Exploratory investigation of virtual lesions in gastrointestinal endoscopy using a novel phase-shift method for three-dimensional shape measurement.

Accurate measurement of the size of lesions or distances between any two points during endoscopic examination of the gastrointestinal tract is difficult owing to the fisheye lens used in endoscopy. To overcome this issue, we developed a phase-shift method to measure three-dimensional (3D) data on a curved surface, which we present herein. Our system allows the creation of 3D shapes on a curved surface by the phase-shift method using a stripe pattern projected from a small projecting device to an object. For evaluation, 88 measurement points were inserted in porcine stomach tissue, attached to a half-pipe jig, with an inner radius of 21 mm. The accuracy and precision of the measurement data for our shape measurement system were compared with the data obtained using an Olympus STM6 measurement microscope. The accuracy of the path length of a simulated protruded lesion was evaluated using a plaster model of the curved stomach and graph paper. The difference in height measures between the measurement microscope and measurement system data was 0.24 mm for the 88 measurement points on the curved surface of the porcine stomach. The error in the path length measurement for a lesion on an underlying curved surface was <1% for a 10-mm lesion. The software was developed for the automated calculation of the major and minor diameters of each lesion. The accuracy of our measurement system could improve the accuracy of determining the size of lesions, whether protruded or depressed, regardless of the curvature of the underlying surface.

Comparison of Effective Imaging Modalities for Detecting Gastric Neoplasms: A Randomized 3-Arm Phase II Trial.

INTRODUCTION: The early detection of gastric neoplasms (GNs) leads to favorable treatment outcomes. The latest endoscopic system, EVIS X1, includes third-generation narrow-band imaging (3G-NBI), texture and color enhancement imaging (TXI), and high-definition white-light imaging (WLI). Therefore, this randomized phase II trial aimed to identify the most promising imaging modality for GN detection using 3G-NBI and TXI. METHODS: Patients with scheduled surveillance endoscopy after a history of esophageal cancer or GN or preoperative endoscopy for known esophageal cancer or GN were randomly assigned to the 3G-NBI, TXI, or WLI groups. Endoscopic observations were performed to detect new GN lesions, and all suspected lesions were biopsied. The primary endpoint was the GN detection rate during primary observation. Secondary endpoints were the rate of missed GNs, early gastric cancer detection rate, and positive predictive value for a GN diagnosis. The decision rule had a higher GN detection rate between 3G-NBI and TXI, outperforming WLI by >1.0%. RESULTS: Finally, 901 patients were enrolled and assigned to the 3G-NBI, TXI, and WLI groups (300, 300, and 301 patients, respectively). GN detection rates in the 3G-NBI, TXI, and WLI groups were 7.3, 5.0, and 5.6%, respectively. The rates of missed GNs were 1.0, 0.7, and 1.0%, the detection rates of early gastric cancer were 5.7, 4.0, and 5.6%, and the positive predictive values for the diagnosis of GN were 36.5, 21.3, and 36.8% in the 3G-NBI, TXI, and WLI groups, respectively. DISCUSSION: Compared with TXI and WLI, 3G-NBI is a more promising modality for GN detection.

Prospective multicenter trial of the cryoballoon ablation system for superficial esophageal squamous cell carcinoma on the post-endoscopic resection scar. A CRYO-SCAR study (EPOC1902).

BACKGROUND AND AIMS: Endoscopic resection (ER) is a minimally invasive treatment for superficial esophageal squamous cell carcinoma (SESCC). Post-ER scars complicate en bloc resection, even with advanced techniques, such as endoscopic submucosal dissection. The cryoballoon ablation system (CBAS) effectively manages Barrett's esophagus but has limited evidence in SESCC treatment, particularly on post-ER scars. This study aimed to evaluate the efficacy and safety of the CBAS for treating SESCC on post-ER scars. METHODS: This prospective study was conducted at two tertiary referral centers in Japan in patients endoscopically diagnosed with T1a SESCC on the post-ER scar. Focal CBAS was used for cryoablation, with specific criteria for lesion selection and treatment method. The primary endpoint was local complete response (L-CR) rate of the primary lesion 48 weeks after the first cryoablation as evaluated by an independent central evaluation committee. RESULTS: From October 2020 to October 2021, 15 patients with 17 lesions underwent cryoablation, with two requiring repeat cryoablation. The L-CR rate for primary and all lesions evaluated by the central evaluation committee was 100%. The endoscopist's evaluation was consistent with these results. The median procedure time was 9 min. Eight patients experienced no pain, and the highest pain score reported on a numeric 1-10 rating scale was 3. The technical success rate was 94.7% (18/19). Throughout the median follow-up period of 14.3 months, recurrences, deaths, or severe treatment-related adverse events were not reported. CONCLUSIONS: CBAS is a potentially safe and effective approach for SESCC on post-ER scars and represents an encouraging alternative to traditional endoscopic treatments.

