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Featured researches published by Dae Gon Ryu.


The Korean Journal of Gastroenterology | 2017

Correction: The Value of Computed Tomography in Preoperative N Staging of Early Gastric Cancer Meeting the Endoscopic Resection Criteria

Su Jin Kim; Tae Un Kim; Cheol Woong Choi; Dae Hwan Kang; Hyung Wook Kim; Su Bum Park; Hyeong Seok Nam; Dae Gon Ryu

This correction is being published to correct Fig. 2B in above article.


World Journal of Gastroenterology | 2016

Assessment of disease activity by fecal immunochemical test in ulcerative colitis

Dae Gon Ryu; Hyung Wook Kim; Su Bum Park; Dae Hwan Kang; Cheol Woong Choi; Su Jin Kim; Hyeong Seok Nam

AIM To evaluate the efficacy of quantitative fecal immunochemical test (FIT) as biomarker of disease activity in ulcerative colitis (UC). METHODS Between February 2013 and November 2014, a total of 82 FIT results, obtained in conjunction with colonoscopies, were retrospectivelyevaluated for 63 patients with UC. The efficacy of FIT for evaluation of disease activity was compared to colonoscopic findings. Quantitative fecal blood with automated equipment examined from collected feces. Endoscopic disease severity were assessed using the Mayo endoscopic subscore (MES) classification. The extent of disease were classified by proctitis (E1), left sided colitis (E2), and extensive colitis (E3). Clinical activity were subgrouped by remission or active. RESULTS All of 21 patients with MES 0 had negative FIT (< 7 ng/mL), but 22 patients with MES 2 or 3 had a mean FIT of > 134.89 ng/mL. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of negative FIT about mucosal healing were 73.33%, 81.82%, 91.49%, 51.43% and 73.17%, respectively. The sensitivity, specificity, PPV, NPV and accuracy of predictive value of positive FIT (cutoff value > 100 ng/mL) about active disease status were 45.45%, 93.33%, 71.43%, 82.35% and 26.83%, respectively. Among patients with clinical remission, FIT was negative in 31 (81.6%) of 38 cases, with a mean fecal hemoglobin concentration of 6.12 ng/mL (range, negative to 80.9 ng/mL) for this group of patients. Among patients with clinical active disease, FIT was negative in 16 (36.4%) out of 44 cases, with a mean fecal hemoglobin concentration > 167.4 ng/mL for this group of patients. FIT was positively correlated with endoscopic activity (r = 0.626, P < 0.01) and clinical activity (r = 0.496, P < 0.01). But, FIT did not correlate with the extent of disease (r = -0.047, P = 0.676) CONCLUSION Quantitative FIT can be a non-invasive and effective biomarker for evaluation of clinical and endoscopic activity in UC, but not predict the extent of disease.


Gastroenterology Research and Practice | 2016

Endoscopic Ultrasound-Guided Drainage without Fluoroscopic Guidance for Extraluminal Complicated Cysts

Hyeong Seok Nam; Hyung Wook Kim; Dae Hwan Kang; Cheol Woong Choi; Su Bum Park; Su Jin Kim; Dae Gon Ryu; Joon ho Jeon

Background. Endoscopic ultrasound- (EUS-) guided drainage is generally performed under fluoroscopic guidance. However, improvements in endoscopic and EUS techniques and experience have led to questions regarding the usefulness of fluoroscopy. This study aimed to retrospectively evaluate the safety and efficacy of EUS-guided drainage of extraluminal complicated cysts without fluoroscopic guidance. Methods. Patients who had undergone nonfluoroscopic EUS-guided drainage of extraluminal complicated cysts were enrolled. Drainage was performed via a transgastric, transduodenal, or transrectal approach. Single or double 7 Fr double pigtail stents were inserted. Results. Seventeen procedures were performed in 15 patients in peripancreatic fluid collections (n = 13) and pelvic abscesses (n = 4). The median lesion size was 7.1 cm (range: 2.8–13.0 cm), and the mean time spent per procedure was 26.2 ± 9.8 minutes (range: 16–50 minutes). Endoscopic drainage was successful in 16 of 17 (94.1%) procedures. There were no complications. All patients experienced symptomatic improvement and revealed partial to complete resolution according to follow-up computed tomography findings. Two patients developed recurrent cysts that were drained during repeat procedures, with eventual complete resolution. Conclusion. EUS-guided drainage without fluoroscopic guidance is a technically feasible, safe, and effective procedure for the treatment of extraluminal complicated cysts.


