Purpose: This study was conducted to develop a convolutional neural network (CNN) algorithm that can diagnose cervical foraminal stenosis using oblique radiographs and evaluate its accuracy. Materials and Methods: A total of 997 patients who underwent cervical MRI and cervical oblique radiographs within a 3-month interval were included. Oblique radiographs were labeled as “foraminal stenosis” or “no foraminal stenosis” according to whether foraminal stenosis was present in the C2–T1 levels based on MRI evaluation as ground truth. The CNN model involved data augmentation, image preprocessing, and transfer learning using DenseNet161. Visualization of the location of the CNN model was performed using gradient-weight class activation mapping (Grad-CAM). Results: The area under the curve (AUC) of the receiver operating characteristic curve based on DenseNet161 was 0.889 (95% confidence interval, 0.851–0.927). The F1 score, accuracy, precision, and recall were 88.5%, 84.6%, 88.1%, and 88.5%, respectively.The accuracy of the proposed CNN model was significantly higher than that of two orthopedic surgeons (64.0%, p<0.001; 58.0%, p<0.001). Grad-CAM analysis demonstrated that the CNN model most frequently focused on the foramen location for the determination of foraminal stenosis, although disc space was also frequently taken into consideration. Conclusion A CNN algorithm that can detect neural foraminal stenosis in cervical oblique radiographs was developed. The AUC, F1 score, and accuracy were 0.889, 88.5%, and 84.6%, respectively. With the current CNN model, cervical oblique radiography could be a more effective screening tool for neural foraminal stenosis.

Methods: We retrospectively reviewed patients who underwent cervical magnetic resonance imaging and computed tomography angiography for preoperative ACDF evaluation. The segments were classified according to the presence of foraminal stenosis. The height, thickness, anteroposterior length, horizontal distance from the uncinate process to the VA, and vertical distance from the uncinate process baseline to the VA of the uncinate process were measured. The distance between the uncinate anterior margin and the resection trajectory (UAM-to-RT) was measured. Results: There were no VA injuries or root injuries among the 101 patients who underwent ACDF (163 segments, mean age of 56.3±12.2). Uncinate anteroposterior length was considerably longer in foramens with foraminal stenosis, whereas uncinate process height, thickness, and distance between the uncinate process and VA were not significantly associated with foraminal stenosis. There were no significant differences in radiographic parameters based on uncinate degeneration. The UAM-to-RT distances for adequate decompression were 1.6±1.4 mm (range, 0–4.8 mm), 3.4±1.7 mm (range, 0–7.1 mm), 4.0±1.7 mm (range, 0–9.0 mm), and 4.5±1.2 mm (range, 2.5–7.5 mm) for C3–C4, C4–C5, C5–C6, and C6–C7, respectively. Conclusions More than half of the uncinate process in the anteroposterior plane should be removed for adequate neural foramen decompression. Foraminal stenosis or uncinate degeneration did not alter the relative anatomy of the uncinate process and the VA and did not impact VA injury risk.

Purpose: When splitting a liver for adult and pediatric graft recipients, the retained left medial section (S4) will undergo ischemic necrosis and the right trisection graft becomes an extended right liver (ERL) graft. We investigated the fates of the retained S4 and its prognostic impact in adult split liver transplantation (SLT) using an ERL graft. Methods: This was a retrospective analysis of 25 adult SLT recipients who received split ERL grafts. Results: The mean model for end-stage liver disease (MELD) score was 27.3 ± 10.9 and graft-recipient weight ratio (GRWR) was 1.98 ± 0.44. The mean donor age was 26.5 ± 7.7 years. The split ERL graft weight was 1,181.5 ± 252.8 g, which resulted in a mean GRWR of 1.98 ± 0.44. Computed tomography of the retained S4 parenchyma revealed small ischemic necrosis in 16 patients (64.0%) and large ischemic necrosis in the remaining 9 patients (36.0%). No S4-associated biliary complications were developed. The mean GRWR was 1.87 ± 0.43 in the 9 patients with large ischemic necrosis and 2.10 ± 0.44 in the 15 cases with small ischemic necrosis (P = 0.283). The retained S4 parenchyma showed gradual atrophy on follow-up imaging studies. The amount of S4 ischemic necrosis was not associated with graft (P = 0.592) or patient (P = 0.243) survival. A MELD score of >30 and pretransplant ventilator support were associated with inferior outcomes. Conclusion The amount of S4 ischemic necrosis is not a prognostic factor in adult SLT recipients, probably due to a sufficiently large GRWR.

