Advanced three-dimensional X-ray imaging unravels structural development of the human thymus compartments.

BACKGROUND: The thymus, responsible for T cell-mediated adaptive immune system, has a structural and functional complexity that is not yet fully understood. Until now, thymic anatomy has been studied using histological thin sections or confocal microscopy 3D reconstruction, necessarily for limited volumes. METHODS: We used Phase Contrast X-Ray Computed Tomography to address the lack of whole-organ volumetric information on the microarchitecture of its structural components. We scanned 15 human thymi (9 foetal and 6 postnatal) with synchrotron radiation, and repeated scans using a conventional laboratory x-ray system. We used histology, immunofluorescence and flow cytometry to validate the x-ray findings. RESULTS: Application to human thymi at pre- and post-natal stages allowed reliable tracking and quantification of the evolution of parameters such as size and distribution of Hassall's Bodies and medulla-to-cortex ratio, whose changes reflect adaptation of thymic activity. We show that Hassall's bodies can occupy 25% of the medulla volume, indicating they should be considered a third thymic compartment with possible implications on their role. Moreover, we demonstrate compatible results can be obtained with standard laboratory-based x-ray equipment, making this research tool accessible to a wider community. CONCLUSIONS: Our study allows overcoming the resolution and/or volumetric limitations of existing approaches for the study of thymic disfunction in congenital and acquired disorders affecting the adaptive immune system.

The thymus is the organ responsible for programming the immune system. It consists of two main compartments, named medulla and cortex. The medulla contains onion-shaped parts known as "Hassall's bodies". By imaging thymi at different stages of development with advanced x-ray methods, we gain understanding of changes that occur over time in 3D. We quantified how much of the thymus was occupied by these different components as they change with age, showing that Hassall's bodies can take up 25% of the medulla, and should therefore be considered a proper part of the thymus with a purpose. Having a better understanding of the thymus can prove important in targeting conditions such as Down syndrome and thymic tumours, as well as provide information about structure.

Diagnosing Necrotizing Enterocolitis via Fine-Grained Visual Classification.

Necrotizing Enterocolitis (NEC) is a devastating condition affecting prematurely born neonates. Reviewing Abdominal X-rays (AXRs) is a key step in NEC diagnosis, staging and treatment decision-making, but poses significant challenges due to the subtle, difficult-to-identify radiological signs of the disease. In this paper, we propose AIDNEC - AI Diagnosis of NECrotizing enterocolitis, a deep learning method to automatically detect and stratify the severity (surgical or medical) of NEC from no pathology in AXRs. The model is trainable end-to-end and integrates a Detection Transformer and Graph Convolution modules for localizing discriminative areas in AXRs, used to formulate subtle local embeddings. These are then combined with global image features to perform Fine-Grained Visual Classification (FGVC). We evaluate AIDNEC on our GOSH NEC dataset of 1153 images from 334 patients, achieving 79.7% accuracy in classifying NEC against No Pathology. AIDNEC outperforms the backbone by 2.6%, FGVC models by 2.5% and CheXNet by 4.2%, with statistically significant (two-tailed p 0.05) improvements, while providing meaningful discriminative regions to support the classification decision. Additional validation in the publicly available Chest X-ray14 dataset yields comparable performance to state-of-the-art methods, illustrating AIDNEC's robustness in a different X-ray classification task.

State of the art medical devices for fluorescence-guided surgery (FGS): technical review and future developments.

