Introduction

The decision to stop biologic medication in Crohn’s Disease (CD) in apparent clinical remission is challenging. We investigated MR enterography (MRE) observations associated with future relapse.

Aims & Methods

49 CD patients discontinuing biologics due to clinical remission and undergoing MRE within 12-months prior, or 1-month after, were identified. Two blinded radiologists subjectively assessed small bowel disease presence/activity and disease length, wall-thickness, fat-wrapping [1] and sMARIA score [2]. 'Relapse' status was assigned based on full clinical records including patient symptoms, biochemistry, imaging and drug prescription. Per-patient analysis was performed using the most severely affected segment and groups were compared with Chi-Square and Wilcox test.

Results

Mean patient age was 30.1 (SD: 13.0, 19 female). Median follow-up was 55 months (6-110). Twenty-five (51%) had disease relapse (DR) and 24 (49%) no relapse (NDR). Sixteen of 24 (67%) and 15/25 (60%) of the NDR and DR respectively still had small bowel disease present on MRE prior to biologic cessation. This was subjectively deemed active in 10/15 (66%) DR vs just 5/16 (31%) of NDR. One patient was excluded from the quantitative analysis due to image artifacts. Maximum wall thickness in the most severely affected segment was the only MRE observation associated with subsequent relapse (Table 1).

Table 1		Relapse?		Difference
		No (N = 24)	Yes (N = 24)	p-value
Number of SB disease segments	0	8 (33%)	9 (38%)	0.88
	1	16 (67%)	13 (54%)
	>1	0 (0%)	2 (8%)
Maximum wall thickness, mm		5.4 [3.4; 6.6]	7.3 [6; 9.6]	0.01
Length of abnormal segment, cm		8 [6; 13]	14 [5; 23]	0.49
Segmental sMaRIA score		1 [1; 2]	1 [1; 2]	0.39
Fat wrap	Absent	13 (54%)	8 (33%)	0.11
	Present	4 (17%)	10 (42%)

Conclusion

Simple presence or absence of residual small bowel abnormality does not in itself predict future relapse. However, in those with residual disease, simple bowel wall thickness is greater in those who relapse and may be a simple tool to guide the decision to discontinue biologic medication.

References

[1] Makanyanga, J. C.. Evaluation of Crohn’s disease activity: Initial validation of a magnetic resonance enterography global score (MEGS) against faecal calprotectin. European Radiology 24, 277–287 (2014).

[2] Ordás, I.. Development and Validation of a Simplified Magnetic Resonance Index of Activity for Crohn’s Disease. Gastroenterology 157, 432–439.e1 (2019).

Disclosure

H E Fitzke has ongoing research collaborations with Motilent, the medical imaging analysis company who develop the image analysis tools and previously received funding from the BBSRC to undertake two internships with Motilent. S A Taylor has ongoing research collaborations and holds share options in Motilent.

Introduction

Motorized spiral enteroscopy (MSE) has shown to be safe and effective for deep small bowel enteroscopy in patients with and without prior abdominal surgery, including patients with Crohn’s disease.
This case series reports our first results regarding the feasibility and safety of the MSE with endoscopic balloon dilatation in patients with small bowel strictures due to Crohn’s disease.

Aims & Methods

Data were collected retrospectively on patients who underwent MSE for endoscopic balloon dilatation of small bowel strictures due to Crohn’s disease. Strictures were either postoperative (P.O.) or post-inflammatory (P.I.).

Results

A total of ten consecutive patients with Crohn’s disease underwent 13 procedures. Propofol sedation without endotracheal intubation was used in all procedures. Demographic and procedure related data are shown in the table. One patient underwent three procedures with 3–4 month intervals. During the third procedure triamcinolone acetonide was injected at four quadrants of the stricture. Fluorescence imaging was used during six procedures. The procedure was technically successful in 12/13 of procedures. In one case, dilatation was not performed because of a longer than anticipated and a sharply angulated stricture.
The number of treated strictures ranged from one to five per procedure. Dilatation of multiple strictures in two patients (4 and 5) was achieved within a relatively short procedure duration of 55 and 70 minutes. Two retained video capsules were retrieved.
Besides the anticipated mild abdominal discomfort and/or sore throat in three patients, no adverse events occurred.

