Enhancing Image-Guided Radiation Therapy for Pancreatic Cancer: Utilizing Aligned Peak Response Beamforming in Flexible Array Transducers.

To develop ultrasound-guided radiotherapy, we proposed an assistant structure with embedded markers along with a novel alternative method, the Aligned Peak Response (APR) method, to alter the conventional delay-and-sum (DAS) beamformer for reconstructing ultrasound images obtained from a flexible array. We simulated imaging targets in Field-II using point target phantoms with point targets at different locations. In the experimental phantom ultrasound images, image RF data were acquired with a flexible transducer with in-house assistant structures embedded with needle targets for testing the accuracy of the APR method. The lateral full width at half maximum (FWHM) values of the objective point target (OPT) in ground truth ultrasound images, APR-delayed ultrasound images with a flat shape, and images acquired with curved transducer radii of 500 mm and 700 mm were 3.96 mm, 4.95 mm, 4.96 mm, and 4.95 mm. The corresponding axial FWHM values were 1.52 mm, 4.08 mm, 5.84 mm, and 5.92 mm, respectively. These results demonstrate that the proposed assistant structure and the APR method have the potential to construct accurate delay curves without external shape sensing, thereby enabling a flexible ultrasound array for tracking pancreatic tumor targets in real time for radiotherapy.

Enhancing travel time prediction with deep learning on chronological and retrospective time order information of big traffic data.

With growing environmental concerns and the exploitation of ubiquitous big data, smart transportation is transforming logistics business and operations into a more sustainable approach. To answer questions in intelligent transportation planning, such as which data are feasible, which methods are applicable for intelligent prediction of such data, and what are the available operations for prediction, this paper offers a new deep learning approach called bi-directional isometric-gated recurrent unit (BDIGRU). It is merged to the deep learning framework of neural networks for predictive analysis of travel time and business adoption for route planning. The proposed new method directly learns high-level features from big traffic data and reconstructs them by its own attention mechanism drawn by temporal orders to complete the learning process recursively in an end-to-end manner. After deriving the computational algorithm with stochastic gradient descent, we use the proposed method to perform predictive analysis of stochastic travel time under various traffic conditions (especially for congestions) and then determine the optimal vehicle route with the shortest travel time under future uncertainty. Based on empirical results with big traffic data, we show that the proposed BDIGRU method can (1) significantly improve the predictive accuracy of one-step 30 min ahead travel time compared to several conventional (data-driven, model-driven, hybrid, and heuristics) methods measured with several performance criteria, and (2) efficiently determine the optimal vehicle route in relation to the predictive variability under uncertainty.

Transition-of-care program from emergency department to gastroenterology clinics improves follow-up.

OBJECTIVES: Patients discharged from the emergency department (ED) with gastrointestinal (GI) symptoms need to appropriately transition their care to a GI outpatient clinic in a timely manner to have their health needs met and avoid significant morbidity. When this transition isn't optimal, patients are lost to follow-up, potentially placing them at risk for adverse events. We sought to study the effectiveness of implementing an electronic medical record (EMR) based transition-of-care (TOC) program from the ED to outpatient GI clinics. METHODS: We performed a retrospective single center cohort study of patients discharged from the ED of a tertiary care academic medical center referred to outpatient GI clinic before (Pre-TOC patients) and after implementation of an EMR based TOC program (TOC patients). We further stratified patients based on the Distressed Communities Index (DCI), which is a composite measure of economic well-being. We compared rates of appointment scheduling and appointment attendance between the two groups, as well as 30-day readmission rates to the ED. We also performed a subgroup analysis to determine if socioeconomic status would affect patient follow-up rates. RESULTS: We included 380 Pre-TOC and 399 TOC patients in our analysis. TOC patients were found to both schedule appointments (50% vs 27% p-value <0.01) as well as show up to appointments (34% vs 24% p-value <0.01) at significantly higher rates compared to Pre-TOC patients. There was no significant difference between 30-day readmission rates between the two groups. In addition, TOC patients from At-Risk and Distressed Communities were over 22 times more likely to schedule an appointment compared to Pre-TOC patients from similar neighborhoods (OR 22.18, 95% CI 4.23-116.32). CONCLUSION: Our study shows that patients who are discharged from the ED with outpatient GI follow-up are more likely to both schedule and show up to appointments with implementation of an EMR-based direct referral program compared to no patient navigation, particularly among patients of lower socioeconomic status.

