Machine Learning Classification of Body Part, Imaging Axis, and Intravenous Contrast Enhancement on CT Imaging.

Purpose: The development and evaluation of machine learning models that automatically identify the body part(s) imaged, axis of imaging, and the presence of intravenous contrast material of a CT series of images. Methods: This retrospective study included 6955 series from 1198 studies (501 female, 697 males, mean age 56.5 years) obtained between January 2010 and September 2021. Each series was annotated by a trained board-certified radiologist with labels consisting of 16 body parts, 3 imaging axes, and whether an intravenous contrast agent was used. The studies were randomly assigned to the training, validation and testing sets with a proportion of 70%, 20% and 10%, respectively, to develop a 3D deep neural network for each classification task. External validation was conducted with a total of 35,272 series from 7 publicly available datasets. The classification accuracy for each series was independently assessed for each task to evaluate model performance. Results: The accuracies for identifying the body parts, imaging axes, and the presence of intravenous contrast were 96.0% (95% CI: 94.6%, 97.2%), 99.2% (95% CI: 98.5%, 99.7%), and 97.5% (95% CI: 96.4%, 98.5%) respectively. The generalizability of the models was demonstrated through external validation with accuracies of 89.7 - 97.8%, 98.6 - 100%, and 87.8 - 98.6% for the same tasks. Conclusions: The developed models demonstrated high performance on both internal and external testing in identifying key aspects of a CT series.

Machine Learning Detection and Characterization of Splenic Injuries on Abdominal Computed Tomography.

BACKGROUND: Multi-detector contrast-enhanced abdominal computed tomography (CT) allows for the accurate detection and classification of traumatic splenic injuries, leading to improved patient management. Their effective use requires rapid study interpretation, which can be a challenge on busy emergency radiology services. A machine learning system has the potential to automate the process, potentially leading to a faster clinical response. This study aimed to create such a system. METHOD: Using the American Association for the Surgery of Trauma (AAST), spleen injuries were classified into 3 classes: normal, low-grade (AAST grade I-III) injuries, and high-grade (AAST grade IV and V) injuries. Employing a 2-stage machine learning strategy, spleens were initially segmented from input CT images and subsequently underwent classification via a 3D dense convolutional neural network (DenseNet). RESULTS: This single-centre retrospective study involved trauma protocol CT scans performed between January 1, 2005, and July 31, 2021, totaling 608 scans with splenic injuries and 608 without. Five board-certified fellowship-trained abdominal radiologists utilizing the AAST injury scoring scale established ground truth labels. The model achieved AUC values of 0.84, 0.69, and 0.90 for normal, low-grade injuries, and high-grade splenic injuries, respectively. CONCLUSIONS: Our findings demonstrate the feasibility of automating spleen injury detection using our method with potential applications in improving patient care through radiologist worklist prioritization and injury stratification. Future endeavours should concentrate on further enhancing and optimizing our approach and testing its use in a real-world clinical environment.

Impact of intracoronary assessments on revascularization decisions: A contemporary evaluation.

OBJECTIVES: To investigate the real-world implementation of intracoronary assessment (ICA) techniques and evaluate their impact on clinical decisions regarding the management of coronary artery disease (CAD) in contemporary practice. BACKGROUND: Coronary angiogram is the gold standard used to diagnose vessel stenosis and guide percutaneous coronary intervention (PCI); however, it is limited by its two-dimensional imaging capabilities. ICA techniques like intravascular ultrasound and optical coherence tomography capture the vessel in three-dimensional images. Comparatively, fractional flow reserve provides information on the physiologic significance of coronary stenosis. Both techniques may improve PCI outcomes if they routinely change physician behavior. METHODS: Patients who underwent ICA between August 2015 and March 2020 were included in the study. The primary outcome was the clinical impact of ICA on physician clinical decision making of a stenotic vessel. The secondary outcome was the clinical changes that occurred following ICA. RESULTS: A total of 1135 patients were included in the study. Physiologic assessment (PA) and image assessment (IA) were performed in 61.4% and 38.6% respectively. Management plans were changed in 38.1% and 23.9% of patients who received PA and IA. Over half of the management change resulted in physicians deciding to not intervene on the stenotic vessel. One-year outcome of these decisions showed no significant increase in major adverse cardiac events (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.40-1.15; p = 0.15) or unplanned revascularization (HR, 0.78; 95% CI, 0.35-1.74; p = 0.55) suggesting reliance on PA/IA data did not increase risk. CONCLUSION: Selected ICA alters physician management of CAD in one-third of patients being evaluated for revascularization-typically leading to fewer interventions. All cause death is numerally lower in patients that received a change in management. However, the 1-year outcome of these altered decisions does not appear to be significantly different.