	Patients (age/F/M)	Type stenosis	Procedure route	No. of strictures/ Location (cm)		Maximal dilatation (mm)	Procedure duration (min)	Fluorescence imaging (+/-)
1	44/M	P.O	Antegrade	1/ 200 cm from Treitz		15/18/18 *	50/45/40*	+/+/-
2	54/F	P.I. and VCE retention	Ante-/retrograde	4/ 300 cm from Treitz/ 150 cm from ICV		15	70	+
3	56/F	Mixed	Antegrade	5/ 150-180 cm from Treitz		18	55	-
4	25/M	P.I. and VCE retention	Antegrade	1/ 100 cm from Treitz		18	35	+
5	26/M	P.O.	Ante-/retrograde	1/ 120 cm from Treitz/280 cm from ICV		18 mm via retrograde route	45	-
6	23/F	P.O.	Ante-/retrograde	1/ 450 cm from Treitz/ 50 cm from ICV		15 mm of ileo-ileal anastomosis (pinpoint)	80	+
7	33/M	P.O.	Ante-/retrograde	1/ 350 cm from Treitz /100 cm from ICV		18 mm via retrograde	60	-
8	52/M	P.O.	Antegrade	1/ 200		18	30	-
9	50/F	P.I.	Retrograde	1/ 100		18	30	+

*= 3 Procedures; P.O= Postoperative; P.I= Post-inflammatory; VCE= Video capsule endoscope; ICV= Ileocecal valve
NB: data on patient number 10 is not shown in the table because of the limited number of rows (10) allowed. No dilatation was done.

Conclusion

These retrospective data show that MSE with CRE dilatation is feasible and safe in a cohort of patients with strictures due to Crohn’s disease, postoperatively as well as post-inflammatory. The fact that the distal 16 cm of the endoscope are not covered by the spiral overtube makes cautious introduction of the endoscope beyond a recently dilated stricture feasible and safe. Therefore, dilatation of multiple strictures in one session is possible, provided that they are at a short distance from each other. Fluorescence imaging guidance may be helpful in severe stenosis, multiple strictures, or sharp angulations.

Introduction

To evaluate the utility of the unroofing technique in the diagnosis of gastrointestinal subepithelial tumors (SETs), we performed a multicenter retrospective study.

Aims & Methods

This study was conducted in 10 hospitals and involved all eligible patients who underwent unroofing techniques to gain biopsy for gastrointestinal SETs between April 2015 and March 2021. The primary endpoint was the rate of correct diagnosis with the unroofing technique, and the secondary endpoints were the incidence of adverse events and the factors contributing to the correct diagnosis.

Results

The study included 61 patients with 61 gastrointestinal SETs, a median tumor size of 20 mm, and a median procedure time of 38 minutes with 82% successful tumor exposure. The rate of tissue acquisition was 98.4%, and the rate of pathological diagnosis was 72.1%. In 44 cases with a pathological diagnosis, two showed discrepancies with the postresection pathological diagnosis. No factors, including facility experience, organ, tumor size, or tumor exposure, significantly affected the correct diagnosis. No significant differences in the correct diagnosis rate were observed between less than ten experiences and more than ten experiences (74.1 vs. 70.6%). The correct diagnosis rates for tumors <20 mm and ≥20 mm were 76.9% and 65.7%, respectively. There was one case of delayed bleeding and two cases of perforations.

Conclusion

The diagnostic yield of the unroofing technique was acceptable. The unroofing technique was beneficial regardless of institutional experience, organ, tumor size, or actual tumor exposure.

Introduction

Long-term outcomes of gastric subepithelial lesions have not been elucidated. To reveal the natural history, we initiated a prospective, 10-year follow-up of patients with small (≤20 mm) gastric subepithelial lesions in September 2014. Here, we report the results of an interim analysis of a prospective observational study.

Aims & Methods

In total, 567 patients with 609 lesions were prospectively registered between September 2014 and August 2016. The location, size, morphology, and number of subepithelial lesions were recorded on a web-based case report form.

Results

The endoscopic follow-up period was 4.60 ± 1.73 years (mean ± SD), and survival data were investigated for 5.28 ± 1.68 years. This interim analysis revealed that the estimated cumulative incidence of a size increase ≥5 mm, after accounting for patients’ death and resection of the tumor as competing risk events, was 4.5%. In addition, the estimated cumulative incidence of lesion size increase ≥5 mm or resection of lesions was 7.7% at 5 years, and that of size increase ≥10 mm or resection of lesions was 4.3% at 5 years.

