bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sheet beam x‐ray fluorescence computed tomography (XFCT) imaging of gold nanoparticles
Authors: Dunning Chelsea A. S. , Bazalova‐Carter Magdalena 
Published: March 2018

PurposeX‐ray fluorescence computed tomography (XFCT) experiments have typically used pencil beams for data acquisition, which yielded good quality images of gold nanoparticles (AuNP) but prolonged the imaging time. Here we propose three novel collimator geometries for use with faster sheet beam XFCT data acquisition. The feasibility of a multipinhole, parallel, and converging collimator was investigated in a Monte Carlo study.MethodsA cylindrical water phantom with 2 cm in diameter and 3 cm in height containing 0.5–2 mm diameter vials with 0.4%–1.6% AuNP concentrations was modelled by FLUKA. A 15 and 81 keV monoenergetic x‐ray sheet beam of 0.4 mm in width was used to image the phantom with L‐shell and K‐shell XFCT, respectively, with a dose of 30 mGy. The collimator thickness for L‐shell and K‐shell data acquisition was 3.3 and 5.1 mm, respectively. The XFCT images resulting from three collimator geometries were generated using the maximum likelihood expectation maximization (MLEM) iterative reconstruction method. With a resolution of 0.4 mm they were corrected for x‐ray attenuation. The sheet beam XFCT images were compared against pencil beam geometry images that were generated using 55 translations. To assess image quality, the contrast‐to‐noise ratio (CNR) was evaluated for each vial. The Rose criterion was used to determine the lowest AuNP concentration detectable for each image.ResultsAmong the three collimator geometry types, the sheet beam L‐shell and K‐shell parallel collimator XFCT images yielded AuNP sensitivity limits at 0.09% and 0.08%, respectively, for a 2 mm diameter vial. The AuNP sensitivity limits of the pencil beam XFCT images were 0.07% and 0.01% for L‐shell and K‐shell XFCT, respectively. The L‐shell parallel collimator AuNP imaging sensitivity approached that of the pencil beam geometry with a 55‐fold reduction in imaging time. The AuNP sensitivity limits for the 1 mm diameter vial for the L‐shell and K‐shell parallel collimator XFCT images were 0.19% and 0.16%, respectively, and those of the pencil beam XFCT images were 0.08% and 0.01% for L‐shell and K‐shell XFCT, respectively. The remaining two collimator geometries resulted in a lower CNR and poorer image quality. For a 2 mm diameter vial, the AuNP sensitivity limits for the L‐shell and K‐shell multipinhole collimator XFCT images were 0.23% and 0.52%, respectively, while for the L‐shell and K‐shell converging collimator XFCT images the AuNP sensitivity limits were 0.38% and 0.13%, respectively.ConclusionThis work demonstrates the feasibility of sheet beam L‐shell XFCT imaging for small animal studies using parallel‐oriented lead collimators which can detect AuNP concentrations approaching the level of pencil beam images with reduced imaging time.
EM‐enhanced US‐based seed detection for prostate brachytherapy
Authors: Dehghan Ehsan , Bharat Shyam , Kung Cynthia , Bonillas Antonio , Beaulieu Luc , Pouliot Jean , Kruecker Jochen 
Published: March 2018

PurposeIntraoperative dosimetry in low‐dose‐rate (LDR) permanent prostate brachytherapy requires accurate localization of the implanted seeds with respect to the prostate anatomy. Transrectal Ultrasound (TRUS) imaging, which is the main imaging modality used during the procedure, is not sufficiently robust for accurate seed localization. We present a method for integration of electromagnetic (EM) tracking into LDR prostate brachytherapy procedure by fusing it with TRUS imaging for seed localization.MethodExperiments were conducted on five tissue mimicking phantoms in a controlled environment. The seeds were implanted into each phantom using an EM‐tracked needle, which allowed recording of seed drop locations. After each needle, we reconstructed a 3D ultrasound (US) volume by compounding a series of 2D US images acquired during retraction of an EM‐tracked TRUS probe. Then, a difference image was generated by nonrigid registration and subtraction of two consecutive US volumes. A US‐only seed detection method was used to detect seed candidates in the difference volume, based on the signature of the seeds. Finally, the EM‐based positions of the seeds were used to detect the false positives of the US‐based seed detection method and also to estimate the positions of the missing seeds. After the conclusion of the seed implant process, we acquired a CT image. The ground truth for seed locations was obtained by localizing the seeds in the CT image and registering them to the US coordinate system.ResultsCompared to the ground truth, the US‐only detection algorithm achieved a localization error mean of 1.7 mm with a detection rate of 85%. By contrast, the EM‐only seed localization method achieved a localization error mean of 3.7 mm with a detection rate of 100%. By fusing EM‐tracking information with US imaging, we achieved a localization error mean of 1.8 mm while maintaining a 100% detection rate without any false positives.ConclusionsFusion of EM‐tracking and US imaging for prostate brachytherapy can combine high localization accuracy of US‐based seed detection with the robustness and high detection rate of EM‐based seed localization. Our phantom experiments serve as a proof of concept to demonstrate the potential value of integrating EM‐tracking into LDR prostate brachytherapy.
Technical Note: An approach to building a Monte Carlo simulation model for a double scattering proton beam system
Authors: Yuan Jiankui , Ellis Rodney , Machtay Mitchell 
Published: March 2018

