the study compared three screening modalities: Fecal Occult Blood Test (FOBT) followed by colonoscopy or sigmoidoscopy, colonoscopy alone, sigmoidoscopy alone and alongside no screening. Over a 10-year period post-diagnosis, the model tracked costs and outcomes based on CRC patients' life expectancy, expressing results using Incremental Cost Effectiveness Ratios (ICERs). Colorectal cancer screening using FOBT followed by colonoscopy or sigmoidoscopy resulted in 7.7 quality-adjusted life years (QALYs) at a cost of USD 3,573. In contrast, no screening achieved 7.2 QALYs but was more expensive, costing USD 4,084. Screening with only sigmoidoscopy or only colonoscopy provided 6.8 QALYs each, at costs of USD 4,905 and USD 5,002, respectively. Sensitivity analyses explored uncertainties in cost and outcome estimates. FOBT followed by colonoscopy or sigmoidoscopy can be considered as an efficient and effective approach towards early detection of CRC. This approach can be used by healthcare policymakers in Kuwait, in the development of population-based CRC screening programs to optimize resource allocation and improve public health outcomes.

Does Colonoscopy as a First Screening Test Still Make Sense?-Counterpoint

Colonoscopy has been widely regarded as the gold standard for its high diagnostic accuracy and preventive potential. However, its invasive nature, high cost, and suboptimal participation rates limit its utility at the population level. Non-invasive screening tests, notably the fecal immunochemical test (FIT) and multitarget stool DNA tests, present promising alternatives that may improve screening participation and reduce barriers to participation. Among these, FIT has demonstrated a consistent advantage in enhancing participation, which subsequently contributes to better long-term outcomes in CRC prevention. FIT-based two-step screening offers several practical advantages, including cost-effectiveness, non-invasiveness, and greater flexibility. Moreover, the quantitative nature of FIT allows for adjustable sensitivity thresholds and the ability of risk stratification, making it adaptable across diverse populations and scenarios. Through serial testing, FIT can increase cumulative detection rates over time. This approach facilitates the identification of high-risk individuals, allowing for more judicious use of colonoscopy resources and reducing unnecessary invasive procedures, especially among low-risk populations. Notably, evidence indicates that participation to FIT-based screening is consistently higher than to colonoscopy, which enhances the detection of early-stage cancers and advanced adenomas in the long run. Given the constraints of limited endoscopic capacity, the aging population, and the recent lowering of the recommended screening age due to the rising incidence of early-onset CRC, FIT emerges as a practical, flexible solution. The role of two-step FIT screening in improving participation and enabling risk-stratified, personalized approaches to CRC prevention is pivotal, advocating for its expanded integration into future screening paradigms.

Clinical consequences of computer-aided colorectal polyp detection

BACKGROUND AND AIM

Randomised trials show improved polyp detection with computer-aided detection (CADe), mostly of small lesions. However, operator and selection bias may affect CADe's true benefit. Clinical outcomes of increased detection have not yet been fully elucidated.

METHODS

In this multicentre trial, CADe combining convolutional and recurrent neural networks was used for polyp detection. Blinded endoscopists were monitored in real time by a second observer with CADe access. CADe detections prompted reinspection. Adenoma detection rates (ADR) and polyp detection rates were measured prestudy and poststudy. Histological assessments were done by independent histopathologists. The primary outcome compared polyp detection between endoscopists and CADe.

RESULTS

In 946 patients (51.9% male, mean age 64), a total of 2141 polyps were identified, including 989 adenomas. CADe was not superior to human polyp detection (sensitivity 94.6% vs 96.0%) but outperformed them when restricted to adenomas. Unblinding led to an additional yield of 86 true positive polyp detections (1.1% ADR increase per patient; 73.8% were <5 mm). CADe also increased non-neoplastic polyp detection by an absolute value of 4.9% of the cases (1.8% increase of entire polyp load). Procedure time increased with 6.6±6.5 min (+42.6%). In 22/946 patients, the additional detection of adenomas changed surveillance intervals (2.3%), mostly by increasing the number of small adenomas beyond the cut-off.

CONCLUSION

Even if CADe appears to be slightly more sensitive than human endoscopists, the additional gain in ADR was minimal and follow-up intervals rarely changed. Additional inspection of non-neoplastic lesions was increased, adding to the inspection and/or polypectomy workload.

Impact of racial disparities in follow-up and quality of colonoscopy on colorectal cancer outcomes

BACKGROUND

The benefits of colorectal cancer (CRC) screening programs rely on completing follow-up colonoscopy when a noncolonoscopy test is abnormal and on quality of colonoscopy screening as measured by the endoscopists' adenoma detection rate. Existing data demonstrate substantially lower follow-up colonoscopy rates and adenoma detection rate for Black Americans than White Americans. However, the contributions of racial differences in follow-up colonoscopy and adenoma detection rate on CRC outcomes have not been rigorously evaluated.

METHODS

We used established and validated CRC-Adenoma Incidence and Mortality (CRC-AIM) model as our analysis platform, with inputs from published literature that report lower follow-up colonoscopy rates and adenoma detection rate in Black adults compared with White adults (15% and 10% lower, respectively). We simulated screening with annual fecal immunochemical test, triennial multitarget stool DNA, and colonoscopy every 10 years between ages 45 and 75 years using real-world utilization of the screening modalities vs no screening. We reported lifetime outcomes per 1000 Black adults.

RESULTS

Elimination of Black-White disparities in follow-up colonoscopy rates would reduce CRC incidence and mortality by 5.2% and 9.3%, respectively, and improve life-years gained with screening by 3.4%. Elimination of Black-White disparities in endoscopists' adenoma detection rate would reduce CRC incidence and mortality by 9.4% and improve life-years gained by 3.7%. Elimination of both disparities would reduce CRC incidence and mortality by 14.6% and 18.7%, respectively, and improve life-years gained by 7.1%.

CONCLUSIONS

This modeling study predicts eliminating racial differences in follow-up colonoscopy rates, and quality of screening colonoscopy would substantially reduce Black-White disparities in CRC incidence and mortality.

The science and practice of imaging-based screening: What the radiologist needs to know

Imaging-based screening is an important public health focus and a fundamental part of Diagnostic Radiology. Hence, radiologists should be familiar with the concepts that drive imaging-based screening practice including goals, risks, biases and clinical trials. This review article discusses an array of imaging-based screening exams including the key epidemiology and evidence that drive screening guidelines for abdominal aortic aneurysm, breast cancer, carotid artery disease, colorectal cancer, coronary artery disease, lung cancer, osteoporosis, and thyroid cancer. We will provide an overview on societal interests in screening, screening-related inequities, and opportunities to address them. Emerging evidence for opportunistic screening and the role of AI in imaging-based screening will be explored. In-depth knowledge and formalized training in imaging-based screening strengthens radiologists as clinician scientists and has the potential to broaden our public health leadership opportunities. SUMMARY SENTENCE: An overview of key screening concepts, the evidence that drives today's imaging-based screening practices, and the need for radiologist leadership in screening policies and evidence development.

Early diagnostic strategies for colorectal cancer

At present, cancer is still an important factor threatening human health. Colorectal cancer (CRC) is one of the top three most common cancers worldwide and one of the deadliest malignancies in humans. The latest data showed that CRC incidence and mortality rank third and second, respectively, among global malignancies. Early and accurate diagnosis is crucial to reduce the morbidity, mortality and improve survival of patients with CRC, but the current early diagnostic methods have limitations. The effectiveness and compliance of diagnostic methods have a certain impact on whether people choose screening. In this editorial, we explore strategies for the early diagnosis of CRC, including stool-based, blood-based, direct visualization, and imaging examinations.

[Colorectal cancer screening with virtual colonography]

BACKGROUND

Since 2003, a decline in the age-standardized incidence rates of colorectal cancer (CRC) has been observed in Germany. Nonetheless, one in eight cancer cases still affects the colon or rectum. The prognosis has improved, with the relative 5‑year survival rate for CRC being approximately 65%.

METHODS

This positive trend is probably a result of preventive measures introduced over the last 20 years. This could be further improved, however, as CRC can not only be detected early but in almost all cases also prevented through the identification of benign precursors. Less than half of all eligible individuals participate in screening via colonoscopy. This implies that further, possibly even imaging, screening test methods should be explored and offered. Studies have reported that virtual colonography techniques have a comparable accuracy to endoscopy of about 90% for polyp sizes larger than 5 mm. The data for computed tomography (CT) is more extensive than for magnetic resonance imaging (MRI).

