Retrospective Estimation Research Articles

Dose coefficients for organ dosimetry in tomosynthesis imaging of adults and pediatrics across diverse protocols.

The gold-standard method for estimation of patient-specific organ doses in digital tomosynthesis (DT) requires protocol-specific Monte Carlo (MC) simulations of radiation transport in anatomically accurate computational phantoms. Although accurate, MC simulations are computationally expensive, leading to a turnaround time in the order of core hours for simulating a single exam. This limits their clinical utility. The purpose of this study is to overcome this limitation by utilizing patient- and protocol-specific MC simulations to develop a comprehensive database of air-kerma-normalized organ dose coefficients for a virtual population of adult and pediatric patient models over an expanded set of exam protocols in DT for retrospective and prospective estimation of radiation dose in clinical tomosynthesis. A clinically representative virtual population of 14 patient models was used, with pediatric models (M and F) at ages 1, 5, 10, and 15 and adult patient models (M and F) with body mass index (BMIs) at 10th, 50th, and 90th percentiles of the US population. A graphics processing unit (GPU)-based MC simulation framework was used to simulate organ doses in the patient models, incorporating the scanner-specific configuration of a clinical DT system (VolumeRad, GE Healthcare, Waukesha, WI, USA) and an expanded set of exam protocols, including 21 distinct acquisition techniques for imaging a variety of anatomical regions (head and neck, thorax, spine, abdomen, and knee). Organ dose coefficients (hn ) were estimated by normalizing organ dose estimates to air kerma at 70cm (X70cm ) from the source in the scout view. The corresponding coefficients for projection radiography were approximated using organ doses estimated for the scout view. The organ dose coefficients were further used to compute air-kerma-normalized patient-specific effective dose coefficients (Kn ) for all combinations of patients and protocols, and a comparative analysis examining the variation of radiation burden across sex, age, and exam protocols in DT, and with projection radiography was performed. The database of organ dose coefficients (hn ) containing 294 distinct combinations of patients and exam protocols was developed and made publicly available. The values of Kn were observed to produce estimates of effective dose in agreement with prior studies and consistent with magnitudes expected for pediatric and adult patients across the different exam protocols, with head and neck regions exhibiting relatively lower and thorax and C-spine (apsc, apcs) regions relatively higher magnitudes. The ratios (r=Kn /Kn ,rad ) quantifying the differences air-kerma-normalized patient-specific effective doses between DT and projection radiography were centered around 1.0 for all exam protocols, with the exception of protocols covering the knee region (pawk, patk). This study developed a database of organ dose coefficients for a virtual population of 14 adult and pediatric XCAT patient models over a set of 21 exam protocols in DT. Using empirical measurements of air kerma in the clinic, these organ dose coefficients enable practical retrospective and prospective patient-specific radiation dosimetry. The computation of air-kerma-normalized patient-specific effective doses further enables the comparison of radiation burden to the patient populations between protocols and between imaging modalities (e.g., DT and projection radiography), as presented in this study.

A real-time data assimilative forecasting system for animal tracking.

Monitoring technologies now provide real‐time animal location information, which opens up the possibility of developing forecasting systems to fuse these data with movement models to predict future trajectories. State‐space modeling approaches are well established for retrospective location estimation and behavioral inference through state and parameter estimation. Here we use a state‐space model within a comprehensive data assimilative framework for probabilistic animal movement forecasting. Real‐time location information is combined with stochastic movement model predictions to provide forecasts of future animal locations and trajectories, as well as estimates of key behavioral parameters. Implementation uses ensemble‐based sequential Monte Carlo methods (a particle filter). We first apply the framework to an idealized case using a nondimensional animal movement model based on a continuous‐time random walk process. A set of numerical forecasting experiments demonstrates the workflow and key features, such as the online estimation of behavioral parameters using state augmentation, the use of potential functions for habitat preference, and the role of observation error and sampling frequency on forecast skill. For a realistic demonstration, we adapt the framework to short‐term forecasting of the endangered southern resident killer whale (SRKW) in the Salish Sea using visual sighting information wherein the potential function reflects historical habitat utilization of SRKW. We successfully estimate whale locations up to 2.5 h in advance with a moderate prediction error (<5 km), providing reasonable lead‐in time to mitigate vessel–whale interactions. It is argued that this forecasting framework can be used to synthesize diverse data types and improve animal movement models and behavioral understanding and has the potential to lead to important advances in movement ecology.