Long-term outcomes after non-curative endoscopic resection for esophageal squamous cell carcinoma followed by additional chemoradiotherapy.

Endoscopic resection (ER) of esophageal squamous cell carcinoma (ESCC) is evaluated pathologically, and additional treatment is recommended for cases resulting in non-curative resection, defined as pMM with lymphovascular invasion (LVI), pSM, or positive vertical margin. This study aimed to assess long-term outcomes and risk factors for recurrence in patients with ESCC treated with non-curative ER followed by additional chemoradiotherapy (CRT). We retrospectively reviewed the clinical courses of patients who underwent non-curative ER followed by additional CRT for ESCCs between August 2007 and December 2017. Recurrence rates and risk factors for recurrence were analyzed. Among 97 patients with non-curative ER, 73 underwent additional CRT. With a median follow-up period of 71 months, recurrences were observed in 10 (14%) of 73 patients, with a median interval of 24.5 (1-59 months). The 3- and 5-year recurrence-free survival were 89 and 85%, respectively, and the 3- and 5-year overall survival rates were 96 and 91%, respectively. Multivariate analysis showed that lymphatic invasion was an independent risk factor for recurrence in patients with non-curative ESCC receiving additional CRT. Among the 10 patients with recurrence, 4, 3, 2, and 1 underwent surgery, chemotherapy, supportive care, and CRT, respectively. Notably, all four patients who underwent surgery survived, regardless of regional and/or distant lymph node metastasis. Lymphatic invasion is an independent risk factor for the recurrence of non-curative ESCCs. Careful follow-up is required for at least 5 years after ER with additional CRT.

Complications of endoscopic resection in the upper gastrointestinal tract.

Endoscopic resection (ER) is widely utilized as a minimally invasive treatment for upper gastrointestinal tumors; however, complications could occur during and after the procedure. Post-ER mucosal defect leads to delayed perforation and bleeding; therefore, endoscopic closure methods (endoscopic hand-suturing, the endoloop and endoclip closure method, and over-the-scope clip method) and tissue shielding methods (polyglycolic acid sheets and fibrin glue) are developed to prevent these complications. During duodenal ER, complete closure of the mucosal defect significantly reduces delayed bleeding and should be performed. An extensive mucosal defect that comprises three-quarters of the circumference in the esophagus, gastric antrum, or cardia is a significant risk factor for post-ER stricture. Steroid therapy is considered the first-line option for the prevention of esophageal stricture, but its efficacy for gastric stricture remains unclear. Methods for the prevention and management of ER-related complications in the esophagus, stomach, and duodenum differ according to the organ; therefore, endoscopists should be familiar with ways of preventing and managing organ-specific complications.

Clinical and endoscopic features of metachronous gastric cancer with possible lymph node metastasis after endoscopic submucosal dissection and Helicobacter pylori eradication.

BACKGROUND: Several studies have reported the metachronous gastric cancers (MGCs) with possible lymph node metastasis (LNM) after endoscopic submucosal dissection (ESD) and Helicobacter pylori (H. pylori) eradication in which a curative ESD had not been achieved. There have been no published reports of evaluations of the features of patients with MGC with possible LNM after ESD and H. pylori eradication. METHODS: We identified 264 patients with 369 MGCs after H. pylori eradication among the 4354 patients with 5059 early gastric cancers (EGCs) who underwent ESD between 1999 and 2017 and divided them into two groups: patients with MGCs with possible LNM (Group I) and patients with MGCs undergone curative ESD (Group II). We retrospectively compared the features of patients with MGCs and patients with EGCs at index ESD in the two groups. RESULT: Group I consisted of 20 patients with 21 MGCs, and Group II consisted of 244 patients with 348 MGCs. Group I lesions were significantly more common in the posterior wall than in the lesser curvature (odds ratio [OR] = 3.97; 95% confidence intervals [CI] 1.20-13.10). Development of Group I was significantly more common in patients with a body mass index (BMI) < 19.0 kg/m2 than in patients with a BMI ≥ 19.0 kg/m2 at index ESD (OR = 4.44; 95% CI 1.30-15.20). CONCLUSIONS: During surveillance endoscopy after gastric ESD and H. pylori eradication, the posterior wall should be carefully examined to detect MGCs early. Lower BMI may be associated with the development of MGCs with possible LNM.