Background: Spinal cord injury (SCI) is a serious clinical condition that impacts a patient's physical, psychological, and socio-economic status. The aim of this pilot study was to evaluate the effects of training with a newly developed powered wearable exoskeleton (Hyundai Medical Exoskeleton [H-MEX]) on functional mobility, physiological health, and quality of life in non-ambulatory SCI patients. Methods: Participants received 60 minutes of walking training with a powered exoskeleton 3 times per week for 10 weeks (total 30 sessions). The 6-minute walking test (6MWT) and timedup-and-go test (TUGT) were performed to assess ambulatory function. The physiological outcomes of interest after exoskeleton-assisted walking training were spasticity, pulmonary function, bone mineral density, colon transit time, and serum inflammatory markers. Effects of walking training on subjective outcomes were estimated by the Korean version of the Falls Efficacy Scale—International and the 36-Item Short-Form Health Survey version 2. Results: Ten participants finished 30 sessions of training and could ambulate independently.No severe adverse events were reported during the study. After training, the mean distance walked in the 6MWT (49.13 m) was significantly enhanced compared with baseline (20.65 m). The results of the TUGT also indicated a statistically significant improvement in the times required to stand up, walk 3 m and sit down. Although not statistically significant, clinically meaningful changes in some secondary physiological outcomes and/or quality of life were reported in some participants. Conclusion In conclusion, this study demonstrated that the newly developed wearable exoskeleton, H-MEX is safe and feasible for non-ambulatory SCI patients, and may have potential to improve quality of life of patients by assisting bipedal ambulation. These results suggest that the H-MEX can be considered a beneficial device for chronic non-ambulatory SCI patients.

Purpose: When splitting a liver for adult and pediatric graft recipients, the retained left medial section (S4) will undergo ischemic necrosis and the right trisection graft becomes an extended right liver (ERL) graft. We investigated the fates of the retained S4 and its prognostic impact in adult split liver transplantation (SLT) using an ERL graft. Methods: This was a retrospective analysis of 25 adult SLT recipients who received split ERL grafts. Results: The mean model for end-stage liver disease (MELD) score was 27.3 ± 10.9 and graft-recipient weight ratio (GRWR) was 1.98 ± 0.44. The mean donor age was 26.5 ± 7.7 years. The split ERL graft weight was 1,181.5 ± 252.8 g, which resulted in a mean GRWR of 1.98 ± 0.44. Computed tomography of the retained S4 parenchyma revealed small ischemic necrosis in 16 patients (64.0%) and large ischemic necrosis in the remaining 9 patients (36.0%). No S4-associated biliary complications were developed. The mean GRWR was 1.87 ± 0.43 in the 9 patients with large ischemic necrosis and 2.10 ± 0.44 in the 15 cases with small ischemic necrosis (P = 0.283). The retained S4 parenchyma showed gradual atrophy on follow-up imaging studies. The amount of S4 ischemic necrosis was not associated with graft (P = 0.592) or patient (P = 0.243) survival. A MELD score of >30 and pretransplant ventilator support were associated with inferior outcomes. Conclusion The amount of S4 ischemic necrosis is not a prognostic factor in adult SLT recipients, probably due to a sufficiently large GRWR.

