Sexual Dimorphism of Radiomic Features in the Brain: An Exploratory Study Using 700 µm MP2RAGE MRI at 7 T.

OBJECTIVES: The aim of this study was to determine whether MRI radiomic features of key cerebral structures differ between women and men, and whether detection of such differences depends on the image resolution. MATERIALS AND METHODS: Ultrahigh resolution (UHR) 3D MP2RAGE (magnetization-prepared 2 rapid acquisition gradient echo) T1-weighted MR images (voxel size, 0.7 × 0.7 × 0.7 mm3) of the brain of 30 subjects (18 women and 12 men; mean age, 39.0 ± 14.8 years) without abnormal findings on MRI were retrospectively included. MRI was performed on a whole-body 7 T MR system. A convolutional neural network was used to segment the following structures: frontal cortex, frontal white matter, thalamus, putamen, globus pallidus, caudate nucleus, and corpus callosum. Eighty-seven radiomic features were extracted respectively: gray-level histogram (n = 18), co-occurrence matrix (n = 24), run-length matrix (n = 16), size-zone matrix (n = 16), and dependence matrix (n = 13). Feature extraction was performed at UHR and, additionally, also after resampling to 1.4 × 1.4 × 1.4 mm3 voxel size (standard clinical resolution). Principal components (PCs) of radiomic features were calculated, and independent samples t tests with Cohen d as effect size measure were used to assess differences in PCs between women and men for the different cerebral structures. RESULTS: At UHR, at least a single PC differed significantly between women and men in 6/7 cerebral structures: frontal cortex (d = -0.79, P = 0.042 and d = -1.01, P = 0.010), frontal white matter (d = -0.81, P = 0.039), thalamus (d = 1.43, P < 0.001), globus pallidus (d = 0.92, P = 0.020), caudate nucleus (d = -0.83, P = 0.039), and corpus callosum (d = -0.97, P = 0.039). At standard clinical resolution, only a single PC extracted from the corpus callosum differed between sexes (d = 1.05, P = 0.009). CONCLUSIONS: Nonnegligible differences in radiomic features of several key structures of the brain exist between women and men, and need to be accounted for. Very high spatial resolution may be required to uncover and further investigate the sexual dimorphism of brain structures on MRI.

Predicting Unplanned Readmissions to the Intensive Care Unit in the Trauma Population.

Background: Unplanned readmission to intensive care units (UR-ICU) in trauma is associated with increased hospital length of stay and significant morbidity and mortality. We identify independent predictors of UR-ICU and construct a nomogram to estimate readmission probability. Materials and Methods: We performed an IRB-approved retrospective case-control study at a Level I trauma center between January 2019 and December 2021. Patients with UR-ICU (n = 175) were matched with patients who were not readmitted (NR-ICU) (n = 175). Univariate and multivariable binary linear regressionanalyses were performed (SPSS Version 28, IBM Corp), and a nomogram was created (Stata 18.0, StataCorp LLC). Results: Demographics, comorbidities, and injury- and hospital course-related factors were examined as potential prognostic indicators of UR-ICU. The mortality rate of UR-ICU was 22.29% vs 6.29% for NR-ICU (P < .001). Binary linear regression identified seven independent predictors that contributed to UR-ICU: shock (P < .001) or intracranial surgery (P = .015) during ICU admission, low hematocrit (P = .001) or sedation administration in the 24 hours before ICU discharge (P < .001), active infection treatment (P = .192) or leukocytosis on ICU discharge (P = .01), and chronic obstructive pulmonary disease (COPD) (P = .002). A nomogram was generated to estimate the probability of UR-ICU and guide decisions on ICU discharge appropriateness. Discussion: In trauma, UR-ICU is often accompanied by poor outcomes and death. Shock, intracranial surgery, anemia, sedative administration, ongoing infection treatment, leukocytosis, and COPD are significant risk factors for UR-ICU. A predictive nomogram may help better assess readiness for ICU discharge.

Gender Disparities in Complications, Costs, and Mortality After Emergency Gastrointestinal Surgery in Kenya.