A National Survey of the Infrastructure and Scope of Practice for Gastroenterology Hospitalists.

BACKGROUND: Hospital-based specialty-trained physicians have become more prevalent with emerging data suggesting benefit in consult and procedure volume, reduced complication rates, and increased practice productivity. Interest in gastroenterology (GI) hospitalist programs has increased in recent years. However, little is known regarding the types of GI hospitalist models that currently exist. AIMS: To characterize the infrastructure of GI hospitalist models across the USA. METHODS: A 50-question survey was distributed to the GI Hospitalist Special Interest Group of the American Society for Gastrointestinal Endoscopy. Information on demographics, hospital infrastructure, and compensation were collected. RESULTS: 31 of 33 (94%) GI hospitalists completed the questionnaire. Respondents were mostly male (65%), white (48%) or Asian (42%). Most GI hospitalists spent at least half of their clinical time dedicated to the inpatient consultation service (73%), during which they had no other clinical duties. Most services had endoscopy suites with dedicated inpatient endoscopy rooms (66%), over 4 h allotted for procedures (83%), and were available on weekends (62%). Over half of GI hospitalists reported having outpatient duties, the most common being performance of direct access endoscopy (69%). Outside of clinical responsibilities, GI hospitalists were most frequently involved in clinical education or fellowship program leadership (48%). Most GI hospitalists were salaried with an incentive-based bonus based on work relative value units. CONCLUSION: GI hospitalist programs are varied throughout the USA but key commonalities exist between most programs.

A phantom-based analysis for tracking intra-fraction pancreatic tumor motion by ultrasound imaging during radiation therapy.

Purpose: In this study, we aim to further evaluate the accuracy of ultrasound tracking for intra-fraction pancreatic tumor motion during radiotherapy by a phantom-based study. Methods: Twelve patients with pancreatic cancer who were treated with stereotactic body radiation therapy were enrolled in this study. The displacement points of the respiratory cycle were acquired from 4DCT and transferred to a motion platform to mimic realistic breathing movements in our phantom study. An ultrasound abdominal phantom was placed and fixed in the motion platform. The ground truth of phantom movement was recorded by tracking an optical tracker attached to this phantom. One tumor inside the phantom was the tracking target. In the evaluation of the results, the monitoring results from the ultrasound system were compared with the phantom motion results from the infrared camera. Differences between infrared monitoring motion and ultrasound tracking motion were analyzed by calculating the root-mean-square error. Results: The 82.2% ultrasound tracking motion was within a 0.5 mm difference value between ultrasound tracking displacement and infrared monitoring motion. 0.7% ultrasound tracking failed to track accurately (a difference value > 2.5 mm). These differences between ultrasound tracking motion and infrared monitored motion do not correlate with respiratory displacements, respiratory velocity, or respiratory acceleration by linear regression analysis. Conclusions: The highly accurate monitoring results of this phantom study prove that the ultrasound tracking system may be a potential method for real-time monitoring targets, allowing more accurate delivery of radiation doses.

Systematic study of the iodinated rectal hydrogel spacer material discrepancy on accuracy of proton dosimetry.