CONCLUSION

Significant challenges are posed however by the fact that in Germany CT colonography (CTC) is not considered a viable screening option due to radiation protection concerns, and MRI screening is not an established screening method. Radiologists should be familiar with classification using the CT Colonography Reporting and Data System (C-RADS), which uses criteria such as CT density, morphology, size, and location for classification. C‑RADS classification follows the categories: C0 (inadequate study), C1 (normal), C2a (indeterminate), C2b (benign), C3 (suspicious), and C4 (malignant), as well as extracolonic categories E1/2 (no clinically significant findings), E3 (likely insignificant findings), and E4 (likely significant findings).

Differences in circulating lymphocyte subpopulations among patients with inflammatory polyps, colorectal adenomas and colorectal cancer

BACKGROUND AND STUDY AIMS

Colorectal cancer (CRC) may develop from focal changes within benign or precancerous polyps. The immune system's failure to detect and eradicate tumor cells due to immune surveillance evasion, allows cancer to develop and spread. This study aims to analyze the differences in circulating lymphocyte subpopulations in patients with colorectal inflammatory polyps, colorectal adenomas and CRC.

PATIENTS AND METHODS

We retrospectively reviewed patients from September 2016 to December 2019 at the Shaoxing Second Hospital. Using flow cytometry, the subset distribution and immunophenotype of T cells, CD4+ T cells, CD8+ T cells, B cells and NK cells were investigated in peripheral blood mononuclear cell samples. The counts of lymphocytes were determined by white blood cell counts.

RESULTS

In total, 518 patients were included in this study. The counts of lymphocytes, T cells and NK cells in patients with inflammatory polyps, colorectal adenomas and CRC were lower than controls. The counts and percentages of CD8+ T cells in patients with inflammatory polyps, colorectal adenomas and CRC were lower than controls. The counts of CD4+ T cells were lower in patients with CRC than inflammatory polyps. The percentages of CD4+ T cells in patients with inflammatory polyps, colorectal adenomas and CRC were higher than controls, but lower in the CRC than inflammatory polyps, colorectal adenomas. The counts and percentages of B cells were lower in CRC patients than colorectal adenomas patients. In addition, the percentages of B cells were higher in patients with inflammatory polyps and colorectal adenomas than in controls.

CONCLUSIONS

The decrease in counts of lymphocyte, T cells, CD8+ T cells and NK cells in patients may be related to the dysplasia of epithelial cells. Furthermore, the B cells and CD4+ T cells may be related to the malignant growth of the dysplastic epithelial cells.

Comparison of adenoma miss rate and adenoma detection rate between conventional colonoscopy and colonoscopy with second-generation distal attachment cuff: a multicenter, randomized, back-to-back trial

BACKGROUND AND AIMS

Endocuff Vision (Olympus Europe, Hamburg, Germany) has been designed to enhance mucosal visualization, thereby improving detection of (pre-)malignant colorectal lesions. This multicenter, international, back-to-back, randomized colonoscopy trial compared the adenoma detection rate (ADR) and adenoma miss rate (AMR) between Endocuff Vision-assisted colonoscopy (EVC) and conventional colonoscopy (CC).

METHODS

Patients aged 40 to 75 years referred for non-immunochemical fecal occult blood test-based screening, surveillance, or diagnostic colonoscopy were included at 10 hospitals and randomized into 4 groups: group 1, 2 × CC; group 2, CC followed by EVC; group 3, EVC followed by CC; and group 4, 2 × EVC. Primary outcomes included ADR and AMR.

RESULTS

A total of 717 patients were randomized, of whom 661 patients (92.2%) had 1 and 646 (90.1%) patients had 2 completed back-to-back colonoscopies. EVC did not significantly improve ADR compared to CC (41.1%; [95% confidence interval (CI), 36.1-46.3] vs 35.5% [95% CI, 30.7-40.6], respectively; P = .125), but EVC did reduce AMR by 11.7% (29.6% [95% CI, 23.6-36.5] vs 17.9% [95% CI, 12.5-23.5], respectively; P = .049). AMR of 2 × CC compared to 2 × EVC was also not significantly different (25.9% [95% CI, 19.3-33.9] vs 18.8% [95% CI, 13.9-24.8], respectively; P = .172). Only 3.7% of the polyps missed during the first procedures had advanced pathologic features. Factors affecting risk of missing adenomas were age (P = .002), Boston Bowel Preparation Scale (P = .008), and region where colonoscopy was performed (P < .001).

CONCLUSIONS

Our trial shows that EVC reduces the risk of missing adenomas but does not lead to a significantly improved ADR. Remarkably, 25% of adenomas are still missed during conventional colonoscopies, which is not different from miss rates reported 25 years ago; reassuringly, advanced features were only found in 3.7% of these missed lesions. (Clinical trial registration number: NCT03418948.).

Acceptance and Preference of Computed Tomographic Colonography and Colonoscopy: Results of a Nationwide Multicenter Comparative Questionnaire Survey in Japan

Objectives

To investigate patient acceptance and preference for computed tomographic colonography (CTC) over colonoscopy.

Methods

Participants were recruited from a nationwide multicenter trial in Japan to assess the accuracy of CTC detection. They were scheduled to undergo colonoscopy after CTC with common bowel preparation on the same day. Some were administered sedative drugs during colonoscopy, depending on the referring clinician and participant's preferences. The participants were requested to complete a questionnaire to evaluate the acceptability of bowel preparation, examinations, and preference for future examinations.

Results

Of the 1,257 enrolled participants, 1,180 (mean age: 60.6 years; women: 43.3%) completed the questionnaire. Sedative drugs were not administered in 687 participants (unsedated colonoscopy group) and were administered intravenously during colonoscopy in 493 participants (sedated colonoscopy group). Before propensity score matching, the mean participants' age, percentages of asymptomatic participants, insufflation of gas during colonoscopy, and number of participants with a history of abdominal/pelvic operation significantly differed between the groups. After propensity score matching, 912 participants from each group were included in the analysis. In the unsedated colonoscopy group, CTC was answered as significantly easier than colonoscopy (p<0.001). Conversely, CTC was significantly more difficult than colonoscopy in the sedated colonoscopy group (p<0.001). In the unsedated colonoscopy group, 48% preferred CTC and 22% preferred colonoscopy for future examinations, whereas in the sedated colonoscopy group, 26% preferred CTC and 38% preferred colonoscopy (p<0.001).

Conclusions

CTC has superior participant acceptability compared with unsedated colonoscopy. However, our study did not observe the advantages of CTC acceptance over sedative colonoscopy.

Colorectal cancer screening at age 45 years in Israel: Cost-effectiveness and global implications

BACKGROUND

Colorectal cancer (CRC) incidence at ages <50 years is increasing worldwide. Screening initiation was lowered to 45 years in the United States. The cost-effectiveness of initiating CRC screening at 45 years in Israel was assessed with the aim of informing national policy and addressing internationally relevant questions.

METHODS

A validated CRC screening model was calibrated to Israeli data and examined annual fecal immunochemical testing (FIT) or colonoscopy every 10 years from 45 to 74 years (FIT45-74 or Colo45-74) versus from 50 to 74 years (FIT50-74 or Colo50-74). The addition of a fourth colonoscopy at 75 years was explored, subanalyses were performed by sex/ethnicity, and resource demands were estimated.

RESULTS

FIT50-74 and Colo50-74 reduced CRC incidence by 57% and 70% and mortality by 70% and 77%, respectively, versus no screening, with greater absolute impact in Jews/Other versus Arabs but comparable relative impact. FIT45-74 further reduced CRC incidence and mortality by an absolute 3% and 2%, respectively. With Colo45-74 versus Colo50-74, CRC cases and deaths increased slightly as three colonoscopies per lifetime shifted to 5 years earlier but mean quality-adjusted life-years gained (QALYGs) per person increased. FIT45-74 and Colo45-74 cost 23,800-53,900 new Israeli shekels (NIS)/QALYG and 110,600-162,700 NIS/QALYG, with the lowest and highest values among Jewish/Other men and Arab women, respectively. A fourth lifetime colonoscopy cost 48,700 NIS/QALYG. Lowering FIT initiation to 45 years with modest participation required 19,300 additional colonoscopies in the first 3 years.

