3D Printed Percutaneous Transhepatic Cholangiography and Drainage (PTCD) Simulator for Interventional Radiology.

PURPOSE: Learning how to perform percutaneous transhepatic bile duct drainage (PTCD) is challenging for interventional radiology (IR) trainees. Therefore, simulators are crucial for IR training and are being increasingly demanded in the evolving healthcare environment of value-based care. To facilitate interventional training, we tried to evaluate our newly developed liver phantom for further use in IR training. METHODS: We developed a liver phantom with a flexible hollow biliary tree, hydrogel-based liver parenchyma, plastic ribs, and silicone skin. The phantom was evaluated by 20 radiology residents from two hospitals. After an introduction, all participants tried to obtain biliary access by fluoroscopic guidance within 25 min. Puncture time, fluoroscopy time, and kerma area product were measured. After 7 days, the participants repeated the procedure on an altered and more difficult model. Additionally, a survey was handed out to every participant (20 residents, 5 experts, and 5 IR fellows) to evaluate the phantom in terms of accuracy and haptic feedback, as well as general questions regarding simulation. RESULTS: The residents performed significantly faster and were more self-confident on Day 7 than on Day 1, significantly decreasing puncture time, fluoroscopy time, and kerma area product (p ≤ 0.0001). The participants were very satisfied with their simulation experience and would trust themselves more in real-life scenarios. CONCLUSION: We were able to develop a phantom with high anatomical accuracy for fluoroscopy and ultrasound-guided interventions. The phantom successfully helped residents learn and improve their PTCD performance.

An optimized 3D-printed perfusion bioreactor for homogeneous cell seeding in bone substitute scaffolds for future chairside applications.

A clinical implementation of cell-based bone regeneration in combination with scaffold materials requires the development of efficient, controlled and reproducible seeding procedures and a tailor-made bioreactor design. A perfusion system for efficient, homogeneous, and rapid seeding with human adipogenic stem cells in bone substitute scaffolds was designed. Variants concerning medium inlet and outlet port geometry, i.e. cylindrical or conical diffuser, cell concentration, perfusion mode and perfusion rates were simulated in silico. Cell distribution during perfusion was monitored by dynamic [18F]FDG micro-PET/CT and validated by laser scanning microscopy with three-dimensional image reconstruction. By iterative feedback of the in silico and in vitro experiments, the homogeneity of cell distribution throughout the scaffold was optimized with adjustment of flow rates, cell density and perfusion properties. Finally, a bioreactor with a conical diffusor geometry was developed, that allows a homogeneous cell seeding (hoover coefficient: 0.24) in less than 60 min with an oscillating perfusion mode. During this short period of time, the cells initially adhere within the entire scaffold and stay viable. After two weeks, the formation of several cell layers was observed, which was associated with an osteogenic differentiation process. This newly designed bioreactor may be considered as a prototype for chairside application.

Percutaneous transhepatic biliary puncture simulator: a cord network prototype.

BACKGROUND: The aim of this study was to present a percutaneous transhepatic biliary puncture simulator that can be used without radiation exposure and that reflects the conventional anatomy of the biliary ducts and its vicinity structures. METHODS: An anatomically based model of the biliary tree was developed using a cord network fixed to a wooden frame. The skin, ribs, intercostal muscles, and right lower lobe pleura were simulated using foam sponge, plastic tubes, a polystyrene foam panel, and an air pad, respectively. For the puncture, we used a 20-G Chiba needle and a wire with distal double arches; these were used to troll a cord, simulating the successful puncture of a bile duct. A camera was also placed above the model to allow the trainees to train eye-hand coordination while viewing the image on a monitor in real time. The simulator was tested with 60 radiology residents to evaluate the confidence and skills transferability of the training model. RESULTS: After receiving an introduction of the system and 5 min of training under tutor surveillance, all participants were able to troll a cord of the biliary simulator by themselves in less than 4 min. Only one participant punctured the simulated pleura. The participants' evaluations showed positive results, with increased user confidence and skills transferability after the training session. CONCLUSIONS: This proposed simulator can be an effective tool to improve a trainee's confidence and competence while achieving procedural and non-procedural interventional radiology skills related to the liver. TRIAL REGISTRATION: Retrospectively registered.

