Objective: To evaluate the effects of microwave (MW) power and antenna approach methods on extrahepatic tumor seeding and ablation zone size using an ex vivo subcapsular tumor-mimic model. Materials and Methods: Forty-one subcapsular tumor mimics were prepared by injecting a mixture of contrast media into bovine liver blocks. Ablation was performed using low- and high-power protocols (75 W and 100 W for 4 and 3 minutes, respectively). The antenna approach was assessed in two directions: parallel and perpendicular to the capsule. CT scans were obtained before and after the ablation to detect contrast leakage on the hepatic surface. The presence of leakage, ablation zone size, and the timing of the first popping sound were compared between the two groups. Results: Five cases of contrast leakage were observed in the low-power group (n = 21) and 17 in the high-power group (n = 20) (23.8% vs. 85.0%, P < 0.001). Contrast leaks were less frequently observed in the low-power protocol compared to the high-power protocol, regardless of the antenna approach (18.2% [2/11] vs. 80.0% [8/10], P = 0.009 for parallel access;30.0% [3/10] vs. 90.0% [9/10], P = 0.020 for perpendicular access). The timing of the first popping sound was significantly delayed in the low-power group compared to the high-power group (137.7 ± 51.4 s vs. 77.8 ± 31.4 s, P < 0.001). The size of the ablation zone did not differ significantly between the two power groups (P = 0.415). The parallel and perpendicular antenna approaches did not show significant differences in the number of contrast leaks, popping sound timing, or ablationzone size (P = 0.536, 0.463, and 0.271, respectively). Conclusion Low-power MW ablation may be superior to a high-power protocol in reducing the risk of tumor seeding in subcapsular tumors, regardless of the antenna approach.

Objective: To evaluate the effects of microwave (MW) power and antenna approach methods on extrahepatic tumor seeding and ablation zone size using an ex vivo subcapsular tumor-mimic model. Materials and Methods: Forty-one subcapsular tumor mimics were prepared by injecting a mixture of contrast media into bovine liver blocks. Ablation was performed using low- and high-power protocols (75 W and 100 W for 4 and 3 minutes, respectively). The antenna approach was assessed in two directions: parallel and perpendicular to the capsule. CT scans were obtained before and after the ablation to detect contrast leakage on the hepatic surface. The presence of leakage, ablation zone size, and the timing of the first popping sound were compared between the two groups. Results: Five cases of contrast leakage were observed in the low-power group (n = 21) and 17 in the high-power group (n = 20) (23.8% vs. 85.0%, P < 0.001). Contrast leaks were less frequently observed in the low-power protocol compared to the high-power protocol, regardless of the antenna approach (18.2% [2/11] vs. 80.0% [8/10], P = 0.009 for parallel access;30.0% [3/10] vs. 90.0% [9/10], P = 0.020 for perpendicular access). The timing of the first popping sound was significantly delayed in the low-power group compared to the high-power group (137.7 ± 51.4 s vs. 77.8 ± 31.4 s, P < 0.001). The size of the ablation zone did not differ significantly between the two power groups (P = 0.415). The parallel and perpendicular antenna approaches did not show significant differences in the number of contrast leaks, popping sound timing, or ablationzone size (P = 0.536, 0.463, and 0.271, respectively). Conclusion Low-power MW ablation may be superior to a high-power protocol in reducing the risk of tumor seeding in subcapsular tumors, regardless of the antenna approach.