CONCLUSIONS

Beginning CRC screening at 45 years in Israel is projected to yield modest clinical benefits at acceptable costs per QALYG. Despite different estimates by sex/ethnicity, a uniform national policy is favored. These findings can inform Israeli guidelines and serve as a case study internationally.

Worldwide productivity and research trend of publications concerning intestinal polyps: A bibliometric study

There is a significant relationship between intestinal polyps and colorectal cancer, and in recent years, research on intestinal polyps has been rapidly developing around the world. However, there is still a lack of adequate quantification and analysis of publications in this field. The aim of this study was to perform a comprehensive bibliometric analysis of publications related to intestinal polyps over the past 20 years. To enhance the understanding of current research hotspots and potential trends, and to point out the direction of future research. Publications related to intestinal polyps were retrieved from the Science Citation Index Expanded in Web of Science Core Collection. the Bibliometric online analysis platform (https://bibliometric.com/app), the Bibliometrix Package, and the CiteSpace are used for bibliometric analysis and visualization, including the overall range of annual output and annual citations, country-region analysis, author and institution analysis, core journal analysis, reference and keyword analysis. Prior to 2017, the amount of research on intestinal polyps was slow to grow, but it picked up speed after that year. In 1019 journals, 4280 papers on intestinal polyps were published in English. The journal with the highest productivity was Gastrointestinal Endoscopy (189, 4.42%). United States (1124, 26.26%), which is also the hub of collaboration in this subject, was the most productive nation. Mayo Clinic (n = 70, 1.64%) is the most productive institution. Intestinal microbiota, endoscopic mucosal resection, gut microbiota, deep learning, tea polyphenol, insulin resistance and artificial intelligence were current hot subjects in the field. Studies of intestinal polyps increased significantly after 2017. The United States contributed the largest number of publications. Countries and institutions were actively cooperating with one another. artificial intelligence is currently an emerging topic.

Natural History of Colorectal Polyps Undergoing Longitudinal in Vivo CT Colonography Surveillance

Background The natural history of colorectal polyps is not well characterized due to clinical standards of care and other practical constraints limiting in vivo longitudinal surveillance. Established CT colonography (CTC) clinical screening protocols allow surveillance of small (6-9 mm) polyps. Purpose To assess the natural history of colorectal polyps followed with CTC in a clinical screening program, with histopathologic correlation for resected polyps. Materials and Methods In this retrospective study, CTC was used to longitudinally monitor small colorectal polyps in asymptomatic adult patients from April 1, 2004, to August 31, 2020. All patients underwent at least two CTC examinations. Polyp growth patterns across multiple time points were analyzed, with histopathologic context for resected polyps. Regression analysis was performed to evaluate predictors of advanced histopathology. Results In this study of 475 asymptomatic adult patients (mean age, 56.9 years ± 6.7 [SD]; 263 men), 639 unique polyps (mean initial diameter, 6.3 mm; volume, 50.2 mm3) were followed for a mean of 5.1 years ± 2.9. Of these 639 polyps, 398 (62.3%) underwent resection and histopathologic evaluation, and 41 (6.4%) proved to be histopathologically advanced (adenocarcinoma, high-grade dysplasia, or villous content), including two cancers and 38 tubulovillous adenomas. Advanced polyps showed mean volume growth of +178% per year (752% per year for adenocarcinomas) compared with +33% per year for nonadvanced polyps and -3% per year for unresected, unretrieved, or resolved polyps (P < .001). In addition, 90% of histologically advanced polyps achieved a volume of 100 mm3 and/or volume growth rate of 100% per year, compared with 29% of nonadvanced and 16% of unresected or resolved polyps (P < .001). Polyp volume-to-diameter ratio was also significantly greater for advanced polyps. For polyps observed at three or more time points, most advanced polyps demonstrated an initial slower growth interval, followed by a period of more rapid growth. Conclusion Small colorectal polyps ultimately proving to be histopathologically advanced neoplasms demonstrated substantially faster growth and attained greater overall size compared with nonadvanced polyps. Clinical trial registration no. NCT00204867 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Dachman in this issue.

Evaluating the clinical performance of SDC2/NDRG4 methylation for colorectal cancer detection

Purpose: The performance and clinical accuracy of combined SDC2/NDRG4 methylation were evaluated in diagnosing colorectal cancer (CRC) and advanced adenoma. Methods: A total of 2333 participants were enrolled to assess the sensitivity and specificity of biomarkers in diagnosing CRC in a multicenter clinical trial through feces DNA methylation tests. Results: SDC2/NDRG4 methylation showed excellent performance for CRC detection in biomarker research and the real world. Its sensitivity for detecting CRC, early CRC and advanced adenoma were 92.06%, 91.45% and 62.61%, respectively. Its specificity was 94.29%, with a total coincidence rate of 88.28%. When interference samples were included, the specificity was still good (82.61%). Therefore, the SDC2/NDRG4 methylation test showed excellent performance in detecting CRC and advanced adenoma under clinical application.

Longitudinal follow-up of incidental renal calculi on computed tomography

RATIONALE AND OBJECTIVES

Measuring small kidney stones on CT is a time-consuming task often neglected. Volumetric assessment provides a better measure of size than linear dimensions. Our objective is to analyze the growth rate and prognosis of incidental kidney stones in asymptomatic patients on CT.

MATERIALS AND METHODS

This retrospective study included 4266 scans from 2030 asymptomatic patients who underwent two or more nonenhanced CT scans for colorectal screening between 2004 and 2016. The DL software identified and measured the volume, location, and attenuation of 883 stones. The corresponding scans were manually evaluated, and patients without follow-up were excluded. At each follow-up, the stones were categorized as new, growing, persistent, or resolved. Stone size (volume and diameter), attenuation, and location were correlated with the outcome and growth rates of the stones.

RESULTS

The stone cohort comprised 407 scans from 189 (M: 124, F: 65, median age: 55.4 years) patients. The median number of stones per scan was 1 (IQR: [1, 2]). The median stone volume was 17.1 mm3 (IQR: [7.4, 43.6]) and the median peak attenuation was 308 HU (IQR: [204, 532]. The 189 initial scans contained 291stones; 91 (31.3%) resolved, 142 (48.8%) grew, and 58 (19.9) remained persistent at the first follow-up. At the second follow-up (for 27 patients with 2 follow-ups), 14/44 (31.8%) stones had resolved, 19/44 (43.2%) grew and 11/44 (25%) were persistent. The median growth rate of growing stones was 3.3 mm3/year, IQR: [1.4,7.4]. Size and attenuation had a moderate correlation (Spearman rho 0.53, P < .001 for volume, and 0.50 P < .001 for peak attenuation) with the growth rate. Growing and persistent stones had significantly greater maximum axial diameter (2.7 vs 2.3 mm, P =.047) and peak attenuation (300 vs 258 HU, P =.031) CONCLUSION: We report a 12.7% prevalence of incidental kidney stones in asymptomatic adults, of which about half grew during follow-up with a median growth rate of about 3.3 mm3/year.

Growth rates and histopathological outcomes of small (6-9 mm) colorectal polyps based on CT colonography surveillance and endoscopic removal

BACKGROUND AND AIMS

The natural history of small polyps is not well established and rests on limited evidence from barium enema studies decades ago. Patients with one or two small polyps (6-9 mm) at screening CT colonography (CTC) are offered CTC surveillance at 3 years but may elect immediate colonoscopy. This practice allows direct observation of the growth of subcentimetre polyps, with histopathological correlation in patients undergoing subsequent polypectomy.

DESIGN

Of 11 165 asymptomatic patients screened by CTC over a period of 16.4 years, 1067 had one or two 6-9 mm polyps detected (with no polyps ≥10 mm). Of these, 314 (mean age, 57.4 years; M:F, 141:173; 375 total polyps) elected immediate colonoscopic polypectomy, and 382 (mean age 57.0 years; M:F, 217:165; 481 total polyps) elected CTC surveillance over a mean of 4.7 years. Volumetric polyp growth was analysed, with histopathological correlation for resected polyps. Polyp growth and regression were defined as volume change of ±20% per year, with rapid growth defined as +100% per year (annual volume doubling). Regression analysis was performed to evaluate predictors of advanced histology, defined as the presence of cancer, high-grade dysplasia (HGD) or villous components.

