Mapping of lithium ion concentrations in 3D structures through development of in situ correlative imaging of X-ray Compton scattering-computed tomography.

Understanding the correlation between chemical and microstructural properties is critical for unraveling the fundamental relationship between materials chemistry and physical structures that can benefit materials science and engineering. Here, we demonstrate novel in situ correlative imaging of the X-ray Compton scattering computed tomography (XCS-CT) technique for studying this fundamental relationship. XCS-CT can image light elements that do not usually exhibit strong signals using other X-ray characterization techniques. This paper describes the XCS-CT setup and data analysis method for calculating the valence electron momentum density and lithium-ion concentration, and provides two examples of spatially and temporally resolved chemical properties inside batteries in 3D. XCS-CT was applied to study two types of rechargeable lithium batteries in standard coin cell casings: (1) a lithium-ion battery containing a cathode of bespoke microstructure and liquid electrolyte, and (2) a solid-state battery containing a solid-polymer electrolyte. The XCS-CT technique is beneficial to a wide variety of materials and systems to map chemical composition changes in 3D structures.

A High-Sensitivity Benchtop X-Ray Fluorescence Emission Tomography (XFET) System With a Full-Ring of X-Ray Imaging-Spectrometers and a Compound-Eye Collimation Aperture.

The advent of metal-based drugs and metal nanoparticles as therapeutic agents in anti-tumor treatment has motivated the advancement of X-ray fluorescence computed tomography (XFCT) techniques. An XFCT imaging modality can detect, quantify, and image the biodistribution of metal elements using the X-ray fluorescence signal emitted upon X-ray irradiation. However, the majority of XFCT imaging systems and instrumentation developed so far rely on a single or a small number of detectors. This work introduces the first full-ring benchtop X-ray fluorescence emission tomography (XFET) system equipped with 24 solid-state detectors arranged in a hexagonal geometry and a 96-pinhole compound-eye collimator. We experimentally demonstrate the system's sensitivity and its capability of multi-element detection and quantification by performing imaging studies on an animal-sized phantom. In our preliminary studies, the phantom was irradiated with a pencil beam of X-rays produced using a low-powered polychromatic X-ray source (90kVp and 60W max power). This investigation shows a significant enhancement in the detection limit of gadolinium to as low as 0.1 mg/mL concentration. The results also illustrate the unique capabilities of the XFET system to simultaneously determine the spatial distribution and accurately quantify the concentrations of multiple metal elements.

Hybrid energy and angle dispersive X-ray diffraction computed tomography.

Pixelated energy resolving detectors enable acquisition of X-ray diffraction (XRD) signals using a hybrid energy- and angle- dispersive technique, potentially paving the way for the development of novel benchtop XRD imaging or computed tomography (XRDCT) systems, utilising readily available polychromatic X-ray sources. In this work, a commercially available pixelated cadmium telluride (CdTe) detector, HEXITEC (High Energy X-ray Imaging Technology), was used to demonstrate such an XRDCT system. Specifically, a novel fly-scan technique was developed and compared to the established step-scan technique, reducing the total scan time by 42% while improving the spatial resolution, material contrast and therefore the material classification.

Resident Wilderness Medicine Curriculum Consensus Guidelines: Summarization and Recommendations for Resident Rotations in Wilderness Medicine.