INTRODUCTION: Little is known about the impact of gender on emergency surgery within Kenya. Therefore, we aimed to investigate the association of gender on outcomes of postoperative complications, health care costs, and mortality. METHODS: We evaluated an established cohort of patients undergoing emergency gastrointestinal surgery in rural Kenya between January 1st, 2016 and June 30th, 2019. Utilizing logistic regression, we examined the association between self-reported patient gender and the outcomes of postoperative complications and mortality. A generalized linear model was created for total hospital costs, inflation-adjusted in international dollars purchasing power parity, to examine the impact of gender. Confounding factors were controlled by Africa Surgical Outcomes Study Surgical Risk Score. RESULTS: Among 484 patients reviewed, 149 (30.8%) were women. 165 (34.1%) patients developed complications, with women experiencing more than men (40.9% versus 31.0%; P = 0.03) and longer hospital stays (median 6 days (4-9) versus 5 (4-7); P = 0.02). After controlling for Africa Surgical Outcomes Study Surgical Risk Score, odds of developing complications for women were 1.67 (95% confidence interval: 1.09-2.55; P = 0.019) times higher than men, and the odds of death were 2.38 (95% confidence interval: 1.12-5.09; P = 0.025) times greater for women than men, despite similar failure-to-rescue rates and intensive care unit utilization. Total hospital costs were increased for women by 531 international dollars purchasing power parity (117-946; P = 0.012) when compared to men, attributed to longer lengths of stay. CONCLUSIONS: These findings demonstrate that a discrepancy exists between men and women undergoing emergency gastrointestinal surgery in our setting. Further exploration of the underlying causes of this inequity is necessary for quality improvement for women in rural Kenya.

Trainee autonomy and surgical outcomes after emergency gastrointestinal surgery.

BACKGROUND: Operative meaningful trainee autonomy is an essential component of surgical training. Reduced trainee autonomy is frequently attributed to patient safety concerns, but this has not been examined within Kenya. We aimed to assess whether meaningful trainee autonomy was associated with a change in patient outcomes. METHODS: We investigated whether meaningful trainee autonomy was associated with a change in severe postoperative complications and all-cause in-hospital mortality in a previously described cohort undergoing emergency gastrointestinal operations. Each operation was reviewed to determine the presence of meaningful autonomy, defined as "supervision only" from faculty. Comparisons were made between faculty-led cases and cases with meaningful trainee autonomy. Multilevel logistic regression models were created for the outcomes of mortality and complications with the exposure of meaningful trainee autonomy, accounting for fixed effects of the Africa Surgical Outcomes Study Risk Score and random effects of discharge diagnoses. RESULTS: After excluding laparoscopy (N = 28) and missing data (N = 3), 451 operations were studied, and 343 (76.1%) had meaningful trainee autonomy. Faculty were more involved in operations with older age, cancer, prior complications, and higher risk scores. On unadjusted analysis, meaningful trainee autonomy was associated with mortality odds of 0.32 (95% confidence interval: 0.17-0.58) compared with faculty-led operations. Similarly, the odds of developing complications were 0.52 (95% confidence interval: 0.32-0.84) with meaningful trainee autonomy compared with faculty-led operations. When adjusting for Africa Surgical Outcomes Study Score and clustering discharge diagnoses, the odds of mortality (odds ratio 0.58; 95% confidence interval: 0.27-1.2) and complication (odds ratio 0.83; 95% confidence interval: 0.47-1.5) were not significant. CONCLUSION: Our findings support that increasing trainee autonomy does not change patient outcomes in selected emergency gastrointestinal operations. Further, trainees and faculty appropriately discern patients at higher risk of complications and mortality, and the selective granting of trainee autonomy does not affect patient safety.

"Early Post-operative Mechanical Small Bowel Obstruction Induced by Unidirectional Barbed Suture".