RESULTS

Of the 314 patients who underwent immediate polypectomy, 67.8% (213/314) harboured adenomas, 2.2% (7/314) with advanced histology; no polyps contained cancer or HGD. Of 382 patients who underwent CTC surveillance, 24.9% (95/382) had polyps that grew, while 62.0% (237/382) remained stable and 13.1% (50/382) regressed in size. Of the 58.6% (224/382) CTC surveillance patients who ultimately underwent colonoscopic resection, 87.1% (195/224) harboured adenomas, 12.9% (29/224) with advanced histology. Of CTC surveillance patients with growing polyps who underwent resection, 23.2% (19/82) harboured advanced histology vs 7.0% (10/142) with stable or regressing polyps (OR: 4.0; p<0.001), with even greater risk of advanced histology in those with rapid growth (63.6%, 14/22, OR: 25.4; p<0.001). Polyp growth, but not patient age/sex or polyp morphology/location were significant predictors of advanced histology.

CONCLUSION

Small 6-9 mm polyps present overall low risk to patients, with polyp growth strongly associated with higher risk lesions. Most patients (75%) with small 6-9 mm polyps will see polyp stability or regression, with advanced histology seen in only 7%. The minority of patients (25%) with small polyps that do grow have a 3-fold increased risk of advanced histology.

Comparison of MiraLAX and magnesium citrate for bowel preparation at CT colonography

PURPOSE

To compare MiraLAX, a hypo-osmotic lavage, and magnesium citrate (MgC), a hyper-osmotic agent for bowel preparation at CTC.

METHODS

398 total screening CTC studies were included in this retrospective, single institution study. 297 underwent preparation with a double-dose MgC regimen (mean age, 61 ± 5.5 years; 142 male/155 female) and 101 with 8.3 oz (equivalent to 238 g PEG) of MiraLAX (mean age, 60 ± 9.6 years; 45 male/56 female). Oral contrast for tagging purposes was utilized in both regimens. Studies were retrospectively analyzed for residual fluid volume and attenuation by automated analysis, as well for subjective oral contrast coating of the normal colonic wall and polyps. 50 patients underwent successive CTC studies utilizing each agent (mean, 6.1 ± 1.7 years apart), allowing for intra-patient comparison. Chi-squared, Fisher's exact, McNemar, and t-tests were used for data comparison.

RESULTS

Residual fluid volume (as percentage of total colonic volume) and fluid density was 7.2 ± 4.2% and 713 ± 183 HU for the MgC cohort and 8.7 ± 3.8% and 1044 HU ± 274 for the MiraLAX cohort, respectively (p = 0.001 and p < 0.001, respectively). Similar results were observed for the intra-patient cohort. Colonic wall coating negatively influencing interpretation was noted in 1.7% of MgC vs. 6.9% of MiraLAX examinations (p = 0.008). Polyps were detected in 12% of all MgC vs. 16% of all MiraLAX CTCs (p = 0.29).

CONCLUSION

CTC bowel preparation with the hypo-osmotic MiraLAX agent appears to provide acceptable diagnostic quality that is comparable to the hyper-osmotic MgC agent, especially when factoring in patient safety and tolerance.

AGA Clinical Practice Update on Risk Stratification for Colorectal Cancer Screening and Post-Polypectomy Surveillance: Expert Review

DESCRIPTION

Since the early 2000s, there has been a rapid decline in colorectal cancer (CRC) mortality, due in large part to screening and removal of precancerous polyps. Despite these improvements, CRC remains the second leading cause of cancer deaths in the United States, with approximately 53,000 deaths projected in 2023. The aim of this American Gastroenterological Association (AGA) Clinical Practice Update Expert Review was to describe how individuals should be risk-stratified for CRC screening and post-polypectomy surveillance and to highlight opportunities for future research to fill gaps in the existing literature.

METHODS

This Expert Review was commissioned and approved by the American Gastroenterological Association (AGA) Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPUC and external peer review through standard procedures of Gastroenterology. These Best Practice Advice statements were drawn from a review of the published literature and from expert opinion. Because systematic reviews were not performed, these Best Practice Advice statements do not carry formal ratings regarding the quality of evidence or strength of the presented considerations. Best Practice Advice Statements BEST PRACTICE ADVICE 1: All individuals with a first-degree relative (defined as a parent, sibling, or child) who was diagnosed with CRC, particularly before the age of 50 years, should be considered at increased risk for CRC. BEST PRACTICE ADVICE 2: All individuals without a personal history of CRC, inflammatory bowel disease, hereditary CRC syndromes, other CRC predisposing conditions, or a family history of CRC should be considered at average risk for CRC. BEST PRACTICE ADVICE 3: Individuals at average risk for CRC should initiate screening at age 45 years and individuals at increased risk for CRC due to having a first-degree relative with CRC should initiate screening 10 years before the age at diagnosis of the youngest affected relative or age 40 years, whichever is earlier. BEST PRACTICE ADVICE 4: Risk stratification for initiation of CRC screening should be based on an individual's age, a known or suspected predisposing hereditary CRC syndrome, and/or a family history of CRC. BEST PRACTICE ADVICE 5: The decision to continue CRC screening in individuals older than 75 years should be individualized, based on an assessment of risks, benefits, screening history, and comorbidities. BEST PRACTICE ADVICE 6: Screening options for individuals at average risk for CRC should include colonoscopy, fecal immunochemical test, flexible sigmoidoscopy plus fecal immunochemical test, multitarget stool DNA fecal immunochemical test, and computed tomography colonography, based on availability and individual preference. BEST PRACTICE ADVICE 7: Colonoscopy should be the screening strategy used for individuals at increased CRC risk. BEST PRACTICE ADVICE 8: The decision to continue post-polypectomy surveillance for individuals older than 75 years should be individualized, based on an assessment of risks, benefits, and comorbidities. BEST PRACTICE ADVICE 9: Risk-stratification tools for CRC screening and post-polypectomy surveillance that emerge from research should be examined for real-world effectiveness and cost-effectiveness in diverse populations (eg, by race, ethnicity, sex, and other sociodemographic factors associated with disparities in CRC outcomes) before widespread implementation.

Narrow Band Imaging versus White Light for the Detection of Sessile Serrated Colorectal Lesions: A Randomized Clinical Trial

Background

Colorectal cancer (CRC) is a leading cause of cancer. The detection of pre-malignant lesions by colonoscopy is associated with reduced CRC incidence and mortality. Narrow band imaging has shown promising but conflicting results for the detection of serrated lesions.

Methods

We performed a randomized clinical trial to compare the mean detection of serrated lesions and hyperplastic polyps ≥10 mm with NBI or high-definition white light (HD-WL) withdrawal. We also compared all sessile serrated lesions (SSLs), adenoma, and polyp prevalence and rates.

Results

Overall, 782 patients were randomized (WL group 392 patients; NBI group 390 patients). The average number of serrated lesions and hyperplastic polyps ≥10 mm detected per colonoscopy (primary endpoint) was similar between the HD-WL and NBI group (0.118 vs. 0.156, p = 0.44). Likewise, the adenoma detection rate (55.2% vs. 53.2%, p = 0.58) and SSL detection rate (6.8% vs. 7.5%, p = 0.502) were not different between the two study groups. Withdrawal time was higher in the NBI group (10.88 vs. 9.47 min, p = 0.004), with a statistically nonsignificant higher total procedure time (20.97 vs. 19.30 min, p = 0.052).

Conclusions

The routine utilization of narrow band imaging does not improve the detection of serrated class lesions or any pre-malignant lesion and increases the withdrawal time.

Calibration and Validation of the Colorectal Cancer and Adenoma Incidence and Mortality (CRC-AIM) Microsimulation Model Using Deep Neural Networks

OBJECTIVES

Machine learning (ML)-based emulators improve the calibration of decision-analytical models, but their performance in complex microsimulation models is yet to be determined.

METHODS

We demonstrated the use of an ML-based emulator with the Colorectal Cancer (CRC)-Adenoma Incidence and Mortality (CRC-AIM) model, which includes 23 unknown natural history input parameters to replicate the CRC epidemiology in the United States. We first generated 15,000 input combinations and ran the CRC-AIM model to evaluate CRC incidence, adenoma size distribution, and the percentage of small adenoma detected by colonoscopy. We then used this data set to train several ML algorithms, including deep neural network (DNN), random forest, and several gradient boosting variants (i.e., XGBoost, LightGBM, CatBoost) and compared their performance. We evaluated 10 million potential input combinations using the selected emulator and examined input combinations that best estimated observed calibration targets. Furthermore, we cross-validated outcomes generated by the CRC-AIM model with those made by CISNET models. The calibrated CRC-AIM model was externally validated using the United Kingdom Flexible Sigmoidoscopy Screening Trial (UKFSST).