Dose Variations Using an X-Ray Cabinet to Establish in vitro Dose-Response Curves for Biological Dosimetry Assays.

In biological dosimetry, dose-response curves are essential for reliable retrospective dose estimation of individual exposure in case of a radiation accident. Therefore, blood samples are irradiated in vitro and evaluated based on the applied assay. Accurate physical dosimetry of the irradiation performance is a critical part of the experimental procedure and is influenced by the experimental setup, especially when X-ray cabinets are used. The aim of this study was to investigate variations and pitfalls associated with the experimental setups used to establish calibration curves in biological dosimetry with X-ray cabinets. In this study, irradiation was performed with an X-ray source (195 kV, 10 mA, 0.5 mm Cu filter, dose rate 0.52 Gy/min, 1st and 2nd half-value layer = 1.01 and 1.76 mm Cu, respectively, average energy 86.9 keV). Blood collection tubes were irradiated with a dose of 1 Gy in vertical or horizontal orientation in the center of the beam area with or without usage of an additional fan heater. To evaluate the influence of the setups, physical dose measurements using thermoluminescence dosimeters, electron paramagnetic resonance dosimetry and ionization chamber as well as biological effects, quantified by dicentric chromosomes and micronuclei, were compared. This study revealed that the orientation of the sample tubes (vertical vs. horizontal) had a significant effect on the radiation dose with a variation of −41% up to +49% and contributed to a dose gradient of up to 870 mGy inside the vertical tubes due to the size of the sample tubes and the associated differences in the distance to the focal point of the tube. The number of dicentric chromosomes and micronuclei differed by ~30% between both orientations. An additional fan heater had no consistent impact. Therefore, dosimetric monitoring of experimental irradiation setups is mandatory prior to the establishment of calibration curves in biological dosimetry. Careful consideration of the experimental setup in collaboration with physicists is required to ensure traceability and reproducibility of irradiation conditions, to correlate the radiation dose and the number of aberrations correctly and to avoid systematical bias influencing the dose estimation in the frame of biological dosimetry.

How do China’s lockdown and post-COVID-19 stimuli impact carbon emissions and economic output? Retrospective estimates and prospective trajectories

SummaryThis paper develops a multi-sector and multi-factor structural gravity model that allows an analytical and quantitative decomposition of the emission and output changes into composition and technique effects. We find that the negative production shock of China’s containment policy propagates globally via supply chains, with the carbon-intensive sectors experiencing the greatest carbon emission shocks. We further reveal that China’s current stimulus package in 2021–2025 is consistent with China’s emission intensity-reduction goals for 2025, but further efforts are required to meet China’s carbon emissions-peaking target in 2030 and Cancun 2°C goal. Short-term changes in carbon emissions resulting from lockdowns and initial fiscal stimuli in “economic rescue” period have minor long-term effects, whereas the transitional direction of future fiscal stimulus exerts more predominant impact on long-term carbon emissions. The efficiency improvement effects are more important than the sectoral structure effects of the fiscal stimulus in achieving greener economic growth.

Self-navigated prospective motion correction for 3D-EPI acquisition.

Although 3D EPI is more susceptible to motion artifacts than 2D EPI, it presents some benefits for functional MRI, including the absence of spin-history artifacts, greater potential for parallel imaging acceleration, and better functional sensitivity in high-resolution imaging. Here we present a self-navigated 3D-EPI sequence suitable for prospective motion-corrected functional MRI without additional hardware or pulses. For each volume acquisition, the first 24 of the 52 partitions being acquired are accumulated to a new feedback block that was added to the image reconstruction pipeline. After zero-filling the remaining partitions, the feedback block constructs a volumetric self-navigator (vSNav), co-registers it to the reference vSNav acquired during the first volume acquisition, and sends motion estimates to the sequence. The sequence then updates its FOV and acquires subsequent partitions with the adjusted FOV, until the next update is received. The sequence was validated without and with intentional motion in phantom and in vivo on a 3T Skyra. For phantom scans, the FOV was updated 0.704 s after acquisition of the vSNav partitions, and for in vivo scans after 0.768 s. Both phantom and in vivo data demonstrated stable motion estimates in the absence of motion. For in vivo acquisitions, prospective head-pose estimates using the vSNav's and retrospective estimates with FLIRT (FMRIB's Linear Image Registration Tool) agreed to within 0.23 mm (< 10% of the slice thickness) and 0.14° in all directions. Depending when motion occurs during a volume acquisition, the proposed method fully corrects the FOV and recovers image quality within one volume acquisition.