PurposeThe purpose of this study was to demonstrate and develop a Monte Carlo (MC) simulation model for a passive double scattering compact proton therapy system based on limited information of the mechanical components.MethodWe built a virtual machine source model (VMSM) which included a detailed definition of each beam‐modifying component in the nozzle. Conceptually, it is similar to the conventional virtual analytical source model (VASM), except that the numerical machine nozzle or beamline is constructed in the VMSM, whereas in the VASM analytical parameters characterizing the energy spectrum and source fluence distribution are sought. All major beam shaping components were included in the VMSM and the model simulates interactions of the beam with a rotating range modulation wheel (RMW) combined with the beam current modulation. The RMWs, the first and second scatterer in the system were generated and tuned to reproduce measurement data as closely as possible. To validate the model, we compared the percent depth dose curves, spread out Bragg peaks (SOBPs) and lateral profiles against measured commissioning beam data.ResultsThe agreement of beam range between the MC calculation and measurement was within 1 mm for all beam options. The distal‐falloff length was in good agreement as well (<1 mm for the large and deep groups, <1.5 mm for the small group). Agreement to within 2.5 mm of measured SOBP widths was obtained for all MC calculations. For lateral profiles, differences were found to be less than 2 mm.ConclusionsWe demonstrated that with limited geometrical information it is possible to build an acceptable source model for MC simulations of a passive double scattering compact proton therapy system. The agreement between the measurements and the MC model provides validation for use of the model for further studies of the dosimetric effects in patient treatments.
MR imaging of magnetic ink patterns via off‐resonance sensitivity
Authors: Perkins Stephanie L. , Daniel Bruce L. , Hargreaves Brian A. 
Published: March 2018

PurposePrinted magnetic ink creates predictable B0 field perturbations based on printed shape and magnetic susceptibility. This can be exploited for contrast in MR imaging techniques that are sensitized to off‐resonance. The purpose of this work was to characterize the susceptibility variations of magnetic ink and demonstrate its application for creating MR‐visible skin markings.MethodsThe magnetic susceptibility of the ink was estimated by comparing acquired and simulated B0 field maps of a custom‐built phantom. The phantom was also imaged using a 3D gradient echo sequence with a presaturation pulse tuned to different frequencies, which adjusts the range of suppressed frequencies. Healthy volunteers with a magnetic ink pattern pressed to the skin or magnetic ink temporary flexible adhesives applied to the skin were similarly imaged.ResultsThe volume‐average magnetic susceptibility of the ink was estimated to be 131 ± 3 parts per million across a 1‐mm isotropic voxel (13,100 parts per million assuming a 10‐μm thickness of printed ink). Adjusting the saturation frequency highlights different off‐resonant regions created by the ink patterns; for example, if tuned to suppress fat, fat suppression will fail near the ink due to the off‐resonance. This causes magnetic ink skin markings placed over a region with underlying subcutaneous fat to be visible on MR images.ConclusionPatterns printed with magnetic ink can be imaged and identified with MRI. Temporary flexible skin adhesives printed with magnetic ink have the potential to be used as skin markings that are visible both by eye and on MR images.
Quantification of lectin fluorescence in GNE myopathy muscle biopsies
Authors: Leoyklang Petcharat , Class Bradley , Noguchi Satoru , Gahl William A , Carrillo Nuria , Nishino Ichizo , Huizing Marjan , Malicdan May Christine 
Published: March 2018