RESULTS

The DNN with proper preprocessing outperformed other tested ML algorithms and successfully predicted all 8 outcomes for different input combinations. It took 473 s for the trained DNN to predict outcomes for 10 million inputs, which would have required 190 CPU-years without our DNN. The overall calibration process took 104 CPU-days, which included building the data set, training, selecting, and hyperparameter tuning of the ML algorithms. While 7 input combinations had acceptable fit to the targets, a combination that best fits all outcomes was selected as the best vector. Almost all of the predictions made by the best vector laid within those from the CISNET models, demonstrating CRC-AIM's cross-model validity. Similarly, CRC-AIM accurately predicted the hazard ratios of CRC incidence and mortality as reported by UKFSST, demonstrating its external validity. Examination of the impact of calibration targets suggested that the selection of the calibration target had a substantial impact on model outcomes in terms of life-year gains with screening.

CONCLUSIONS

Emulators such as a DNN that is meticulously selected and trained can substantially reduce the computational burden of calibrating complex microsimulation models.

HIGHLIGHTS

Calibrating a microsimulation model, a process to find unobservable parameters so that the model fits observed data, is computationally complex.We used a deep neural network model, a popular machine learning algorithm, to calibrate the Colorectal Cancer Adenoma Incidence and Mortality (CRC-AIM) model.We demonstrated that our approach provides an efficient and accurate method to significantly speed up calibration in microsimulation models.The calibration process successfully provided cross-model validation of CRC-AIM against 3 established CISNET models and also externally validated against a randomized controlled trial.

[CT colonography : Technique and indications]

BACKGROUND

Dedicated radiological expertise and a high-quality examination, performed according to current technical standards and for accepted indications, are prerequisite to achieve excellent results with CT colonography (CTC).

OBJECTIVES

The aim of this article is to review current standards of the examination technique as well as indications and contraindications for CTC based on recent recommendations and guidelines.

MATERIALS AND METHODS

Based on extensive literature research, current knowledge about the examination technique and the indications and contraindications is summarized.

RESULTS

CTC is the radiological examination of choice for the detection of colorectal neoplasia. Beside incomplete or refused colonoscopy and contraindications to colonoscopy, CTC is also a noninvasive option for opportunistic colorectal cancer screening. The examination technique is based on a CTC-specific patient preparation scheme that includes fecal tagging, colonic distension, low-dose CT scans in two patient positions and a combined 2D and 3D data evaluation.

CONCLUSIONS

Performing CTC according to current technical standards is prerequisite for high-quality examinations and is, thus, also a key factor to obtain a correct diagnosis. CTC is a noninvasive examination, capable of providing clinically relevant diagnoses for a wide range of indications.

Robustness Analysis of Colorectal Cancer Colonoscopy Screening Strategies

Colorectal Cancer (CRC) is a leading cause of cancer deaths in the United States. Despite significant overall declines in CRC incidence and mortality, there has been an alarming increase in CRC among people younger than 50. This study uses an established microsimulation model, CRC-SPIN, to perform a 'stress test' of colonoscopy screening strategies. First, we expand CRC-SPIN to include birth-cohort effects. Second, we estimate natural history model parameters via Incremental Mixture Approximate Bayesian Computation (IMABC) for two model versions to characterize uncertainty while accounting for increased early CRC onset. Third, we simulate 26 colonoscopy screening strategies across the posterior distribution of estimated model parameters, assuming four different colonoscopy sensitivities (104 total scenarios). We find that model projections of screening benefit are highly dependent on natural history and test sensitivity assumptions, but in this stress test, the policy recommendations are robust to the uncertainties considered.

Acceptability of alternative technologies compared with faecal immunochemical test and/or colonoscopy in colorectal cancer screening: A systematic review

OBJECTIVE

Colorectal cancer (CRC) is the third most common cancer and the second largest cause of cancer-related death worldwide. Current CRC screening in various countries involves stool-based faecal immunochemical testing (FIT) and/or colonoscopy, yet public uptake remains sub-optimal. This review assessed the literature regarding acceptability of alternative CRC screening modalities compared to standard care in average-risk adults.

METHOD

Systematic searches of MEDLINE, EMBASE, CINAHL, Cochrane and Web of Science were conducted up to February 3rd, 2022. The alternative interventions examined were computed tomography colonography, flexible sigmoidoscopy, colon capsule endoscopy and blood-based biomarkers. Outcomes for acceptability were uptake, discomfort associated with bowel preparation, discomfort associated with screening procedure, screening preferences and willingness to repeat screening method. A narrative data synthesis was conducted.

RESULTS

Twenty-one studies met the inclusion criteria. Differences between intervention and comparison modalities in uptake did not reach statistical significance in most of the included studies. The findings do suggest FIT as being more acceptable as a screening modality than flexible sigmoidoscopy. There were no consistent significant differences in bowel preparation discomfort, screening procedure discomfort, screening preference and willingness to repeat screening between the standard care and alternative modalities.

CONCLUSION

Current evidence comparing standard colonoscopy and stool-based CRC screening with novel modalities does not demonstrate any clear difference in acceptability. Due to the small number of studies available and included in each screening comparison and lack of observed differences, further research is needed to explore factors influencing acceptability of alternative CRC modalities that might result in improvement in population uptake within different contexts.

Three dimensional condylar positional and morphological changes following mandibular reconstruction based on CBCT analysis: a prospective study

OBJECTIVE

This study aimed to evaluate the condylar positional changes following mandibular reconstruction with preservation of the condylar head using Cone-Beam Computed Tomography (CBCT). Also, to assess joint space changes and the overall volumetric space compared to the preoperative status.

METHODOLOGY

This prospective study included 30 patients (60 joints) subjected to unilateral mandibular resection and reconstruction with preservation of the condylar head. The Helkimo index and preoperative (T1), two weeks postoperative (T2), and follow-up CBCTs (T3) after at least six months were gathered and processed to evaluate the condylar position and TMJ joint space using Anatomage Invivo 6. A student's t-test and repeated-measures ANOVA statistics were used. A P value of less than 0.05 was considered statistically significant.

RESULTS

Thirty patients (14 males, 16 females) with a mean age of 40.01 ± 12.7 years (a range of 18.1-62.9 years) were included. On the tumor side, there were significant variances in the vertical and mediolateral condylar positions between the three-time points (T1, T2, T3). Immediately after the operation, the condyles were significantly displaced in a downward direction at T2, which became larger after the last follow-up period (T3) (p = 0.007). The condylar positions at the anteroposterior direction were relatively stable without significant differences between the three times points (p = 0.915). On the non-tumor side, the condylar positions were relatively stable in the mediolateral and anteroposterior positions. In the tumor side, all of the TMJ spaces were significantly increased in size following the mandibular reconstructions (T2 and T3). However, on the non-tumor side, the anterior, posterior, and medial joint spaces were significantly changed postoperatively.

CONCLUSION

After mandibular reconstruction with condylar preservation, the condylar position and volumetric measurement immediately changed noticeably and continued to be a permanent change over time compared to relatively stable condyles on the non-tumor side. According to Helkimo index, patients become adapted to the postoperative changes without significant differences between the two sides.

Heterogeneity in the Utilization of Fecal Occult Blood Testing and Colonoscopy among Migrants and Non-Migrants in Austria: Results of the Austrian Health Interview Survey

Many European studies report lower participation in colorectal cancer screening among migrants than non-migrants. A major limitation of these studies is that usually, the heterogeneity of migrants cannot be accounted for. The aim of this investigation was to examine differences in the utilization of fecal occult blood testing and colonoscopy between non-migrants and the five largest migrant groups residing in Austria using data from the Austrian Health Interview Survey 2019. The two outcomes were compared between non-migrants and migrants using multivariable logistic regression adjusted for socioeconomic and health variables. Migrants from a Yugoslav successor state (OR = 0.61; 95%-CI: 0.44–0.83), Turkish (OR = 0.35; 95%-CI: 0.22–0.55), Hungarian (OR = 0.37; 95%-CI: 0.16–0.82) and German migrants (OR = 0.70; 95%-CI: 0.51–0.98) were less likely to have used a fecal occult blood test compared to non-migrants. Participation in colonoscopy was lower among Turkish migrants (OR = 0.42; 95%-CI: 0.27–0.67) and migrants from a Yugoslav successor state (OR = 0.56; 95%-CI: 0.42–0.75) than among non-migrants. The findings are consistent with studies from other countries and highlight barriers migrants face in accessing the health care system. To address these barriers, the heterogeneity of the population must be taken into account when developing educational materials in order to promote informed decisions about whether or not to participate in colorectal cancer screening.