Conclusion

These results indicate that approximately one in 13 patients with small (≤20 mm) gastric subepithelial lesions may require resection or further investigation for increased tumor size (≥5 mm) within five years under active surveillance.

References

Nishida T, Hirota S, Yanagisawa A et al. Clinical practice guidelines for gastrointestinal stromal tumor (GIST) in Japan: English version. Int J Clin Oncol 2008; 13: 416-30.

Disclosure

This study has been conducted as an Academic Committee Working Group of the Japan Gastroenterological Endoscopy Society.

Introduction

We have focused on the morphology of subepithelial tumors (SETs) and examined the possibility of noninvasive differentiation method based on differences in tumor morphology on endoscopic ultrasonography (EUS) still images. In a previous study, we found that leiomyoma has a lower circularity (4π×area/perimeter²; range = 0-1, 1 = a true circle) on EUS images than gastrointestinal stromal tumor (GIST) and schwannoma in lesions ≥2 cm, and that two-dimensional morphological evaluation was useful for the differentiation of gastrointestinal mesenchymal tumors (GIMTs) (Koizumi E, et al. Digestion 2022). In this study, we performed an interim analysis of the prospective study to assess the validity of this concept including lesions ≥1 cm, and further examined the feasibility of three-dimensional evaluation by measuring sphericity (a surface area of a sphere having the same volume as the object divided by a surface area of the object; range = 0-1, 1 = a true sphere) by using CT images.

Aims & Methods

For 54 cases of 1-5 cm gastric GIMTs with pathological diagnosis accumulated at two institutions from 2020 to the present, one representative EUS image, which showed a maximum cross-sectional surface of tumors, was selected. Two endoscopists who were blind to the histology of lesions independently measured the circularity three times per image by using an image analyzing software, and an average of six values in total was defined as individual circularity of each lesion for the analysis. Then, circularity of the leiomyoma group and the GIST + schwannoma group were compared, and the diagnostic performance at the optimal cutoff value was evaluated. Additionally, in four GIMT cases that had undergone thin-slice CT before the tissue sampling, we attempted to construct the lesion in three-dimensional image and measure the sphericity.

Results

The number of cases of leiomyoma/GIST/schwannoma were 8/42/4, respectively, and the mean tumor diameter was 14/22/25 mm, respectively. The circularity of the leiomyoma group was significantly lower than that of the GIST+ schwannoma group (0.83 vs. 0.90, p = 0.005), with a cutoff value of 0.92 and the highest diagnostic rate of 63% (area under the curve = 0.80, sensitivity 57%, specificity 100%). In addition, sphericity could be measured in all four cases in which three-dimensional evaluation was performed (one leiomyoma case and three GIST cases), and the mean value of calculated sphericity was 0.84.

Conclusion

The interim analysis suggested that two-dimensional morphological evaluation of SETs would be useful for differentiating leiomyoma even in small lesions by using the circularity assessment. It was also possible to construct a three-dimensional structure, which could more adequately represent the overall shape and expected more precise morphological evaluation by using the sphericity evaluation.

Introduction

Recently, artificial intelligence (AI)-based diagnostic support tools for early gastric cancer have been developed and reported to be superior to endoscopists (accuracy: 70% and sensitivity: 85%).¹ However, These tools could not guarantee reliable diagnostic accuracy in clinical practice. In previous reports, magnifying endoscopy has been recognized as superior to white-light imaging endoscopy for endoscopic diagnosis of early gastric cancers. Therefore, we developed an AI-based diagnostic support system using magnifying endoscopy with narrow band imaging (M-NBI) for early gastric cancers² and improved its application in clinical practice using nondegraded images obtained from selective depth inspection (SDI) output for real-time diagnosis. This study is the first to create an AI-based diagnostic support system using non-degraded M-NBI images obtained from SDI output, as several previous papers have analyzed damaged M-NBI images that were converted from various recording devices.^3,4

Aims & Methods

We built a new AI system (M-NBI AI) which was assembled using four different image recognition models with non-degraded M-NBI images (normal mucosa:1776 images, gastric cancers: 1947 images, and non-neoplastic lesions: 2451 images). We evaluated the performance of this M-NBI AI for diagnosis of early gastric cancer. The diagnostic performances of M-NBI AI and endoscopists (five specialists and five non-specialists) were compared using non-degraded M-NBI images (three images per lesion) of 50 early gastric cancer and 50 non-cancerous lesions. Early gastric cancers included histopathological types of well, moderately, and poorly differentiated adenocarcinomas and signet-ring cell adenocarcinomas. The primary outcome was the superiority of the M-NBI AI (based on accuracy) over the endoscopists. The secondary outcome was the superiority of the M-NBI AI (based on sensitivity) over the endoscopists.

