Design consideration on integration of mechanical intravascular ultrasound and electromagnetic tracking sensor for intravascular reconstruction.

PURPOSE: Considering vessel deformation, endovascular navigation requires intraoperative geometric information. Mechanical intravascular ultrasound (IVUS) with an electromagnetic (EM) sensor can be used to reconstruct blood vessels with thin diameter. However, the integration design should be evaluated based on the factors affecting the reconstruction error. METHODS: The interference between the mechanical IVUS and EM sensor was measured in different relative positions. Two designs of the integrated catheter were evaluated by measuring the reconstruction errors using a rigid vascular phantom. RESULTS: When the distance from the EM sensor to the field generator was 75 mm, the interference from mechanical IVUS to an EM sensor was negligible, with position and rotation errors less than 0.1 mm and 0.6°, respectively. The reconstructed vessel model for proximal IVUS transducer had a smooth surface but an inaccurate shape at large curvature of the vascular phantom. When the distance to the field generator was 175 mm, the error increased significantly. CONCLUSION: Placing the IVUS transducer on the proximal side of the EM sensor is superior in terms of interference reduction but inferior in terms of mechanical stability compared to a distal transducer. The distal side is preferred due to better mechanical stability during catheter manipulation at larger curvature. With this configuration, surface reconstruction errors less than 1.7 mm (with RMS 0.57 mm) were achieved when the distance to the field generator was less than 175 mm.

Tissue histology on the correlation between fracture energy and elasticity.

PURPOSE: Preemptively estimating tissue damage is crucial for a safe surgical procedure. We previously investigated the possibility of estimating the fracture energies of biological tissues based on their elasticities. However, the reason behind the presence of these correlations is poorly understood. In this study, we investigate the effect of a tissue's histology on the correlation between the fracture energy and elasticity. We hypothesize that two tissues with similar fibrous structure will show a similar correlation between the fracture energy and elasticity. METHODS: Porcine duodenum were used for this study. Two tensile tests were performed for each porcine duodenum specimen to determine its elasticity and tearing energy. The correlation between fracture energy and elasticity was then investigated using the results from the mechanical tests. Furthermore, duodenum specimens were fixed in 10% formalin while under tension. Microscopic images were then taken to visualize the fibrous structure within the duodenum tissues under tension. RESULTS: The results from the tensile test showed that the fracture energy had an isotropic positive and linear correlation with the elasticity to the negative 0.5th power (R2 = 0.89), which was also previously reported in small intestinal (jejunum) specimens. Furthermore, the tearing patterns of the duodenum were identical to the ones reported in the jejunum. Hematoxylin and eosin staining on tissues fixed under tension showed that the endomysium fibers are involved in providing resistance toward traction. CONCLUSION: Through mechanical tests, we showed that porcine duodenum tissues also have a correlation between its fracture energy and elasticity. We also discussed that the histological structure of a tissue is an important factor that dictates how the tearing energy of a tissue will correlate to the elasticity. We understood that since the tearing mechanism between the duodenum and jejunum was similar, the correlations between their fracture energies and elasticities were also similar.

Laparoscopic observations of adhesions between peritoneal dialysis catheters and intraperitoneal organs: A retrospective, observational study.

Laparoscopy provides extensive data for the decannulation of a peritoneal dialysis catheter and is being increasingly used to diagnose encapsulating peritoneal sclerosis. However, there are few reports on the methods of decannulation of peritoneal dialysis catheters. In this study, we examined the laparoscopic findings and postoperative complications of patients undergoing peritoneal dialysis catheter removal. A total of 119 laparoscopic decannulations of peritoneal dialysis catheters were performed between 2003 and 2018 at the Juntendo University Hospital and Juntendo University Nerima Hospital. Laparoscopy was performed during peritoneal dialysis catheter removal by a gastrointestinal surgeon. Patient characteristics such as age, sex, duration of peritoneal dialysis, history of peritonitis and age at the time of peritoneal dialysis termination were assessed. Of these 119 cases, 19 (16.0%) showed adhesion between the peritoneal dialysis catheter and intraperitoneal organs. There were 13 (10.9%) cases involving a tangled omentum, 4 (3.4%) cases involving the small intestine and 2 (1.7%) cases of adhesions extending from the bowels to the abdominal wall. No postoperative complications were associated with the laparoscopic surgery. In these cases, blind decannulation of the peritoneal dialysis catheter may result in injury to the gastrointestinal tract in patients with adhesions. Therefore, we need to pay attention to adhesions between peritoneal dialysis catheters and intraperitoneal organs, and laparoscopy could be a valuable tool in detecting such adhesions and ensuring patient safety.