Automated Assessment of Renal Calculi in Serial Computed Tomography Scans

An automated pipeline is developed for the serial assessment of renal calculi using computed tomography (CT) scans obtained at multiple time points. This retrospective study included 722 scans from 330 patients chosen from 8544 asymptomatic patients who underwent two or more CTC (CT colonography) or non-enhanced abdominal CT scans between 2004 and 2016 at a single medical center. A pre-trained deep learning (DL) model was used to segment the kidneys and the calculi on the CT scans at each time point. Based on the output of the DL, 330 patients were identified as having a stone candidate on at least one time point. Then, for every patient in this group, the kidneys from different time points were registered to each other, and the calculi present at multiple time points were matched to each other using proximity on the registered scans. The automated pipeline was validated by having a blinded radiologist assess the changes manually. New graph-based metrics are introduced in order to evaluate the performance of our pipeline. Our method shows high fidelity in tracking changes in renal calculi over multiple time points.

Advances in tests for colorectal cancer screening and diagnosis

INTRODUCTION

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths globally. Nonetheless, with early detection of CRC or its precancerous lesions, mortality, and CRC incidence can be reduced. Although colonoscopy is currently the gold standard for CRC screening and diagnosis, its invasive nature, and troublesome bowel preparation deter patient participation. Therefore, there is a need to expand the use of noninvasive or minimally invasive methods to increase patient compliance.

AREAS COVERED

This review summarizes advances in different methods for CRC screening, including stool bacterial and metagenomic markers, fecal proteins, genetic and epigenetic markers in blood and stools, and imaging modalities. The cost-effectiveness of these methods is also discussed. FIT is more cost-effective compared to virtual colonoscopy, mSEPT9 test, and Multitarget Stool DNA test, while the cost-effectiveness of other noninvasive methods requires further evaluation.

EXPERT OPINION

Recent evidence has well demonstrated the usefulness of gut microbiome and certain fecal bacterial markers in the noninvasive diagnosis of CRC and its precancerous lesions. Many of the fecal biomarkers, from host cells or the gut environment, show better diagnostic sensitivity than FIT. New screening tests based on these fecal biomarkers can be expected to replace FIT with higher cost-effectiveness in the near future.

Fully Automated Abdominal CT Biomarkers for Type 2 Diabetes Using Deep Learning

Background CT biomarkers both inside and outside the pancreas can potentially be used to diagnose type 2 diabetes mellitus. Previous studies on this topic have shown significant results but were limited by manual methods and small study samples. Purpose To investigate abdominal CT biomarkers for type 2 diabetes mellitus in a large clinical data set using fully automated deep learning. Materials and Methods For external validation, noncontrast abdominal CT images were retrospectively collected from consecutive patients who underwent routine colorectal cancer screening with CT colonography from 2004 to 2016. The pancreas was segmented using a deep learning method that outputs measurements of interest, including CT attenuation, volume, fat content, and pancreas fractal dimension. Additional biomarkers assessed included visceral fat, atherosclerotic plaque, liver and muscle CT attenuation, and muscle volume. Univariable and multivariable analyses were performed, separating patients into groups based on time between type 2 diabetes diagnosis and CT date and including clinical factors such as sex, age, body mass index (BMI), BMI greater than 30 kg/m², and height. The best set of predictors for type 2 diabetes were determined using multinomial logistic regression. Results A total of 8992 patients (mean age, 57 years ± 8 [SD]; 5009 women) were evaluated in the test set, of whom 572 had type 2 diabetes mellitus. The deep learning model had a mean Dice similarity coefficient for the pancreas of 0.69 ± 0.17, similar to the interobserver Dice similarity coefficient of 0.69 ± 0.09 (P = .92). The univariable analysis showed that patients with diabetes had, on average, lower pancreatic CT attenuation (mean, 18.74 HU ± 16.54 vs 29.99 HU ± 13.41; P < .0001) and greater visceral fat volume (mean, 235.0 mL ± 108.6 vs 130.9 mL ± 96.3; P < .0001) than those without diabetes. Patients with diabetes also showed a progressive decrease in pancreatic attenuation with greater duration of disease. The final multivariable model showed pairwise areas under the receiver operating characteristic curve (AUCs) of 0.81 and 0.85 between patients without and patients with diabetes who were diagnosed 0-2499 days before and after undergoing CT, respectively. In the multivariable analysis, adding clinical data did not improve upon CT-based AUC performance (AUC = 0.67 for the CT-only model vs 0.68 for the CT and clinical model). The best predictors of type 2 diabetes mellitus included intrapancreatic fat percentage, pancreatic fractal dimension, plaque severity between the L1 and L4 vertebra levels, average liver CT attenuation, and BMI. Conclusion The diagnosis of type 2 diabetes mellitus was associated with abdominal CT biomarkers, especially measures of pancreatic CT attenuation and visceral fat. © RSNA, 2022 Online supplemental material is available for this article.

A deep learning system for automated kidney stone detection and volumetric segmentation on noncontrast CT scans

PURPOSE

Early detection and size quantification of renal calculi are important for optimizing treatment and preventing severe kidney stone disease. Prior work has shown that volumetric measurements of kidney stones are more informative and reproducible than linear measurements. Deep learning-based systems that use abdominal noncontrast computed tomography (CT) scans may assist in detection and reduce workload by removing the need for manual stone volume measurement. Prior to this work, no such system had been developed for use on noisy low-dose CT or tested on a large-scale external dataset.

METHODS

We used a dataset of 91 CT colonography (CTC) scans with manually marked kidney stones combined with 89 CTC scans without kidney stones. To compare with a prior work half the data was used for training and half for testing. A set of CTC scans from 6185 patients from a separate institution with patient-level labels were used as an external validation set. A 3D U-Net model was employed to segment the kidneys, followed by gradient-based anisotropic denoising, thresholding, and region growing. A 13 layer convolutional neural network classifier was then applied to distinguish kidney stones from false positive regions.

RESULTS

The system achieved a sensitivity of 0.86 at 0.5 false positives per scan on a challenging test set of low-dose CT with many small stones, an improvement over an earlier work that obtained a sensitivity of 0.52. The stone volume measurements correlated well with manual measurements (r 2 = 0.95 $r^2 = 0.95$ ). For patient-level classification, the system achieved an area under the receiver-operating characteristic of 0.95 on an external validation set (sensitivity = 0.88, specificity = 0.91 at the Youden point). A common cause of false positives were small atherosclerotic plaques in the renal sinus that simulated kidney stones.

CONCLUSIONS

Our deep-learning-based system showed improvements over a previously developed system that did not use deep learning, with even higher performance on an external validation set.

Diagnostic accuracy of ultra-low-dose CT colonography for the detection of colorectal polyps: a feasibility study

PURPOSE

The aim of this feasibility study was to evaluate the diagnostic accuracy of ultra-low-dose CT colonography using iterative reconstruction algorithms with reference to standard colonoscopy.

MATERIALS AND METHODS

Prior to this study, a phantom study was performed to investigate the optimal protocol for ultra-low-dose CT colonography. A total of 206 patients with average/high risk of colorectal cancer were recruited. After undergoing full bowel preparation, the patients were scanned in the prone and supine positions with the CT conditions set to 120 kV, standard deviation 45 to 50, and an adaptive iterative reconstruction algorithm applied. Two expert readers read the images independently. The main outcome measures were the per-patient and per-polyp accuracies for the detection of polyps ≥ 10 mm, with colonoscopy results as the reference standard.

RESULTS

Two hundred patients (102 females, mean age 67.5 years) underwent both ultra-low-dose CT colonography and colonoscopy on the same day. The mean radiation exposure dose was 0.64 ± 0.34 mSv. On colonoscopy, 39 patients had 45 polyps ≥ 10 mm (non-polypoid morphology 7), including 4 cancers. Per-patient sensitivity, specificity, and accuracy of CT colonography for polyps ≥ 10 mm were 0.74, 0.96, and 0.92 for reader one, and 0.74, 0.99, and 0.94 for reader two, respectively. Per-polyp sensitivities for polyps ≥ 10 mm were 0.73 for reader one and 0.71 for reader two. On subgroup analysis by morphology, non-polypoid polyps ≥ 10 mm were not detected by both readers.