PURPOSE: Iodination of rectal hydrogel spacer increases the computed tomography (CT) visibility. The effect of iodinated hydrogel spacer material on the accuracy of proton dosimetry has not been fully studied yet. We presented a systematic study to determine the effect of iodination on proton dosimetry accuracy during proton therapy (PT). METHODS: PT plans were designed for 20 prostate cancer patients with rectal hydrogel spacer. Three variations of hydrogel density were considered. First, as the ground truth, the true elemental composition of hydrogel true material (TM), verified by our measurement of spacer stopping power ratio, was used for plan optimization and Monte Carlo dose calculation. The dose distribution was recalculated with (1) no material (NM) override based on the CT intensity of the iodinated spacer, and (2) the water material (WM) override, where spacer material was replaced by water. The plans were compared with the ground truth using the metrics of gamma index (GI) and dosimetric indices. RESULTS: The iodination of hydrogel spacer affected the proton dose distribution with the NM scenario showing the most deviation from the ground truth. The iodination of spacer resulted in a notable increase in CT intensity and led to the treatment planning systems mistreating the iodinated spacer as a high-density material. Among the structures adjacent to the target, neurovascular bundles showed the largest dose difference, up to 350 cGy or about 5% of the prescribed dose with NM. Compared to the WM scenario, dose distribution similarity and GI passing ratios were lower in the NM scenario. CONCLUSION: The inaccurate CT intensity-based material for iodinated spacer resulted in errors in PT dose calculation. We found that the error was negligible if the iodinated spacer was replaced with water. Water density can be used as a clinically accessible and convenient alternative material override to true spacer material.

Clinical risk factors for mortality in an analysis of 1375 patients admitted for COVID treatment.

The goal of the present work was to examine clinical risk factors for mortality in 1375 COVID + patients admitted to a hospital in Suffolk County, NY. Data were collated by the hospital epidemiological service for patients admitted from 3/7/2020 to 9/1/2020. Time until final discharge or death was the outcome. Cox proportional hazards models were used to estimate time until death among admitted patients. In total, all cases had resolved leading to 207 deaths. Length of stay was significantly longer in those who died as compared to those who did not (p = 0.007). Of patients who had been discharged, 54 were readmitted and nine subsequently died. Multivariable-adjusted Cox proportional hazards regression revealed that in addition to older age, male sex, and a history of chronic heart failure, chronic obstructive pulmonary disease, and diabetes, that a history of premorbid depression was a risk factors for COVID-19 mortality (aHR = 2.42 [1.38-4.23] P = 0.002), and that this association remained after adjusting for age and for neuropsychiatric conditions as well as medical comorbidities including cardiovascular disease and pulmonary conditions. Sex-stratified analyses revealed that associations between mortality and depression was strongest in males (aHR = 4.45 [2.04-9.72], P < 0.001), and that the association between heart failure and mortality was strongest in participants aged < 65 years old (aHR = 30.50 [9.17-101.48], P < 0.001). While an increasing number of studies have identified several comorbid medical conditions including chronic heart failure and age of patient as risk factors for mortality in COVID + patients, this study confirmed several prior reports and also noted that a history of depression is an independent risk factor for COVID-19 mortality.

The Role of the Gastrointestinal Hospitalist in Optimizing Endoscopic Operations.

The gastroenterology (GI) hospitalist model has improved endoscopic operations through improved interdisciplinary coordination, efficiencies introduced in endoscopy unit workflow, and increased patient access to both inpatient and outpatient GI care. The challenges and opportunities associated with a GI hospitalist model and supporting a GI hospitalist team are reviewed, especially in relation to advanced endoscopy. The roles of the GI hospitalist in endoscopy quality measurement and value-based care are also explored. Greater awareness of the GI hospitalist model and tailoring it to fit the needs of the GI practice or endoscopy unit will be key to practice sustainability and growth.

Mixed-Stable Models: An Application to High-Frequency Financial Data.

The paper extends the study of applying the mixed-stable models to the analysis of large sets of high-frequency financial data. The empirical data under review are the German DAX stock index yearly log-returns series. Mixed-stable models for 29 DAX companies are constructed employing efficient parallel algorithms for the processing of long-term data series. The adequacy of the modeling is verified with the empirical characteristic function goodness-of-fit test. We propose the smart-Δ method for the calculation of the α-stable probability density function. We study the impact of the accuracy of the computation of the probability density function and the accuracy of ML-optimization on the results of the modeling and processing time. The obtained mixed-stable parameter estimates can be used for the construction of the optimal asset portfolio.