Clinical course and management of adverse events after endoscopic resection of superficial duodenal epithelial tumors: Multicenter retrospective study.

OBJECTIVES: This study aimed to elucidate the clinical course and management of adverse events (AEs) after endoscopic resection (ER) for superficial duodenal epithelial tumors (SDETs). METHODS: Consecutive patients who underwent ER of SDETs between January 2008 and July 2018 at 18 Japanese institutions were retrospectively enrolled. The study outcomes included the clinical course, management, and risk of surgical conversion with perioperative AEs after ER for SDETs. RESULTS: Of the 226 patients with AEs, the surgical conversion rate was 8.0% (18/226), including 3.7% (4/108), 1.0% (1/99), and 50.0% (12/24) of patients with intraoperative perforation, delayed bleeding, or delayed perforation, respectively. In the multivariate logistic analysis, involvement of the major papilla (odds ratio [OR] 12.788; 95% confidence interval [CI] 2.098-77.961, P = 0.006) and delayed perforation (OR 37.054; 95% CI 10.219-134.366, P < 0.001) were significant risk factors for surgical conversion after AEs. Delayed bleeding occurred from postoperative days 1-14 or more, whereas delayed perforation occurred within 3 days in all cases. CONCLUSIONS: The surgical conversion rate was higher for delayed perforation than those for other AEs after ER of SDETs. Involvement of the major papilla and delayed perforation were significant risk factors for surgical conversion following AEs. In addition, reliable prevention of delayed perforation is required for 3 days after duodenal ER to prevent the need for surgical interventions.

Characteristics of synchronous and metachronous duodenal tumors and association with colorectal cancer: a supplementary analysis.

BACKGROUND: We previously reported outcomes of endoscopic resection for duodenal tumors in a large cohort. This study investigated the frequency and characteristics of synchronous and metachronous lesions, and their association with colorectal advanced adenoma (CAA) and colorectal cancer (CRC). METHODS: Patients underwent duodenal endoscopic resection during January 2008 to December 2018. Background and characteristics, incidence of synchronous and metachronous lesions, and incidence of CAA and CRC were investigated. Patients without synchronous lesions were classified as the single group, and those with synchronous lesions as the synchronous group. Patients were also classified as the metachronous and non-metachronous groups. The characteristics among the groups were compared. RESULTS: We included 2658 patients with 2881 duodenal tumors: 2472 (93.0%) patients had single, 186 (7.0%) had synchronous, and 54 (2.0%) had metachronous lesions. The 5-year cumulative incidence of metachronous lesions was 4.1%. In total, 208 (7.8%) had CAA and 127 (4.8%) patients had CRC, and colonoscopy was performed in 936 (35.2%) patients. The incidence of CAA in the synchronous groups tended to be higher compared with that in the single groups (11.8% vs 7.5%, adjusted risk ratio 1.56), and the incidence of CRC in the metachronous groups tended to be higher compared with that in the non-metachronous groups (13.0% vs 4.6%, adjusted risk ratio 2.75), but there was no difference after adjusting for colonoscopy. CONCLUSIONS: This study showed the incidence of synchronous and metachronous duodenal lesions. There was no significant difference in incidence of CAA and CRC among each group, but further studies are warranted.

Oncologic significance of lymphovascular invasion in patients with superficial esophageal squamous cell carcinoma reaching the muscularis mucosae or with slight invasion of the submucosa.