Unidirectional barbed suture is widely used in minimally invasive procedures as a secure alternative to traditional knot tying. In this report, a 44-year-old female with endometriosis and complex gynecological history presented to our emergency department 2 weeks after undergoing minimally invasive gynecological surgery. She had persistent, progressive signs and symptoms typical of intermittent partial small bowel obstruction. On her third admission within 7 days for this pattern, laparoscopic abdominal exploration was performed. She was noted to have small bowel obstruction secondary to ingrowth of the tail of a unidirectional barbed suture kinking the terminal ileum during this procedure. We discuss small bowel obstruction due to unidirectional barbed suture and make recommendations on how to avoid this complication.

Implementation of a Surgical Critical Care Service Reduces Failure to Rescue in Emergency Gastrointestinal Surgery in Rural Kenya.

OBJECTIVE: We aimed to evaluate the implementation of a dedicated Surgical critical care service (SCCS) on failure to rescue (FTR) rates in rural Kenya. SUMMARY BACKGROUND DATA: FTR adversely impacts perioperative outcomes. In the resource-limited contexts of low- and middle-income countries, emergency gastrointestinal surgery carries high morbidity and mortality rates. Quality improvement initiatives that decrease FTR rates are essential for improving perioperative care. METHODS: All patients who underwent emergency gastrointestinal surgery between January 2016 and June 2019 at Tenwek Hospital in rural Kenya were reviewed. Critical care capabilities were constant throughout the study period. A supervised surgical resident was dedicated to the daily care of critically ill surgical patients beginning in January 2018. The impact of the SCCS initiation on the outcome of FTR was evaluated, controlling for patient complexity via the African Surgical Outcomes Study Surgical Risk Score. RESULTS: A total of 484 patients were identified, consisting of 278 without and 206 with an active SCCS. A total of 165 (34.1%) patients experienced postoperative complications, including 49 mortalities (10.1%) yielding an FTR rate of 29.7%. The FTR rate decreased after SCCS implementation from 36.8% (95% CI: 26.7%-47.8%) to 21.8% (95% CI: 13.2%-32.6%) ( P = 0.035) despite an increase in the average patient African Surgical Outcomes Study score from 14.5 (95% CI, 14.1-14.9) to 15.2 (95% CI, 14.7-15.7) ( P =0.03). CONCLUSIONS: The implementation of an SCCS in rural Kenya resulted in decreased rates of FTR despite an increase in patient complexity and severity of critical illness.

Mood and Anxiety Disorders and Suicidality in Patients With Newly Diagnosed Focal Epilepsy: An Analysis of a Complex Comorbidity.

BACKGROUND AND OBJECTIVES: Mood, anxiety disorders, and suicidality are more frequent in people with epilepsy than in the general population. Yet, their prevalence and the types of mood and anxiety disorders associated with suicidality at the time of the epilepsy diagnosis are not established. We sought to answer these questions in patients with newly diagnosed focal epilepsy and to assess their association with suicidal ideation and attempts. METHODS: The data were derived from the Human Epilepsy Project study. A total of 347 consecutive adults aged 18-60 years with newly diagnosed focal epilepsy were enrolled within 4 months of starting treatment. The types of mood and anxiety disorders were identified with the Mini International Neuropsychiatric Interview, whereas suicidal ideation (lifetime, current, active, and passive) and suicidal attempts (lifetime and current) were established with the Columbia Suicidality Severity Rating Scale (CSSRS). Statistical analyses included the t test, χ2 statistics, and logistic regression analyses. RESULTS: A total of 151 (43.5%) patients had a psychiatric diagnosis; 134 (38.6%) met the criteria for a mood and/or anxiety disorder, and 75 (21.6%) reported suicidal ideation with or without attempts. Mood (23.6%) and anxiety (27.4%) disorders had comparable prevalence rates, whereas both disorders occurred together in 43 patients (12.4%). Major depressive disorders (MDDs) had a slightly higher prevalence than bipolar disorders (BPDs) (9.5% vs 6.9%, respectively). Explanatory variables of suicidality included MDD, BPD, panic disorders, and agoraphobia, with BPD and panic disorders being the strongest variables, particularly for active suicidal ideation and suicidal attempts. DISCUSSION: In patients with newly diagnosed focal epilepsy, the prevalence of mood, anxiety disorders, and suicidality is higher than in the general population and comparable to those of patients with established epilepsy. Their recognition at the time of the initial epilepsy evaluation is of the essence.

