Background/Aims: Inaccurate prediction of lymph node metastasis (LNM) may lead to unnecessary surgery following endoscopic resection of T1 colorectal cancer (CRC). We aimed to validate the usefulness of artificial intelligence (AI) models for predicting LNM in patients with T1 CRC. Methods: We analyzed the clinical data, laboratory results, pathological reports, and endoscopic findings of patients who underwent radical surgery for T1 CRC. We developed AI models to predict LNM using four algorithms: regularized logistic regression classifier (RLRC), random forest classifier (RFC), CatBoost classifier (CBC), and the voting classifier (VC). Four histological factors and four endoscopic findings were included to develop AI models. Areas under the receiver operating characteristics curves (AUROCs) were measured to distinguish AI model performance in accordance with the Japanese Society for Cancer of the Colon and Rectum guidelines. Results: Among 1,386 patients with T1 CRC, 173 patients (12.5%) had LNM. The AUROC values of the RLRC, RFC, CBC, and VC models for LNM prediction were significantly higher (0.673, 0.640, 0.679, and 0.677, respectively) than the 0.525 suggested in accordance with the Japanese Society for Cancer of the Colon and Rectum guidelines (vs RLRC, p<0.001; vs RFC, p=0.001; vs CBC, p<0.001; vs VC, p<0.001). The AUROC value was similar between T1 colon versus T1 rectal cancers (0.718 vs 0.615, p=0.700). The AUROC value was also similar between the initial endoscopic resection and initial surgery groups (0.581 vs 0.746, p=0.845). Conclusions AI models trained on the basis of endoscopic findings and pathological features performed well in predicting LNM in patients with T1 CRC regardless of tumor location and initial treatment method.

Background/Aims: The study investigated the incidence, risk factors, and clinical outcomes of chronic antibiotic-refractory pouchitis (CARP) in Korean patients with ulcerative colitis (UC). Methods: This single-center retrospective study included patients with UC who underwent total proctocolectomy with ileal pouch-anal anastomosis at the Asan Medical Center in Korea between January 1987 and December 2022. The primary outcomes were endoscopic remission and pouch failure. The Cox’s proportional hazard model was used to identify the risk factors for CARP. Results: The clinical data of 232 patients were analyzed. The most common cause of surgery was steroid refractoriness (50.9%), followed by dysplasia/colorectal cancer (26.7%). Among 74 patients (31.9%) with chronic pouchitis (CP), 31 (13.4%) had CARP, and 43 (18.5%) had chronic antibiotic-dependent pouchitis (CADP). The most frequent endoscopic phenotype was focal inflammation of the pouch (CP, 47.3%; CARP, 35.5%; CADP, 55.8%). Patients with CARP were less likely to use concomitant probiotics than patients with CADP (29.0% vs 72.1%, p<0.01). The endoscopic remission rate of CP, CARP, and CADP was 14.9%, 9.7%, and 18.6%, respectively.The pouch failure rate associated with CP, CARP, and CADP was 13.5%, 16.1%, and 11.6%, respectively. Current smoking status (adjusted hazard ratio [aHR], 2.96; 95% confidence interval [CI], 1.27 to 6.90; p=0.01) and previous use of biologics/small molecules (aHR, 2.40; 95% CI, 1.05 to 5.53; p=0.04) were significantly associated with CARP development. Conclusions UC patients who were current smokers and previously used biologics/small molecules had a higher risk of developing CARP. Concomitant use of probiotics was less likely to be associated with CARP development.

Purpose: Since 1995, the Korean Gastric Cancer Association (KGCA) has been periodically conducting nationwide surveys on patients with surgically treated gastric cancer. This study details the results of the survey conducted in 2023. Materials and Methods: The survey was conducted from March to December 2024 using a standardized case report form. Data were collected on 86 items, including patient demographics, tumor characteristics, surgical procedures, and surgical outcomes. The results of the 2023 survey were compared with those of previous surveys. Results: Data from 12,751 cases were collected from 66 institutions. The mean patient age was 64.6 years, and the proportion of patients aged ≥71 years increased from 9.1% in 1995 to 31.7% in 2023. The proportion of upper-third tumors slightly decreased to 16.8% compared to 20.9% in 2019. Early gastric cancer accounted for 63.1% of cases in 2023.Regarding operative procedures, a totally laparoscopic approach was most frequently applied (63.2%) in 2023, while robotic gastrectomy steadily increased to 9.5% from 2.1% in 2014.The most common anastomotic method was the Billroth II procedure (48.8%) after distal gastrectomy and double-tract reconstruction (51.9%) after proximal gastrectomy in 2023.However, the proportion of esophago-gastrostomy with anti-reflux procedures increased to 30.9%. The rates of post-operative mortality and overall complications were 1.0% and 15.3%, respectively. Conclusions The results of the 2023 nationwide survey demonstrate the current status of gastric cancer treatment in Korea. This information will provide a basis for future gastric cancer research.