INTRODUCTION: Wilderness medicine education is one of the fastest growing facets of both graduate and undergraduate medical education. Currently, there are curriculum guidelines for both student electives and fellowships in wilderness medicine. However, there are no guidelines for resident elective curricula. The student/resident education committee of the Wilderness Medical Society (WMS) convened a task force to develop curriculum guidelines for these electives. METHODS: A survey of previously described core wilderness medicine topics was sent to a cohort of educators involved in wilderness medicine resident electives. They were asked to rank topics on the basis of their importance of being included on a Likert scale. Multivariate analysis of medians was used to distinguish among topics to determine which topics were voted most and least necessary for a curriculum. RESULTS: Of the database members contacted, 35 responded to the survey. The described current state of residency electives was that 16 institutions offered their own elective (46%). For subject preferences, multivariate analysis of scoring distribution medians demonstrated a significantly higher pattern of responses (P<0.01) for subjects with a median of 3 (must include) than for the lowest-scoring subjects that had a median of 1 (can include). Every topic was rated "must" by at least 1 respondent. Topics were further subdivided into an educational framework reflecting a common approach to education of wilderness medicine fellows focusing on education, leadership, knowledge, and skills. CONCLUSIONS: There was a wide variety in the ranking of topics; however, there were multiple topics on which a consensus for inclusion was reached. These topics are organized and presented here as a suggested curriculum by the student/resident education committee of the WMS.

Medullary Screw Fixation and the Pilot Hole Technique for the Correction of Hammertoe Deformity.

BACKGROUND: Historically, Kirschner wires have been used for fixation of the interphalangeal joints of the toe. They are still the most popular form of fixation, likely due to training patterns, ease of use, and decreased cost. Recently, numerous medullary fixation devices have become available, including medullary screws. METHODS: After performing various forms of fixation for the correction of toe deformities, the authors have developed a new pilot hole technique for screw fixation advancing on the previously described pilot hole technique for Kirschner wire fixation. RESULTS: The authors have found this method to provide intraoperative confidence that improper hardware placement has not occurred. CONCLUSIONS: The pilot hole technique described in this paper is a safe and effective technique that may be employed by surgeons using screw fixation for the treatment of hammertoe deformities. The technique reduces the possibility of surgeon error and helps to ensure that the screw is properly placed within the phalanges when properly employed.

3D Correlative Imaging of Lithium Ion Concentration in a Vertically Oriented Electrode Microstructure with a Density Gradient.

The performance of Li+ ion batteries (LIBs) is hindered by steep Li+ ion concentration gradients in the electrodes. Although thick electrodes (≥300 µm) have the potential for reducing the proportion of inactive components inside LIBs and increasing battery energy density, the Li+ ion concentration gradient problem is exacerbated. Most understanding of Li+ ion diffusion in the electrodes is based on computational modeling because of the low atomic number (Z) of Li. There are few experimental methods to visualize Li+ ion concentration distribution of the electrode within a battery of typical configurations, for example, coin cells with stainless steel casing. Here, for the first time, an interrupted in situ correlative imaging technique is developed, combining novel, full-field X-ray Compton scattering imaging with X-ray computed tomography that allows 3D pixel-by-pixel mapping of both Li+ stoichiometry and electrode microstructure of a LiNi0.8 Mn0.1 Co0.1 O2 cathode to correlate the chemical and physical properties of the electrode inside a working coin cell battery. An electrode microstructure containing vertically oriented pore arrays and a density gradient is fabricated. It is shown how the designed electrode microstructure improves Li+ ion diffusivity, homogenizes Li+ ion concentration through the ultra-thick electrode (1 mm), and improves utilization of electrode active materials.

Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors.

Cadmium zinc telluride (CdZnTe) detectors are known to suffer from polarization effects under high photon flux due to poor hole transport in the crystal material. This has led to the development of a high-flux capable CdZnTe material (HF-CdZnTe). Detectors with the HF-CdZnTe material have shown promising results at mitigating the onset of the polarization phenomenon, likely linked to improved crystal quality and hole carrier transport. Better hole transport will have an impact on charge collection, particularly in pixelated detector designs and thick sensors (>1 mm). In this paper, the presence of charge sharing and the magnitude of charge loss were calculated for a 2 mm thick pixelated HF-CdZnTe detector with 250 µm pixel pitch and 25 µm pixel gaps, bonded to the STFC HEXITEC ASIC. Results are compared with a CdTe detector as a reference point and supported with simulations from a Monte-Carlo detector model. Charge sharing events showed minimal charge loss in the HF-CdZnTe, resulting in a spectral resolution of 1.63 ± 0.08 keV Full Width at Half Maximum (FWHM) for bipixel charge sharing events at 59.5 keV. Depth of interaction effects were shown to influence charge loss in shared events. The performance is discussed in relation to the improved hole transport of HF-CdZnTe and comparison with simulated results provided evidence of a uniform electric field.