The Role of the Gastroenterology Hospitalist in Modern Practice.

Over the last 2 decades, there has been an increase in acuity among hospitalized patients and patients who present to the emergency department. As such, the role of the hospitalist as an inpatient medicine specialist has become increasingly important to many health systems. More recently, subspecialties in medicine have begun adopting the hospitalist model to care for their inpatients. This care delivery model helps provide continuity, potentially decreased cost and length of stay, and a better quality of life with a more predictable schedule for hospitalists and their outpatient colleagues. This model also aims to provide more timely consultation for inpatients, to help improve communication among inpatient caregiver teams, and to reduce redundant tests while also enhancing patient satisfaction. As a primarily outpatient procedure (and clinic)-based specialty, gastroenterology may benefit from the hospitalist model by being able to provide highly specialized care to acutely ill hospitalized patients with less disruption to outpatient schedules. This article discusses the structure of the gastroenterology hospitalist model, advantages to gastroenterologists and their practices, and the challenges of developing and implementing this model, as well as highlights the increasingly recognized value of this new paradigm in gastroenterology.

Poor compliance with ACG guidelines for nutrition and antibiotics in the management of acute pancreatitis: a North American survey of gastrointestinal specialists and primary care physicians.

CONTEXT: Despite recent updates in the treatment of acute pancreatitis emphasizing enteral nutrition over parenteral nutrition as well as minimizing antibiotic usage, mortality rates from acute pancreatitis have not improved. Data has been limited regarding physician compliance to these guidelines in the United States. METHODS: A 20 question survey regarding practice patterns in the management of acute pancreatitis was distributed to physicians at multiple internal medicine and gastroenterology conferences in North America between 2009 and 2010. Responses were analyzed using the chi-square test and multivariate logistic regression. RESULTS: Out of 406 available respondents, 43.3% of physicians utilize total parenteral nutrition/peripheral parenteral nutrition (TPN/PPN) and 36.5% utilize nasojejunal (NJ) feedings. The preferred route of nutrition was significantly related to practice type (P<0.001): academic physicians were more likely to use NJ tube feeding than private practice physicians (52.1% vs. 19.9%) while private practitioners were more likely to utilize TPN/PPN than academic physicians (70.2% vs. 20.5%). Gastroenterologists and primary care physicians were equally non-compliant as both groups favored parenteral nutrition. Multivariate logistic regression demonstrated that practice type (P<0.001) was the only independent predictor of route of nutrition. Most survey respondents appropriately do not routinely utilize antibiotics for acute pancreatitis, but when antibiotics are initiated, they are for inappropriate indications such as fever and infection prophylaxis. CONCLUSIONS: Many North American physicians are noncompliant with current ACG practice guidelines for the use of artificial nutrition in the management of acute pancreatitis, with overuse of TPN/PPN and underutilization of jejunal feedings. Antibiotics are initiated in acute pancreatitis for inappropriate indications, although there are conflicting recommendations for antibiotics in severe acute pancreatitis. Improved compliance with guidelines is needed to improve patient outcomes.

An efficient Si light-emitting diode based on an n- ZnO/SiO2-Si nanocrystals-SiO2/p-Si heterostructure.

Si nanocrystals embedded in a SiO2 matrix and an n-type Al-doped ZnO (ZnO:Al) layer were applied to improve the external quantum efficiency from Si in n- ZnO/SiO2-Si nanocrystals-SiO2/p-Si heterojunction light-emitting diodes (LEDs). The Si nanocrystals were grown by low pressure chemical vapor deposition and the ZnO:Al layer was prepared by atomic layer deposition. The n-type ZnO:Al layer acts as an electron injection layer, a transparent conductive window, and an anti-reflection coating to increase the light extraction efficiency. Owing to the spatial confinement of carriers and surface passivation by the surrounding SiO2, the Si nanocrystals embedded in the SiO2 matrix lead to a significant enhancement of the light emission efficiency from Si. An external quantum efficiency up to 4.3 x 10(-4) at the wavelength corresponding to the indirect bandgap of Si was achieved at room temperature.