Detrusor contractility to parasympathetic mediators is differentially altered in the compensated and decompensated states of diabetic bladder dysfunction.

Diabetic bladder dysfunction (DBD) affects up to 50% of all patients with diabetes, characterized by symptoms of both overactive and underactive bladder. Although most diabetic bladder dysfunction studies have been performed using models with type 1 diabetes, few have been performed in models of type 2 diabetes, which accounts for ~90% of all diabetic cases. In a type 2 rat model using a high-fat diet (HFD) and two low doses of streptozotocin (STZ), we examined voiding measurements and functional experiments in urothelium-denuded bladder strips to establish a timeline of disease progression. We hypothesized that overactive bladder symptoms (compensated state) would develop and progress into symptoms characterized by underactive bladder (decompensated state). Our results indicated that this model developed the compensated state at 1 wk after STZ and the decompensated state at 4 mo after STZ administration. Diabetic bladders were hypertrophied compared with control bladders. Increased volume per void and detrusor muscle contractility to exogenous addition of carbachol and ATP confirmed the development of the compensated state. This enhanced contractility to carbachol was not due to increased levels of M3 receptor expression. Decompensation was characterized by increased volume per void, number of voids, and contractility to ATP but not carbachol. Thus, progression from the compensated to decompensated state may involve decreased contractility to muscarinic stimulation. These data suggest that the compensated state of DBD progresses temporally into the decompensated state in the male HFD/STZ model of diabetes; therefore, this male HFD/STZ model can be used to study the progression of DBD.

Methodological Rigor in Preclinical Cardiovascular Studies: Targets to Enhance Reproducibility and Promote Research Translation.

RATIONALE: Methodological sources of bias and suboptimal reporting contribute to irreproducibility in preclinical science and may negatively affect research translation. Randomization, blinding, sample size estimation, and considering sex as a biological variable are deemed crucial study design elements to maximize the quality and predictive value of preclinical experiments. OBJECTIVE: To examine the prevalence and temporal patterns of recommended study design element implementation in preclinical cardiovascular research. METHODS AND RESULTS: All articles published over a 10-year period in 5 leading cardiovascular journals were reviewed. Reports of in vivo experiments in nonhuman mammals describing pathophysiology, genetics, or therapeutic interventions relevant to specific cardiovascular disorders were identified. Data on study design and animal model use were collected. Citations at 60 months were additionally examined as a surrogate measure of research impact in a prespecified subset of studies, stratified by individual and cumulative study design elements. Of 28 636 articles screened, 3396 met inclusion criteria. Randomization was reported in 21.8%, blinding in 32.7%, and sample size estimation in 2.3%. Temporal and disease-specific analyses show that the implementation of these study design elements has overall not appreciably increased over the past decade, except in preclinical stroke research, which has uniquely demonstrated significant improvements in methodological rigor. In a subset of 1681 preclinical studies, randomization, blinding, sample size estimation, and inclusion of both sexes were not associated with increased citations at 60 months. CONCLUSIONS: Methodological shortcomings are prevalent in preclinical cardiovascular research, have not substantially improved over the past 10 years, and may be overlooked when basing subsequent studies. Resultant risks of bias and threats to study validity have the potential to hinder progress in cardiovascular medicine as preclinical research often precedes and informs clinical trials. Stroke research quality has uniquely improved in recent years, warranting a closer examination for interventions to model in other cardiovascular fields.