The costs of complications after emergency gastrointestinal surgery in Kenya.

BACKGROUND: The financial burden of surgery is substantial worldwide. Postoperative complications increase costs in high-resource settings, but this is not well studied in other settings. Our objective was to review the financial impact of postoperative complications. METHOD: Patients undergoing emergency gastrointestinal operations at a center in Kenya were reviewed between January 2017 and June 2019. In a cost analysis, we ascertained the outcome of total hospital costs, adjusted for inflation, and converted to international dollars using purchasing power parities. Costs were analyzed for their association with a postoperative complication, defined using standardized criteria. We calculated the Africa Surgical Outcomes Study surgical risk scores and clustered for discharge diagnosis in a mixed-effects generalized linear model accounting for confounding factors related to costs and complications. RESULTS: A total of 361 individuals had cost data available. The cohort had 251 men (69.5%) and 110 women (30.5%) with a median age of 41 years (interquartile range: 29-57 years). A total of 122 (33.8%) patients experienced a postoperative complication with an overall all-cause mortality rate of 10.5%. The median total cost of hospitalization was 1,949 (interquartile range: 1,516-2,788) international dollar purchasing power parities. When controlling for patient factors and diagnoses, patients who did not develop complications had costs of 2,119 (95% confidence interval 1,898-2,340) compared to costs of 3,747 (95% confidence interval 3,327-4,167) for patients who developed a postoperative complication, leading to a 77% increase of 1,628 international dollar purchasing power parities for patients with complications. CONCLUSION: Our findings demonstrated a substantial financial burden generated by postoperative complications in patients undergoing emergency gastrointestinal operations. Reducing complications could allow cost savings, an important consideration in variable-resource settings.

Structural Neuroimaging in Adults and Adolescents With Newly Diagnosed Focal Epilepsy: The Human Epilepsy Project.

BACKGROUND AND OBJECTIVES: Identification of an epileptogenic lesion on structural neuroimaging in individuals with focal epilepsy is important for management and treatment planning. The objective of this study was to determine the frequency of MRI-identified potentially epileptogenic structural abnormalities in a large multicenter study of adolescent and adult patients with newly diagnosed focal epilepsy. METHODS: Patients with a new diagnosis of focal epilepsy enrolled in the Human Epilepsy Project observational cohort study underwent 3-Tesla (3T) brain MRI using a standardized protocol. Imaging findings were classified as normal, abnormal, or incidental. Abnormal findings were classified as focal or diffuse, and as likely epilepsy-related or of unknown relationship to epilepsy. Fisher exact tests were performed to determine whether abnormal imaging or abnormality type was associated with clinical characteristics. RESULTS: 418 participants were enrolled. 218 participants (59.3%) had no abnormalities detected, 149 (35.6%) had abnormal imaging, and 21 (5.0%) had incidental findings. 78 participants (18.7%) had abnormalities that were considered epilepsy-related and 71 (17.0%) had abnormalities of unknown relationship to epilepsy. Older participants were more likely to have imaging abnormalities, while participants with focal and epilepsy-related imaging abnormalities were younger than those without these abnormalities. 131 participants (31.3%) had a family history of epilepsy. Epilepsy-related abnormalities were not associated with participant sex, family history of epilepsy, or seizure type. DISCUSSION: We found that one in five patients with newly diagnosed focal epilepsy has an MRI finding that is likely causative and may alter treatment options. An additional one in five patients has abnormalities of unknown significance. This information is important for patient counseling, prognostication, and management.

A Semistructured Interview for Surgical Residency Targeting Nontechnical Skills.