Occlusion-robust scene flow-based tissue deformation recovery incorporating a mesh optimization model.

PURPOSE: Tissue deformation recovery is to reconstruct the change in shape and surface strain caused by tool-tissue interaction or respiration, which is essential for providing motion and shape information that benefits the improvement of the safety of minimally invasive surgery. The binocular vision-based approach is a practical candidate for deformation recovery as no extra devices are required. However, previous methods suffer from limitations such as the reliance on biomechanical priors and the vulnerability to the occlusion caused by surgical instruments. To address the issues, we propose a deformation recovery method incorporating mesh structures and scene flow. METHODS: The method can be divided into three modules. The first one is the implementation of the two-step scene flow generation module to extract the 3D motion from the binocular sequence. Second, we propose a strain-based filtering method to denoise the original scene flow. Third, a mesh optimization model is proposed that strengthens the robustness to occlusion by employing contextual connectivity. RESULTS: In a phantom and an in vivo experiment, the feasibility of the method in recovering surface deformation in the presence of tool-induced occlusion was demonstrated. Surface reconstruction accuracy was quantitatively evaluated by comparing the recovered mesh surface with the 3D scanned model in the phantom experiment. Results show that the overall error is 0.70 ± 0.55 mm. CONCLUSION: The method has been demonstrated to be capable of continuously recovering surface deformation using mesh representation with robustness to the occlusion caused by surgical forceps and promises to be suitable for the application in actual surgery.

Tissue damage force estimation in porcine small intestine from its elasticity.

PURPOSE: Post-surgical complications are correlated to the surgeon's technical skill level. Thus, efforts are being put in finding ways to improve the surgeon's technical skills, such as not causing unwanted damage to tissues during surgery. In this study, we aim to investigate the possibility of estimating biological tissue damage, in view of preventing unwanted damage during surgery. METHODS: A series of tensile tests were performed on porcine small intestinal tissue to determine the elasticity and the tearing force. The tissue was then microscopically observed to investigate the influence of fibrous protein configuration in the tissue's mechanical properties. RESULTS: The results from the tensile test showed that the fracture energy had a positive and linear correlation with the elasticity to the negative 0.5th power (R2 = 0.897), which was also suggested by an existing damage model for polymeric materials (Lake-Thomas model). The results from the microscopic observations also showed a resembling influence of fiber configuration on the elasticity as suggested in polymer mechanics (affine network model). CONCLUSION: We showed that the fracture energy had a correlation with the elasticity in porcine small intestinal tissues, which was also suggested in polymer mechanics, thus being a promising avenue toward the ability to estimate the maximum applicable force onto a biological tissue without causing damage during surgery. Attention should also be pointed, however, towards investigating the extent at which polymer mechanics and biomechanics overlap.

A pilot study on an electromagnetic tracking system using tunneling magnetoresistance (TMR) sensors applicable to a 4F catheter (1.4 mm in diameter).

PURPOSE: Tracking the position and orientation of a 4F catheter ([Formula: see text] 1.4 mm) is required in superselective intra-arterial chemotherapy (SSIAC). Tunneling magnetoresistance (TMR) sensors, which measure magnetic fields, are promising candidates because the size of the TMR sensor can be less than a few tenths of a millimeter. The purpose of this paper is to prove the feasibility of an EMT system utilizing TMR sensors as magnetometers. METHODS: Three 1-axis TMR sensors (0.3 mm × 0.3 mm) were packaged on a flexible printed circuit board (PCB) together with an amplifier chip. The PCB was integrated into a 4F catheter. Six field generator coils driven by alternating current (AC) at different frequencies were used. Magnetic field measurement errors were evaluated to assess the effect of electromotive force (EMF) on TMR-based sensing by changing the coils' driving frequencies. The tracking error was also evaluated. As a result, the feasibility of catheter navigation utilizing the EMT system was demonstrated. RESULTS: There was a positive correlation between the frequency and the magnetic field measurement error using the TMR sensor (R2 = 0.999). With magnetic field frequencies less than 603 Hz, the average position and orientation estimation error were 10.1 mm and 2.3 degree, respectively. Under ideal conditions, the average estimation error values were 0.9 mm and 0.3 degree, respectively. CONCLUSION: The position and orientation errors varied with frequency owing to the induced electromotive force. We should consider the effect of electromotive force on TMR sensor assemblies caused by alternating magnetic fields. An EMT system using TMR sensors was validated, although room for further improvement was identified.