Outcomes of Ankle Arthrodesis Conversion to Total Ankle Arthroplasty: A Systematic Review.

Ankle arthrodesis (AA) provides reliable pain relief, good patient satisfaction scores, and improved overall function. However, this procedure has been associated with numerous complications and sequelae, such as pseudoarthrosis, malunion, gait abnormalities, increased demand on surrounding joints, and a long period of convalescence. Conversion to total ankle arthroplasty (TAA) is a potential option in the management of these complex and challenging situations. The purpose of this study is to investigate the outcomes of AA conversion to TAA. A systematic review of electronic databases was performed. Six studies involving 172 ankles met inclusion criteria. The weighted mean preoperative Visual Analogue Scale (VAS) score at the time of TAA conversion was 7.8 and the weighted mean postoperative VAS score at the time of final follow-up was 2.5. The weighted mean preoperative AOFAS score at the time of TAA conversion was 32 and the weighted mean postoperative AOFAS score at the time of final follow-up was 72.4. The rate of salvage tibiotalocalcaneal arthrodesis was 2.3% and rate of transtibial amputation was also 2.3% after attempted conversion from initial AA to TAA. Conversion of AA to TAA appears to be a viable option to improve patient outcomes and prevent extensive hindfoot arthrodesis and transtibial amputation. More prospective studies with consistent reporting of outcomes, complications, and revision rates with long-term follow-up are needed.

An operando spatially resolved study of alkaline battery discharge using a novel hyperspectral detector and X-ray tomography.

An experimental technique is described for the collection of time-resolved X-ray diffraction information from a complete commercial battery cell during discharging or charging cycles. The technique uses an 80 × 80 pixel 2D energy-discriminating detector in a pinhole camera geometry which can be used with a polychromatic X-ray source. The concept was proved in a synchrotron X-ray study of commercial alkaline Zn-MnO2 AA size cells. Importantly, no modification of the cell was required. The technique enabled spatial and temporal changes to be observed with a time resolution of 20 min (5 min of data collection with a 15 min wait between scans). Chemical changes in the cell determined from diffraction information were correlated with complementary X-ray tomography scans performed on similar cells from the same batch. The clearest results were for the spatial and temporal changes in the Zn anode. Spatially, there was a sequential transformation of Zn to ZnO in the direction from the separator towards the current collector. Temporally, it was possible to track the transformation of Zn to ZnO during the discharge and follow the corresponding changes in the cathode.

Preliminary Assessment of a Telehealth Approach to Evaluating, Treating, and Discharging Low-Acuity Patients With Suspected COVID-19.

BACKGROUND: Telemedicine is uniquely positioned to address challenges posed to emergency departments (EDs) by the Coronavirus Disease 2019 (COVID-19) pandemic. By reducing in-person contact, it should decrease provider risk of infection and preserve personal protective equipment (PPE). OBJECTIVES: To describe and assess the early results of a novel telehealth workflow in which remote providers collaborate with in-person nursing to evaluate and discharge well-appearing, low-risk ED patients with suspected COVID-19 infection. METHODS: Retrospective chart review was completed 3 weeks after implementation. Metrics include the number of patients evaluated, number of patients discharged without in-person contact, telehealth wait time and duration, collection of testing, ED length of stay (ED-LOS), 72-h return, number of in-person health care provider contacts, and associated PPE use. RESULTS: Among 302 patients evaluated by telehealth, 153 patients were evaluated and discharged by a telehealth provider with reductions in ED-LOS, PPE use, and close contact with health care personnel. These patients had a 62.5% shorter ED-LOS compared with other Emergency Severity Index level 4 patients seen over the same time period. Telehealth use for these 153 patients saved 413 sets of PPE. We observed a 3.9% 72-h revisit rate. One patient discharged after telehealth evaluation was hospitalized on a return visit 9 days later. CONCLUSION: Telehealth can be safely and efficiently used to evaluate, treat, test, and discharge ED patients suspected to have COVID-19. This workflow reduces infection risks to health care providers, PPE use, and ED-LOS. Additionally, it allows quarantined but otherwise well clinicians to continue working.