Scandinavian Journal of Gastroenterology | 2018

Endoscopic predictive factors associated with local recurrence after gastric endoscopic submucosal dissection

Hyeong Seok Nam; Cheol Woong Choi; Su Jin Kim; Dae Hwan Kang; Hyung Wook Kim; Su Bum Park; Dae Gon Ryu

Abstract Objective: Endoscopic submucosal dissection (ESD) has been accepted as the treatment of choice for gastric epithelial neoplasia. Endoscopic characteristics of the primary lesion and post-ESD scars may be informative to predict the possibility of local recurrence. Methods: Between November 2008 and July 2015, a retrospective study was conducted in a single-tertiary referral hospital. Consecutive patients who underwent ESD for early gastric cancer (EGC) or high-grade dysplasia were analyzed to evaluate the incidence of local recurrence and associated endoscopic characteristics. Results: A total of 639 lesions were analyzed. The rates of en-bloc and complete resection were 98.1% and 95.5%, respectively. A total of 15 local recurrent lesions were found (2.3%). The endoscopic findings of primary lesions associated with local recurrence were a lesion size ≥20 mm (odds ratio, OR, 4.408; 95% confidence interval, CI, 1.369–14.186, p = .013) and incomplete endoscopic resection (OR 17.059, 95% CI 4.887–59.551, p < .001). During follow-up endoscopic examinations, atypical scar findings (non-flat morphology, erythematous color change and uneven surface pattern) were significant endoscopic findings to predict local recurrence. Local recurrence was absent for ESD scars with even-flat morphology without erythema. Conclusion: Lesions with larger size (≥ 20 mm) and incompletely resected lesions had higher risk of local recurrence. Endoscopic forceps biopsy is unnecessary for even-flat ESD scar without erythematous changes.


Scandinavian Journal of Gastroenterology | 2018

Endoscopic submucosal dissection of gastric neoplasms using a snare tip

Su Jin Kim; Cheol Woong Choi; Dae Hwan Kang; Hyung Wook Kim; Su Bum Park; Hyeong Seok Nam; Dae Gon Ryu

Abstract Background: Endoscopic submucosal dissection (ESD) enables the complete removal of gastric lesions regardless of tumor size. ESD is typically performed using one of several available electrocautery knives and endoscopic mucosal resection (EMR) is performed using a diathermic snare. We aimed to investigate the clinical outcomes and complications in patients in whom a snare tip was used for ESD. Materials and methods: We retrospectively evaluated the medical records of 30 patients who underwent removal of a gastric lesion using a snare tip by ESD or hybrid ESD (ESD with snaring). For hybrid ESD, snaring was performed after an adequate submucosal dissection. The clinical outcomes according to the endoscopic procedure performed were evaluated. Results: ESD was performed in 12 patients and hybrid ESD was performed in 26 patients. Overall en-bloc and complete resection rates were both 97.4%. There was one case where piece-meal resection was performed in the hybrid ESD group. There were no procedure related complications such as perforation or bleeding. The mean specimen size was 2.8 ± 0.6 cm in the ESD group and 2.3 ± 0.5 cm in the hybrid ESD group (p = .031). The mean procedure time did not differ between the two methods (12.8 min in ESD and 9.7 min in hybrid ESD, p = .060). Conclusions: The snare tip can be used as an electrocautery knife to incise the mucosa and dissect the submucosa during removal of a gastric lesion.