OBJECTIVE: We review the development, implementation, and initial outcomes of a semistructured interview process to assess the nontechnical skills of surgical residency applicants. DESIGN: In 2018, we restructured our residency selection interview process. Through semistructured faculty interviews, we sought to evaluate candidates along seven nontechnical skills (grit, ownership, rigor, teamwork, presence, impact, and organizational alignment). We plotted each candidate's scores on a radar plot for graphical representation and calculated the plot area of each candidate. We retrospectively evaluated 3 years of data, comparing the nontechnical skill scores of matriculants into the training program to those of nonmatriculants. SETTING: Tenwek Hospital is a 361-bed tertiary teaching and referral hospital in rural western Kenya with a 5-year general surgery residency program. PARTICIPANTS: Thirty-one applicants were interviewed over 3 years. Thirteen matriculated into the program. RESULTS: Scores for grit, (4.8 vs 3.9; p = 0.0004), impact (4.2 vs 3.5; p = 0.014), ownership (4.2 vs 3.6; p = 0.01), and organizational alignment (4.3 vs 3.8; p = 0.008) were significantly higher in matriculants. CONCLUSIONS: This semistructured interview process provides a robust and beneficial mechanism for assessing applicants' nontechnical skills, which may allow for the matriculation of more well-rounded candidates into surgical residency and, ultimately, surgical practice.

In-scanner head motion and structural covariance networks.

In-scanner head motion systematically reduces estimated regional gray matter volumes obtained from structural brain MRI. Here, we investigate how head motion affects structural covariance networks that are derived from regional gray matter volumetric estimates. We acquired motion-affected and low-motion whole brain T1-weighted MRI in 29 healthy adult subjects and estimated relative regional gray matter volumes using a voxel-based morphometry approach. Structural covariance network analyses were undertaken while systematically increasing the number of included motion-affected scans. We demonstrate that the standard deviation in regional gray matter estimates increases as the number of motion-affected scans increases. This increases pairwise correlations between regions, a key determinant for construction of structural covariance networks. We further demonstrate that head motion systematically alters graph theoretic metrics derived from these networks. Finally, we present evidence that weighting correlations using image quality metrics can mitigate the effects of head motion. Our findings suggest that in-scanner head motion is a source of error that violates the assumption that structural covariance networks reflect neuroanatomical connectivity between brain regions. Results of structural covariance studies should be interpreted with caution, particularly when subject groups are likely to move their heads in the scanner.

Optimization of a Pyrimidinone Series for Selective Inhibition of Ca2+/Calmodulin-Stimulated Adenylyl Cyclase 1 Activity for the Treatment of Chronic Pain.

Adenylyl cyclase type 1 (AC1) is involved in signaling for chronic pain sensitization in the central nervous system and is an emerging target for the treatment of chronic pain. AC1 and a closely related isoform AC8 are also implicated to have roles in learning and memory signaling processes. Our team has carried out cellular screening for inhibitors of AC1 yielding a pyrazolyl-pyrimidinone scaffold with low micromolar potency against AC1 and selectivity versus AC8. Structure-activity relationship (SAR) studies led to analogues with cellular IC50 values as low as 0.25 µM, selectivity versus AC8 and other AC isoforms as well as other common neurological targets. A representative analogue displayed modest antiallodynic effects in a mouse model of inflammatory pain. This series represents the most potent and selective inhibitors of Ca2+/calmodulin-stimulated AC1 activity to date with improved drug-like physicochemical properties making them potential lead compounds for the treatment of inflammatory pain.

Design of a Novel Online, Modular, Flipped-classroom Surgical Curriculum for East, Central, and Southern Africa.

Objective: We describe a structured approach to developing a standardized curriculum for surgical trainees in East, Central, and Southern Africa (ECSA). Summary Background Data: Surgical education is essential to closing the surgical access gap in ECSA. Given its importance for surgical education, the development of a standardized curriculum was deemed necessary. Methods: We utilized Kern's 6-step approach to curriculum development to design an online, modular, flipped-classroom surgical curriculum. Steps included global and targeted needs assessments, determination of goals and objectives, the establishment of educational strategies, implementation, and evaluation. Results: Global needs assessment identified the development of a standardized curriculum as an essential next step in the growth of surgical education programs in ECSA. Targeted needs assessment of stakeholders found medical knowledge challenges, regulatory requirements, language variance, content gaps, expense and availability of resources, faculty numbers, and content delivery method to be factors to inform curriculum design. Goals emerged to increase uniformity and consistency in training, create contextually relevant material, incorporate best educational practices, reduce faculty burden, and ease content delivery and updates. Educational strategies centered on developing an online, flipped-classroom, modular curriculum emphasizing textual simplicity, multimedia components, and incorporation of active learning strategies. The implementation process involved establishing thematic topics and subtopics, the content of which was authored by regional surgeon educators and edited by content experts. Evaluation was performed by recording participation, soliciting user feedback, and evaluating scores on a certification examination. Conclusions: We present the systematic design of a large-scale, context-relevant, data-driven surgical curriculum for the ECSA region.