This study aimed to establish infection control strategies for preventing the spread of scabies within a single institution by analyzing the epidemiological characteristics of patients diagnosed with scabies. Methods: This was a retrospective descriptive study. The electronic medical records of 430 patients diagnosed with scabies at the dermatology outpatient department of Uijeongbu St. Mary’s Hospital from January 2020 to December 2022 were used to collect data on their characteristics. The subjects were divided into three groups: patients, family of confirmed patients, and healthcare workers. General and epidemiological characteristics were analyzed. Results: The average age was 60.89 ± 22.39 years. The number of days from symptom onset to diagnosis was unknown in many cases (65.3%), although the average was 63.42 ± 64.18 days. Repeated visits after treatment were observed in 193 patients (67.5%), 38 family members of confirmed patients (55.1%), and 35 healthcare workers (46.7%), showing a statistically significant difference (p = .002). The most common place of residence before the visit was home (56.2%), and the most common suspected origin of contagion was the home (38.3%), and the most common category of the suspected contagious person was family (49.6%). Conclusion: Cases of scabies were disproportionately common in women and older adults. The interval from symptom onset to diagnosis was long, and about half of the cases involved itching but no skin lesions. More than one-thirds of cases did not revisit for a follow-up after 2 weeks. In the overall results, unlike previous studies, factors related to home and family were frequently observed as epidemiological characteristics.

Objective: Mammography is essential for reducing breast cancer mortality; however, its performance varies globally. This study aimed to evaluate mammography screening outcomes in Korea over 12 years and investigate regional variations. Materials and Methods: We analyzed mammography data from 42 million Korean women, aged 40 years and older, who participated in the Korean National Cancer Screening Program (KNCSP) from 2009 to 2020. Performance metrics—including recall rate (RR), positive predictive value (PPV), sensitivity, specificity, false positive rate (FPR), cancer detection rate (CDR), interval cancer rate (ICR), and dense breast rate (DBR), were computed. Twelve-year trends in these metrics were analyzed using Joinpoint regression. Regional variations were also examined across Korea’s 237 districts, stratified by age groups. Results: From 2009 to 2020, 42165405 mammography screenings were conducted through the KNCSP, increasing from 2821132 screenings in 2009 to 3596204 in 2020. The RR decreased from 17.2% in 2009 to 11.2% in 2020 (average annual percent change [AAPC] = -3.7%), while the PPV increased from 0.8% to 2.8%; AAPC = 10.7%), the CDR increased from 1.5 to 3.1 per 1000; AAPC = 7.3%), and the ICR rose from 0.9 to 1.6 per 1000; (AAPC = 5.2%). Regional variations were noted; however, differences in the RR, sensitivity, specificity, and FPR decreased over time. Conclusion While mammography performance improved from 2009 to 2020, the PPV and sensitivity remain suboptimal, underscoring the need for continuous monitoring. Regional disparities in performance, although reduced, persist. These findings provide essential baseline data for improving mammography quality and addressing inequities in breast cancer screening.