Development of a multi-detector readout circuitry for ultrahigh energy resolution single-photon imaging applications.

In this paper, we present the design and preliminary performance evaluation of a novel external multi-channel readout circuitry for small-pixel room-temperature semiconductor detectors, namely CdZnTe (CZT) and CdTe, that provide an excellent intrinsic spatial (250 and 500 µm pixel size) and an ultrahigh energy resolution (~1% at 122 keV) for X-ray and gamma-ray imaging applications. An analog front-end printed circuit board (PCB) was designed and developed for data digitization, data transfer and ASIC control of pixelated CZT or CdTe detectors. Each detector unit is 2 cm × 2 cm in size and 1 or 2 mm in thickness, being bump-bonded onto a HEXITEC ASIC, and wire-bonded to a readout detector module PCB. The detectors' front-end is then connected, through flexible cables of up to 10 m in length, to a remote data acquisition system that interfaces with a PC through USB3.0 connection. We present the design and performance of a prototype multi-channel readout system that can read out up to 24 detector modules synchronously. Our experimental results demonstrated that the readout circuitry offers an ultrahigh spectral resolution (0.8 keV at 60 keV and 1.05 keV at 122 keV) with the Cd(Zn)Te/HEXITEC ASIC modules tested. This architecture was designed to allow easy expansion to accommodate a larger number of detector modules, and the flexibility of arranging the detector modules in a large and deformable detector array without degrading the excellent energy resolution.

Central Adjudication Identified Additional and Prognostically Important Myocardial Infarctions in Patients Undergoing Percutaneous Coronary Intervention.

BACKGROUND: In the CHAMPION PHOENIX trial, cangrelor reduced the primary composite end point of death, myocardial infarction (MI), ischemia-driven revascularization, or stent thrombosis at 48 hours. This study aimed to explore the impact of event adjudication and the prognostic importance of MI reported by a clinical events committee (CEC) or site investigators (SIs). METHODS AND RESULTS: Data from the CHAMPION PHOENIX trial of patients undergoing elective or nonelective percutaneous coronary intervention were analyzed. A CEC systematically identified and adjudicated MI using predefined criteria, a computer algorithm to identify suspected events, and semilogarithmic plots to review biomarker changes. Thirty-day death was modeled using baseline characteristics. Of 10 942 patients, 462 (4.2%) patients had at least 1 MI by 48 hours identified by the CEC (207 [3.8%] cangrelor; 255 [4.7%] clopidogrel; odds ratio [OR] 0.80; 95% CI, 0.67-0.97; P=0.022), and 143 patients had at least 1 MI by 48 hours reported by the SI (60 [1.1%] cangrelor; 83 [1.5%] clopidogrel; OR, 0.72; 95% CI, 0.52-1.01; P=0.053). Of the 462 MIs identified by the CEC, 92 (20%) were reported by SI, and 370 (80%) were not. Of the 143 MI reported by the SI, 51 (36%) were not confirmed by CEC. All categories were associated with an increased adjusted risk for 30-day death (CEC: OR, 5.35; 95% CI, 2.56-11.2; P<0.001; SI: 9.08 [4.01-20.5]; P<0.001; CEC and SI: 10.9 [3.23-36.6]; P<0.001; CEC but not SI: 4.69 [1.94-11.3]; P<0.001; SI but not CEC: 15.4 [5.26-44.9]; P<0.001). CONCLUSIONS: In patients undergoing percutaneous coronary intervention, CEC procedures identified 3 times as many MIs as the SI reported. Compared with clopidogrel, cangrelor significantly reduced MIs identified by the CEC with a qualitatively similar relative risk reduction in MIs reported by the SI. MIs identified by CEC or reported by SI were independently associated with worse 30-day death. Central adjudication identified additional, prognostically important events. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01156571.