Objective: To evaluate the effects of microwave (MW) power and antenna approach methods on extrahepatic tumor seeding and ablation zone size using an ex vivo subcapsular tumor-mimic model. Materials and Methods: Forty-one subcapsular tumor mimics were prepared by injecting a mixture of contrast media into bovine liver blocks. Ablation was performed using low- and high-power protocols (75 W and 100 W for 4 and 3 minutes, respectively). The antenna approach was assessed in two directions: parallel and perpendicular to the capsule. CT scans were obtained before and after the ablation to detect contrast leakage on the hepatic surface. The presence of leakage, ablation zone size, and the timing of the first popping sound were compared between the two groups. Results: Five cases of contrast leakage were observed in the low-power group (n = 21) and 17 in the high-power group (n = 20) (23.8% vs. 85.0%, P < 0.001). Contrast leaks were less frequently observed in the low-power protocol compared to the high-power protocol, regardless of the antenna approach (18.2% [2/11] vs. 80.0% [8/10], P = 0.009 for parallel access;30.0% [3/10] vs. 90.0% [9/10], P = 0.020 for perpendicular access). The timing of the first popping sound was significantly delayed in the low-power group compared to the high-power group (137.7 ± 51.4 s vs. 77.8 ± 31.4 s, P < 0.001). The size of the ablation zone did not differ significantly between the two power groups (P = 0.415). The parallel and perpendicular antenna approaches did not show significant differences in the number of contrast leaks, popping sound timing, or ablationzone size (P = 0.536, 0.463, and 0.271, respectively). Conclusion Low-power MW ablation may be superior to a high-power protocol in reducing the risk of tumor seeding in subcapsular tumors, regardless of the antenna approach.

Objective: To evaluate the effects of microwave (MW) power and antenna approach methods on extrahepatic tumor seeding and ablation zone size using an ex vivo subcapsular tumor-mimic model. Materials and Methods: Forty-one subcapsular tumor mimics were prepared by injecting a mixture of contrast media into bovine liver blocks. Ablation was performed using low- and high-power protocols (75 W and 100 W for 4 and 3 minutes, respectively). The antenna approach was assessed in two directions: parallel and perpendicular to the capsule. CT scans were obtained before and after the ablation to detect contrast leakage on the hepatic surface. The presence of leakage, ablation zone size, and the timing of the first popping sound were compared between the two groups. Results: Five cases of contrast leakage were observed in the low-power group (n = 21) and 17 in the high-power group (n = 20) (23.8% vs. 85.0%, P < 0.001). Contrast leaks were less frequently observed in the low-power protocol compared to the high-power protocol, regardless of the antenna approach (18.2% [2/11] vs. 80.0% [8/10], P = 0.009 for parallel access;30.0% [3/10] vs. 90.0% [9/10], P = 0.020 for perpendicular access). The timing of the first popping sound was significantly delayed in the low-power group compared to the high-power group (137.7 ± 51.4 s vs. 77.8 ± 31.4 s, P < 0.001). The size of the ablation zone did not differ significantly between the two power groups (P = 0.415). The parallel and perpendicular antenna approaches did not show significant differences in the number of contrast leaks, popping sound timing, or ablationzone size (P = 0.536, 0.463, and 0.271, respectively). Conclusion Low-power MW ablation may be superior to a high-power protocol in reducing the risk of tumor seeding in subcapsular tumors, regardless of the antenna approach.

Objective: To evaluate the effects of microwave (MW) power and antenna approach methods on extrahepatic tumor seeding and ablation zone size using an ex vivo subcapsular tumor-mimic model. Materials and Methods: Forty-one subcapsular tumor mimics were prepared by injecting a mixture of contrast media into bovine liver blocks. Ablation was performed using low- and high-power protocols (75 W and 100 W for 4 and 3 minutes, respectively). The antenna approach was assessed in two directions: parallel and perpendicular to the capsule. CT scans were obtained before and after the ablation to detect contrast leakage on the hepatic surface. The presence of leakage, ablation zone size, and the timing of the first popping sound were compared between the two groups. Results: Five cases of contrast leakage were observed in the low-power group (n = 21) and 17 in the high-power group (n = 20) (23.8% vs. 85.0%, P < 0.001). Contrast leaks were less frequently observed in the low-power protocol compared to the high-power protocol, regardless of the antenna approach (18.2% [2/11] vs. 80.0% [8/10], P = 0.009 for parallel access;30.0% [3/10] vs. 90.0% [9/10], P = 0.020 for perpendicular access). The timing of the first popping sound was significantly delayed in the low-power group compared to the high-power group (137.7 ± 51.4 s vs. 77.8 ± 31.4 s, P < 0.001). The size of the ablation zone did not differ significantly between the two power groups (P = 0.415). The parallel and perpendicular antenna approaches did not show significant differences in the number of contrast leaks, popping sound timing, or ablationzone size (P = 0.536, 0.463, and 0.271, respectively). Conclusion Low-power MW ablation may be superior to a high-power protocol in reducing the risk of tumor seeding in subcapsular tumors, regardless of the antenna approach.

