Uni- and bidirectional wide angle CT colonography: effect on missed areas, surface visualization, viewing time and polyp conspicuity

CT Colonography Reporting and Data System (C-RADS): Version 2023 Update

The CT Colonography Reporting and Data System (C-RADS) has withstood the test of time and proven to be a robust classification scheme for CT colonography (CTC) findings. C-RADS version 2023 represents an update on the scheme used for colorectal and extracolonic findings at CTC. The update provides useful insights gained since the implementation of the original system in 2005. Increased experience has demonstrated confusion on how to classify the mass-like appearance of the colon consisting of soft tissue attenuation that occurs in segments with acute or chronic diverticulitis. Therefore, the update introduces a new subcategory, C2b, specifically for mass-like diverticular strictures, which are likely benign. Additionally, the update simplifies extracolonic classification by combining E1 and E2 categories into an updated extracolonic category of E1/E2 since, irrespective of whether a finding is considered a normal variant (category E1) or an otherwise clinically unimportant finding (category E2), no additional follow-up is required. This simplifies and streamlines the classification into one category, which results in the same management recommendation.

Immersive Virtual Colonoscopy

Virtual colonoscopy (VC) is a non-invasive screening tool for colorectal polyps which employs volume visualization of a colon model reconstructed from a CT scan of the patient's abdomen. We present an immersive analytics system for VC which enhances and improves the traditional desktop VC through the use of VR technologies. Our system, using a head-mounted display (HMD), includes all of the standard VC features, such as the volume rendered endoluminal fly-through, measurement tool, bookmark modes, electronic biopsy, and slice views. The use of VR immersion, stereo, and wider field of view and field of regard has a positive effect on polyp search and analysis tasks in our immersive VC system, a volumetric-based immersive analytics application. Navigation includes enhanced automatic speed and direction controls, based on the user's head orientation, in conjunction with physical navigation for exploration of local proximity. In order to accommodate the resolution and frame rate requirements for HMDs, new rendering techniques have been developed, including mesh-assisted volume raycasting and a novel lighting paradigm. Feedback and further suggestions from expert radiologists show the promise of our system for immersive analysis for VC and encourage new avenues for exploring the use of VR in visualization systems for medical diagnosis.

Advances in CRC Prevention: Screening and Surveillance

Colorectal cancer (CRC) is among the most commonly diagnosed cancers and causes of death from cancer across the world. CRC can, however, be detected in asymptomatic patients at a curable stage, and several studies have shown lower mortality among patients who undergo screening compared with those who do not. Using colonoscopy in CRC screening also results in the detection of precancerous polyps that can be directly removed during the procedure, thereby reducing the incidence of cancer. In the past decade, convincing evidence has appeared that the effectiveness of colonoscopy as CRC prevention tool is associated with the quality of the procedure. This review aims to provide an up-to-date overview of recent efforts to improve colonoscopy effectiveness by enhancing detection and improving the completeness and safety of resection of colorectal lesions.

CT colonography interpretation: how to maximize polyp detection and minimize overcalling

This article outlines how to achieve maximum accuracy in interpreting CT colonography (CTC) regarding colonic findings. Interpreting extracolonic findings seen on CTC is a separate diagnostic task and will not be addressed in this article. While many interpretive pitfalls are in fact related to CTC techniques, this article focuses on issues that are related to interpretive knowledge and skills, avoiding in-depth discussions on CTC techniques. Principal methods and further tips for detecting possible polyp candidates and for confirming true soft-tissue polyps will be discussed. Specific points about optimizing interpretation strategies for difficult flat polyps including sessile serrated polyp will be raised. There are numerous interpretive pitfalls regarding the colonic interpretation of CTC. Knowledge of these pitfalls will shorten the learning curve and help achieve accurate reads.

Cap cuff-assisted colonoscopy versus standard colonoscopy for adenoma detection: a randomized back-to-back study

BACKGROUND AND AIMS

EndoCuff is a disposable device applied to standard colonoscopes to improve mucosal visualization. Randomized parallel trials have shown that EndoCuff increases the adenoma detection rate (ADR). The primary aim of this study was to compare the ADR between EndoCuff-assisted colonoscopies (EAC) and standard colonoscopies within a randomized back-to-back trial.