Incidence and risk factors for proximal and distal junctional kyphosis following surgical treatment for Scheuermann kyphosis: minimum five-year follow-up.

STUDY DESIGN: Retrospective case review at a single center. OBJECTIVE: To analyze the incidence and risk factors associated with proximal junctional kyphosis (PJK) and distal junctional kyphosis (DJK) in patients undergoing instrumented spinal fusion for Scheuermann kyphosis. SUMMARY OF BACKGROUND DATA: Previously reported risk factors for junctional kyphosis include improper end vertebrae selection, curve correction greater than 50%, or excessive junctional soft tissue dissection. METHODS: Clinical and radiographic data on 67 patients (mean age 37) from a single center treated with instrumented fusion for Scheuermann kyphosis were reviewed. All patients had complete radiographic data with a minimum 5-year follow-up (mean: 73 months). Abnormal PJK was defined by a proximal junctional angle greater than 10 degrees and at least 10 degrees greater than the corresponding preoperative measurement. DJK was similarly defined between the caudal endplate of the lower instrumented vertebra to the caudal endplate that was 1 vertebra below. RESULTS: The incidence of PJK as defined above was seen in 20 patients (30%). The development of PJK was associated with failure to incorporate the proximal end vertebra (15 patients), disruption of junctional ligamentum flavum (3 patients), or combination of both (2 patients). The most common cause of inappropriate end vertebra selection was poor visualization of the upper thoracic vertebra.DJK occurred in 8 patients (12%) and 7 of them had fusion short of including the first lordotic disc. CONCLUSION: The incidence of PJK can be minimized by the appropriate selection of the upper end vertebra to be fused and avoiding disruption of the junctional ligamentum flavum. The development of DJK can be minimized by incorporation of the first lordotic disc into the fusion construct.

Preventing distal pullout of posterior spine instrumentation in thoracic hyperkyphosis: a biomechanical analysis.

STUDY DESIGN: An in vitro biomechanical study. OBJECTIVE: Compare the mechanical behavior of 5 different constructs used to terminate dual-rod posterior spinal instrumentation in resisting forward flexion moment. SUMMARY OF BACKGROUND DATA: Failure of the distal fixation construct can be a significant problem for patients undergoing surgical treatment for thoracic hyperkyphosis. We hypothesize that augmenting distal pedicle screws with infralaminar hooks or sublaminar cables significantly increases the strength and stiffness of these constructs. METHODS: Thirty-seven thoracolumbar (T12 to L2) calf spines were implanted with 5 configurations of distal constructs: (1) infralaminar hooks, (2) sublaminar cables, (3) pedicle screws, (4) pedicle screws+infralaminar hooks, and (5) pedicle screws+sublaminar cables. Progressive bending moment was applied to each construct until failure. The mode of failure was noted and the construct's stiffness and failure load determined from the load-displacement curves. RESULTS: Bone density and vertebral dimensions were equivalent among the groups (F=0.1 to 0.9, P>0.05). One-way analysis of covariance (adjusted for differences in density and vertebral dimension) demonstrated that all of the screw-constructs (screw, screw+hook, and screw+cable) exhibited significantly higher stiffness and ultimate failure loads compared with either sublaminar hook or cable alone (P<0.05). The screw+hook constructs (109+/-11 Nm/mm) were significantly stiffer than either screws alone (88+/-17 Nm/mm) or screw+cable (98+/-13 Nm/mm) constructs, P<0.05. Screw+cable construct exhibited significantly higher failure load (1336+/-328 N) compared with screw constructs (1102+/-256 N, P<0.05), whereas not statistically different from the screw+hook construct (1220+/-75 N). The cable and hook constructs failed by laminar fracture, screw construct failed in uniaxial shear (pullout), whereas the screws+(hooks or wires) failed by fracture of caudal vertebral body. CONCLUSIONS: Posterior dual rod constructs fixed distally using pedicle screws were stiffer and stronger in resisting forward flexion compared with cables or hooks alone. Augmenting these screws with either infralaminar hooks or sublaminar cables provided additional resistance to failure.