A Short Performance Anxiety Scale for Musicians.

Given the prevalence of debilitating anxiety associated with music performance, there is a need for rapid, pinpointed assessment of the extent to which an individual experiences music performance anxiety (MPA). A short, five item scale, the Mazzarolo Music Performance Anxiety Scale (M-MPAS), was developed to capture retrospective self-reported estimates of the frequency, intensity and aversion tendency associated with performing music. 102 musicians completed the scale, as well as an established MPA inventory. The M-MPAS was found to be internally reliable (Cronbach’s alpha = 0.894) with all items being statistically relevant to the overall scale. Furthermore, the M-MPAS was correlated with the relevant factors of an established MPA measure (r = 0.791), suggesting that the new scale exhibited good construct validity. M-MPAS is easy to score, with a scale range of 0–30. A score of 11 or above is suggested as the range in which a diagnosis of potential high MPA can be made, but more research into this and the psychometric robustness of the scale is called for. Nevertheless, the reliability and validity demonstrated in the present study, along with the brevity of the M-MPAS suggest that the newly proposed scale may offer considerable triaging benefits for pinpointed assessment of the extent to which an individual experiences MPA.

Trial-based Cost-effectiveness Analysis of an Immediate Postoperative Mitomycin C Instillation in Patients with Non–muscle-invasive Bladder Cancer

BackgroundBladder cancer imposes a significant public health burden on the European Union. There is a need for cost-effective treatment and follow-up regimens. ObjectiveTo assess the cost-effectiveness of immediate mitomycin C (MMC) instillation within 1 d after surgery compared to delayed MMC instillation within 2 wk after surgery with further adjuvant treatment, depending on the patient’s risk group. Design, setting, and participantsThis economic evaluation was based on a randomized controlled trial among 2243 Dutch patients with non-muscle-invasive bladder cancer (NMIBC) patients from a health care perspective over a 3-yr time period. Outcome measurements and statistical analysisThe treatment effect was measured as time to recurrence and recurrence-free survival. Missing effect data were imputed with multiple imputation. Health care utilization and related costs were estimated on the basis of treatment protocols for NMIBC patients in the Netherlands. Statistical uncertainty was estimated using bootstrapping and is graphically presented using cost-effectiveness planes and cost-effectiveness acceptability curves. Results and limitationsTime to recurrence was significantly longer for immediate MMC instillation (27.31 mo) than for delayed MMC instillation (24.97 mo), with an adjusted mean difference of 2.21 mo (95% confidence interval [CI] 1.58–2.84). The proportion of patients with recurrence-free survival was significantly higher after immediate MMC instillation (0.65) than after delayed MMC instillation (0.56), with an adjusted mean difference of 0.08 (95% CI 0.06–0.11). Total mean health care costs per patient were significantly lower for immediate MMC instillation (€22959) than for delayed MMC instillation (€24624), with an adjusted mean difference of −€1350 (95% CI −€1799 to −€900). The study is limited by the retrospective estimation of costs. ConclusionsThis trial-based cost-effectiveness analysis shows that from a health care perspective, immediate MMC instillation is more effective and less expensive compared to delayed MMC instillation. Patient summaryWe assessed the cost-effectiveness of immediate bladder instillation of mitomycin C after surgery to reduce the risk of recurrence after removal of the bladder tumor as compared to delayed instillation in a large Dutch population of patients with non–muscle-invasive bladder cancer. We found that immediate instillation was more effective and less expensive than delayed instillation. We conclude that immediate mitomycin C instillation is a cost-effective treatment for non–muscle-invasive bladder cancer.