BACKGROUND: The clinicopathological features and the distribution of lymph node metastasis in patients with T1a-MM and T1b-SM1 superficial esophageal squamous cell carcinoma remain unclear; therefore, the optimal treatment strategy is still controversial. METHODS: One hundred and ninety-one patients who had undergone a thoracic esophagectomy with 3-field lymphadenectomy and who were pathologically confirmed to have thoracic superficial esophageal squamous cell carcinoma that had reached the T1a-MM or T1b-SM1 stage were retrospectively reviewed. Risk factors of lymph node metastasis, the distribution of lymph node metastasis, and long-term outcomes were evaluated. RESULTS: A multivariate analysis revealed that lymphovascular invasion was the only independent risk factor of lymph node metastasis (odds ratio: 6.410, P < .001). Patients with primary tumors in the middle thoracic region had lymph node metastasis in all 3 fields, whereas patients with primary tumors in the upper or lower thoracic region did not have distant lymph node metastasis. The frequencies of neck (P = .045) and abdominal (P < .001) lymph node metastasis were significantly higher in lymphovascular invasion-positive patients than those in lymphovascular invasion-negative patients in all cohort. MM/lymphovascular invasion-positive patients with middle thoracic tumors had lymph node metastasis spread from the neck to the abdomen. SM1/lymphovascular invasion-negative patients with middle thoracic tumors did not have lymph node metastasis in the abdominal region. The SM1/pN+ group had a significantly poorer overall survival and relapse-free survival than the other groups. CONCLUSION: The present study revealed that lymphovascular invasion was associated with not only the frequency of lymph node metastasis, but also the distribution of lymph node metastasis. It also suggested that superficial esophageal squamous cell carcinoma patients with T1b-SM1 and lymph node metastasis had a significantly poorer outcome than those with T1a-MM and lymph node metastasis.

Endoscopic Resection of Undifferentiated Early Gastric Cancer.

Endoscopic resection (ER) is widely performed for early gastric cancer (EGC) with a negligible risk of lymph node metastasis (LNM) in Eastern Asian countries. In particular, endoscopic submucosal dissection (ESD) leads to a high en bloc resection rate, enabling accurate pathological evaluation. As undifferentiated EGC (UD-EGC) is known to result in a higher incidence of LNM and infiltrative growth than differentiated EGC (D-EGC), the indications for ER are limited compared with those for D-EGC. Previously, clinical staging as intramucosal UD-EGC ≤2 cm, without ulceration, was presented as 'weakly recommended' or 'expanded indications' for ER in the guidelines of the United States, Europe, Korea, and Japan. Based on promising long-term outcomes from a prospective multicenter study by the Japan Clinical Oncology Group (JCOG) 1009/1010, the status of this indication has expanded and is now considered 'absolute indications' in the latest Japanese guidelines published in 2021. In this study, which comprised 275 patients with UD-EGC (cT1a, ≤2 cm, without ulceration) treated with ESD, the 5-year overall survival (OS) was 99.3% (95% confidence interval, 97.1%-99.8%), which was higher than the threshold 5-year OS (89.9%). Currently, the levels of evidence grades and recommendations for ER of UD-EGC differ among Japan, Korea, and Western countries. Therefore, a further discussion is warranted to generalize the indications for ER of UD-EGC in countries besides Japan.

Comparison of treatment outcomes between endoscopic submucosal dissection with the needle-type knife and insulated-tip knife for superficial esophageal neoplasms.

Our study aimed to compare the treatment outcomes between endoscopic submucosal dissection (ESD) with an insulated-tip knife (ESD-IT) and a needle-type knife (ESD-N) for large superficial esophageal neoplasms, as no study of this kind has been previously reported. We used the dataset of a multicenter, randomized controlled trial that compared conventional ESD (C-ESD) and traction-assisted ESD (TA-ESD) for superficial esophageal neoplasms. We compared the procedural outcomes between ESD-IT and ESD-N in a post hoc analysis and conducted sub-analyses based on traction assistance and electrical knife type. We included 223 (EST-IT, n = 169; ESD-N, n = 54) patients with no significant differences in baseline characteristics. The operator handover rate due to ESD difficulties was significantly higher in ESD-N (ESD-IT = 0.6% vs. ESD-N = 13.0%, P = 0.001), while the injection volume was significantly higher in ESD-IT than in ESD-N (40.0 vs. 20.5 mL, P < 0.001). Other outcomes were comparable between both groups (procedural time: 51.0 vs. 49.5 minute, P = 0.89; complete resection: 90.5% vs. 90.7%, P > 0.99; and complication rate: 1.8% vs. 3.7%, P = 0.60 for ESD-IT and ESD-N, respectively). In the sub-analyses, the handover rate was significantly lower with TA-ESD than with C-ESD for ESD-N (3.2% vs. 26.1%, P = 0.034), and a significantly smaller injection volume was used in TA-ESD than in C-ESD for ESD-IT (31.5 vs. 47.0 mL, P < 0.01). ESD with either endoscopic device achieved favorable treatment outcomes with low complication rates. The handover rate in ESD-N and the injection volume in ESD-IT improved with the traction method.

Endoscopic resection of esophageal squamous cell carcinoma: Current indications and treatment outcomes.