Comparison of outcomes using the rituximab originator MabThera with the biosimilar Truxima in patients with ANCA-associated vasculitis.

OBJECTIVES: The use of rituximab (MabThera®), an anti-CD20 monoclonal antibody, is the most significant development in the management of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) since the introduction of cytotoxic therapy in 1950. Truxima® is the first anti-CD20 biosimilar approved for the same indications, and has been available in the UK since 2017. Significant cost savings have been reported when switching to biosimilars, which could lead to greater patient access to such treatment. Therefore, it is important to know whether patients' clinical and laboratory parameters respond equally well to biosimilars as to reference medicines, tested in clinical trials. METHOD: We retrospectively reviewed the clinical outcomes and laboratory parameters in 257 consecutive patients treated with anti-CD20 depletion therapy using MabThera or Truxima, for induction and maintenance of remission, in two tertiary renal centres between 2010 and 2019. RESULTS: We demonstrated no difference between patients treated with MabThera or Truxima in rates of remission, relapse, and hospitalization with infection when used for either induction or maintenance of remission of AAV. In one hospital subgroup analysis, we showed comparable levels of hypogammaglobulinaemia, B-cell depletion, and frequency of infusion reactions, with no significant differences. CONCLUSION: The efficacy and safety of the rituximab biosimilar Truxima are not inferior to the originator MabThera in patients with AAV. Truxima represents a cheaper and safe therapeutic alternative that could increase patient access to rituximab.

Continued Relevance of Initial Temperature Measurement in Trauma Patients.

OBJECTIVES: Hypothermia occurs in 30-50% of severely injured trauma patients and is associated with multiple metabolic derangements and worsened outcomes. However, hypothermia continues to be under-diagnosed which leads to inadequate triage and treatment in trauma patients. Our study set out to determine if hypothermia is an independent predictor of mortality in trauma patients. METHODS: We retrospectively reviewed data of all trauma activation patients over a 5-year period. Data were collected on patient demographics, initial core temperature, Glasgow Coma Scale (GCS) on presentation, and injury severity score (ISS). Patients were then stratified into groups based on presenting temperature, ISS, and GCS. Outcomes compared were mortality, blood products received, and intensive care unit (ICU) length of stay. Correlations and logistic regression were used to test the hypotheses. RESULTS: Survival and temperature data were reviewed on 15,567 patients. Initial temperature was not significantly associated with ICU length of stay or blood products transfused (P = .21 and P = .08, respectively). However, odds ratio of mortality in hypothermic patients (<35°C) compared to normothermic patients (35-39°C) was 3.95 (95% CI 2.90-5.41). When controlling for GCS and ISS, separately, temperature remained an independent predictor of mortality. CONCLUSIONS: Hypothermia is an independent risk factor for mortality in trauma patients. It remains crucial to obtain accurate presenting temperatures in trauma patients in order to triage and treat hypothermia. Based on our data, obtaining core temperatures and rapidly treating hypothermia continues to be a vital part of the secondary survey of trauma patients.

Artificial intelligence for classification of temporal lobe epilepsy with ROI-level MRI data: A worldwide ENIGMA-Epilepsy study.