The Incidence of Nonunion of the Naviculocuneiform Joint Arthrodesis:A Systematic Review.

Naviculocuneiform (NC) joint arthrodesis is an effective procedure to treat pain and provide stability to the medial column. Various forms of fixation have been described for NC arthrodesis. Despite this, the available literature is scant and questions remain regarding nonunion rate and contributory factors. A systematic review of the literature was undertaken to determine the rate of nonunion for NC joint arthrodesis. Seven studies involving 139 NC joint arthrodeses met inclusion criteria. The nonunion rate was 6.5% at a weighted mean follow-up of 73.2 months. There is insufficient evidence to provide a practice guideline based on the current literature. Adequately powered prospective clinical trials comparing well-matched patient groups with long-term follow-up are required to limit systematic error and enhance external validity. Specific outcomes measures should include union, functional assessment, complications, and cost-benefit analysis.

Incidence of Nonunion of the Hallux Interphalangeal Joint Arthrodesis: A Systematic Review.

Hallux interphalangeal joint arthrodesis is an effective procedure to treat pain and provide stability and is often performed for intrinsic pain to the hallux interphalangeal joint. Additionally, this procedure is typically used in concert with the Jones tenosuspension. Although this as an accepted technique, the available data are scant, and questions remain regarding nonunion rates and contributory factors to poor healing. A systematic review of the reported data were undertaken to determine the rate of nonunion for hallux interphalangeal joint arthrodesis. Seven studies involving 313 hallux interphalangeal joint arthrodeses met the inclusion criteria. The nonunion rate was 28.3% at a weighted mean follow-up period of 8.4 months. The overall complication rate was 33.0%. Considering the increased rate of complications and nonunion rate for this commonly used procedure, additional prospective comparative analyses are needed regarding this topic to identify important patient demographic data and determine superior fixation constructs.

Antithrombotic Reversal Agents.

The actively bleeding anticoagulated patient presenting to the emergency department requires rapid evaluation and treatment, which is made increasingly complicated by the ever-evolving antithrombotic treatment options used in medicine. Even with excellent supportive care, the timeliness with which reversal decisions need to be made continues to demand of the emergency practitioner a familiarity with the properties and general characteristics of a variety of antithrombotic agents. Reversal options vary and may include vitamin K, FFP, PCC, rFVIIa, platelets, and desmopressin, among others.

Cardiovascular adverse events in the drug-development program of bupropion for smoking cessation: A systematic retrospective adjudication effort.

BACKGROUND: In 2011, the US Food and Drug Administration requested that GlaxoSmithKline perform retrospective adjudication of cardiovascular (CV) events reported in the bupropion drug-development trials for smoking cessation. HYPOTHESIS: Retrospective adjudication of clinical trial data will not increase the identification of adverse events. METHODS: We performed a comprehensive retrospective analysis of adverse events in 19 previously completed controlled US clinical trials of bupropion marketed for the treatment of smoking cessation, yielding 9479 subjects (5290 bupropion, 2927 placebo, 1018 active control [ACT], and 244 treated concurrently with bupropion and ACT). All adverse events were sent to the Duke Clinical Research Institute for adjudication by Clinical Events Classification (CEC) physician reviewers. The primary endpoint was a composite of major adverse CV events: CV death, nonfatal myocardial infarction (MI), and nonfatal stroke. RESULTS: Overall, 416 nonfatal CV events in 366 subjects, and 22 deaths, were identified and processed for adjudication. Of these, 7 nonfatal MIs (4 bupropion, 3 placebo, 0 ACT), 5 nonfatal strokes (1 bupropion, 3 placebo, 1 ACT), and 9 CV deaths (4 bupropion, 4 placebo, 1 ACT) were confirmed by the CEC Committee. The primary endpoint occurred in 3/4297 (0.07%) subjects in the bupropion group and in 4/2927 (0.14%) subjects in the placebo group (log-rank P value: 0.613). CONCLUSIONS: CV events in bupropion clinical trials for smoking cessation were uncommon, with no observed increase among subjects assigned to bupropion vs placebo. However, this effort was limited by a paucity of quality data.