Photoplethysmography using a smartphone application for assessment of ulnar artery patency: a randomized clinical trial.

BACKGROUND: Radial artery access is commonly performed for coronary angiography and invasive hemodynamic monitoring. Despite limitations in diagnostic accuracy, the modified Allen test (manual occlusion of radial and ulnar arteries followed by release of the latter and assessment of palmar blush) is used routinely to evaluate the collateral circulation to the hand and, therefore, to determine patient eligibility for radial artery access. We sought to evaluate whether a smartphone application may provide a superior alternative to the modified Allen test. METHODS: We compared the modified Allen test with a smartphone heart rate-monitoring application (photoplethysmography readings detected using a smartphone camera lens placed on the patient's index finger) in patients undergoing a planned cardiac catheterization. Test order was randomly assigned in a 1:1 fashion. All patients then underwent conventional plethysmography of the index finger, followed by Doppler ultrasonography of the radial and ulnar arteries (the diagnostic standard). The primary outcome was diagnostic accuracy of the heart rate-monitoring application. RESULTS: Among 438 patients who were included in the study, we found that the heart rate-monitoring application had a superior diagnostic accuracy compared with the modified Allen test (91.8% v. 81.7%, p = 0.002), attributable to its greater specificity (93.0% v. 82.8%, p = 0.001). We also found that this application had greater diagnostic accuracy for assessment of radial or ulnar artery patency in the ipsilateral and contralateral wrist (94.0% v. 84.0%, p < 0.001). INTERPRETATION: A smartphone application used at the bedside was diagnostically superior to traditional physical examination for confirming ulnar patency before radial artery access. This study highlights the potential for smartphone-based diagnostics to aid in clinical decision-making at the patient's bedside. Trial registration: Clinicaltrials.gov, no. NCT02519491.

Utility of MRI to Differentiate Clear Cell Renal Cell Carcinoma Adrenal Metastases From Adrenal Adenomas.

OBJECTIVE: The purpose of this study is to compare MRI features of clear cell renal cell carcinoma (RCC) adrenal metastases and adenomas. MATERIALS AND METHODS: Fifteen clear cell RCC adrenal metastases imaged with MRI were compared to 29 consecutive adenomas between 2006 and 2015. Two blinded radiologists assessed homogeneity (homogeneous vs heterogeneous), signal intensity (SI) decrease on chemical-shift MRI, and T2-weighted SI (isointense, mildly hyperintense, or markedly hyperintense) relative to muscle. A third blinded radiologist measured the chemical-shift SI index, adrenal-to-spleen SI ratio, T2-weighted SI ratio, AUC for contrast-enhanced MRI, and histogram analysis. Analyses were performed using chi-square, linear regression, ROC, and logistic regression modeling. RESULTS: Clear cell RCC metastases were larger than adenomas (mean [± SD], 5.0 ± 4.2 cm [range, 1.1-15 cm] vs 2.0 ± 0.7 cm [range, 1.2-3.7 cm]; p < 0.0001). Subjectively, 33.3% (5/15) of metastases and 68.9% (20/29) of adenomas showed an SI decrease on chemical-shift MRI (p = 0.0421; κ = 0.76). Chemical-shift SI index (mean, 9.2% ± 20.6%; range, -30.0% to 57.9%) and adrenal-to-spleen SI ratio (0.94 ± 0.23 [range, 0.44-1.33]) for metastases differed significantly from those for adenomas (47.3% ± 27.8% [range, -9.4% to 86%] and 0.52 ± 0.28 [range, 0.13-1.11], respectively) (p < 0.0001). Twenty percent (3/15) of metastases had chemical-shift SI index in the adenoma range (> 16.5%). Metastases had higher T2-weighted SI than did adenomas, both quantitatively (5.1 ± 3.0 [range, 1.5-10.6] vs 1.8 ± 0.8 [range, 0.5-3.8]; p < 0.0001) and subjectively (p < 0.0001; κ = 0.89). Metastases had higher entropy than did adenomas (6.76 ± 0.61 vs 6.1 ± 0.74; p = 0.0051) and were subjectively more heterogeneous (p < 0.0001; κ = 0.86). The contrast-enhanced MRI AUC, skewness, and kurtosis did not differ between groups (p > 0.05). The ROC AUCs were 0.91 (95% CI, 0.79-1.0) for T2-weighted SI ratio and 0.85 (95% CI, 0.68-1.0) for entropy. The logistic regression model of T2-weighted SI ratio plus entropy improved accuracy (ROC AUC, 0.97; 95% CI, 0.93-1.0]) compared with either feature alone (p = 0.0215). CONCLUSION: Increased T2-weighted SI and heterogeneity are features that can differentiate clear cell RCC adrenal metastases from adenomas using quantitative and subjective analysis.