Artificial intelligence has recently gained popularity across different medical fields to aid in the detection of diseases based on pathology samples or medical imaging findings. Brain magnetic resonance imaging (MRI) is a key assessment tool for patients with temporal lobe epilepsy (TLE). The role of machine learning and artificial intelligence to increase detection of brain abnormalities in TLE remains inconclusive. We used support vector machine (SV) and deep learning (DL) models based on region of interest (ROI-based) structural (n = 336) and diffusion (n = 863) brain MRI data from patients with TLE with ("lesional") and without ("non-lesional") radiographic features suggestive of underlying hippocampal sclerosis from the multinational (multi-center) ENIGMA-Epilepsy consortium. Our data showed that models to identify TLE performed better or similar (68-75%) compared to models to lateralize the side of TLE (56-73%, except structural-based) based on diffusion data with the opposite pattern seen for structural data (67-75% to diagnose vs. 83% to lateralize). In other aspects, structural and diffusion-based models showed similar classification accuracies. Our classification models for patients with hippocampal sclerosis were more accurate (68-76%) than models that stratified non-lesional patients (53-62%). Overall, SV and DL models performed similarly with several instances in which SV mildly outperformed DL. We discuss the relative performance of these models with ROI-level data and the implications for future applications of machine learning and artificial intelligence in epilepsy care.

Estimation of in-scanner head pose changes during structural MRI using a convolutional neural network trained on eye tracker video.

INTRODUCTION: In-scanner head motion is a common cause of reduced image quality in neuroimaging, and causes systematic brain-wide changes in cortical thickness and volumetric estimates derived from structural MRI scans. There are few widely available methods for measuring head motion during structural MRI. Here, we train a deep learning predictive model to estimate changes in head pose using video obtained from an in-scanner eye tracker during an EPI-BOLD acquisition with participants undertaking deliberate in-scanner head movements. The predictive model was used to estimate head pose changes during structural MRI scans, and correlated with cortical thickness and subcortical volume estimates. METHODS: 21 healthy controls (age 32 ± 13 years, 11 female) were studied. Participants carried out a series of stereotyped prompted in-scanner head motions during acquisition of an EPI-BOLD sequence with simultaneous recording of eye tracker video. Motion-affected and motion-free whole brain T1-weighted MRI were also obtained. Image coregistration was used to estimate changes in head pose over the duration of the EPI-BOLD scan, and used to train a predictive model to estimate head pose changes from the video data. Model performance was quantified by assessing the coefficient of determination (R2). We evaluated the utility of our technique by assessing the relationship between video-based head pose changes during structural MRI and (i) vertex-wise cortical thickness and (ii) subcortical volume estimates. RESULTS: Video-based head pose estimates were significantly correlated with ground truth head pose changes estimated from EPI-BOLD imaging in a hold-out dataset. We observed a general brain-wide overall reduction in cortical thickness with increased head motion, with some isolated regions showing increased cortical thickness estimates with increased motion. Subcortical volumes were generally reduced in motion affected scans. CONCLUSIONS: We trained a predictive model to estimate changes in head pose during structural MRI scans using in-scanner eye tracker video. The method is independent of individual image acquisition parameters and does not require markers to be to be fixed to the patient, suggesting it may be well suited to clinical imaging and research environments. Head pose changes estimated using our approach can be used as covariates for morphometric image analyses to improve the neurobiological validity of structural imaging studies of brain development and disease.

High resolution automated labeling of the hippocampus and amygdala using a 3D convolutional neural network trained on whole brain 700 µm isotropic 7T MP2RAGE MRI.

Image labeling using convolutional neural networks (CNNs) are a template-free alternative to traditional morphometric techniques. We trained a 3D deep CNN to label the hippocampus and amygdala on whole brain 700 µm isotropic 3D MP2RAGE MRI acquired at 7T. Manual labels of the hippocampus and amygdala were used to (i) train the predictive model and (ii) evaluate performance of the model when applied to new scans. Healthy controls and individuals with epilepsy were included in our analyses. Twenty-one healthy controls and sixteen individuals with epilepsy were included in the study. We utilized the recently developed DeepMedic software to train a CNN to label the hippocampus and amygdala based on manual labels. Performance was evaluated by measuring the dice similarity coefficient (DSC) between CNN-based and manual labels. A leave-one-out cross validation scheme was used. CNN-based and manual volume estimates were compared for the left and right hippocampus and amygdala in healthy controls and epilepsy cases. The CNN-based technique successfully labeled the hippocampus and amygdala in all cases. Mean DSC = 0.88 ± 0.03 for the hippocampus and 0.8 ± 0.06 for the amygdala. CNN-based labeling was independent of epilepsy diagnosis in our sample (p = .91). CNN-based volume estimates were highly correlated with manual volume estimates in epilepsy cases and controls. CNNs can label the hippocampus and amygdala on native sub-mm resolution MP2RAGE 7T MRI. Our findings suggest deep learning techniques can advance development of morphometric analysis techniques for high field strength, high spatial resolution brain MRI.