Machine-learning-based approach for predicting postoperative skeletal changes for orthognathic surgical planning.

BACKGROUND: Manually surgical planning becomes an increasing workload of surgeons because of the fast-growing patient population. This study introduced a machine-learning-based approach to assist surgical planning in orthognathic surgery. METHODS: Both preoperative and one-year-later postoperative computerised tomography images of 56 patients were collected. A 12-layers cascaded deep neural network structure with two successive models was proposed to yield an end-to-end solution, where the first model extracts landmarks from 2D patches of 3D volume and the second model predicts postoperative skeletal changes. RESULTS: The experimental results showed that the model obtained a prediction accuracy of 5.4 mm at the landmark level in 42.9 s. It also represented 74.4% of 3D regions at volume level when compared with the ground truth of human surgeons. CONCLUSIONS: This study demonstrated the feasibility of predicting postoperative skeletal changes for orthognathic surgical planning by using machine learning, showing great potential for reducing the workload of surgeons.

Multicenter laparoscopic evaluation of the peritoneum in peritoneal dialysis patients.

Laparoscopic findings have been used to confirm peritoneal degenerations in peritoneal dialysis (PD) therapy. This study evaluated morphological changes in the peritoneum and their clinical relevance in patients undergoing PD. Laparoscopic findings at the rectovesical peritoneum were evaluated and scored using an imaging system at the time of PD catheter removal in this multicenter study. Angiogenesis evaluated by the vascular score (VS), color changes score (CCS), plaque score (PS), PD duration, history of peritonitis, dialysate/plasma creatinine (D/P Cr) levels, and age at PD termination were statistically analyzed. The VS of patients with PD duration more than 96 months was significantly decreased compared with that of the other patients and was negatively correlated with D/P Cr levels at PD termination. The CCS for patients with PD duration more than 96 months were significantly higher than those for the other patients and positively correlated with D/P Cr levels at PD termination. The PS of patients with recurring peritonitis were significantly higher than those of the other patients. Diminished vascularity and increased color changes in the peritoneum may be predictive of D/P Cr levels with peritoneal degradation. Laparoscopic evaluation of the abdominal cavity can provide detailed information about peritoneal injury.

Exercise-Induced Acute Kidney Injury in a Police Officer with Hereditary Renal Hypouricemia.

Hereditary renal hypouricemia is characterized by hypouricemia with hyper-uric acid clearance due to a defect in renal tubular transport. Patients with hereditary renal hypouricemia have a higher risk of exercise-induced acute kidney injury (EAKI) and reduced kidney function. Although the best preventive measure is avoiding exercise, there are many kinds of jobs that require occupational exercise. A 27-year-old male police officer suffered from stage 3 AKI after performing a 20-m multistage shuttle run test. His mother had previously been diagnosed as having renal hypouricemia at another facility. The patient had reported having hypouricemia during a health check at a previous police station, but his serum uric acid concentration was within the normal range at our hospital. After treatment, he recovered from EAKI and exhibited low serum uric acid and hyper-uric acid clearance. Since the patient desired to continue his career requiring strenuous exercise, it was difficult to establish a preventive plan against the recurrence of EAKI. Patients with hereditary renal hypouricemia who must undergo strenuous occupational anaerobic exercise are at higher risk of developing EAKI than other workers. The risks of EAKI among patients with hypouricemia should be considered when undergoing physical occupational training.

MPGN Type 3 Associated with Pemphigus Herpetiformis Mimicking PGNMID and Dermatitis Herpetiformis.

A 45-year-old man suffering from dermal blistering disease with proteinuria and hematuria underwent renal biopsy. The renal biopsy specimen suggested proliferative glomerulonephritis with monoclonal IgG deposits under routine light, immunofluorescence and electron microscopy. The staining for IgG subclasses (IgG1 and IgG2) and κ/λ light chain indicated secondary immune complex type MPGN type 3. The patient had been diagnosed as having dermatitis herpetiformis (DH), a phenotype of gluten hypersensitivity prior to the appearance of the renal abnormality. Although common autoantibodies might be related to the pathogenesis of disorders in the skin and kidney, DH is mainly driven by IgA autoantibody, while MPGN is induced by IgG immune complexes. IgA was not observed in the glomeruli by immunofluorescence. Neither the examination for DH specific autoantibodies nor HLA-DQB1 genotype supported the diagnosis of DH. Reassessment of the skin biopsy record revealed that the blister was localized in the epidermis, suggesting pemphigus herpetiformis by IgG class anti-epidermal autoantibody, which also affected the renal disorder.