ABSTRACTIntroduction: GNE myopathy is an adult‐onset muscle disorder characterized by impaired sialylation of (muscle) glycans, detectable by lectin histochemistry. We describe a standardized method to quantify (lectin‐) fluorescence in muscle sections, applicable for diagnosis and response to therapy for GNE myopathy. Methods: Muscle sections were fluorescently labeled with the sialic acid‐binding Sambucus nigra agglutinin (SNA) lectin and antibodies to sarcolemma residence protein caveolin‐3 (CAV‐3). Entire tissue sections were imaged in tiles and fluorescence was quantified. Results: SNA fluorescence co‐localizing with CAV‐3 was ∼50% decreased in GNE myopathy biopsies compared with muscle‐matched controls, confirming previous qualitative results. Discussion: This quantitative fluorescence method can accurately determine sialylation status of GNE myopathy muscle biopsies. This method is adaptable for expression of other membrane‐associated muscle proteins, and may be of benefit for disorders in which therapeutic changes in expression are subtle and difficult to assess by other methods. Muscle Nerve 58: 286–292, 2018
Utility of catheterized specimens in reducing overdiagnosis of urinary tract infections in women
Authors: Aisen Carrie M. , Ditkoff Erica , RoyChoudhury Arindam , Corish Michele , Rutman Matthew P. , Chung Doreen E. , Badalato Gina M. , Cooper Kimberly L. 
Published: March 2018

AimsTo evaluate the utility of catheterized samples in reducing overdiagnosis of UTI based on voided specimens among patients presenting with a range of urinary symptoms. We also aimed to determine variables that may modify the predictive value of the voided midstream urine culture.MethodsPatient charts were reviewed to identify female patients referred to our voiding dysfunction clinic with a range of complaints warranting urine studies (5/2014‐8/2016). Patients with a positive voided urine culture who also had a catheterized urine culture in our system were included. Multiple logistic regression analysis was performed to identify patient characteristics associated with a negative catheterized specimen despite a positive voided specimen.ResultsOne hundred and seven women were included in the study. Eighty percent of the cohort was post‐menopausal. Although all patients had positive voided specimens, only 53 (49.5%) had positive catheterized specimens. On multivariate analysis negative nitrites on clean catch UA was a significant predictor of a negative catheterized sample (adjusted OR 8.9, 95%CI 2.2‐43.7, P = 0.003). WBC/HPF <10 on clean catch UA trended towards significance (adjusted OR 4.72, 95%CI 1.1‐26.1, P = 0.05).ConclusionsRelying on clean catch urine samples may lead to significant over‐diagnosis of UTIs. Our study suggests that in female patients who have vague symptoms of UTI, obtaining catheterized specimens may be beneficial in avoiding the overdiagnosis of UTIs and the overuse of antibiotics. Larger, prospective studies testing our hypothesis are necessary, and would greatly assist in establishing clinical practices that reduce the amount of antibiotics inappropriately prescribed.
Damage accumulation and probability of kill for gun and target engagements
Authors: Chircop Paul A. , Kachoyan Bernard J. 
Published: March 2018

AbstractDetermination of the gunfire probability of kill against a target requires two parameters to be taken into consideration: the likelihood of hitting the target (susceptibility) and the conditional probability of kill given a hit (vulnerability). Two commonly used methods for calculating the latter probability are (1) treating each hit upon the target independently, and (2) setting an exact number of hits to obtain a target kill. Each of these methods contains an implicit assumption about the probability distribution of the number of hits‐to‐kill. Method (1) assumes that the most likely kill scenario occurs with exactly one hit, whereas (2) implies that achieving a precise number of hits always results in a kill. These methods can produce significant differences in the predicted gun effectiveness, even if the mean number of hits‐to‐kill for each distribution is the same. We therefore introduce a new modeling approach with a more general distribution for the number of hits‐to‐kill. The approach is configurable to various classes of damage mechanism and is able to match both methods (1) and (2) with a suitable choice of parameter. We use this new approach to explore the influence of various damage accumulation models on the predicted effectiveness of weapon‐target engagements.
Cerebral perfusion characteristics show differences in younger versus older children with sickle cell anaemia: Results from a multiple‐inflow‐time arterial spin labelling study
Authors: Kawadler Jamie M. , Hales Patrick W. , Barker Simon , Cox Timothy C. S. , Kirkham Fenella J. , Clark Chris A. 
Published: March 2018