BACKGROUND: Medical devices for fluorescence-guided surgery (FGS) are becoming available at a fast pace. The main challenge for surgeons lies in the lack of in-depth knowledge of optical imaging, different technical specifications and poor standardisation, and the selection of the best device based on clinical application. METHODS: This manuscript aims to provide an up-to-date description of the commercially available fluorescence imaging platforms by comparing their mode of use, required settings, image types, compatible fluorophores, regulatory approval, and cost. We obtained this information by performing a broad literature search on PubMed and by contacting medical companies directly. The data for this review were collected up to November 2023. RESULTS: Thirty-two devices made by 19 medical companies were identified. Ten systems are surgical microscopes, 5 can be used for both open and minimally invasive surgery (MIS), 6 can only be used for open surgery, and 10 only for MIS. One is a fluorescence system available for the Da Vinci robot. Nineteen devices can provide an overlay between fluorescence and white light image. All devices are compatible with Indocyanine Green, the most common fluorescence dye used intraoperatively. There is significant variability in the hardware and software of each device, which resulted in different sensitivity, fluorescence intensity, and image quality. All devices are CE-mark regulated, and 30 were FDA-approved. CONCLUSION: There is a prolific market of devices for FGS and healthcare professionals should have basic knowledge of their technical specifications to use it at best for each clinical indication. Standardisation across devices must be a priority in the field of FGS, and it will enhance external validity for future clinical trials in the field.

Experimental Induction of Complex Gastroschisis in the Fetal Lamb: Systematic Review.

We systematically reviewed experiments in the fetal lamb model of gastroschisis using PubMed, Embase, Web of Science, and Scopus, seeking for standardized surgical techniques to obtain complex gastroschisis. Eligible were studies where an abdominal wall defect was surgically induced and gross anatomical findings at birth were available. The primary outcome was complex gastroschisis, defined by the presence of bowel stenosis, atresia, volvulus, perforation, and/or necrosis. Secondary outcomes were fetal death and additional readouts reported. Of ten eligible studies, six included lambs that had no additional prenatal manipulations and were assessed at term (35 lambs). Gastroschisis was induced at day 70-80 (term = 140-145), typically (n = 4/6 studies) in the left lower abdomen with defect size ranging from 0.5 to 4.0 cm. Only one study, in which a 1.5 cm diameter silicone ring was utilized, resulted in complex gastroschisis in 100% of term survivors. Fetal loss was more frequent in studies where a silicone ring and/or a right-sided defect were used. No changes unique to complex gastroschisis were identified in additional readouts, including bowel histology. When gastroschisis becomes "complex" following induction is uncertain. This knowledge is essential in studying potential prenatal interventions that may change the natural course.

Biliary atresia.

Biliary atresia (BA) is a progressive inflammatory fibrosclerosing disease of the biliary system and a major cause of neonatal cholestasis. It affects 1:5,000-20,000 live births, with the highest incidence in Asia. The pathogenesis is still unknown, but emerging research suggests a role for ciliary dysfunction, redox stress and hypoxia. The study of the underlying mechanisms can be conceptualized along the likely prenatal timing of an initial insult and the distinction between the injury and prenatal and postnatal responses to injury. Although still speculative, these emerging concepts, new diagnostic tools and early diagnosis might enable neoadjuvant therapy (possibly aimed at oxidative stress) before a Kasai portoenterostomy (KPE). This is particularly important, as timely KPE restores bile flow in only 50-75% of patients of whom many subsequently develop cholangitis, portal hypertension and progressive fibrosis; 60-75% of patients require liver transplantation by the age of 18 years. Early diagnosis, multidisciplinary management, centralization of surgery and optimized interventions for complications after KPE lead to better survival. Postoperative corticosteroid use has shown benefits, whereas the role of other adjuvant therapies remains to be evaluated. Continued research to better understand disease mechanisms is necessary to develop innovative treatments, including adjuvant therapies targeting the immune response, regenerative medicine approaches and new clinical tests to improve patient outcomes.

The characteristics of eating, drinking and oro-pharyngeal swallowing difficulties associated with repaired oesophageal atresia/tracheo-oesophageal fistula: a systematic review and meta-proportional analysis.