PLOS ONE | 2018

Preprocedural prediction of non-curative endoscopic submucosal dissection for early gastric cancer

Hyeong Seok Nam; Cheol Woong Choi; Su Jin Kim; Dae Hwan Kang; Hyung Wook Kim; Su Bum Park; Dae Gon Ryu; Jung Sik Choi

Background and aim Endoscopic submucosal dissection (ESD) has been accepted as the treatment of choice for early gastric cancer (EGC) without lymph node metastasis. However, additional surgical gastrectomy should be considered after non-curative endoscopic resection. We aimed to evaluate the predictive factors associated with non-curative endoscopic resection. Methods Between November 2008 and June 2015, a retrospective study was conducted in a single, tertiary, referral hospital. A total of 596 EGC lesions resected by ESD were analyzed. Non-curative endoscopic resection was defined as the occurrence of lesions associated with piecemeal resection, positive resection margins, lymphovascular invasion, or lesions that did not meet the expanded indications for ESD. Results The rate of non-curative endoscopic resection was 16.1%. The mean follow-up period was 35.3 ± 25.0 months. Associated predictive factors for non-curative endoscopic resection were female sex (OR, 2.470; p = 0.004), lesion size ≥ 20 mm (OR 3.714; p < 0.001), longer procedure time (OR 2.449, p = 0.002), ulceration (OR 3.538, p = 0.002), nodularity (OR 2.967, p<0.001), depression (OR 1.806, p = 0.038), undifferentiated carcinoma (OR 2.825, p = 0.031) and lesion located in the mid or upper third of stomach (OR 7.135 and OR 4.155, p<0.001, respectively). As the number of risk factors increased, the risk of non-curative ESD also increased. Conclusions Prior to selection of ESD, the risks associated with non-curative ESD should be considered so that appropriate treatment modalities may be selected.


World Journal of Gastroenterology | 2017

Efficacy and safety of limited endoscopic sphincterotomy before self-expandable metal stent insertion for malignant biliary obstruction

Hyeong Seok Nam; Dae Hwan Kang; Hyung Wook Kim; Cheol Woong Choi; Su Bum Park; Su Jin Kim; Dae Gon Ryu

AIM To evaluate the safety and efficacy of limited endoscopic sphincterotomy (ES) before placement of self-expandable metal stent (SEMS). METHODS This was a retrospective analysis of 244 consecutive patients with unresectable malignant biliary obstruction, who underwent placement of SEMSs following limited ES from December 2008 to February 2015. The diagnosis of malignant biliary obstruction and assessment of patient eligibility for the study was established by a combination of clinical findings, laboratory investigations, imaging and pathological results. All patients were monitored in the hospital for at least 24 h following endoscopic retrograde cholangio pancreatography (ERCP). The incidence of immediate or early post-ERCP complications such as post-ERCP pancreatitis (PEP) and bleeding related to limited ES were considered as primary outcomes. Also, characteristics and complications according to the cancer type were classified. RESULTS Among the 244 patients included, the underlying diagnosis was cholangiocarcinoma in 118 patients, pancreatic cancer in 79, and non-pancreatic or non-biliary malignancies in the remaining 47 patients. Early post-ERCP complications occurred in 9 patients (3.7%), with PEP in 7 patients (2.9%; mild, 6; moderate, 1) and mild bleeding in 2 patients (0.8%). There was no significant association between the incidence of post-ERCP complications and the type of malignancy (cholangiocarcinoma vs pancreatic cancer vs others, P = 0.696) or the type of SEMS used (uncovered vs covered, P = 1.000). Patients who had more than one SEMS placed at the first instance were at a significantly higher risk of post-ERCP complications (one SEMS vs two SEMS, P = 0.031). No other factors were predictive of post-ERCP complications. CONCLUSION Limited ES is feasible and safe, and effectively facilitates the placement of SEMS, without any significant risk of PEP or severe bleeding.