A method for small-area estimation of population mortality in settings affected by crises

BackgroundPopulations affected by crises (armed conflict, food insecurity, natural disasters) are poorly covered by demographic surveillance. As such, crisis-wide estimation of population mortality is extremely challenging, resulting in a lack of evidence to inform humanitarian response and conflict resolution.MethodsWe describe here a ‘small-area estimation’ method to circumvent these data gaps and quantify both total and excess (i.e. crisis-attributable) death rates and tolls, both overall and for granular geographic (e.g. district) and time (e.g. month) strata. The method is based on analysis of data previously collected by national and humanitarian actors, including ground survey observations of mortality, displacement-adjusted population denominators and datasets of variables that may predict the death rate. We describe the six sequential steps required for the method’s implementation and illustrate its recent application in Somalia, South Sudan and northeast Nigeria, based on a generic set of analysis scripts.ResultsDescriptive analysis of ground survey data reveals informative patterns, e.g. concerning the contribution of injuries to overall mortality, or household net migration. Despite some data sparsity, for each crisis that we have applied the method to thus far, available predictor data allow the specification of reasonably predictive mixed effects models of crude and under 5 years death rate, validated using cross-validation. Assumptions about values of the predictors in the absence of a crisis provide counterfactual and excess mortality estimates.ConclusionsThe method enables retrospective estimation of crisis-attributable mortality with considerable geographic and period stratification, and can therefore contribute to better understanding and historical memorialisation of the public health effects of crises. We discuss key limitations and areas for further development.

Pets and a Pandemic: An Exploratory Mixed Method Analysis of How the COVID-19 Pandemic Affected Dogs, Cats, and Owners

Abstract The purpose of the present study was to explore how the COVID-19 pandemic impacted dogs, cats, and interactions between these pets and their owners. Participants included 102 dog and/or cat owners residing primarily in the United States. Participants completed an online questionnaire between late April to late May 2020. Analyses included t -tests comparing retrospective estimates of pre-pandemic functioning and functioning during the pandemic, and qualitative thematic analysis was used to analyze participants’ responses to three open-ended questions. Quantitative analyses found that pets and owners spent significantly more time together, with increases in physical contact between owners and pets, exercise with dogs, and engagement in dog-related activities. No significant changes were found regarding owners’ percentage of pet care responsibility, attachment to their pets, pleasantness derived from pet-related activities, or upset feelings toward their pets when comparing pre-pandemic and during pandemic scores. Five themes arose from the thematic analysis: Social/Attachment (i.e., changes to owner-pet, pet-pet, and owner-owner relationships), Physical (i.e., increases in owners’ physical contact and proximity with pets, physical benefits to pets and owners), Psychological (i.e., changes in owners’ and pets’ behavior and emotionality), Safety/Well-Being (i.e., health concerns regarding owners and pets), and Responsibilities/Routines (i.e., changes in owners’ and pets’ daily routines, changes in owners’ responsibilities and productivity). These findings provide valuable insight into how dogs, cats, owners, and interactions between these pets and owners were affected by the COVID-19 pandemic as well as considerations for animal welfare in the wake of the pandemic. Additionally, the study generated many hypotheses pertaining to how and why these changes occurred, providing a foundation for additional research in this area.

The ways to improve the results of the pylorus-preserving gastric resection

Objective. To enhance the results efficacy of the pylorus-preserving gastric resection.&#x0D; Materials and methods. Retrospective estimation of results of the pylorus-preserving gastric resection was conducted while various operative procedures application in 64 patients, ageing 34-75 yrs old. The average age of the patients was (52.5 ± 6.2) yrs old.&#x0D; Results. The patients were divided into two Groups. In Group I (n = 36) the pylorus-preserving gastric resection was performed in accordance to conventional procedure - without identification of infrapyloric arteries and veins as well as vagal branches, innervating pyloric sphincter. In Group II (n = 28) accurate dissection was performed, using special optic technique for preservation of all vascular structures, going to pylorus.&#x0D; Conclusion. The pylorus-preserving gastric resection owes several advantages, because it prevents the postgastrectomy syndrome development.