Regulation of mitogen-activated protein kinase by protein kinase C and mitogen-activated protein kinase phosphatase-1 in vascular smooth muscle.

Vascular smooth muscle contraction is primarily regulated by phosphorylation of myosin light chain. There are also modulatory pathways that control the final level of force development. We tested the hypothesis that protein kinase C (PKC) and mitogen-activated protein (MAP) kinase modulate vascular smooth muscle activity via effects on MAP kinase phosphatase-1 (MKP-1). Swine carotid arteries were mounted for isometric force recording and subjected to histamine stimulation in the presence and absence of inhibitors of PKC [bisindolylmaleimide-1 (Bis)], MAP kinase kinase (MEK) (U0126), and MKP-1 (sanguinarine) and flash frozen for measurement of MAP kinase, PKC-potentiated myosin phosphatase inhibitor 17 (CPI-17), and caldesmon phosphorylation levels. CPI-17 was phosphorylated in response to histamine and was inhibited in the presence of Bis. Caldesmon phosphorylation levels increased in response to histamine stimulation and were decreased in response to MEK inhibition but were not affected by the addition of Bis. Inhibition of PKC significantly increased p42 MAP kinase, but not p44 MAP kinase. Inhibition of MEK with U0126 inhibited both p42 and p44 MAP kinase activity. Inhibition of MKP-1 with sanguinarine blocked the Bis-dependent increase of MAP kinase activity. Sanguinarine alone increased MAP kinase activity due to its effects on MKP-1. Sanguinarine increased MKP-1 phosphorylation, which was inhibited by inhibition of MAP kinase. This suggests that MAP kinase has a negative feedback role in inhibiting MKP-1 activity. Therefore, PKC catalyzes MKP-1 phosphorylation, which is reversed by MAP kinase. Thus the fine tuning of vascular contraction is due to the concerted effort of PKC, MAP kinase, and MKP-1.

Effect of type II diabetes on male rat bladder contractility.

Type II diabetes is the most prevalent form of diabetes. One of the primary complications of diabetes that significantly affects quality of life is bladder dysfunction. Many studies on diabetic bladder dysfunction have been performed in models of type I diabetes; however, few have been performed in animal models of type II diabetes. Using the Zucker Diabetic Fatty (ZDF) rat model of type II diabetes, we examined the contractility and sensitivity of bladder smooth muscle in response to mediators of depolarization-induced contraction, muscarinic receptor-mediated contraction, ATP-induced contraction, and neurogenic contraction. Studies were performed at 16 and 27 wk of age to monitor the progression of diabetic bladder dysfunction. Voiding behavior was also quantified. The entire bladder walls of diabetic rats were hypertrophied compared with that of control rats. Contractility and sensitivity to carbachol and ATP were increased at 27 wk in bladder smooth muscle strips from diabetic rats, suggesting a compensated state of diabetic bladder dysfunction. Purinergic signaling was increased in response to exogenous ATP in bladders from diabetic animals; however, the purinergic component of neurogenic contractions was decreased. The purinergic component of neurogenic contraction was reduced by P2X receptor desensitization, but was unchanged by P2X receptor inhibition in diabetic rats. Residual and tetrodotoxin-resistant components of neurogenic contraction were increased in bladder strips from diabetic animals. Overall, our results suggest that in the male ZDF rat model, the bladder reaches the compensated stage of function by 27 wk and has increased responsiveness to ATP.