The Korean Journal of Gastroenterology | 2017

A Case of Intramural Hematoma of the Esophagus Mimicking Acute Coronary Syndrome

Dae Gon Ryu; Cheol Woong Choi; Dae Hwan Kang; Hyung Wook Kim; Dong Il Jeong; Wan Chul Kim; Jae Gyu Shin; Tae Won Lim

Intramural hematoma of the esophagus is a rare condition that can be spontaneous or secondary to trauma, toxic ingestion, or intervention. If it is the spontaneous type, it usually presents initially with epigastric pain, hematemesis or dysphagia. We present a case of intramural hematoma of the esophagus mimicking acute coronary syndrome. A 63-year-old man presented with severe acute chest pain. He has four coronary stents that were inserted five years ago, from a different hospital, and is on dual antiplatelet agents. Coronary angiography was performed immediately under the suspicion of acute coronary syndrome, and we found that there was no obvious clogging of the coronary arteries. Next, chest computed tomography was performed due to suspected aortic dissection, and the result was also negative. Four days later, endoscopy was performed and intramural hematoma covered with large ulcers was diagnosed.


The Korean Journal of Gastroenterology | 2017

Hemosuccus Pancreaticus in the Simple Mucinous Cyst of the Pancreas

Il Eok Jo; Dae Hwan Kang; Cheol Woong Choi; Hyung Wook Kim; Su Jin Kim; Hyeong Seok Nam; Dae Gon Ryu

Hemosuccus pancreaticus is an unusual gastrointestinal hemorrhage through the main pancreatic duct. We report a rare case of hemosuccus pancreaticus due to a simple mucinous cyst of the pancreas. A 52-year-old man who had been followed-up for a suspected branch duct intraductal papillary mucinous neoplasm (IPMN) visited the emergency room due to hematochezia. Endoscopy showed active bleeding from the ampulla. Computed tomography revealed hemorrhage in a 2.0-cm cystic mass in the pancreatic body. The patient was diagnosed with hemosuccus pancreaticus caused by bleeding into the main pancreatic duct from suspected IPMN. Elective laparoscopic distal pancreatectomy was performed. The histopathological diagnosis was a simple mucinous cyst with squamous metaplasia based upon the pathological finding involving the absence of ovarian-type stroma. In conclusion, it should be recognized that a pancreatic cyst including simple mucinous cyst may cause hemosuccus pancreaticus, and these cysts should be viewed as neoplastic and approached similarly as other mucinous pancreatic neoplasms.


The Korean Journal of Gastroenterology | 2017

Clinical Outcomes of Dilation Therapy for Anastomotic Esophageal Stricture

Cheol Woong Choi; Dae Hwan Kang; Hyung Wook Kim; Su Bum Park; Su Jin Kim; Hyeong Seok Nam; Dae Gon Ryu

Background/Aims Benign esophageal stricture after esophagectomy is not an infrequent complication. Anastomotic esophageal stricture requires frequent multiple dilations. We aimed to evaluate the clinical outcomes of dilation therapies using an endoscopic balloon or bougie dilator and analyzed the risk factors associated with refractory stricture. Methods Between January 2009 and May 2016, the medical records of 21 patients treated with endoscopic balloon dilation or bougie dilation for esophageal anastomotic strictures were retrospectively reviewed. Results During the study periods, a total of 21 patients were diagnosed with esophageal anastomotic stricture and included for analysis (17 male; mean age, 68.2±7.2 years at the first procedure). The mean stricture length was 6.4±8.1 mm. The refractory stricture was found in 28.6% of patients, and successful relief of dysphagia was achieved in 71.4% of patients. The major complication associated with dilations was absent. Factors associated with refractory stricture were stricture length (> 10 mm, p<0.049) and diabetes mellitus (p=0.035). Additive bougie dilations achieved clinical success in 4 out of 7 patients. Conclusions Dilation with endoscopic balloon or bougie dilator was an effective and safe procedure for benign anastomotic esophageal strictures of less than 10 mm in length.

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Dae Hwan Kang

Pusan National University

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Hyung Wook Kim

Catholic University of Korea

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Hyeong Seok Nam

Pusan National University

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Su Bum Park

Pusan National University

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Hyeong Jin Kim

Pusan National University

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Jeong Seok Lee

Pusan National University

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Jae Gyu Shin

Pusan National University

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Ji Ha Kim

Pusan National University

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