Background: s/Aims: Reported incidence of extrahepatic bile duct cancer is higher in Asians than in Western populations. Korea, in particular, is one of the countries with the highest incidence rates of extrahepatic bile duct cancer in the world. Although research and innovative therapeutic modalities for extrahepatic bile duct cancer are emerging, clinical guidelines are currently unavailable in Korea. The Korean Society of Hepato-Biliary-Pancreatic Surgery in collaboration with related societies (Korean Pancreatic and Biliary Surgery Society, Korean Society of Abdominal Radiology, Korean Society of Medical Oncology, Korean Society of Radiation Oncology, Korean Society of Pathologists, and Korean Society of Nuclear Medicine) decided to establish clinical guideline for extrahepatic bile duct cancer in June 2021. Methods: Contents of the guidelines were developed through subgroup meetings for each key question and a preliminary draft was finalized through a Clinical Guidelines Committee workshop. Results: In November 2021, the finalized draft was presented for public scrutiny during a formal hearing. Conclusions The extrahepatic guideline committee believed that this guideline could be helpful in the treatment of patients.

Background/Aims: The recent update on Selecting Therapeutic Targets in Inflammatory Bowel Disease initiative has added a decrease in fecal calprotectin (FC) to an acceptable range as an intermediate target for Crohn’s disease (CD). We aimed to investigate whether postinduction FC could predict future persistent remission (PR) and endoscopic healing (EH) after 1 year of treatment with infliximab (IFX) in pediatric patients with CD. Methods: This multicenter retrospective observational study included pediatric patients with CD who were followed up for at least 1 year after starting IFX. The association of postinduction FC with PR and EH was investigated. Results: A total of 132 patients were included in this study. PR and EH were observed in 71.2% (94/132) and 73.9% (82/111) of the patients, respectively. In multivariate logistic regression analysis, only the postinduction FC level was associated with PR (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.08 to 0.66; p=0.009). The FC levels at initiation of IFX and postinduction were significantly associated with EH (OR, 0.73; 95% CI, 0.53 to 0.99; p=0.044 and OR, 0.20; 95% CI, 0.06 to 0.49; p=0.002, respectively). According to the receiver operating characteristic curve analysis, the optimal cutoff level for postinduction FC associated with PR was 122 mg/kg, and that associated with EH was 377 mg/kg. Conclusions Postinduction FC was associated with PR and EH after 1 year of treatment with IFX in pediatric patients with CD. Our findings emphasize the importance of FC as an intermediate target in the treat-to-target era.