Patient, family and productivity costs of end-stage renal disease in the Netherlands; exposing non-healthcare related costs

BackgroundHealthcare costs related to ESRD are well-described, but broader societal costs of ESRD are less known. This study aimed to estimate patient and family costs, including informal care costs and out-of-pocket costs, and costs due to productivity loss related to ESRD, for patients receiving dialysis and living with a kidney transplant, using a bottom-up approach.MethodsA total of 655 patients were asked to complete a digital questionnaire consisting of two standardised instruments (iMCQ and iPCQ) from November 2016 through January 2017. We applied a retrospective bottom-up cost estimation by combining data from the questionnaire with unit prices from the Dutch costing manual.ResultsOur study sample consisted of 230 patients, of which 165 were kidney transplant recipients and 65 received dialysis. The total annual non-healthcare related costs were estimated at €8284 (SD: €14,266) for transplant recipients and €23,488 (SD: €39,434) for dialysis patients. Costs due to productivity loss contributed most to the total non-healthcare costs (66% for transplant recipients and 65% for dialysis patients), followed by informal care costs (26% resp. 29%) and out-of-pocket costs, such as medication and travel expenses (8% resp. 6%).ConclusionBy exposing patient, family and productivity costs, our study revealed that dialysis and transplantation are not only costly within the healthcare system, but also incur high non-healthcare costs (18–23% resp. 35% of the total societal costs). It is important to reveal these types of non-healthcare costs in order to understand the full burden of ESRD for society and the potential impact of new therapies.

The impact of cognitive load on prospective and retrospective time estimates at long durations: An investigation using a visual and memory search paradigm.

As human beings, we are bound by time. It is essential for daily functioning, and yet our ability to keep track of time is influenced by a myriad of factors (Block & Zakay, 1997, Psychonomic Bulletin & Review, 4[2], 184-197). First and foremost, time estimation has been found to depend on whether participants estimate the time prospectively or retrospectively (Hicks et al., 1976, The American Journal of Psychology, 89[4], 719-730). However, there is a paucity of research investigating differences between these two conditions in tasks over two minutes (Tobin et al., 2010, PLOS ONE, 5[2], Article e9271). Moreover, estimates have also been shown to be influenced by cognitive load. We thus investigated participants' ability to keep track of time during a visual and memory search task and manipulated its difficulty and duration. Two hundred and ninety-two participants performed the task for 8 or 58 minutes. Participants in the prospective time judgment condition were forewarned of an impending time estimate, whereas participants in the retrospective condition were not. Cognitive load was manipulated and assessed by altering the task's difficulty. The results revealed a higher overestimation of time in the prospective condition compared with the retrospective condition. However, this was found in the 8-minute task only. Overall, participants significantly overestimated the duration of the 8-minute task and underestimated the 58-minute task. Finally, cognitive load had no effect on participants' time estimates. Thus, the well-known cross-over interaction between cognitive load and estimation paradigm (Block et al., 2010, Acta Psychologica, 134[3], 330-343) did not extend to a longer duration in this experiment.

Distinguishing between Fatigue and Fatigability in Multiple Sclerosis

Fatigue is one of the most common debilitating symptoms reported by persons with multiple sclerosis (MS). It reflects feelings of tiredness, lack of energy, low motivation, and difficulty in concentrating. It can be measured at a specific instant in time as a perception that arises from interoceptive networks involved in the regulation of homeostasis. Such ratings indicate the state level of fatigue and likely reflect an inability to correct deviations from a balanced homeostatic state. In contrast, the trait level of fatigue is quantified in terms of work capacity (fatigability), which can be either estimated (perceived fatigability) or measured (objective fatigability). Clinically, fatigue is most often quantified with questionnaires that require respondents to estimate their past capacity to perform several cognitive, physical, and psychosocial tasks. These retrospective estimates provide a measure of perceived fatigability. In contrast, the change in an outcome variable during the actual performance of a task provides an objective measure of fatigability. Perceived and objective fatigability do not assess the same underlying construct. Persons with MS who report elevated trait levels of fatigue exhibit deficits in interoceptive networks (insula and dorsal anterior cingulate cortex), including increased functional connectivity during challenging tasks. The state and trait levels of fatigue reported by an individual can be modulated by reward and pain pathways. Understanding the distinction between fatigue and fatigability is critical for the development of effective strategies to reduce the burden of the symptom for individuals with MS.