Bronchoalveolar lavage-detected SARS-CoV-2 infection in presence of serial negative nasopharyngeal swabs: a case report.

We describe a case of a SARS coronavirus 2 (SARS-CoV-2) infection in a Swiss 54-years-old immunocompromised patient (lymphoma, therapy with the anti-CD20 antibody Rituximab® ), with initial scarce respiratory symptoms but typical coronavirus disease 2019 (COVID-19) radiological presentation, and symptoms onset during a holiday trip to Texas (USA). Three nasopharyngeal swabs in the 96 hours following hospital admission were negative, despite a CT thorax suggestive for an early stage of infection. COVID-infection was finally confirmed in the bronchoalveolar lavage (BAL) fluid, performed for exclusion of an alternative diagnosis in immunocompromised. In the BAL an increased cellularity with marked lymphocytosis of 35%, a reduced CD4/CD8 ratio of 0.1 and borderline neutrophilia of 3% were found. This finding might be due to the concomitant therapy with anti-CD20 antibodies, but the presence of lymphocytosis in the BAL despite peripheral lymphopenia with decreased CD4/CD8 T-cells ratio are described here for the first time in a SARS-CoV-2 infection. Persistent gastrointestinal symptoms (diarrhea), fever and initially headache were the predominant symptoms. The respiratory symptoms were scarce (variable mild dyspnea mMRC1). The respiratory conditions worsened during the hospital stay, with tachypnea up to 35/min, increased need for supplemental oxygen up to 8 L/min and worsening lung infiltrates on CT thorax on day 5. A therapy with hydroxychloroquine (HCQ) and an immunoglobulin-supplementation were given, with clinical and respiratory improvement, without need for intensive care or any ventilator support, and hospital discharge on day 16. Our case highlights some diagnostic and therapeutical challenges occurring in patients with COVID-19 infection. As take-home message, in the presence of clinical and radiological findings compatible with SARS-CoV-2 infection we outline the importance of treating patients accordingly, also in presence of repeated negative nasopharyngeal swabs. In selected patients as in our case a bronchoscopic BAL should be considered to exclude other infections, but in our opinion not primarily to confirming COVID-19 infection. Our unique finding of a lymphocytosis in the BAL during a COVID-19 infection needs further investigations.

COVID-19 and the role of imaging: early experiences in Central Switzerland.

The SARS-CoV-2 virus (COVID-19) was initially observed in a group of Chinese patients with unclear pneumonia in Wuhan, Hubei [1] in late December 2019. The first positive case in Switzerland was confirmed on 25 February 2020 in a patient from canton Tessin, who most likely caught the virus during a visit to Milan, Italy [2]. The country has since been preparing for an imminent public health emergency caused by the pandemic. As of 14 May 2020, the Swiss healthcare system is facing a total of 30,463 corona virus-positive people [3]. With numbers of new infections decreasing after the first pandemic wave, the continuing endemic situation will continue to be a major challenge for the Swiss healthcare system. It remains crucial to separate the clinically low-symptomatic from the severely affected patients in order to offer a specific therapeutic strategy to every SARS-CoV-2 patient. Reports from Chinese cohorts describe an increasing role of imaging strategies in the detection and surveillance of COVID-19 patients because of insufficient testing sensitivity of real-time reverse transcription polymerase chain reaction (RT-PCR) tests [4]. Chest computed tomography (CT), with a reported sensitivity of up to 97% [5, 6], gained importance particularly in patients with false negative RT-PCR results. In this short communication, we describe our first clinical experiences with 55 COVID-19 patients in Central Switzerland, who were either imaged with a standard chest x-ray, chest CT, or both. We provide an illustrative and schematic description of typical COVID-19 imaging features and suggest that imaging plays an important role in the clinical work-up of suspected or confirmed COVID-19 patients. This study was approved by the national ethics review committee (EKNZ, Switzerland) and patients’ informed consent was waived.