Does stent strut design impact clinical outcomes: comparative safety and efficacy of Endeavor Resolute versus Resolute Integrity zotarolimus-eluting stents.

UNLABELLED: Percutaneous coronary intervention is the most commonly performed method of revascularizing obstructive coronary artery disease. The impact of stent strut design on clinical outcomes remains unclear. The Endeavour Resolute (ER-ZES) and the Resolute Integrity (RI-ZES) zotarolimus-eluting stents utilize identical polymers and anti-proliferative agents, differing only in their respective strut design. This study assessed the comparative safety and efficacy of these two stents in unrestricted contemporary real-world practice. METHODS: A total of 542 patients were identified, corresponding to 340 ER-ZES and 480 RI-ZES. The primary endpoint was major adverse cardiac events (MACE) defined by a composite of death, nonfatal myocardial infarction and stroke. Secondary endpoints included post-procedural length of stay, in-stent restenosis, target lesion revascularization, target vessel revascularization, coronary artery bypass grafting and stent thrombosis. RESULTS: MACE occurred in 3.2% of the ER-ZES cohort and 5.0% of the RI-ZES cohort (p= 0.43). Adjusted analysis utilizing propensity score-adjusted odds ratio for MACE, was 1.37 (95% CI 0.46-4.07, p=0.57). The mortality rate (0.9% ER-ZES vs. 1.9% RI-ZES, p=0.59), non-fatal MI (2.3% ER-ZES vs. 3.1% RI-ZES, p=0.75) and stroke (0.0% ER-ZES vs. 0.3% RI-ZES, p=0.85) were not different. Additionally, there was no difference in any of secondary outcomes. CONCLUSIONS: The clinical performance and safety of both ER-ZES and RI-ZES were not statistically different, despite differences in stent strut design.

Vision Transformer-based Decision Support for Neurosurgical Intervention in Acute Traumatic Brain Injury: Automated Surgical Intervention Support Tool.

Purpose To develop an automated triage tool to predict neurosurgical intervention for patients with traumatic brain injury (TBI). Materials and Methods A provincial trauma registry was reviewed to retrospectively identify patients with TBI from 2005 to 2022 treated at a specialized Canadian trauma center. Model training, validation, and testing were performed using head CT scans with binary reference standard patient-level labels corresponding to whether the patient received neurosurgical intervention. Performance and accuracy of the model, the Automated Surgical Intervention Support Tool for TBI (ASIST-TBI), were also assessed using a held-out consecutive test set of all patients with TBI presenting to the center between March 2021 and September 2022. Results Head CT scans from 2806 patients with TBI (mean age, 57 years ± 22 [SD]; 1955 [70%] men) were acquired between 2005 and 2021 and used for training, validation, and testing. Consecutive scans from an additional 612 patients (mean age, 61 years ± 22; 443 [72%] men) were used to assess the performance of ASIST-TBI. There was accurate prediction of neurosurgical intervention with an area under the receiver operating characteristic curve (AUC) of 0.92 (95% CI: 0.88, 0.94), accuracy of 87% (491 of 562), sensitivity of 87% (196 of 225), and specificity of 88% (295 of 337) on the test dataset. Performance on the held-out test dataset remained robust with an AUC of 0.89 (95% CI: 0.85, 0.91), accuracy of 84% (517 of 612), sensitivity of 85% (199 of 235), and specificity of 84% (318 of 377). Conclusion A novel deep learning model was developed that could accurately predict the requirement for neurosurgical intervention using acute TBI CT scans. Keywords: CT, Brain/Brain Stem, Surgery, Trauma, Prognosis, Classification, Application Domain, Traumatic Brain Injury, Triage, Machine Learning, Decision Support Supplemental material is available for this article. © RSNA, 2024 See also commentary by Haller in this issue.

Ca2+ sensitization pathways accessed by cholinergic neurotransmission in the murine gastric fundus.