The ages of zone of proximal development for retrospective time assessment and anticipation of time event

From childhood to adulthood, an individual’s ability to estimate and anticipate the timing of events changes continuously. This study investigated the ability of 287 children aged 5–14 years to estimate the duration of prior events and anticipate the timing of future events for determination of the age at which children improve their timing skills. The Luria neuropsychological assessment battery and the Wechsler Intelligence Scale for Children (WISC-IV) were applied to find correlations between timing skills and the development of cognitive functions. The findings demonstrated that retrospective estimation of duration has a zone of proximal development in children between the ages of six to eight; in these children, the accuracy of time assessment significantly improved after receiving the prompt. However, improvement in time estimation was significantly lower in those children who achieved lower results in the attention and memory tests and demonstrated reduced spatial and verbal reasoning skills. The zone of proximal development for the ability to anticipate the timing of future events was demonstrated in children between the ages of nine to eleven years. The improvement of time anticipation was negatively correlated with the number of mistakes made during the dynamic praxis test.

A matter of time: how does emotion influence temporal aspects of remembering?

ABSTRACT Spatiotemporal context is an intrinsic aspect of episodic memory. Although a large literature has demonstrated that emotion enhances episodic memory, less research has considered whether and how emotion affects memory for the timing of an experience, despite theoretical and practical importance. In this review, we bridge three heavily researched cognitive domains – memory, emotion, and time – by discussing findings from a burgeoning literature on their intersection. We identify and review two broad ways in which memory for time has been conceptualised in the emotional memory literature, namely (1) memory for relative aspects of event timing (“when” an event detail occurred), which includes studies of temporal-order and source memory; and (2) memory for the time that elapsed during an event (“how long”), which includes studies of retrospective duration estimation. Emerging trends demonstrate that although temporal-order memory can be impaired or enhanced by emotion depending on study demands, temporal source memory, instead, is usually enhanced. Studies of duration memory show that the remembered duration of negative experiences is dilated, but it is less clear how duration memory is affected for positive events. These findings are considered under the lens of broader emotional memory literature theories, and directions for future research are proposed.

Prospective and Retrospective Verbal Time Estimationin Children with ADHD.

There is increasing evidence that timing deficits represent a primary cause of key symptoms in ADHD. However, results in experiments on timing may vary with different methods of assessing timing competencies. The present study directly compared two central paradigms, namely, prospective and retrospective time estimation in children with (n = 30) and without (n = 29) ADHD. In both conditions, durations were estimated considerably longer by children with ADHD. Children with ADHD significantly overestimated the real duration of the task compared to children without ADHD in the retrospective but not in the prospective condition. In general, prospective estimates were more accurate than retrospective ones. The findings corroborate the essential role that timing deficits and a faster internal clock play in ADHD. Furthermore, the results demonstrate the importance of careful differentiation between prospective and retrospective time estimation.

Transmitting Desire: An Experiment on a Novel Measure of Gun Desirability in a Pandemic

The COVID-19 pandemic and protests have marked an unprecedented increase in U.S. gun sales. But America has long been an outlier; the stockpile of private guns climbed to almost 300 million in 2017. Scholars use multiple theories to explain why gun sales have tripled since the early 2000s, and why disruptions like the pandemic might cause gun sales. However, scholars have difficulty evaluating these theories with existing retrospective estimates of gun sales and other measures, limiting their ability to test theory or suggest policy changes. This study uses the known increase in gun sales during the COVID-19 pandemic to introduce and experimentally validate a novel measure of gun desirability. With a sample of 4,240 U.S. residents, this project demonstrates that gun desirability is a valid measure of inclination toward gun ownership, and that a pandemic video vignette significantly increases overall gun desirability relative to a control video vignette. These results serve as a foundation for future scholarship to (1) discern gun desirability trends, (2) evaluate theorized causes of gun desirability, and (3) consider interventions on those conditions that arouse desire for gun ownership.

Scout accelerated motion estimation and reduction (SAMER).