Sickle cell anaemia (SCA) is associated with chronic anaemia and oxygen desaturation, which elevate cerebral blood flow (CBF) and increase the risk of neurocognitive complications. Arterial spin labelling (ASL) provides a methodology for measuring CBF non‐invasively; however, ASL techniques using only a single inflow time are not sufficient to fully characterize abnormal haemodynamic behaviour in SCA. This study investigated haemodynamic parameters from a multi‐inflow‐time ASL acquisition in younger (8–12 years) and older (13–18 years) children with SCA with and without silent cerebral infarction (SCI+/−) (n = 20 and 19 respectively, 6 and 4 SCI+ respectively) and healthy controls (n = 9 and 7 respectively). Compared with controls, CBF was elevated globally in both groups of patients. In the younger SCA patients, blood oxygen content was negatively correlated with CBF in the middle and posterior cerebral artery territories and significantly positively correlated with bolus arrival time (BAT) in the anterior and middle cerebral artery territories. In older children, SCA patients had significantly shorter BAT than healthy controls and there was a significant negative correlation between CBF and oxygen content only in the territory of the posterior cerebral artery, with a trend for a correlation in the anterior cerebral artery but no relationship for the middle cerebral artery territory. In the younger group, SCI+ patients had significantly higher CBF in the posterior cerebral artery territory (SCI+ mean = 92.78 ml/100 g/min; SCI− mean = 72.71 ml/100 g/min; F = 4.28, p = 0.04), but this no longer reached significance when two children with abnormal transcranial Doppler and one with haemoglobin SC disease were excluded, and there were no significant differences between patients with and without SCI in the older children. With age, there appears to be increasing disparity between patients and controls in terms of the relationship between CBF and oxygen content in the anterior circulation, potentially predicting the risk of acute and chronic compromise of brain tissue.
Oscillating gradient diffusion kurtosis imaging of normal and injured mouse brains
Authors: Wu Dan , Li Qiang , Northington Frances J. , Zhang Jiangyang 
Published: March 2018

Recent advances in diffusion MRI employ multiple diffusion encoding schemes with varying diffusion direction, weighting, and diffusion time to investigate specific microstructural properties in biological tissues. In this study, we examined time‐dependent diffusion kurtosis contrast in adult mouse brains and in neonatal mouse brains after hypoxic–ischemic (HI) injury. In vivo diffusion kurtosis maps were acquired with a short diffusion time using an oscillating gradient spin echo (OGSE) sequence at 100 Hz and with a relatively long diffusion time (20 ms) using a pulsed gradient spin echo (PGSE) sequence. In the adult mouse brain, we found that the cortex and hippocampus showed larger differences between OGSE kurtosis and PGSE kurtosis than major white matter tracts. In neonatal mouse brains with unilateral HI injury, the OGSE kurtosis map overall provided stronger edema contrast than the PGSE kurtosis map, and the differences between OGSE and PGSE kurtosis measurements in the edema region reflected heterogeneity of injury. This is the first in vivo study that has demonstrated multi‐direction OGSE kurtosis contrasts in the mouse brain. Comparing PGSE and OGSE kurtosis measures may provide additional information on microstructural changes after ischemic stroke.
Nutrition Support Team Guide to Maternal Diet for the Human‐Milk‐Fed Infant
Authors: Copp Kathleen , DeFranco Emily A. , Kleiman Jeanne , Rogers Lynette K. , Morrow Ardythe L. , Valentine Christina J. 
Published: March 2018