Ca(2+) sensitization of contraction has typically been investigated by bathing muscles in solutions containing agonists. However, it is unknown whether bath-applied agonists and enteric neurotransmission activate similar Ca(2+) sensitization mechanisms. We investigated protein kinase C (PKC)-potentiated phosphatase inhibitor protein of 17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation in murine gastric fundus muscles stimulated by bath-applied carbachol (CCh) or cholinergic motor neurotransmission. CCh increased MYPT1 phosphorylation at Thr696 (pT696) and Thr853 (pT853), CPI-17 at Thr38 (pT38), and myosin light chain at Ser19 (pS19). Electrical field stimulation (EFS) only increased pT38. In the presence of neostigmine, EFS increased pT38, pT853 and pS19. In fundus muscles of W/W(v) mice, EFS alone increased pT38 and pT853. Atropine blocked all contractions and all increases in pT696, pT853, pT38 and pS19. The Rho kinase (ROCK) inhibitor SAR1x blocked increases in pT853 and pT696. The PKC inhibitors Go6976 and Gf109203x or nicardipine blocked increases in pT38 and pT696. These findings suggest that cholinergic motor neurotransmission activates PKC-dependent CPI-17 phosphorylation. Bath-applied CCh recruits additional ROCK-dependent MYPT1 phosphorylation due to exposure of the agonist to a wider population of muscarinic receptors. Intramuscular interstitial cells of Cajal (ICC-IMs) and cholinesterases restrict ACh accessibility to a select population of muscarinic receptors, possibly only those expressed by ICC-IMs. These results provide the first biochemical evidence for focalized (or synaptic-like) neurotransmission, rather than diffuse 'volume' neurotransmission in a smooth muscle tissue. Furthermore, these findings demonstrate that bath application of contractile agonists to gastrointestinal smooth muscles does not mimic physiological responses to cholinergic neurotransmission.

Effect of estrogen on molecular and functional characteristics of the rodent vaginal muscularis.

INTRODUCTION: Vaginal atrophy is a consequence of menopause; however, little is known concerning the effect of a decrease in systemic estrogen on vaginal smooth muscle structure and function. As the incidence of pelvic floor disorders increases with age, it is important to determine if estrogen regulates the molecular composition and contractility of the vaginal muscularis. AIM: The goal of this study was to determine the effect of estrogen on molecular and functional characteristics of the vaginal muscularis utilizing a rodent model of surgical menopause. METHODS: Three- to 4-month old Sprague-Dawley rats underwent sham laparotomy (Sham, N = 18) or ovariectomy (Ovx, N = 39). Two weeks following surgery, animals received a subcutaneous osmotic pump containing vehicle (Sham, Ovx) or 17ß-estradiol (Ovx). Animals were euthanized 1 week later, and the proximal vagina was collected for analysis of contractile protein expression and in vitro studies of contractility. Measurements were analyzed using a one-way analysis of variance followed by Tukey's post hoc analysis (α = 0.05). MAIN OUTCOME MEASURES: Protein and mRNA transcript expression levels of contractile proteins, in vitro measurements of vaginal contractility. RESULTS: Ovariectomy decreased the expression of carboxyl-terminal myosin heavy chain isoform (SM1) and h-caldesmon and reduced the amplitude of contraction of the vaginal muscularis in response to KCl. Estradiol replacement reversed these changes. No differences were detected in the % vaginal muscularis, mRNA transcript expression of amino-terminal MHC isoforms, l-caldesmon expression, and maximal velocity of shortening. CONCLUSION: Systemic estrogen replacement restores functional and molecular characteristics of the vaginal muscularis of ovariectomized rats. Our results indicate that menopause is associated with changes in the vaginal muscularis, which may contribute to the increased incidence of pelvic floor disorders with age.

Understanding Ballistic Injuries.