White matter abnormalities across different epilepsy syndromes in adults: an ENIGMA-Epilepsy study.

The epilepsies are commonly accompanied by widespread abnormalities in cerebral white matter. ENIGMA-Epilepsy is a large quantitative brain imaging consortium, aggregating data to investigate patterns of neuroimaging abnormalities in common epilepsy syndromes, including temporal lobe epilepsy, extratemporal epilepsy, and genetic generalized epilepsy. Our goal was to rank the most robust white matter microstructural differences across and within syndromes in a multicentre sample of adult epilepsy patients. Diffusion-weighted MRI data were analysed from 1069 healthy controls and 1249 patients: temporal lobe epilepsy with hippocampal sclerosis (n = 599), temporal lobe epilepsy with normal MRI (n = 275), genetic generalized epilepsy (n = 182) and non-lesional extratemporal epilepsy (n = 193). A harmonized protocol using tract-based spatial statistics was used to derive skeletonized maps of fractional anisotropy and mean diffusivity for each participant, and fibre tracts were segmented using a diffusion MRI atlas. Data were harmonized to correct for scanner-specific variations in diffusion measures using a batch-effect correction tool (ComBat). Analyses of covariance, adjusting for age and sex, examined differences between each epilepsy syndrome and controls for each white matter tract (Bonferroni corrected at P < 0.001). Across 'all epilepsies' lower fractional anisotropy was observed in most fibre tracts with small to medium effect sizes, especially in the corpus callosum, cingulum and external capsule. There were also less robust increases in mean diffusivity. Syndrome-specific fractional anisotropy and mean diffusivity differences were most pronounced in patients with hippocampal sclerosis in the ipsilateral parahippocampal cingulum and external capsule, with smaller effects across most other tracts. Individuals with temporal lobe epilepsy and normal MRI showed a similar pattern of greater ipsilateral than contralateral abnormalities, but less marked than those in patients with hippocampal sclerosis. Patients with generalized and extratemporal epilepsies had pronounced reductions in fractional anisotropy in the corpus callosum, corona radiata and external capsule, and increased mean diffusivity of the anterior corona radiata. Earlier age of seizure onset and longer disease duration were associated with a greater extent of diffusion abnormalities in patients with hippocampal sclerosis. We demonstrate microstructural abnormalities across major association, commissural, and projection fibres in a large multicentre study of epilepsy. Overall, patients with epilepsy showed white matter abnormalities in the corpus callosum, cingulum and external capsule, with differing severity across epilepsy syndromes. These data further define the spectrum of white matter abnormalities in common epilepsy syndromes, yielding more detailed insights into pathological substrates that may explain cognitive and psychiatric co-morbidities and be used to guide biomarker studies of treatment outcomes and/or genetic research.

Hydrogen migration at restructuring palladium-silver oxide boundaries dramatically enhances reduction rate of silver oxide.

Heterogeneous catalysts are complex materials with multiple interfaces. A critical proposition in exploiting bifunctionality in alloy catalysts is to achieve surface migration across interfaces separating functionally dissimilar regions. Herein, we demonstrate the enhancement of more than 104 in the rate of molecular hydrogen reduction of a silver surface oxide in the presence of palladium oxide compared to pure silver oxide resulting from the transfer of atomic hydrogen from palladium oxide islands onto the surrounding surface formed from oxidation of a palladium-silver alloy. The palladium-silver interface also dynamically restructures during reduction, resulting in silver-palladium intermixing. This study clearly demonstrates the migration of reaction intermediates and catalyst material across surface interfacial boundaries in alloys with a significant effect on surface reactivity, having broad implications for the catalytic function of bimetallic materials.