Endoscopic resection (ER) is an alternate minimally invasive treatment for superficial esophageal squamous cell carcinoma (SESCC). We aimed to review the clinical indications and treatment outcomes of ER for SESCC. Endoscopic mucosal resection is relatively easy and efficient for SESCC ≤ 15 mm. In contrast, endoscopic submucosal dissection (ESD) is recommended to achieve en bloc resection for lesions >15 mm, in view of the accurate pathological evaluation. The Japan Gastroenterological Endoscopy Society guidelines recommend ER for non-circumferential cT1a-EP/LPM (epithelium/lamina propria mucosae), cT1a-MM/T1b-SM1 (muscularis mucosa/superficial submucosa ≤ 200µm) SESCC, and whole-circumferential T1a-EP/LPM SESCC ≤ 50 mm (upon implementing preventive measures for stenosis), considering the risk-benefit balance of ER. It defines pT1a-EP/LPM without lymphovascular invasion as a curative endoscopic resection. The guidelines recommend additional esophagectomy or chemoradiotherapy for pT1b SESCC or any SESCC, with lymphovascular invasion. However, there is no recommendation for or against the administration of additional treatments for pT1a-MM without lymphovascular invasion, owing to limited evidence. Researchers have reported on high en bloc and R0 resection rates of ESD, and a randomized controlled trial demonstrated that clip-line traction-assisted ESD could significantly reduce the ESD procedural time. Moreover, steroid treatment has been developed to prevent post-ESD esophageal strictures. There have been reports on favorable long-term outcomes of ESD. However, most of them are retrospective studies. Further robust data in prospective trials are warranted to achieve a definitive evidence of ESD, which will be beneficial to patients with SESCC.

Visibility of early gastric cancer in texture and color enhancement imaging.

Objective: There are little data regarding the efficacy of texture and color enhancement imaging (TXI) for early gastric cancer (EGC) diagnosis. This study aimed to compare the color difference and visibility of EGC between white light imaging (WLI) and TXI. Methods: This study included 20 EGCs of 18 patients undergoing endoscopic submucosal dissection. Still images of EGC in WLI, TXI mode 1 (with color enhancement), and TXI mode 2 (without color enhancement), which were consistent in distance, angle, and air insufflation, were constructed by computer simulation. The center of the lesion, eight equal peripheral points 5 mm outside the lesion, and eight inner points two-thirds of the distance from peripheral points to the EGC lesion center were annotated. Mean color differences (ΔE) of the area between peripheral and inner points per lesion in WLI, TXI mode 1, and TXI mode 2 were analyzed. In addition, four endoscopists independently scored the visibility of EGC images of TXI mode 1 and 2 compared with WLI. Results: Clinicopathological characteristics were as follows: 0-IIa/0-IIb/0-IIc/0-IIa+IIc = 6/1/11/2, reddish/pale = 10/10, differentiated/undifferentiated = 18/2, median tumor size = 13.5 mm. Mean ΔE ± SD = WLI/TXI mode1/TXI mode2 = 10.3 ± 4.7, 15.5 ± 7.8, and 12.7 ± 6.1, respectively. Mean ΔE was significantly higher in TXI mode 1 than in WLI. Visibility (improved/no change/decreased) was 7/13/0 and 4/16/0 in TXI mode 1 and 2, respectively. The visibility was significantly more commonly improved in the macroscopic type 0-IIc or 0-IIb than in 0-IIa or IIa+IIc in TXI mode 1. Conclusions: TXI could improve the visibility of EGC compared with WLI.

Pivotal trial of a biodegradable stent for patients with refractory benign esophageal stricture.

OBJECTIVE: Benign esophageal strictures (BES) cause dysphagia and decrease patients' quality of life. Although mechanical dilation is the standard of care for BES, in some patients, dysphagia is unrelieved despite repeated procedures. The biodegradable stent was developed to resolve refractory BES, with reported favorable outcomes, but it is unapproved in Japan. Thus, we evaluated the safety and efficacy of the biodegradable stent (BDS) for patients with refractory BES for regulatory approval. METHODS: This was a nonrandomized single-arm prospective trial conducted at eight institutions. We included patients with BES after ≥ 5 times of dilation or ≥ one time of radial incision and cutting whose dysphagia score (DS) was 2 or worse and an endoscope could not admit. The primary endpoint was the proportion of patients whose DS improvement of ≤ 1 was maintained at 3 months. RESULTS: Thirty patients (median age: 69 years, male/female: 27:3) were enrolled and treated; BDS placement failed in 1 patient. Fourteen patients maintained their DS improvement until 3 months after placement (proportion of DS improvement at 3 months 46.7% [95% CI: 28.3-65.7]), and the median dysphagia-free survival was 98 days [95% CI: 68-123]. Most adverse events could be managed conservatively; however, a patient with BES after chemoradiotherapy (CRT) developed an esophago-left atrium fistula and died approximately 4 months after stent placement. CONCLUSION: The BDS was effective for refractory BES and the safety was acceptable. However, the indication for this procedure in patients RECEIVING CRT for esophageal cancer should be carefully considered.