Understanding the pathophysiology of a disease allows physicians to make a diagnosis, alter its natural course, and develop and implement appropriate preventative and management strategies. With ballistic injuries, an understanding of how the mechanism of injury translates to the injuries observed makes it possible to make sense of what can, at times be a complex imaging appearance and mitigate against the long-term complications of gunshot wounds. In this article, the authors describe the different types of ballistic projectiles, their mechanism of injury as well as the injury patterns they cause. In addition, both lead arthropathy and MR imaging safety in patients with retained ballistic debris are discussed.

Augmentation of the RSNA Pulmonary Embolism CT Dataset with Bounding Box Annotations and Anatomic Localization of Pulmonary Emboli.

Supplemental material is available for this article. Keywords: CT, Pulmonary Arteries, Embolism/Thrombosis, Feature Detection © RSNA, 2023.

Bladder smooth muscle organ culture preparation maintains the contractile phenotype.

Smooth muscle cells, when subjected to culture, modulate from a contractile to a secretory phenotype. This has hampered the use of cell culture for molecular techniques to study the regulation of smooth muscle biology. The goal of this study was to develop a new organ culture model of bladder smooth muscle (BSM) that would maintain the contractile phenotype and aid in the study of BSM biology. Our results showed that strips of BSM subjected to up to 9 days of organ culture maintained their contractile phenotype, including the ability to achieve near-control levels of force with a temporal profile similar to that of noncultured tissues. The technical aspects of our organ culture preparation that were responsible, in part, for the maintenance of the contractile phenotype were a slight longitudinal stretch during culture and subjection of the strips to daily contraction-relaxation. The tissues contained viable cells throughout the cross section of the strips. There was an increase in extracellular collagenous matrix, resulting in a leftward shift in the passive length-tension relationship. There were no significant changes in the content of smooth muscle-specific α-actin, calponin, h-caldesmon, total myosin heavy chain, protein kinase G, Rho kinase-I, or the ratio of SM1 to SM2 myosin isoforms. Moreover the organ cultured tissues maintained functional voltage-gated calcium channels and large-conductance calcium-activated potassium channels. Therefore, we propose that this novel BSM organ culture model maintains the contractile phenotype and will be a valuable tool for the use in cellular/molecular biology studies of bladder myocytes.

A novel MRI-compatible brain ventricle phantom for validation of segmentation and volumetry methods.

PURPOSE: To create a standardized, MRI-compatible, life-sized phantom of the brain ventricles to evaluate ventricle segmentation methods using T(1) -weighted MRI. An objective phantom is needed to test the many different segmentation programs currently used to measure ventricle volumes in patients with Alzheimer's disease. MATERIALS AND METHODS: A ventricle model was constructed from polycarbonate using a digital mesh of the ventricles created from the 3 Tesla (T) MRI of a subject with Alzheimer's disease. The ventricle was placed in a brain mold and surrounded with material composed of 2% agar in water, 0.01% NaCl and 0.0375 mM gadopentetate dimeglumine to match the signal intensity properties of brain tissue in 3T T(1) -weighted MRI. The 3T T(1) -weighted images of the phantom were acquired and ventricle segmentation software was used to measure ventricle volume. RESULTS: The images acquired of the phantom successfully replicated in vivo signal intensity differences between the ventricle and surrounding tissue in T(1) -weighted images and were robust to segmentation. The ventricle volume was quantified to 99% accuracy at 1-mm voxel size. CONCLUSION: The phantom represents a simple, realistic and objective method to test the accuracy of lateral ventricle segmentation methods and we project it can be extended to other anatomical structures.

Student Perspectives on Implementing Stop the Bleed Training into Medical School Curriculum.

BACKGROUND: Following the Hartford Consensus guidelines and recommendations, third-year medical students from a single institution were offered an optional Stop the Bleed (STB) training course in August 2018. The aim of this study was to assess medical students' confidence in performing bleeding control techniques and teaching others after completing the STB course. The secondary goal was to assess student perception on integrating mandatory STB training into the medical school curriculum. MATERIALS AND METHODS: A 24-question survey using a 4-point Likert scale was administered to all medical students who completed STB training. Students were anonymously asked to self-report their confidence in performing bleeding control techniques, training others after STB training, and their perception on integrating STB training into medical school curriculum. RESULTS: After completing the STB course, 95% of students were comfortable applying a tourniquet, 92% of students were confident in packing wounds, and 99% of students could apply direct pressure to wounds to stop bleeding. Overall, 94% of students reported that STB training would be helpful for their clinical rotations. CONCLUSION: These results demonstrate that medical students are positively impacted by Stop the Bleed courses and validate that the implementation of mandatory STB courses into medical school curriculum will improve medical students' knowledge and skills for hemorrhage control.