Development and preliminary evaluation of an autonomous surgical system for oral and maxillofacial surgery.

BACKGROUND: Human-related factors affect the accuracy and safety of the oral and maxillofacial surgery (OMS). This study proposed an autonomous surgical system aiming to conduct the OMS under the assistance and surveillance of the surgeon. METHODS: A markerless navigation module and a compact OMS robot were seamlessly integrated into this system. The specifications of each module and the working concept of the system were elaborated in this paper. A drilling experiment was conducted on five 3D-printed mandible models to test the pose detecting capability and evaluate the operational performance. RESULTS: The experiment showed that this system could successfully guide the robot finishing the operation regardless of the mandible pose. The accuracy of software and hardware are acceptable and potential performance improvement can be achieved in positioning accuracy. CONCLUSION: This system proposed a novel concept and a practical solution to decrease the human-related factors on the OMS, which may change the role of the surgeon in the future operating room and finally benefit the outcomes of OMS.

Scavenging of reactive oxygen species by astaxanthin inhibits epithelial-mesenchymal transition in high glucose-stimulated mesothelial cells.

BACKGROUND: High glucose concentrations influence the functional and structural development of the peritoneal membrane. We previously reported that the oral administration of astaxanthin (AST) suppressed peritoneal fibrosis (PF) as well as inhibited oxidative stress, inflammation, and epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) in a chlorhexidine-induced PF rat model. This suggests that oxidative stress induction of EMT is a key event during peritoneal damage. The present study evaluated the therapeutic effect of AST in suppressing EMT, in response to glucose-induced oxidative stress. METHODS: Temperature-sensitive mesothelial cells (TSMCs) were cultured in the presence or absence of AST and then treated with 140 mM glucose for 3 or 12 hours. Expression levels of TNF-α, TGF-ß, and VEGF were determined at the mRNA and protein levels, and nuclear factor kappa B (NF-κB) activity was evaluated. We measured NO2-/NO3- concentrations in cellular supernatants and determined 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in mitochondrial and nuclear DNA. The expressions of E-cadherin and alpha-smooth muscle actin (α-SMA) were evaluated by double immunofluorescence and protein levels. RESULTS: High glucose concentrations induced overproduction of reactive oxidative species (ROS), increasing 8-OHdG mitochondrial DNA and cytokine levels. The NF-κB pathway was activated in response to high glucose concentrations, whereas de novo α-SMA expression was observed with decreased E-cadherin expression. AST treatment attenuated ROS production, inflammatory cytokine production, NF-κB activation, and EMT. CONCLUSION: The findings of the present study indicate that AST may have an anti-EMT effect due to anti-oxidative and anti-inflammatory activities by scavenging glucose-induced ROS from mitochondria in PMCs. AST may be an efficacious treatment for PF.

Paracrine effects of transplanted mesothelial cells isolated from temperature-sensitive SV40 large T-antigen gene transgenic rats during peritoneal repair.

BACKGROUND: The prevention and restoration of peritoneal damage is a critical mission in peritoneal dialysis (PD). Transplantation of mesothelial cells has been suggested to suppress peritoneal injury during PD. Few studies have examined the efficacy and safety of cell transplantation. We evaluated the paracrine effects of mesothelial transplantation during peritoneal repair using immortalized temperature-sensitive mesothelial cells (TSMCs) in chlorhexidine gluconate (CG)-induced peritoneal fibrosis rats. METHODS: Continuous-infusion pumps containing 8% CG were placed into the abdominal cavity for 21 days. After the removal of the pumps, the TSMCs were injected into the peritoneal cavity at Day 22 (Tx-1 group) or 29 (Tx-2 group). Morphological findings and mRNA expressions of regeneration-related factors were examined at Days 22, 29 and 35. RESULTS: Peritoneal thickness was aggravated in the Tx-1 group. Levels of transforming growth factor (TGF)-ß, vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 mRNA in the Tx-1 group at Day 35 were comparable with those at Day 22. The levels of Snail, B-Raf and ERK-1, markers of epithelial to mesenchymal transition and of the RAS/MAPK pathway in the Tx-1 group, were significantly higher than those in the Tx-2 group. TGF-ß and VEGF were produced from the transplanted mesothelial cells and the surrounding cells in the Tx-1 group. CONCLUSION: It appears that the paracrine effect of transplanted mesothelial cells during peritoneal repair is associated with its surrounding condition. It is important to determine the most appropriate time for developing peritoneal repair through mesothelial transplantation.