INTRODUCTION: Eating, drinking and swallowing difficulties are commonly reported morbidities for individuals born with OA/TOF. This study aimed to determine the nature and prevalence of eating, drinking and oro-pharyngeal swallowing difficulties reported in this population. METHOD: A systematic review and meta-proportional analysis were conducted (PROSPERO: CRD42020207263). MEDLINE, EMBASE, CINAHL, Pubmed, Scopus, Web of Science databases and grey literature were searched. Quantitative and qualitative data were extracted relating to swallow impairment, use of mealtime adaptations and eating and drinking-related quality of life. Quantitative data were summarised using narrative and meta-proportional analysis methods. Qualitative data were synthesised using a meta-aggregation approach. Where quantitative and qualitative data described the same phenomenon, a convergent segregated approach was used to synthesise data. RESULTS: Sixty-five studies were included. Six oro-pharyngeal swallow characteristics were identified, and pooled prevalence calculated: aspiration (24%), laryngeal penetration (6%), oral stage dysfunction (11%), pharyngeal residue (13%), nasal regurgitation (7%), delayed swallow initiation (31%). Four patient-reported eating/drinking difficulties were identified, and pooled prevalence calculated: difficulty swallowing solids (45%), difficulty swallowing liquids (6%), odynophagia (30%), coughing when eating (38%). Three patient-reported mealtime adaptations were identified, and pooled prevalence calculated: need for water when eating (49%), eating slowly (37%), modifying textures (28%). Mixed methods synthesis of psychosocial impacts identified 34% of parents experienced mealtime anxiety and 25% report challenging mealtime behaviours reflected in five qualitative themes: fear and trauma associated with eating and drinking, isolation and a lack of support, being aware and grateful, support to cope and loss. CONCLUSIONS: Eating and drinking difficulties are common in adults and children with repaired OA/TOF. Oro-pharyngeal swallowing difficulties may be more prevalent than previously reported. Eating, drinking and swallowing difficulties can impact on psychological well-being and quality of life, for the individual and parents/family members. Long-term, multi-disciplinary follow-up is warranted.

Comprehensive meta-analysis of surgical procedure for congenital diaphragmatic hernia: thoracoscopic versus open repair.

PURPOSE: Previous studies have shown a higher recurrence rate and longer operative times for thoracoscopic repair (TR) of congenital diaphragmatic hernia (CDH) compared to open repair (OR). An updated meta-analysis was conducted to re-evaluate the surgical outcomes of TR. METHODS: A comprehensive literature search comparing TR and OR in neonates was performed in accordance with the PRISMA statement (PROSPERO: CRD42020166588). RESULTS: Fourteen studies were selected for quantitative analysis, including a total of 709 patients (TR: 308 cases, OR: 401 cases). The recurrence rate was higher [Odds ratio: 4.03, 95% CI (2.21, 7.36), p < 0.001] and operative times (minutes) were longer [Mean Difference (MD): 43.96, 95% CI (24.70, 63.22), p < 0.001] for TR compared to OR. A significant reduction in the occurrence of postoperative bowel obstruction was observed in TR (5.0%) compared to OR (14.8%) [Odds ratio: 0.42, 95% CI (0.20, 0.89), p = 0.02]. CONCLUSIONS: TR remains associated with higher recurrence rates and longer operative times. However, the reduced risk of postoperative bowel obstruction suggests potential long-term benefits. This study emphasizes the importance of meticulous patient selection for TR to mitigate detrimental effects on patients with severe disease.

Tracheomalacia and tracheomegaly in infants and children with congenital diaphragmatic hernia managed with and without fetoscopic endoluminal tracheal occlusion (FETO): a multicentre, retrospective cohort study.