Background: Spinal cord injury (SCI) is a serious clinical condition that impacts a patient's physical, psychological, and socio-economic status. The aim of this pilot study was to evaluate the effects of training with a newly developed powered wearable exoskeleton (Hyundai Medical Exoskeleton [H-MEX]) on functional mobility, physiological health, and quality of life in non-ambulatory SCI patients. Methods: Participants received 60 minutes of walking training with a powered exoskeleton 3 times per week for 10 weeks (total 30 sessions). The 6-minute walking test (6MWT) and timedup-and-go test (TUGT) were performed to assess ambulatory function. The physiological outcomes of interest after exoskeleton-assisted walking training were spasticity, pulmonary function, bone mineral density, colon transit time, and serum inflammatory markers. Effects of walking training on subjective outcomes were estimated by the Korean version of the Falls Efficacy Scale—International and the 36-Item Short-Form Health Survey version 2. Results: Ten participants finished 30 sessions of training and could ambulate independently.No severe adverse events were reported during the study. After training, the mean distance walked in the 6MWT (49.13 m) was significantly enhanced compared with baseline (20.65 m). The results of the TUGT also indicated a statistically significant improvement in the times required to stand up, walk 3 m and sit down. Although not statistically significant, clinically meaningful changes in some secondary physiological outcomes and/or quality of life were reported in some participants. Conclusion In conclusion, this study demonstrated that the newly developed wearable exoskeleton, H-MEX is safe and feasible for non-ambulatory SCI patients, and may have potential to improve quality of life of patients by assisting bipedal ambulation. These results suggest that the H-MEX can be considered a beneficial device for chronic non-ambulatory SCI patients.

BACKGROUND: Hepatocellular carcinoma (HCC) recurrence and development of de novo malignancy (DNM) after liver transplantation (LT) are the major causes of late recipient death.METHODS: We analyzed the incidence of extrahepatic DNM following living donor LT according to the status of pretransplant hepatic malignancy. We selected 2,076 adult patients who underwent primary LDLT during 7 years from January 2010 to December 2016.RESULTS: The pretransplant hepatic malignancy group (n = 1,012) showed 45 cases (4.4%) of the following extrahepatic DNMs: posttransplant lymphoproliferative disease (PTLD) in 10; lung cancer in 10; stomach cancer in 6; colorectal cancer in 5; urinary bladder cancer in 3; and other cancers in 11. The pretransplant no hepatic malignancy group (n = 1,064) showed 25 cases (2.3%) of the following extrahepatic DNMs: colorectal cancer in 3; stomach cancer in 3; leukemia in 3; lung cancer in 3; PTLD in 2; prostate cancer in 2; and other cancers in 9. Incidences of extrahepatic DNM in the pretransplant hepatic malignancy and no hepatic malignancy groups were as follows: 1.1% and 0.5% at 1 year, 3.2% and 2.0% at 3 years, 4.6% and 2.5% at 5 years, and 5.4% and 2.8% at 8 years, respectively (P = 0.006). Their overall patient survival rates were as follows: 97.3% and 97.2% at 1 year, 91.6% and 95.9% at 3 years, 89.8% and 95.4% at 5 years, and 89.2% and 95.4% at 8 years, respectively (P < 0.001). Pretransplant hepatic malignancy was the only significant risk factor for posttransplant extrahepatic DNM.CONCLUSION: Our results suggest that patients who had pretransplant hepatic malignancy be followed up more strictly because they have a potential risk of primary hepatic malignancy recurrence as well as a higher risk of extrahepatic DNM than patients without pretransplant hepatic malignancy.

PURPOSE: Hepatorenal syndrome (HRS) is a fatal complication in patients with end-stage liver disease awaiting liver transplantation (LT). HRS often develops in patients with high model for end-stage liver disease (MELD) score. This study investigated the outcomes of peritransplant management of HRS in a high-volume LT center in Korea for 2 years. METHODS: A total of 157 recipients that deceased donor liver transplantation (DDLT) from January 2017 to December 2018 were included. In-hospital mortality (IHM) was analyzed in relation to pre- and posttransplant application of renal replacement therapy (RRT). RESULTS: Primary diagnoses for DDLT were alcoholic liver disease (n = 61), HBV-associated liver cirrhosis (n = 48), retransplantation for chronic graft failure (n = 24), and others (n = 24). Mean MELD score was 34.6 ± 6.2 with 72 patients at Korean Network for Organ Sharing MELD status 2 (45.9%), 43 at status 3 (27.4%), 36 at status 4 (22.9%), and 6 at status 5 (3.8%). Pretransplant RRT was performed in 16 patients (10.2%) that did not show IHM. Posttransplant RRT was performed in 69 patients (44.0%), for whom IHM incidence was 15.9%. In 53 patients that had undergone de novo posttransplant RRT, IHM incidence increased to 20.8%. IHM in the 88 patients not requiring RRT was 2.3%. CONCLUSION The majority of adult DDLT recipients in Korean MELD score-based allocation system have very high MELD scores, which is often associated with HRS. Pretransplant RRT appears to improve posttransplant survival outcomes. We thereby recommend that, if indicated, pretransplant RRT be performed while awaiting DDLT.