Emerging texture and color enhancement imaging in early gastric cancer.

Screening endoscopy improves detection and prognosis of patients with gastric cancer. However, even expert endoscopists can miss early gastric cancer under standard white light imaging. Texture and color enhancement imaging (TXI) is an image-enhanced endoscopy that enhances brightness, surface irregularities such elevation or depression, and subtle color changes. A few image-oriented studies have compared the gastric color differences between neoplastic and peripheral areas under both white light imaging and TXI. The results not only suggested that the overall color differences to be more pronounced in TXI, but also that TXI mode 1 was superior to white light imaging in the visibility of early gastric cancer. Despite the promising results in these initial studies, it is unclear whether the superiority of the image-enhanced endoscopy will translate into an improvement in early gastric cancer detection in real practice. Therefore, large-scale prospective studies are necessary to investigate the efficacy of this new technology in the evaluation of patients undergoing screening endoscopy.

Outcomes of endoscopic resection for superficial duodenal tumors: 10 years' experience in 18 Japanese high volume centers.

BACKGROUND: Data on endoscopic resection (ER) for superficial duodenal epithelial tumors (SDETs) are insufficient owing to their rarity. There are two main ER techniques for SDETs: endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). In addition, modified EMR techniques, such as underwater EMR (UEMR) and cold polypectomy, are becoming popular. We conducted a large-scale retrospective multicenter study to clarify the detailed outcomes of duodenal ER. METHODS: Patients with SDETs who underwent ER at 18 institutions from January 2008 to December 2018 were included. The rates of en bloc resection and delayed adverse events (AEs; defined as delayed bleeding or perforation) were analyzed. Local recurrence was analyzed using the Kaplan-Meier method. RESULTS: In total, 3107 patients (including 1017 undergoing ESD) were included. En bloc resection rates were 79.1 %, 78.6 %, 86.8 %, and 94.8 %, and delayed AE rates were 0.5 %, 2.2 %, 2.8 %, and 6.8 % for cold polypectomy, UEMR, EMR and ESD, respectively. The delayed AE rate was significantly higher in the ESD group than in non-ESD groups for lesions < 19 mm (7.4 % vs. 1.9 %; P < 0.001), but not for lesions > 20 mm (6.1 % vs. 7.1 %; P = 0.64). The local recurrence rate was significantly lower in the ESD group than in the non-ESD groups (P < 0.001). Furthermore, for lesions > 30 mm, the cumulative local recurrence rate at 2 years was 22.6 % in the non-ESD groups compared with only 1.6 % in the ESD group (P < 0.001). CONCLUSIONS: ER outcomes for SDETs were generally acceptable. ESD by highly experienced endoscopists might be an option for very large SDETs.

Preclinical Efficacy and Clinical Feasibility of a Novel Aerosol-Exposure Protection Mask for Esophagogastroduodenoscopy.

BACKGROUND/AIMS: This study aimed to assess the efficacy of a novel aerosol-exposure protection (AP) mask in preventing coronavirus disease in healthcare professionals during upper gastrointestinal endoscopy and to evaluate its clinical feasibility. METHODS: In Study 1, three healthy volunteers volitionally coughed with and without the AP mask in a cleanroom. Microparticles were visualized and counted with a specific measurement system and compared with and without the AP mask. In Study 2, 30 patients underwent endoscopic resection with the AP mask covering the face, and the SpO2 was measured throughout the procedure. RESULTS: In Study 1, the median number of microparticles in volunteers 1, 2, and 3 with and without the AP mask was 8.5 and 110.0, 7.0 and 51.5, and 8.0 and 95.0, respectively (p<0.01). Using the AP mask, microparticles were reduced by approximately 92%. The median distances of microparticle scattering without the AP mask were 60, 0, and 68 in volunteers 1, 2, and 3, respectively. In Study 2, the mean SpO2 was 96.3%, and desaturation occurred in three patients. CONCLUSION: The AP mask could provide protection from aerosol exposure and can be safely used for endoscopy in clinical practice.