BACKGROUND: Temporary fetoscopic endoluminal tracheal occlusion (FETO) promotes lung growth and increases survival in selected fetuses with congenital diaphragmatic hernia (CDH). FETO is performed percutaneously by inserting into the trachea a balloon designed for vascular occlusion. However, reports on the potential postnatal side-effects of the balloon are scarce. This study aimed to evaluate the prevalence of tracheomalacia in infants with CDH managed with and without FETO and other consequences related to the use of the balloon. METHODS: In this multicentre, retrospective cohort study, we included infants who were live born with CDH, either with FETO or without, who were managed postnatally at four centres (UZ Leuven, Leuven, Belgium; Antoine Béclère, Clamart, France; BCNatal, Barcelona, Spain; and HCor-Heart Hospital, São Paulo, Brazil) between April 5, 2002, and June 2, 2021. We primarily assessed the prevalence of all (symptomatic and asymptomatic) tracheomalacia as reported in medical records among infants with and without FETO. Secondarily we assessed the prevalence of symptomatic tracheomalacia and its resolution as reported in medical records, and compared tracheal diameters as measured on postnatal x-rays. Crude and adjusted risk ratios (aRRs) and 95% CIs were calculated via modified Poisson regression models with robust error variances for potential association between FETO and tracheomalacia. Variables included in the adjusted model were the side of the hernia, observed-to-expected lung-to-head ratio, and gestational age at birth. Crude and adjusted mean differences and 95% CIs were calculated via linear regression models to assess the presence and magnitude of association between FETO and tracheal diameters. In infants who had undergone FETO we also assessed the localisation of balloon remnants on x-rays, and the methods used for reversal of occlusion and potential complications associated with balloon remnants as documented in clinical records. Finally we investigated whether the presence of balloon remnants was influenced by the interval between balloon removal and delivery. FINDINGS: 505 neonates were included in the study, of whom 287 had undergone FETO and 218 had not. Tracheomalacia was reported in 18 (6%) infants who had undergone FETO and in three (1%) who had not (aRR 6·17 [95% CI 1·83-20·75]; p=0·0030). Tracheomalacia was first reported in the FETO group at a median of 5·0 months (IQR 0·8-13·0). Symptomatic tracheomalacia was reported in 13 (5%) infants who had undergone FETO, which resolved in ten (77%) children by 55·0 months (IQR 14·0-83·0). On average, infants who had undergone FETO had a 31·3% wider trachea (with FETO tracheal diameter 7·43 mm [SD 1·24], without FETO tracheal diameter 5·10 mm [SD 0·84]; crude mean difference 2·32 [95% CI 2·11-2·54]; p<0·0001; adjusted mean difference 2·62 [95% CI 2·35-2·89]; p<0·0001). At birth, the metallic component was visible within the body in 75 (37%) of 205 infants with available thoraco-abdominal x-rays: it was located in the gastrointestinal tract in 60 (80%) and in the lung in 15 (20%). No side-effects were reported for any of the infants during follow-up. The metallic component was more likely to be in the lung than either outside the body or the gastrointestinal tract when the interval between occlusion reversal and birth was less than 24 h. INTERPRETATION: Although FETO was associated with an increased tracheal diameter and an increased probability of tracheomalacia, symptomatic tracheomalacia typically resolved over time. There is a higher risk of retention of metallic balloon components if reversal of the occlusion occurs less than 24 h before delivery. Finally, there were no reported side-effects of the metallic component of the balloon persisting in the body during follow-up. Longer-term follow-up is needed to ensure that no tracheal problems arise later in life. FUNDING: None.

Self-reported respiratory and gastrointestinal outcomes in children with isolated congenital diaphragmatic hernia: A prospective multicentre study.

OBJECTIVE: To evaluate medium-term self-reported respiratory and gastrointestinal (GI) outcomes in children with congenital diaphragmatic hernia (CDH). DESIGN: Self-reported respiratory and GI outcomes correlated with prenatal severity indicators. SETTING: Prospective study at three fetal medicine units. POPULATION: Families of children prenatally diagnosed with isolated, left-sided CDH surviving for >1 year. METHODS: Families received validated questionnaires for GI outcomes (Infant Gastroesophageal Reflux Questionnaire Revised, I-GERQ-R, for infants aged <2 years, or Paediatric Gastro-oesophageal Symptom and Quality of Life Questionnaire, PGSQ, for children aged aged 2-8 years or >9 years) and respiratory outcomes (preschool respiratory outcome questionnaire, for children aged ≤5 years, or the International Study of Asthma and Allergies in Childhood asthma questionnaire, for children aged 6-8 years or ≥9 years). Prenatal data collected from the medical records included lung size (percentage observed/expected lung-to-head ratio, O/E LHR %), liver position, fetal endoluminal tracheal occlusion (FETO) gestational age (GA) at delivery, and perinatal data included birthweight, location, patch repair and respiratory support. MAIN OUTCOME MEASURES: The GI and respiratory scores were correlated with O/E LHR using linear and logistic regression models. Univariate analysis was used to evaluate associations with perinatal variables. RESULTS: We obtained 142 responses from 342 families (representing a response rate of 45%). The baseline characteristics of participants and non-participants were comparable. No correlations between perinatal variables and respiratory or GI scores were identified. Children aged ≤5 years with lower O/E LHR values reported higher respiratory scores (P = 0.0175); this finding was not reported in older children. Overall, the children who underwent FETO (n = 51) had GI (P = 0.290) and respiratory (P = 0.052) scores that were comparable with those of children who were expectantly managed. CONCLUSIONS: Families and children with prenatally diagnosed CDH reported fewer respiratory symptoms with increasing age. There was no correlation between O/E LHR or the use of FETO and self-reported outcomes.