METHODS

This was a single-center randomized crossover study (NCT02374515) involving adult patients undergoing screening, surveillance, or diagnostic colonoscopy. Participants received back-to-back standard colonoscopies and EACs in a random order, performed by the same endoscopist. All polyps were excised, but only those proven at histology to be adenomas were considered for analysis.

RESULTS

From February 2015 to March 2016, a total of 288 patients were enrolled, and 274 were included in the per-protocol analysis. Compared with standard colonoscopies, EACs increased the ADR (29.6% vs 26.3%; P < .01) and the number of diagnosed adenomas (176 vs 129; P < .01), particularly in the left (73 vs 46; P < .01) and right sides of the colon (83 vs 63; P < .01). EAC increased the detection of adenomas <5 mm (129 vs 84; P < .01), but no difference was found with regard to larger lesions. In 7.3% of patients, findings of EndoCuff shortened the surveillance interval determined by standard colonoscopy findings. EndoCuff caused 7 mucosal erosions (2.5% of patients), requiring a mucosal adrenaline injection in 1 case.

CONCLUSIONS

The use of EndoCuff increases the number of identified adenomas, primarily small adenomas in the left and right sides of the colon. This increases the ADR and allows a better definition of the surveillance program. (Clinical trial registration number: NCT02374515.).

Recent Advances in Diagnostic Colonoscopy for Colorectal Cancer Screening: An Update for Radiologists

OBJECTIVE

Colonoscopy accuracy in detecting colorectal neoplasia is critical for colorectal cancer prevention but has been shown to be operator- and technology-dependent. This article will discuss several recent improvements in the technique and technology of colonoscopy.

CONCLUSION

More rigorous training and retraining programs, active monitoring of endoscopist technique and outcomes, and exclusion of poorly performing endoscopists are urgently needed to improve the ultimate efficacy of colorectal cancer screening programs.

Adenoma detection with Endocuff colonoscopy versus conventional colonoscopy: a multicentre randomised controlled trial

BACKGROUND AND AIMS

Colonoscopy is the current reference standard for the detection of colorectal neoplasia, but nevertheless adenomas remain undetected. The Endocuff, an endoscopic cap with plastic projections, may improve colonic visualisation and adenoma detection. The aim of this study was to compare the mean number of adenomas per patient (MAP) and the adenoma detection rate (ADR) between Endocuff-assisted colonoscopy (EAC) and conventional colonoscopy (CC).

METHODS

We performed a multicentre, randomised controlled trial in five hospitals and included fecal immonochemical test (FIT)-positive screening participants as well as symptomatic patients (>45 years). Consenting patients were randomised 1:1 to EAC or CC. All colonoscopies were performed by experienced colonoscopists (≥500 colonoscopies) who were trained in EAC. All colonoscopy quality indicators were prospectively recorded.

FINDINGS

Of the 1063 included patients (52% male, median age 65 years), 530 were allocated to EAC and 533 to CC. More adenomas were detected with EAC, 722 vs 621, but the gain in MAP was not significant: on average 1.36 per patient in the EAC group versus 1.17 in the CC group (p=0.08). In a per-protocol analysis, the gain was 1.44 vs 1.19 (p=0.02), respectively. In the EAC group, 275 patients (52%) had one or more adenomas detected versus 278 in the CC group (52%; p=0.92). For advanced adenomas these numbers were 109 (21%) vs 117 (22%). The adjusted caecal intubation rate was lower with EAC (94% vs 99%; p<0.001), however when allowing crossover from EAC to CC, they were similar in both groups (98% vs 99%; p value=0.25).

INTERPRETATION

Though more adenomas are detected with EAC, the routine use of Endocuff does not translate in a higher number of patients with one or more adenomas detected. Whether increased detection ultimately results in a lower rate of interval carcinomas is not yet known.

TRIAL REGISTRATION NUMBER

http://www.trialregister.nl Dutch Trial Register: NTR3962.

A feasibility study of unidirectional 240°-angle 3D CT colonography

In three-dimensional (3D) CT colonography (CTC), a wider viewing angle provides a larger field of view. The purpose of this study was to investigate the polyp detection rate and time efficiency of unidirectional 240°-angle 3D CTC compared with bidirectional 120°-angle CTC. CTC data sets of 40 patients were reviewed by two readers using the two methods. The unidirectional 240°-angle CTC showed a performance in polyp detection similar to the bidirectional 120°-angle CTC with improved time efficiency.