Adjacent two-level lumbar discectomy: outcome and SF-36 functional assessment.

STUDY DESIGN: A retrospective outcomes study. OBJECTIVES: To examine the outcome following adjacent two-level lumbar discectomy using both surgeon-based evaluation criteria and validated patient-based quality of life instrument (SF-36). SUMMARY OF BACKGROUND DATA: Lumbar discectomies have documented success rates between 49% and 98% for single-level procedures. However, no prior study has specifically examined the outcome following adjacent two-level lumbar discectomy in a large series of patients. METHODS: This study analyzed 55 patients with a minimum 2-year follow-up. All patients underwent adjacent two-level lumbar discectomy for radicular pain attributable to nerve root impingement at the corresponding levels. The patients were divided into two diagnostic groups based on their preoperative radiographic studies. Patients with two-level adjacent posterolateral lumbar disc herniations without concomitant osseous degenerative changes at the same levels constituted Group 1 (22 patients). Patients with associated osseous degenerative changes at the same levels made up Group 2 (33 patients). The patients' clinical outcome was assessed using the MacNab classification and SF-36 questionnaire. RESULTS: The average duration of follow-up was 41 months (range 24-96 months). The group consisted of 35 males and 20 females with average age of 49 years (range 19-82 years). Excellent results were observed in 49%, good in 20%, fair in 15%, and poor in 16%. However, patients in Group 1 have 86% excellent/good results, whereas patients in Group 2 have 57% excellent/good results. Overall, 15% of the patients required reoperation and subsequent spinal fusion. Analysis of the SF-36 scores revealed significant differences based on patient's diagnostic grouping as well. Patients in Group 1 have physical and mental summary scores comparable with age- and sex-adjusted population norms and significantly higher than those in Group 2 (P < 0.01). CONCLUSIONS: Two-level discectomy is an effective treatment with clinical outcome comparable with single-level discectomy. Patients with posterolateral disc herniations and definitive radiculopathy without osseous degenerative changes at the same levels have better clinical outcome and quality of life scores compared with those patients having concomitant degenerative arthritis at the same levels. Patients having two-level discectomy may be at increased risk of requiring subsequent lumbar fusion compared with those with single-level discectomy.

Peripheral circulation in patients with myelodysplasia.

Patients with myelodysplasia have increased wound dehiscence and ulcer formation compared with the normal population. While neurologic deficits and resultant muscle imbalance are the presumed etiologies for these complications, no study has investigated the role of peripheral circulation in myelodysplasia. Eighty-two patients (ages 2-20) were prospectively recruited for this study, consisting of 41 patients with myelodysplasia and 41 age-matched controls. Peripheral circulation was quantified using systolic blood pressures in arms and legs (ankle-brachial index [ABI]) and transcutaneous pO2 measurements (TcO2) in a standardized location in the forefoot. Both groups had similar mean age. Patients with myelodysplasia had a lower ABI but similar TcO2 compared with the control group. Among the patients with myelodysplasia, the ABI and TcO2 did not vary according to the level of neurologic deficit or the patient's age. However, those with prior surgical procedures had significantly higher ABI and TcO2 compared with those without prior surgery (P < 0.05). This study suggests that patients with myelodysplasia may have decreased peripheral circulation compared with normal controls. Vascular insufficiency may therefore contribute to increased wound healing complications and ulcer formation in these patients.