Results

	M-NBI AI	Endoscopists
		Specialists	Non-specialists
Accuracy, % (95% CI)	87.0 (0.80–0.94)	80.0 (0.72–0.88)	71.0 (0.62–0.79)
Sensitivity, % (95% CI)	86.3 (0.77–0.96)	74.2 (0.63–0.85)	70.6 (0.58–0.83)
Specificity, % (95% CI)	88.0 (0.79–0.97)	89.0 (0.80–0.99)	71.0 (0.59–0.84)
PPV, % (95% CI)	88.0 (0.79–0.97)	92.0 (0.84–0.99)	72.0 (0.60–0.84)
NPV, % (95% CI)	86.0 (0.76–0.96)	68.0 (0.55–0.81)	70.0 (0.57–0.83)
PPV, positive predictive value; NPV, negative predictive value

The M-NBI AI was superior to the non-specialists based on accuracy (87.0%, 95%CI: 0.80–0.94 versus 71.0 %, 95%CI: 0.62–0.79; p<0.01), without being superior to the specialists (87.0%, 95%CI: 0.80–0.94 versus 80.0%, 95%CI: 0.72–0.88; p=0.18). The M-NBI AI was superior to the specialists and non-specialists based on sensitivity (86.3%, 95%CI: 0.77–0.96 versus 74.2%, 95%CI: 0.63–0.85 and 70.6%, 95%CI: 0.58–0.83; p<0.05, respectively).

Conclusion

The M-NBI AI was created as a new AI system that could be implemented for current endoscopy systems as a real-time diagnostic support tool for early gastric cancers. It demonstrated a robust performance and may indicate equalization of diagnostic accuracy and superadded effect over the white-light endoscopy for diagnosis of early gastric cancers in clinical practice.

References

1. Ishioka M et al. Dig Endosc. 2022. doi: 10.1111/den.14455.
2. Ueyama H et al. J Gastroenterol Hepatol. 2021;36(2):482-489.
3. Horiuchi Y et al. Dig. Dis. Sci. 2020;65:1355–1363.
4. He X et al. Gastrointest Endosc. 2022;95(4):671-678.

Introduction

In recent years, there has been a surge in the development of artificial intelligence (AI) systems for endoscopic applications, such as Barrett’s neoplasia detection and polyp characterization. While these systems have shown promising results, the vast majority is trained and validated on small, retrospective, single-center or expert-acquired data sets. Current AI systems are particularly prone to a so-called domain-shift: a system only performs well on data it has been trained on. As real-world scenarios in the endoscopy suite can be complex and diverse, the risk of poor generalization of AI should not be underestimated.

Aims & Methods

In this study we aim to provide a quantitative analysis of this domain shift and propose several strategies to improve generalization to clinical practice. We trained three AI systems for commonly used applications in gastrointestinal endoscopy, using publicly available data sets with high quality standards. In order to identify the limitations of these systems, all test sets were artificially degraded in a stepwise manner with clinically prevalent artifacts: blur, inadequate exposure and color variability. These degradations represent the heterogeneity of image quality in daily clinical practice. Severity of degradation was clinically calibrated by a panel of expert endoscopists. Two levels of degradation were identified: 1) mild degradation, still considered as high quality data; 2) moderate degradation, considered as image quality that could still be encountered in daily clinical practice. The trained models were subsequently evaluated for their appropriate performance metrics on the gradually degraded test sets. After implementation of several training strategies to mitigate potential performance loss, the models were re-evaluated on the same test sets.

Results

All three models display a considerable decrease in performance when exposed to various types of clinically relevant image degradation. Mean loss was 7.4% and 16.6% for respective mild and moderate degradation. Implementation of specific training strategies to improve robustness resulted in substantial reduction of performance loss on all degraded test sets.

Conclusion

This study highlights the potential limitations of current AI systems in endoscopic applications which may lead to poor generalization. Specific training strategies can mitigate this risk and improve robustness of these systems. Development of robust and reliable AI systems that deliver consistent and accurate performance is crucial to ensure safe implementation into daily clinical practice.