CONCLUSION

Extreme ultra-low-dose CT colonography had an insufficient diagnostic performance for the detection of polyps ≥ 10 mm, because it was unable to detect non-polypoid polyps. This study showed that the problem with ultra-low-dose CT colonography was the lack of detectability of small-size polyps, especially non-polypoid polyps. To use ultra-low-dose CT colonography clinically, it is necessary to resolve the problems identified by this study.

Can Computed Tomography Colonography Replace Optical Colonoscopy in Detecting Colorectal Lesions?: State of the Art

Colorectal cancer is an important cause of morbidity and mortality worldwide. Optical colonoscopy (OC) is widely accepted as the reference standard for the screening of colorectal polyps and cancers, and computed tomography colonography (CTC) is a valid alternative to OC. The purpose of this review was to assess the diagnostic accuracy of OC and CTC for colorectal lesions. A literature search was performed in PubMed, Embase, and Cochrane Library, and 18 articles were included. CTC has emerged in recent years as a potential screening examination with high accuracy for the detection of colorectal lesions. However, the clinical application of CTC as a screening technique is limited because it is highly dependent on the size of the lesions and has poor performance in detecting individual lesions <5 mm or flat lesions, which, although rarely, can have a malignant potential.

Colorectal Cancer: Performance and Evaluation for CT Colonography Screening- A Multicenter Cluster-randomized Controlled Trial

Background Most radiologists reporting CT colonography (CTC) do not undergo compulsory performance accreditation, potentially lowering diagnostic sensitivity. Purpose To determine whether 1-day individualized training in CTC reporting improves diagnostic sensitivity of experienced radiologists for 6-mm or larger lesions, the durability of any improvement, and any associated factors. Materials and Methods This prospective, multicenter cluster-randomized controlled trial was performed in National Health Service hospitals in England and Wales between April 2017 and January 2020. CTC services were cluster randomized into intervention (1-day training plus feedback) or control (no training or feedback) arms. Radiologists in the intervention arm attended a 1-day workshop focusing on CTC reporting pitfalls with individualized feedback. Radiologists in the control group received no training. Sensitivity for 6-mm or larger lesions was tested at baseline and 1, 6, and 12 months thereafter via interpretation of 10 CTC scans at each time point. The primary outcome was the mean difference in per-lesion sensitivity between arms at 1 month, analyzed using multilevel regression after adjustment for baseline sensitivity. Secondary outcomes included per-lesion sensitivity at 6- and 12-month follow-up, sensitivity for flat neoplasia, and effect of prior CTC experience. Results A total of 69 hospitals were randomly assigned to the intervention (31 clusters, 80 radiologists) or control (38 clusters, 59 radiologists) arm. Radiologists were experienced (median, 500-999 CTC scans interpreted) and reported CTC scans routinely (median, 151-200 scans per year). One-month sensitivity improved after intervention (66.4% [659 of 992]) compared with sensitivity in the control group (42.4% [278 of 655]; difference = 20.8%; 95% CI: 14.6, 27.0; P < .001). Improvements were maintained at 6 (66.4% [572 of 861] vs 50.5% [283 of 560]; difference = 13.0%; 95% CI: 7.4, 18.5; P < .001) and 12 (63.7% [310 of 487] vs 44.4% [187 of 421]; difference = 16.7%; 95% CI: 10.3, 23.1; P < .001) months. This beneficial effect applied to flat lesions (difference = 22.7%; 95% CI: 15.5, 29.9; P < .001) and was independent of career experience (≥1500 CTC scans: odds ratio = 1.09; 95% CI: 0.88, 1.36; P = .22). Conclusion For radiologists evaluating CT colonography studies, a 1-day training intervention yielded sustained improvement in detection of clinically relevant colorectal neoplasia, independent of previous career experience. Clinical trial registration no. NCT02892721 © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Pickhardt in this issue.

Contribution of Epithelial and Gut Microbiome Inflammatory Biomarkers to the Improvement of Colorectal Cancer Patients' Stratification

In order to ensure that primary endpoints of clinical studies are attained, the patients' stratification is an important aspect. Selection criteria include age, gender, and also specific biomarkers, such as inflammation scores. These criteria are not sufficient to achieve a straightforward selection, however, in case of multifactorial diseases, with unknown or partially identified mechanisms, occasionally including host factors, and the microbiome. In these cases, the efficacy of interventions is difficult to predict, and as a result, the selection of subjects is often random. Colorectal cancer (CRC) is a highly heterogeneous disease, with variable clinical features, outcomes, and response to therapy; the CRC onset and progress involves multiple sequential steps with accumulation of genetic alterations, namely, mutations, gene amplification, and epigenetic changes. The gut microbes, either eubiotic or dysbiotic, could influence the CRC evolution through a complex and versatile crosstalk with the intestinal and immune cells, permanently changing the tumor microenvironment. There have been significant advances in the development of personalized approaches for CRC screening, treatment, and potential prevention. Advances in molecular techniques bring new criteria for patients' stratification-mutational analysis at the time of diagnosis to guide treatment, for example. Gut microbiome has emerged as the main trigger of gut mucosal homeostasis. This may impact cancer susceptibility through maintenance of the epithelial/mucus barrier and production of protective metabolites, such as short-chain fatty acids (SCFAs) via interactions with the hosts' diet and metabolism. Microbiome dysbiosis leads to the enrichment of cancer-promoting bacterial populations, loss of protective populations or maintaining an inflammatory chronic state, all of which contribute to the development and progression of CRC. Meanwhile, variations in patient responses to anti-cancer immuno- and chemotherapies were also linked to inter-individual differences in intestine microbiomes. The authors aim to highlight the contribution of epithelial and gut microbiome inflammatory biomarkers in the improvement of CRC patients' stratification towards a personalized approach of early diagnosis and treatment.

Chinese consensus on prevention of colorectal neoplasia (2021, Shanghai)

Most patients with colorectal cancer (CRC) were diagnosed in advanced stage and the prognosis is poor. Therefore, early detection and prevention of CRC are very important. As with other cancers, there is also the tertiary prevention for CRC. The primary prevention is etiological prevention, which is mainly the treatment of adenoma or inflammation for preventing the development into cancer. The secondary prevention is the early diagnosis and early treatment for avoiding progressing to advanced cancer. The tertiary prevention belongs to the broad category of prevention, mainly for advanced CRC, through surgical treatment and postoperative adjuvant chemotherapy, radiotherapy, targeted therapy, immunotherapy for preventing tumor recurrence or metastasis. This consensus is based on the recent domestic and international consensus guidelines and the latest progress of international researches in the past five years. This consensus opinion seminar was hosted by the Chinese Society of Gastroenterology and Cancer Collaboration Group of Chinese Society of Gastroenterology, and was organized by the Division of Gastroenterology and Hepatology & Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University. The consensus opinion contains 60 statement clauses, the standard and basis of the evidence-based medicine grade and voting grade of the statement strictly complied with the relevant international regulations and practice.

Sequentially calibrating a Bayesian microsimulation model to incorporate new information and assumptions

BACKGROUND

Microsimulation models are mathematical models that simulate event histories for individual members of a population. They are useful for policy decisions because they simulate a large number of individuals from an idealized population, with features that change over time, and the resulting event histories can be summarized to describe key population-level outcomes. Model calibration is the process of incorporating evidence into the model. Calibrated models can be used to make predictions about population trends in disease outcomes and effectiveness of interventions, but calibration can be challenging and computationally expensive.

METHODS

This paper develops a technique for sequentially updating models to take full advantage of earlier calibration results, to ultimately speed up the calibration process. A Bayesian approach to calibration is used because it combines different sources of evidence and enables uncertainty quantification which is appealing for decision-making. We develop this method in order to re-calibrate a microsimulation model for the natural history of colorectal cancer to include new targets that better inform the time from initiation of preclinical cancer to presentation with clinical cancer (sojourn time), because model exploration and validation revealed that more information was needed on sojourn time, and that the predicted percentage of patients with cancers detected via colonoscopy screening was too low.

RESULTS

The sequential approach to calibration was more efficient than recalibrating the model from scratch. Incorporating new information on the percentage of patients with cancers detected upon screening changed the estimated sojourn time parameters significantly, increasing the estimated mean sojourn time for cancers in the colon and rectum, providing results with more validity.

CONCLUSIONS

A sequential approach to recalibration can be used to efficiently recalibrate a microsimulation model when new information becomes available that requires the original targets to be supplemented with additional targets.