Human enteric nervous system progenitor transplantation improves functional responses in Hirschsprung disease patient-derived tissue.

OBJECTIVE: Hirschsprung disease (HSCR) is a severe congenital disorder affecting 1:5000 live births. HSCR results from the failure of enteric nervous system (ENS) progenitors to fully colonise the gastrointestinal tract during embryonic development. This leads to aganglionosis in the distal bowel, resulting in disrupted motor activity and impaired peristalsis. Currently, the only viable treatment option is surgical resection of the aganglionic bowel. However, patients frequently suffer debilitating, lifelong symptoms, with multiple surgical procedures often necessary. Hence, alternative treatment options are crucial. An attractive strategy involves the transplantation of ENS progenitors generated from human pluripotent stem cells (hPSCs). DESIGN: ENS progenitors were generated from hPSCs using an accelerated protocol and characterised, in detail, through a combination of single-cell RNA sequencing, protein expression analysis and calcium imaging. We tested ENS progenitors' capacity to integrate and affect functional responses in HSCR colon, after ex vivo transplantation to organotypically cultured patient-derived colonic tissue, using organ bath contractility. RESULTS: We found that our protocol consistently gives rise to high yields of a cell population exhibiting transcriptional and functional hallmarks of early ENS progenitors. Following transplantation, hPSC-derived ENS progenitors integrate, migrate and form neurons/glia within explanted human HSCR colon samples. Importantly, the transplanted HSCR tissue displayed significantly increased basal contractile activity and increased responses to electrical stimulation compared with control tissue. CONCLUSION: Our findings demonstrate, for the first time, the potential of hPSC-derived ENS progenitors to repopulate and increase functional responses in human HSCR patient colonic tissue.

Age-specific nasal epithelial responses to SARS-CoV-2 infection.

Children infected with SARS-CoV-2 rarely progress to respiratory failure. However, the risk of mortality in infected people over 85 years of age remains high. Here we investigate differences in the cellular landscape and function of paediatric (<12 years), adult (30-50 years) and older adult (>70 years) ex vivo cultured nasal epithelial cells in response to infection with SARS-CoV-2. We show that cell tropism of SARS-CoV-2, and expression of ACE2 and TMPRSS2 in nasal epithelial cell subtypes, differ between age groups. While ciliated cells are viral replication centres across all age groups, a distinct goblet inflammatory subtype emerges in infected paediatric cultures and shows high expression of interferon-stimulated genes and incomplete viral replication. In contrast, older adult cultures infected with SARS-CoV-2 show a proportional increase in basaloid-like cells, which facilitate viral spread and are associated with altered epithelial repair pathways. We confirm age-specific induction of these cell types by integrating data from in vivo COVID-19 studies and validate that our in vitro model recapitulates early epithelial responses to SARS-CoV-2 infection.

An investigation into augmentation and preprocessing for optimising X-ray classification in limited datasets: a case study on necrotising enterocolitis.