Comparison of diagnostic accuracy and interpretation times for a standard and an advanced 3D visualisation technique in CT colonography

OBJECTIVE

To compare the diagnostic accuracy of a standard bi-directional, three-dimensional (3D) CT colonography (CTC) fly-through (standard view, SV) with a unidirectional, 3D unfolding technique (panoramic view, PV).

METHODS

150 consecutive endoscopically-validated CTC patient datasets were retrospectively reviewed twice by two expert radiologists: first, with bidirectional SV, second, after 6-15 months, with unidirectional PV. Per-polyp sensitivities, percentage of visualised colonic mucosa, and reading times were calculated for both 3D visualisations. Results were tested for statistical significance by equivalence analysis for paired proportions and Student's paired t-test.

RESULTS

In 81 patients, 236 polyps (101 adenomas, 135 non-adenomas) were detected. Sensitivities for polyps ≤5 mm, 6-9 mm and ≥10 mm were 60.1% (113/188), 92.9% (26/28) and 95.0% (19/20) with bidirectional SV, and 60.6% (114/188), 96.4% (27/28) and 95.0% (19/20) with unidirectional PV. Overall sensitivity for adenomas was 86.1% and 84.2% for SV and PV. Both methods provided equivalent polyp detection, with an equivalence limit set at 5%. PV and SV visualised 98.9 ± 1.1% (97.0-99.9%) and 96.2 ± 2.3% (91.4-98.8%) of the colonic mucosa (p > 0.05). Mean interpretation time decreased from 14.6 ± 2.5 (9.2-22.8) minutes with SV to 7.5 ± 3.2 (5.0-14.4) using PV (p < 0.0001).

CONCLUSION

3D CTC interpretation using unidirectional PV is equally as accurate, but significantly faster than an interpretation based on bidirectional SV.

Comparison of accuracy and time-efficiency of CT colonography between conventional and panoramic 3D interpretation methods: an anthropomorphic phantom study

PURPOSE

To retrospectively compare the conventional three-dimensional (3D) interpretation method with the panoramic 3D method with regard to accuracy and time-efficiency in the detection of colonic polyps, using pig colonic phantoms as the standard of reference.

MATERIALS AND METHODS

One-hundred and sixty-two polyps were created in 18 pig colonic phantoms. CT colonography was performed with a 64-row detector CT scanner. Two-week interval reviews for the CTC image dataset with both the conventional and the panoramic 3D interpretation method were independently performed by three radiologists. The sensitivities of both methods were compared with the McNemar test. The mean interpretation time for each interpretation method was also assessed and compared with the Wilcoxon signed-rank test.

RESULTS

Compared with the conventional 3D method (0.96 for reader 1, 0.89 for reader 2, and 0.97 for reader 3), the panoramic method revealed comparable sensitivities (0.91 for reader 1, 0.86 for reader 2, and 0.93 for reader 3) (p>0.05). Interpretation time was significantly shorter with the panoramic method (115.1±32.7 s for reader 1, 229.7±72.2 s for reader 2, and 282.6±113.7 s for reader 3) than with the conventional method (218.9±59.9 s for reader 1, 379.4±117.0 s for reader 2, and 458.7±149.4 s for reader 3) for all readers (p<0.05).

CONCLUSION

Compared with the conventional 3D interpretation method, the panoramic 3D interpretation method shows improved time-efficiency and comparable sensitivity in the detection of colonic polyps.

Improving the accuracy of CTC interpretation: computer-aided detection

Computer-aided polyp detection aims to improve the accuracy of the colonography interpretation. The computer searches the colonic wall to look for polyplike protrusions and presents a list of suspicious areas to a physician for further analysis. Computer-aided polyp detection has developed rapidly in the past decade in the laboratory setting and has sensitivities comparable with those of experts. Computer-aided polyp detection tends to help inexperienced readers more than experienced ones and may also lead to small reductions in specificity. In its currently proposed use as an adjunct to standard image interpretation, computer-aided polyp detection serves as a spellchecker rather than an efficiency enhancer.