Current and future colorectal cancer screening strategies

Despite strong evidence of effectiveness, colorectal cancer (CRC) screening remains underused. Currently, there are several options for CRC screening, each with its own performance characteristics and considerations for practice. This Review aims to cover current CRC screening guidelines and highlight future blood-based and imaging-based options for screening. In current practice, the leading non-invasive option is the faecal immunochemical test (FIT) based on its high specificity, good sensitivity, low cost and ease of use in mailed outreach programmes. There are currently five blood-based CRC screening tests in varying stages of evaluation, including one that is currently sold in the USA as a laboratory-developed test. There are ongoing studies on the diagnostic accuracy and longitudinal performance of blood tests and they have the potential to disrupt the CRC screening landscape. Imaging-based options, including the colon capsule, MR colonography and the CT capsule, are also being tested in active studies. As the world attempts to recover from the COVID-19 pandemic and adapts to the start of CRC screening among people at average risk starting at age 45 years, non-invasive options will become increasingly important.

Too Good to Be True? Evaluation of Colonoscopy Sensitivity Assumptions Used in Policy Models

BACKGROUND

Models can help guide colorectal cancer (CRC) screening policy. While models are carefully calibrated and validated, there is less scrutiny of assumptions about test performance.

METHODS

We examined the validity of the CRC-SPIN model and colonoscopy sensitivity assumptions. Standard sensitivity assumptions, consistent with published decision analyses, assume sensitivity equal to 0.75 for diminutive adenomas (<6mm), 0.85 for small adenomas (6-10mm), 0.95 for large adenomas ( {greater than or equal to} 10mm), and 0.95 for preclinical cancer. We also selected adenoma sensitivity that resulted in more accurate predictions. Targets were drawn from the Wheat Bran Fiber study. We examined how well the model predicted outcomes measured over a three-year follow-up period, including: the number of adenomas detected, the size of the largest adenoma detected, and incident CRC.

RESULTS

Using standard sensitivity assumptions, the model predicted adenoma prevalence that was too low (42.5% versus 48.9% observed, with 95% confidence interval 45.3%-50.7%) and detection of too few large adenomas (5.1% versus 14.% observed, with 95% confidence interval 11.8%-17.4%). Predictions were close to targets when we set sensitivities to 0.20 for diminutive adenomas, 0.60 for small adenomas, 0.80 for 10-20mm adenomas, and 0.98 for adenomas 20mm and larger.

CONCLUSIONS

Colonoscopy may be less accurate than currently assumed, especially for diminutive adenomas. Alternatively, the CRC-SPIN model may not accurately simulate onset and progression of adenomas in higher-risk populations.

IMPACT

Misspecification of either colonoscopy sensitivity or disease progression in high-risk populations may impact the predicted effectiveness of CRC screening. When possible, decision analyses used to inform policy should address these uncertainties.

Implications of colonic and extra-colonic findings on CT colonography in FIT positive patients in the Dutch bowel cancer screening program

OBJECTIVES

In the Dutch National colorectal cancer (CRC) screening program, patients with a positive faecal immunochemical test (FIT) are referred for a colonoscopy. In a small proportion, because of contraindications, a computed tomographic colonography (CTC) is performed to rule out advanced neoplasia. The aim of our study is to evaluate the intra- and extra-colonic yield of CTC and its clinical implications.

MATERIALS AND METHODS

In this retrospective cohort study, all FIT positive patients who underwent primary (instead of colonoscopy) or secondary CTC (after incomplete colonoscopy) between January 2014 and January 2018 were included. Relevant intra-colonic lesions on CTC were defined as lesions suspected for CRC or >10 mm. Relevant extra-colonic findings were defined as E3 and E4 using the E-RADS classification.

RESULTS

Of the 268 included patients, 66 (24.6%) were suspected to have CRC or 10 mm + lesion on CTC and 56 of them (84.8%) underwent an additional endoscopy. Another 20 patients with <10 mm lesions on CTC underwent additional endoscopy. Overall, 76/268 patients (28.4%) underwent confirmatory endoscopy of which 50 (18.7%) had histologic confirmed advanced neoplasia; 4.9% had CRC and 13.8% advanced adenoma. New relevant extra-colonic findings were detected in 13.8%.

CONCLUSIONS

In the Dutch National CRC screening program, a CTC was followed by an endoscopic procedure in more than a quarter of patients, resulting in a significant number of advanced neoplasia. Overall, one out of seven CTCs showed new relevant extra-colonic findings which may lead to further diagnostic/therapeutic work-up. Our results can be important for the informed consent procedure.

Colorectal Cancer Screening: Have We Addressed Concerns and Needs of the Target Population?

Despite the recognized benefits of colorectal cancer (CRC) screening, uptake is still suboptimal in many countries. In addressing this issue, one important element that has not received sufficient attention is population preference. Our review provides a comprehensive summary of the up-to-date evidence relative to this topic. Four OVID databases were searched: Ovid MEDLINE® ALL, Biological Abstracts, CAB Abstracts, and Global Health. Among the 742 articles generated, 154 full texts were selected for a more thorough evaluation based on predefined inclusion criteria. Finally, 83 studies were included in our review. The general population preferred either colonoscopy as the most accurate test, or fecal occult blood test (FOBT) as the least invasive for CRC screening. The emerging blood test (SEPT9) and capsule colonoscopy (nanopill), with the potential to overcome the pitfalls of the available techniques, were also favored. Gender, age, race, screening experience, education and beliefs, the perceived risk of CRC, insurance, and health status influence one’s test preference. To improve uptake, CRC screening programs should consider offering test alternatives and tailoring the content and delivery of screening information to the public’s preferences. Other logistical measures in terms of the types of bowel preparation, gender of endoscopist, stool collection device, and reward for participants can also be useful.

Fully Automated Deep Learning Tool for Sarcopenia Assessment on CT: L1 Versus L3 Vertebral Level Muscle Measurements for Opportunistic Prediction of Adverse Clinical Outcomes

BACKGROUND. Sarcopenia is associated with adverse clinical outcomes. CT-based skeletal muscle measurements for sarcopenia assessment are most commonly performed at the L3 vertebral level. OBJECTIVE. The purpose of this article is to compare the utility of fully automated deep learning CT-based muscle quantitation at the L1 versus L3 level for predicting future hip fractures and death. METHODS. This retrospective study included 9223 asymptomatic adults (mean age, 57 ± 8 [SD] years; 4071 men, 5152 women) who underwent unenhanced low-dose abdominal CT. A previously validated fully automated deep learning tool was used to assess muscle for myosteatosis (by mean attenuation) and myopenia (by cross-sectional area) at the L1 and L3 levels. Performance for predicting hip fractures and death was compared between L1 and L3 measures. Performance for predicting hip fractures and death was also evaluated using the established clinical risk scores from the fracture risk assessment tool (FRAX) and Framingham risk score (FRS), respectively. RESULTS. Median clinical follow-up interval after CT was 8.8 years (interquartile range, 5.1-11.6 years), yielding hip fractures and death in 219 (2.4%) and 549 (6.0%) patients, respectively. L1-level and L3-level muscle attenuation measurements were not different in 2-, 5-, or 10-year AUC for hip fracture (p = .18-.98) or death (p = .19-.95). For hip fracture, 5-year AUCs for L1-level muscle attenuation, L3-level muscle attenuation, and FRAX score were 0.717, 0.709, and 0.708, respectively. For death, 5-year AUCs for L1-level muscle attenuation, L3-level muscle attenuation, and FRS were 0.737, 0.721, and 0.688, respectively. Lowest quartile hazard ratios (HRs) for hip fracture were 2.20 (L1 attenuation), 2.45 (L3 attenuation), and 2.53 (FRAX score), and for death were 3.25 (L1 attenuation), 3.58 (L3 attenuation), and 2.82 (FRS). CT-based muscle cross-sectional area measurements at L1 and L3 were less predictive for hip fracture and death (5-year AUC ≤ 0.571; HR ≤ 1.56). CONCLUSION. Automated CT-based measurements of muscle attenuation for myosteatosis at the L1 level compare favorably with previously established L3-level measurements and clinical risk scores for predicting hip fracture and death. Assessment for myopenia was less predictive of outcomes at both levels. CLINICAL IMPACT. Alternative use of the L1 rather than L3 level for CT-based muscle measurements allows sarcopenia assessment using both chest and abdominal CT scans, greatly increasing the potential yield of opportunistic CT screening.