PURPOSE: Obtaining large volumes of medical images, required for deep learning development, can be challenging in rare pathologies. Image augmentation and preprocessing offer viable solutions. This work explores the case of necrotising enterocolitis (NEC), a rare but life-threatening condition affecting premature neonates, with challenging radiological diagnosis. We investigate data augmentation and preprocessing techniques and propose two optimised pipelines for developing reliable computer-aided diagnosis models on a limited NEC dataset. METHODS: We present a NEC dataset of 1090 Abdominal X-rays (AXRs) from 364 patients and investigate the effect of geometric augmentations, colour scheme augmentations and their combination for NEC classification based on the ResNet-50 backbone. We introduce two pipelines based on colour contrast and edge enhancement, to increase the visibility of subtle, difficult-to-identify, critical NEC findings on AXRs and achieve robust accuracy in a challenging three-class NEC classification task. RESULTS: Our results show that geometric augmentations improve performance, with Translation achieving +6.2%, while Flipping and Occlusion decrease performance. Colour augmentations, like Equalisation, yield modest improvements. The proposed Pr-1 and Pr-2 pipelines enhance model accuracy by +2.4% and +1.7%, respectively. Combining Pr-1/Pr-2 with geometric augmentation, we achieve a maximum performance increase of 7.1%, achieving robust NEC classification. CONCLUSION: Based on an extensive validation of preprocessing and augmentation techniques, our work showcases the previously unreported potential of image preprocessing in AXR classification tasks with limited datasets. Our findings can be extended to other medical tasks for designing reliable classifier models with limited X-ray datasets. Ultimately, we also provide a benchmark for automated NEC detection and classification from AXRs.

A Population-Based Cohort Study on Diagnosis and Early Management of Anorectal Malformation in the UK and Ireland.

BACKGROUND: This study describes the presentation and initial management of anorectal malformation (ARM); evaluating the frequency, causes and consequences of late diagnosis. METHODS: A prospective, population cohort study was undertaken for newly diagnosed ARMs in the UK and Ireland from 01/10/2015 and 30/09/2016. Follow-up was completed at one year. Data are presented as n (%), appropriate statistical methods used. Factors associated with late diagnosis; defined as: detection of ARM either following discharge or more than 72 h after birth were assessed with univariable logistic regression. RESULTS: Twenty six centres reported on 174 cases, 158 of which were classified according to the type of malformation and 154 had completed surgical data. Overall, perineal fistula was the most commonly detected anomaly 43/158 (27%); of the 41 of these children undergoing surgery, 15 (37%) had a stoma formed. 21/154 (14%, CI95{9-20}) patients undergoing surgery experienced post-operative complications. Thirty-nine (22%) were diagnosed late and 12 (7%) were detected >30 days after birth. Factors associated with late diagnosis included female sex (OR 2.06; 1.0-4.26), having a visible perineal opening (OR 2.63; 1.21-5.67) and anomalies leading to visible meconium on the perineum (OR 18.74; 2.47-141.73). 56/174 (32%) had a diagnosis of VACTERL association (vertebral, anorectal, cardiac, tracheal, oesophageal, renal and limb); however, not all infants were investigated for commonly associated anomalies. 51/140 (36%) had a cardiac anomaly detected on echocardiogram. CONCLUSION: There is room for improvement within the care for infants born with ARM in the UK and Ireland. Upskilling those performing neonatal examination to allow timely diagnosis, instruction of universal screening for associated anomalies and further analysis of the factors leading to clinically unnecessary stoma formation are warranted. LEVEL OF EVIDENCE: II (Prospective Cohort Study <80% follow-up).

Single-cell guided prenatal derivation of primary fetal epithelial organoids from human amniotic and tracheal fluids.

Isolation of tissue-specific fetal stem cells and derivation of primary organoids is limited to samples obtained from termination of pregnancies, hampering prenatal investigation of fetal development and congenital diseases. Therefore, new patient-specific in vitro models are needed. To this aim, isolation and expansion of fetal stem cells during pregnancy, without the need for tissue samples or reprogramming, would be advantageous. Amniotic fluid (AF) is a source of cells from multiple developing organs. Using single-cell analysis, we characterized the cellular identities present in human AF. We identified and isolated viable epithelial stem/progenitor cells of fetal gastrointestinal, renal and pulmonary origin. Upon culture, these cells formed clonal epithelial organoids, manifesting small intestine, kidney tubule and lung identity. AF organoids exhibit transcriptomic, protein expression and functional features of their tissue of origin. With relevance for prenatal disease modeling, we derived lung organoids from AF and tracheal fluid cells of congenital diaphragmatic hernia fetuses, recapitulating some features of the disease. AF organoids are derived in a timeline compatible with prenatal intervention, potentially allowing investigation of therapeutic tools and regenerative medicine strategies personalized to the fetus at clinically relevant developmental stages.