Objective: To establish local diagnostic reference levels (DRLs) for pediatric neck CT based on age, weight, and water-equivalent diameter (WED) across multiple university hospitals in South Korea. Materials and Methods: This retrospective study analyzed pediatric neck CT examinations from nine university hospitals, involving patients aged 0–18 years. Data were categorized by age, weight, and WED, and radiation dose metrics, including volume CT dose index (CTDIvol) and dose length product, were recorded. Data retrieval and analysis were conducted using a commercially available dose-management system (Radimetrics, Bayer Healthcare). Local DRLs were established following the International Commission on Radiological Protection guidelines, using the 75th percentile as the reference value. Results: A total of 1159 CT examinations were analyzed, including 169 scans from Institution 1, 132 from Institution 2, 126 from Institution 3, 129 from Institution 4, 128 from Institution 5, 105 from Institution 6, 162 from Institution 7, 127 from Institution 8, and 81 from Institution 9. Radiation dose metrics increased with age, weight, and WED, showing significant variability both within and across institutions. For patients weighing less than 10 kg, the DRL for CTDIvol was 5.2 mGy. In the 10–19 kg group, the DRL was 5.8 mGy; in the 20–39 kg group, 7.6 mGy; in the 40–59 kg group, 11.0 mGy; and for patients weighing 60 kg or more, 16.2 mGy. DRLs for CTDIvol by age groups were as follows: 5.3 mGy for infants under 1 year, 5.7 mGy for children aged 1–4 years, 7.6 mGy for ages 5–9 years, 11.2 mGy for ages 10–14 years, and 15.6 mGy for patients 15 years or older. Conclusion Local DRLs for pediatric neck CT were established based on age, weight, and WED across nine university hospitals in South Korea.

Objective: To assess the feasibility of ultrafast brain magnetic resonance imaging (MRI) in pediatric patients. Materials and Methods: We retrospectively reviewed 194 pediatric patients aged 0 to 19 years (median 10.2 years) who underwent both ultrafast and conventional brain MRI between May 2019 and August 2020. Ultrafast MRI sequences included T1 and T2-weighted images (T1WI and T2WI), fluid-attenuated inversion recovery (FLAIR), T2*-weighted image (T2*WI), and diffusion-weighted image (DWI). Qualitative image quality and lesion evaluations were conducted on 5-point Likert scales by two blinded radiologists, with quantitative assessment of lesion count and size on T1WI, T2WI, and FLAIR sequences for each protocol. Wilcoxon signed-rank tests and intraclass correlation coefficient (ICC) analyses were used for comparison. Results: The total scan times for equivalent image contrasts were 1 minute 44 seconds for ultrafast MRI and 15 minutes 30 seconds for conventional MRI. Overall, image quality was lower in ultrafast MRI than in conventional MRI, with mean quality scores ranging from 2.0 to 4.8 for ultrafast MRI and 4.8 to 5.0 for conventional MRI across sequences (P < 0.001 for T1WI, T2WI, FLAIR, and T2*WI for both readers; P = 0.018 [reader 1] and 0.031 [reader 2] for DWI). Lesion detection rates on ultrafast MRI relative to conventional MRI were as follows: T1WI, 97.1%; T2WI, 99.6%; FLAIR, 92.9%; T2*WI, 74.1%; and DWI, 100%. The ICC (95% confidence interval) for lesion size measurements between ultrafast and conventional MRI was as follows: T1WI, 0.998 (0.996–0.999); T2WI, 0.998 (0.997–0.999); and FLAIR, 0.99 (0.985–0.994). Conclusion Ultrafast MRI significantly reduces scan time and provides acceptable results, albeit with slightly lower image quality than conventional MRI, for evaluating intracranial abnormalities in pediatric patients.

Objective: The upper lumbar region has distinctive anatomical characteristics that contribute to the challenges of performing discectomy. We introduce far-lateral transforaminal unilateral biportal endoscopic (UBE) lumbar discectomy for central or paracentral disc herniations in the upper lumbar region. Methods: We conducted retrospective review of the patients who underwent a far-lateral transforaminal UBE lumbar discectomy at our institution from January 2018 to September 2024. The electronic medical records, operative records, and radiologic images of the patients were reviewed. Results: A total of 27 patients underwent far-lateral transforaminal UBE lumbar discectomy for central or paracentral disc herniations in the upper lumbar region. The patient had a mean age of 54.0 ± 13.7 years. Operation was performed at the L1–2 level in 3 patients (11.1%), L2–3 in 9 patients (33.3%), and L3–4 in 15 patients (55.6%). The patients were followed-up for a mean of 27.7 ± 19.3 months. The Oswestry Disability Index was significantly decreased from 36.3 ± 6.8 preoperatively to 3.7 ± 3.3 at last follow-up (p < 0.001). The visual analogue scale (VAS) back was significantly decreased from 7.8 ± 0.9 preoperatively to 3.1 ± 0.6 postoperative day 2 (p < 0.001). The VAS leg was significantly decreased from 8.1 ± 0.8 preoperatively to 2.3 ± 0.7 postoperative day 2 (p < 0.001). Conclusion The far-lateral transforaminal UBE lumbar discectomy would be a viable surgical option for upper lumbar disc herniations.