To demonstrate a navigator/tracking-free retrospective motion estimation technique that facilitates clinically acceptable reconstruction time. Scout accelerated motion estimation and reduction (SAMER) uses a single 3-5 s, low-resolution scout scan and a novel sequence reordering to independently determine motion states by minimizing the data-consistency error in a SENSE plus motion forward model. This eliminates time-consuming alternating optimization as no updates to the imaging volume are required during the motion estimation. The SAMER approach was assessed quantitatively through extensive simulation and was evaluated in vivo across multiple motion scenarios and clinical imaging contrasts. Finally, SAMER was synergistically combined with advanced encoding (Wave-CAIPI) to facilitate rapid motion-free imaging. The highly accelerated scout provided sufficient information to achieve accurate motion trajectory estimation (accuracy ~0.2 mm or degrees). The novel sequence reordering improved the stability of the motion parameter estimation and image reconstruction while preserving the clinical imaging contrast. Clinically acceptable computation times for the motion estimation (~4 s/shot) are demonstrated through a fully separable (non-alternating) motion search across the shots. Substantial artifact reduction was demonstrated in vivo as well as corresponding improvement in the quantitative error metric. Finally, the extension of SAMER to Wave-encoding enabled rapid high-quality imaging at up to R = 9-fold acceleration. SAMER significantly improved the computational scalability for retrospective motion estimation and correction.

Manifold-based respiratory phase estimation enables motion and distortion correction of free-breathing cardiac diffusion tensor MRI.

For in vivo cardiac DTI, breathing motion and B0 field inhomogeneities produce misalignment and geometric distortion in diffusion-weighted (DW) images acquired with conventional single-shot EPI. We propose using a dimensionality reduction method to retrospectively estimate the respiratory phase of DW images and facilitate both distortion correction (DisCo) and motion compensation. Free-breathing electrocardiogram-triggered whole left-ventricular cardiac DTI using a second-order motion-compensated spin echo EPI sequence and alternating directionality of phase encoding blips was performed on 11 healthy volunteers. The respiratory phase of each DW image was estimated after projecting the DW images into a 2D space with Laplacian eigenmaps. DisCo and motion compensation were applied to the respiratory sorted DW images. The results were compared against conventional breath-held T2 half-Fourier single shot turbo spin echo. Cardiac DTI parameters including fractional anisotropy, mean diffusivity, and helix angle transmurality were compared with and without DisCo. The left-ventricular geometries after DisCo and motion compensation resulted in significantly improved alignment of DW images with T2 reference. DisCo reduced the distance between the left-ventricular contours by 13.2% ± 19.2%, P < .05 (2.0 ± 0.4 for DisCo and 2.4 ± 0.5 mm for uncorrected). DisCo DTI parameter maps yielded no significant differences (mean diffusivity: 1.55 ± 0.13 × 10-3 mm2 /s and 1.53 ± 0.13 × 10-3 mm2 /s, P = .09; fractional anisotropy: 0.375 ± 0.041 and 0.379 ± 0.045, P = .11; helix angle transmurality: 1.00% ± 0.10°/% and 0.99% ± 0.12°/%, P = .44), although the orientation of individual tensors differed. Retrospective respiratory phase estimation with LE-based DisCo and motion compensation in free-breathing cardiac DTI resulting in significantly reduced geometric distortion and improved alignment within and across slices.

Pulmonary Pathology Diagnoses in the US Military During the Global War on Terrorism.

To document and compare prevalences of pulmonary pathology diagnoses among US Service members deployed during the Global War on Terrorism and non-deployed US service members. Difficulties establishing associations between deployment-related exposures and pulmonary pathology reported among US military service members deployed during the Global War on Terrorism include retrospective estimations of exposures, documenting medical outcomes and lack of comparison groups. Pulmonary diagnoses reported between 2002 and 2015 were identified from the records of the former Armed Forces Institute of Pathology and The Joint Pathology Center. Military service and deployment were confirmed by the Defense Manpower Data Center. Diagnoses were reviewed and coded due to variations in diagnostic terminology. Propensity matching and adjusted binomial modeling were applied to comparisons between the deployed and non-deployed to address possible confounding variables. 404 deployed and 2006 non-deployed service members were included. Demographic differences and the date of pathology report complicate unadjusted comparisons. The deployed had no significant increased prevalence of neoplastic conditions. Propensity matching identified a significant increased prevalence of organizing pneumonia in the non-deployed. An adjusted binomial model identified significant increased prevalences of small airways disease, constrictive bronchiolitis and hypersensitivity pneumonitis in the deployed. Both diagnoses were strongly associated with the date of pathology report. Small airways disease, constrictive bronchiolitis comprised 5% of deployed surgical lung biopsy diagnoses. This is the largest study of post-deployment pulmonary pathology diagnoses to date, and contains a comparison group. It provides context for studies of pulmonary outcomes among the deployed.