Purpose: Renal tumors account for approximately 7% of all childhood cancers. These include Wilms tumor (WT), clear cell sarcoma of the kidney (CCSK), malignant rhabdoid tumor of the kidney (MRTK), renal cell carcinoma (RCC), congenital mesoblastic nephroma (CMN) and other rare tumors. We investigated the epidemiology of pediatric renal tumors in Korea. Materials and Methods: From January 2001 to December 2015, data of pediatric patients (0–18 years) newly-diagnosed with renal tumors at 26 hospitals were retrospectively analyzed. Results: Among 439 patients (male, 240), the most common tumor was WT (n=342, 77.9%), followed by RCC (n=36, 8.2%), CCSK (n=24, 5.5%), MRTK (n=16, 3.6%), CMN (n=12, 2.7%), and others (n=9, 2.1%). Median age at diagnosis was 27.1 months (range 0-225.5) and median follow-up duration was 88.5 months (range 0-211.6). Overall, 32 patients died, of whom 17, 11, 1, and 3 died of relapse, progressive disease, second malignant neoplasm, and treatment-related mortality. Five-year overall survival and event free survival were 97.2% and 84.8% in WT, 90.6% and 82.1% in RCC, 81.1% and 63.6% in CCSK, 60.3% and 56.2% in MRTK, and 100% and 91.7% in CMN, respectively (p < 0.001). Conclusion The pediatric renal tumor types in Korea are similar to those previously reported in other countries. WT accounted for a large proportion and survival was excellent. Non-Wilms renal tumors included a variety of tumors and showed inferior outcome, especially MRTK. Further efforts are necessary to optimize the treatment and analyze the genetic characteristics of pediatric renal tumors in Korea.

In healthy peripheral blood stem cell (PBSC) donors, rare cases of transient thrombocytopenia have been reported due to the administration of granulocyte colony-stimulating factor (G-CSF) or the apheresis itself. Meanwhile, differentiating pseudothrombocytopenia induced by anticoagulants is crucial, as it can result in false low platelet counts. This study aimed to investigate the causes of thrombocytopenia in healthy PBSC donors. We investigated PBSC donors who experienced thrombocytopenia during transplantation at St. Mary’s Hospital, Seoul. Three donors were identified and donor workup studies were within the normal limits. After G-CSF administration prior to transplantation, the donors experienced a significant reduction in platelet counts. Apheresis resulted in lower levels, yet platelet counts returned to normal levels approximately two weeks later. In donor 3, thrombocytopenia was seen during the donor workup and ethylenediaminetetraacetic acid (EDTA)-induced pseudothrombocytopenia was identified after the supplementation of amikacin. For donor 3, we investigated whether his recipient’s sample showed EDTA-induced pseudothrombocytopenia through a review of any platelet clumping in the apheresis product and the presence of immunoglobulin M (IgM) or IgG antiplatelet antibodies in the recipient’s peripheral blood. In conclusion, the risk of severe thrombocytopenia with G-CSF administration in PBSC donors should be considered and accurate differentiation of pseudothrombocytopenia is imperative.

Background/Aims: Although mucosal healing (MH) is acknowledged as the treatment target in the treat-to-target era, there are limitations on repeated endoscopic examinations, especially in pediatric patients. We aimed to investigate whether fecal calprotectin (FC) could serve as a surrogate marker for the assessment of MH in pediatric patients with Crohn’s disease (CD) who have achieved sustained clinical remission (CR) while treated with anti-tumor necrosis factor (TNF) agents. Methods: This multicenter retrospective cross-sectional study included pediatric CD patients who had sustained a CR for at least 6 months with anti-TNF agents and who simultaneously underwent ileocolonoscopy and FC tests during follow-up. MH was defined as the absence of any ulcer on ileocolonoscopy. Results: A total of 131 patients were included in this study. MH was observed in 87 patients (66.7%). The FC level was significantly lower in patients with MH than in those without MH (median 49.0 mg/kg vs 599.0 mg/kg; p<0.001). According to the multivariate logistic regression analysis, FC was the only factor associated with MH (odds ratio, 0.62; 95% confidence interval [CI], 0.52 to 0.73; p<0.001). According to the receiver operating characteristic curve analysis, the optimal cutoff value for FC for the association with MH was <140 mg/kg (area under the curve 0.890, 95% CI 0.829 to 0.951, sensitivity 78.2%, specificity 88.6%, p<0.001). Conclusions FC was associated with MH in pediatric patients with CD who had achieved a sustained CR for at least 6 months with anti-TNF agents. In these patients, FC can be used to stratify patients and guide decisions regarding ileocolonoscopy in the treat-to-target era.