Purpose: A cryopreserved iliac artery homograft (IAH) has not been considered suitable for middle hepatic vein (MHV) reconstruction during living donor liver transplantation (LDLT), primarily due to the low patency from its small diameter. We revised our surgical techniques for MHV reconstruction using an IAH to improve its patency. Methods: This study analyzed the causes of early conduit occlusion and developed revised techniques to address this that had clinical application. Results: The potential risk factors for early conduit occlusion were the small IAH size, small graft in the segment V vein (V5) and segment VIII vein (V8) opening, and small recipient MHV-left hepatic vein stump. These factors were reflected to our revised surgical methods which included endarterectomy of the atherosclerotic plaque, unification of the internal and external iliac artery branches for large V5, and branch-patch arterioplasty for large V8. IAH endarterectomy, branch unification technique, and branch-patch arterioplasty were applied to 8, 5, and 5 patients, respectively and resulted in 1-month occlusion rates of 37.5%, 20.0%, and 40.0%, respectively. The overall patency rates of the IAH-MHV conduits in our 18 patients were 66.7% at 1 month, 38.9% at 3 months, and 33.3% at 1 year. Conclusion Our refined MHV reconstruction using an IAH improved short-term MHV conduit patency, but did not effectively prevent early conduit occlusion, particularly with a small- or medium-sized IAH. Individualized reconstruction designs during LDLT operation are needed when an IAH is used for a modified right liver graft.

BACKGROUND: Hepatocellular carcinoma (HCC) recurrence and development of de novo malignancy (DNM) after liver transplantation (LT) are the major causes of late recipient death. METHODS: We analyzed the incidence of extrahepatic DNM following living donor LT according to the status of pretransplant hepatic malignancy. We selected 2,076 adult patients who underwent primary LDLT during 7 years from January 2010 to December 2016. RESULTS: The pretransplant hepatic malignancy group (n = 1,012) showed 45 cases (4.4%) of the following extrahepatic DNMs: posttransplant lymphoproliferative disease (PTLD) in 10; lung cancer in 10; stomach cancer in 6; colorectal cancer in 5; urinary bladder cancer in 3; and other cancers in 11. The pretransplant no hepatic malignancy group (n = 1,064) showed 25 cases (2.3%) of the following extrahepatic DNMs: colorectal cancer in 3; stomach cancer in 3; leukemia in 3; lung cancer in 3; PTLD in 2; prostate cancer in 2; and other cancers in 9. Incidences of extrahepatic DNM in the pretransplant hepatic malignancy and no hepatic malignancy groups were as follows: 1.1% and 0.5% at 1 year, 3.2% and 2.0% at 3 years, 4.6% and 2.5% at 5 years, and 5.4% and 2.8% at 8 years, respectively (P = 0.006). Their overall patient survival rates were as follows: 97.3% and 97.2% at 1 year, 91.6% and 95.9% at 3 years, 89.8% and 95.4% at 5 years, and 89.2% and 95.4% at 8 years, respectively (P < 0.001). Pretransplant hepatic malignancy was the only significant risk factor for posttransplant extrahepatic DNM. CONCLUSION Our results suggest that patients who had pretransplant hepatic malignancy be followed up more strictly because they have a potential risk of primary hepatic malignancy recurrence as well as a higher risk of extrahepatic DNM than patients without pretransplant hepatic malignancy.