Nonwoven fiber meshes for oxygen sensing.

Accurate oxygen sensing and cost-effective fabrication are crucial for the adoption of wearable devices inside and outside the clinical setting. Here we introduce a simple strategy to create nonwoven polymeric fibrous mats for a notable contribution towards addressing this need. Although morphological manipulation of polymers for cell culture proliferation is commonplace, especially in the field of regenerative medicine, non-woven structures have not been used for oxygen sensing. We used an airbrush spraying, i.e. solution blowing, to obtain nonwoven fiber meshes embedded with a phosphorescent dye. The fibers serve as a polymer host for the phosphorescent dye and are shown to be non-cytotoxic. Different composite fibrous meshes were prepared and favorable mechanical and oxygen-sensing properties were demonstrated. A Young's modulus of 9.8 MPa was achieved and the maximum oxygen sensitivity improved by a factor of ∼2.9 compared to simple drop cast film. The fibers were also coated with silicone rubbers to produce mechanically robust sensing films. This reduced the sensing performance but improved flexibility and mechanical properties. Lastly, we are able to capture oxygen concentration maps via colorimetry using a smartphone camera, which should offer unique advantages in wider usage. Overall, the introduced composite fiber meshes show a potential to significantly improve cell cultures and healthcare monitoring via absolute oxygen sensing.

High-fidelity, low-cost synthetic training model for fetoscopic spina bifida repair.

BACKGROUND: Fetoscopic spina bifida repair is increasingly being practiced, but limited skill acquisition poses a barrier to widespread adoption. Extensive training in relevant models, including both ex vivo and in vivo models may help. To address this, a synthetic training model that is affordable, realistic, and that allows skill analysis would be useful. OBJECTIVE: This study aimed to create a high-fidelity model for training in the essential neurosurgical steps of fetoscopic spina bifida repair using synthetic materials. In addition, we aimed to obtain a cheap and easily reproducible model. STUDY DESIGN: We developed a 3-layered, silicon-based model that resemble the anatomic layers of a typical myelomeningocele lesion. It allows for filling of the cyst with fluid and conducting a water tightness test after repair. A compliant silicon ball mimics the uterine cavity and is fixed to a solid 3-dimensional printed base. The fetal back with the lesion (single-use) is placed inside the uterine ball, which is reusable and repairable to allow for practicing port insertion and fixation multiple times. Following cannula insertion, the uterus is insufflated and a clinical fetoscopic or robotic or prototype instruments can be used. Three skilled endoscopic surgeons each did 6 simulated fetoscopic repairs using the surgical steps of an open repair. The primary outcome was surgical success, which was determined by water tightness of the repair, operation time <180 minutes and an Objective Structured Assessment of Technical Skills score of ≥18 of 25. Skill retention was measured using a competence cumulative sum analysis of a composite binary outcome of surgical success. Secondary outcomes were cost and fabrication time of the model. RESULTS: We made a model that can be used to simulate the neurosurgical steps of spina bifida repair, including anatomic details, port insertion, placode release and descent, undermining of skin and muscular layer, and endoscopic suturing. The model was made using reusable 3-dimensional printed molds and easily accessible materials. The 1-time startup cost was €211, and each single-use, simulated myelomeningocele lesion cost €9.5 in materials and 50 minutes of working time. Two skilled endoscopic surgeons performed 6 simulated, 3-port fetoscopic repairs, whereas a third used a Da Vinci surgical robot. Operation times decreased by more than 30% from the first to the last trial. Six experiments per surgeon did not show an obvious Objective Structured Assessment of Technical Skills score improvement. Competence cumulative sum analysis confirmed competency for each surgeon. CONCLUSION: This high-fidelity, low-cost spina bifida model allows simulated dissection and closure of a myelomeningocele lesion. VIDEO ABSTRACT.