Impact of atrial fibrillation on the risk of major adverse cardiac events following coronary revascularisation.

OBJECTIVE: Atrial fibrillation (AF) remains a highly prevalent arrhythmia with significant burden on morbidity and mortality. The impact of AF in the revascularised population remains incompletely described. Given the high prevalence of AF in the revascularised population, we sought to evaluate the incidence and prognosis in patients with pre-existing and new-onset AF following revascularisation. METHODS: We used the University of Ottawa Heart Institute Revascularisation Registry to identify patients who underwent revascularisation between August 2015 and March 2020, who were prospectively followed for an average of one year. We conducted a retrospective cohort study analysing the association between AF and clinical outcomes. The primary outcome of interest was 1-year major adverse cardiac events (MACE) defined as a composite of death, myocardial infarction, unplanned revascularisation and cerebrovascular accidents. Moreover, secondary outcomes include the individual components of MACE and bleeding. RESULTS: A total of 6704 patients underwent revascularisation and completed 1-year clinical follow-up. Median time to follow-up was 12.8 (IQR 11.2-15.9) months. One-year MACE occurred in 166 (21.8%) and 683 (11.5%) patients in AF and non-AF groups, respectively (adjusted HR, 1.61; 95% CI 1.29 to 2.01; p<0.0001). AF was independently predictive of 1-year mortality, myocardial infarction, unplanned revascularisation, cerebrovascular accident and bleeding. Within 1 year, 299 (4.5%) episodes of new-onset AF was observed. New-onset AF following revascularisation was also associated with 1-year MACE, mortality, myocardial infarction, cerebrovascular accident and unplanned revascularisation. CONCLUSIONS: Preprocedural and new-onset AF following revascularisation remains highly predictive 1-year MACE. AF should be considered in addition to traditional risk factors for adverse outcomes following revascularisation.

Physician prediction of 1-year mortality in the cardiac catheterization laboratory: comparison to a validated risk score.

BACKGROUND: Physician perception of procedural risk and clinical outcome can affect revascularization decision making. Public reporting of percutaneous coronary intervention outcomes accentuates the need for accuracy in risk prediction in order to avoid a treatment paradox of undertreating the highest risk patients. Our study compares a validated risk score to physician prediction (PP) of 1-year mortality based on clinical impression at the time of invasive angiography. METHODS AND RESULTS: We performed a cohort study between August 2015 and May 2018 to determine the discriminative accuracy of interventional cardiologists on one-year mortality of the treated patient. PP of one-year mortality was compared to the New York State Percutaneous Coronary Intervention Reporting System (NYPCIRS) score in predicting mortality. Three thousand seven hundred ninety-two patients were followed with a median follow-up period of 14.4 months (interquartile range 12.4-18.1 months) and 165 patients (4.4%) died within one-year. PP of mortality was associated with one-year mortality with a hazard ratio of 8.78 (95% confidence interval 5.24-14.71, P < 0.0001). Clinical presentation in the form of cardiogenic shock, return of spontaneous circulation, and liver and renal dysfunction were associated with PP. Diagnostic accuracy and specificity were improved in PP compared to NYPCIRS. The combination of PP to NYPCIRS improved the overall c-statistic and diagnostic yield. CONCLUSION: PP appears to be especially specific and accurate for prediction of mortality compared to NYPCIRS though it lacks sensitivity. Furthermore, the combination of PP with NYPCIRS improved the c-statistic and diagnostic yield. Overall, the utility of PP with an objective risk score improves the diagnostic accuracy of mortality prediction.