High Energy Resolution Hyperspectral X-Ray Imaging for Low-Dose Contrast-Enhanced Digital Mammography.

Contrast-enhanced digital mammography (CEDM) is an alternative to conventional X-ray mammography for imaging dense breasts. However, conventional approaches to CEDM require a double exposure of the patient, implying higher dose, and risk of incorrect image registration due to motion artifacts. A novel approach is presented, based on hyperspectral imaging, where a detector combining positional and high-resolution spectral information (in this case based on Cadmium Telluride) is used. This allows simultaneous acquisition of the two images required for CEDM. The approach was tested on a custom breast-equivalent phantom containing iodinated contrast agent (Niopam 150®). Two algorithms were used to obtain images of the contrast agent distribution: K-edge subtraction (KES), providing images of the distribution of the contrast agent with the background structures removed, and a dual-energy (DE) algorithm, providing an iodine-equivalent image and a water-equivalent image. The high energy resolution of the detector allowed the selection of two close-by energies, maximising the signal in KES images, and enhancing the visibility of details with the low surface concentration of contrast agent. DE performed consistently better than KES in terms of contrast-to-noise ratio of the details; moreover, it allowed a correct reconstruction of the surface concentration of the contrast agent in the iodine image. Comparison with CEDM with a conventional detector proved the superior performance of hyperspectral CEDM in terms of the image quality/dose tradeoff.

Acute Kidney Injury as a Risk Factor for Delirium and Coma during Critical Illness.

RATIONALE: Acute kidney injury may contribute to distant organ dysfunction. Few studies have examined kidney injury as a risk factor for delirium and coma. OBJECTIVES: To examine whether acute kidney injury is associated with delirium and coma in critically ill adults. METHODS: In a prospective cohort study of intensive care unit patients with respiratory failure and/or shock, we examined the association between acute kidney injury and daily mental status using multinomial transition models adjusting for demographics, nonrenal organ failure, sepsis, prior mental status, and sedative exposure. Acute kidney injury was characterized daily using the difference between baseline and peak serum creatinine and staged according to Kidney Disease Improving Global Outcomes criteria. Mental status (normal vs. delirium vs. coma) was assessed daily with the Confusion Assessment Method for the ICU and Richmond Agitation-Sedation Scale. MEASUREMENTS AND MAIN RESULTS: Among 466 patients, stage 2 acute kidney injury was a risk factor for delirium (odds ratio [OR], 1.55; 95% confidence interval [CI], 1.07-2.26) and coma (OR, 2.04; 95% CI, 1.25-3.34) as was stage 3 injury (OR for delirium, 2.56; 95% CI, 1.57-4.16) (OR for coma, 3.34; 95% CI, 1.85-6.03). Daily peak serum creatinine (adjusted for baseline) values were also associated with delirium (OR, 1.35; 95% CI, 1.18-1.55) and coma (OR, 1.44; 95% CI, 1.20-1.74). Renal replacement therapy modified the association between stage 3 acute kidney injury and daily peak serum creatinine and both delirium and coma. CONCLUSIONS: Acute kidney injury is a risk factor for delirium and coma during critical illness.