AbstractBackgroundHuman milk feeding is encouraged for all infants; however, the mammary gland depends on maternal dietary intake of vitamins A, B1, B2, B6, B12, D, docosahexaenoic acid (DHA), choline, and iodine. Nutrition support team knowledge of maternal feeding guidelines for these nutrient sources can therefore impact infant intake. We hypothesized that these key nutrients for lactation in the mother's diet would be less than the dietary guidelines in the United States.MethodsThis was a secondary analysis of nutrition data collected during a randomized, controlled trial. Dietary records were analyzed from 16 mothers (13 with singleton and 3 with multiple births) completing the study. Mean dietary intakes of selected nutrients were calculated and compared with the current dietary reference intakes.ResultsMean maternal dietary intake for singletons was significantly (P < .05) lower than the dietary reference intakes for (vitamin A (58%), vitamin D (44%), and choline (58%);) DHA comprised only 5% of the current expert recommendation. Based on singleton recommendations, mothers to twins consumed an adequate intake except for DHA.ConclusionsWomen providing breast milk for singleton preterm infants did not consume dietary reference intakes for key nutrients. Twin mothers’ diets were adequate except for DHA, but these guidelines are based on singleton pregnancies and remain poorly understood for twin needs. The nutrition support team can have a unique role in maternal dietary education to impact human milk nutrient delivery to the infant.
Effect of Vitamin D Level on Clinical Outcomes in Patients Undergoing Left Ventricular Assist Device Implantation
Authors: Obeid Fadi Abou , Yost Gardner , Bhat Geetha , Drever Erin , Tatooles Antone 
Published: March 2018

AbstractBackgroundVitamin D is an important hormone that regulates cardiac myocyte function. Low levels contribute to the development of cardiovascular disease and have been implicated in immune function and the inflammatory cascade. Patients who undergo left ventricular assist device (LVAD) implantation are at risk for driveline infection, stroke, and gastrointestinal (GI) bleeding. We investigated whether serum 25‐hydroxy (25‐OH) vitamin D levels affect clinical outcomes after LVAD.Methods212 patients who underwent LVAD implantation between 2010 and 2015 were included. We measured preoperative 25‐OH vitamin D level and postoperative adverse events during the first year. Vitamin D level was classified into 3 categories: normal (>30 ng/mL), insufficient (20–30 ng/mL), and deficient (<20 ng/mL). Clinical outcomes in both insufficient and deficient categories were compared with the normal category.ResultsThe odds ratio (OR) of being admitted ≥2 times was 2.46 (95% confidence interval [CI]: 1.067–5.769) for deficiency and 2.5 (95% CI: 0.970–6.443) for insufficiency. The OR of driveline infection was 6.185 (95% CI: 0.80–49.2; P = .07) for insufficiency and 11.467 (95% CI: 1.204–109.26; P = .03) for deficiency. Vitamin D levels were not associated with GI bleeding, length of stay, or stroke.ConclusionsIn patients with LVAD, both deficiency and insufficiency of 25‐OH vitamin D levels are independently associated with increased postoperative driveline infection risk and higher rate of readmission. Further trials are needed to confirm whether a repletion regimen could be a promising means of decreasing the risk for these postoperative adverse events.
Validation of Nutritional Risk Screening‐2002 in a Hospitalized Adult Population
Authors: Bolayir Başak , Arik Güneş , Yeşil Yusuf , Kuyumcu Mehmet Emin , Varan Hacer Doğan , Kara Özgür , Güngör Anil Evrim , Yavuz Burcu Balam , Cankurtaran Mustafa , Halil Meltem Gülhan 
Published: March 2018

AbstractBackgroundMalnutrition in hospitalized patients is a serious problem and is associated with a number of adverse outcomes. The Nutritional Risk Screening‐2002 (NRS‐2002) tool was designed to identify patients at nutrition risk. The validation of NRS‐2002 compared with detailed clinical assessment of nutrition status was not studied before in hospitalized Turkish adults. The aim of this study is to determine validity, sensitivity, and specificity of the Turkish version of NRS‐2002 in a hospitalized adult population.MethodsA total of 271 consecutive hospitalized patients aged >18 years admitted to surgical and medical wards of a university hospital in Turkey were included in this single‐center non interventional validity study. Assessment by geriatricians was used as the reference method. Two geriatricians experienced in the field of malnutrition interpreted the patients' nutrition status after the evaluation of several parameters. Patients were divided into “at nutrition risk” and “not at nutrition risk” groups by geriatricians. Concordance between the 2 geriatricians' clinical assessments was analyzed by κ statistics. Excellent concordance was found; therefore, the first geriatrician's decisions were accepted as the gold standard. The correlation of nutrition status of the patients, determined with NRS‐2002 and experienced geriatrician's decisions, was evaluated for the validity.ResultsNRS‐2002 has a sensitivity of 88% and specificity of 92% when compared with professional assessment. The positive and negative predictive values were 87% and 92%, respectively. Testretest agreement was excellent as represented by a κ coefficient of 0.956.ConclusionsNRS‐2002 is a valid tool to assess malnutrition risk in Turkish hospitalized patients.