Large Vessel Occlusion Prediction in the Emergency Department with National Institutes of Health Stroke Scale Components: A Machine Learning Approach.

OBJECTIVE: To determine the feasibility of using a machine learning algorithm to screen for large vessel occlusions (LVO) in the Emergency Department (ED). MATERIALS AND METHODS: A retrospective cohort of consecutive ED stroke alerts at a large comprehensive stroke center was analyzed. The primary outcome was diagnosis of LVO at discharge. Components of the National Institutes of Health Stroke Scale (NIHSS) were used in various clinical methods and machine learning algorithms to predict LVO, and the results were compared with the baseline method (aggregate NIHSS score with threshold of 6). The Area-Under-Curve (AUC) was used to measure the overall performance of the models. Bootstrapping (n = 1000) was applied for the statistical analysis. RESULTS: Of 1133 total patients, 67 were diagnosed with LVO. A Gaussian Process (GP) algorithm significantly outperformed other methods including the baseline methods. AUC score for the GP algorithm was 0.874 ± 0.025, compared with the simple aggregate NIHSS score, which had an AUC score of 0.819 ± 0.024. A dual-stage GP algorithm is proposed, which offers flexible threshold settings for different patient populations, and achieved an overall sensitivity of 0.903 and specificity of 0.626, in which sensitivity of 0.99 was achieved for high-risk patients (defined as initial NIHSS score > 6). CONCLUSION: Machine learning using a Gaussian Process algorithm outperformed a clinical cutoff using the aggregate NIHSS score for LVO diagnosis. Future studies would be beneficial in exploring prospective interventions developed using machine learning in screening for LVOs in the emergent setting.

Auditing RadExam: Employing Psychometrics to Improve Exam Quality.

INTRODUCTION: RadExam is a question item and exam database jointly developed by the Association of Program Directors in Radiology and the American College of Radiology to provide formative resident assessment, offering performance metrics benchmarked against institutional and national resident performance. Beyond resident performance, data is available on question and exam performance. Despite considerable investment in the education and training of its question writers and editors and meticulous attention to current psychometrically validated methods, it was anticipated a minority of exam questions would still perform poorly. Audits were performed to identify these questions, identify reasons for poor performance, and modify or replace so-affected questions. Exam performance was also assessed. METHODS: Two audits were performed, the first after the February-May 2018 RadExam pilot phase, and the second nearly 1 year after the full implementation of RadExam. In each audit, RadExam subspecialty editors evaluated all exam questions and exams using statistical data: question and test number of administrations, question p value, question Discrimination Index (DI), question Bloom's taxonomy learning level, exam P-value, and the number of image-based questions in each exam. Identified questions were modified or removed and replaced. RESULTS: Audit 1 was performed after the administration of 3114 exams comprised of 2520 questions administered across 100 residency programs. Audit 1 identified 617 questions with DI <0.1 and 565 questions with unacceptable P-values, all of which were modified or replaced. Audit 2 was performed after the administration of 16,416 exams, comprised of 2,507 questions. Audit 2 identified 229 questions with DI <0.1 and 290 questions with unacceptable P-values, representing a 49.1% decrease in total flagged questions compared to Audit 1. Statistically significant decreases were seen in questions with both DI and P-values outside of the desired range across nearly all subspecialties. CONCLUSION: The positive impact of our audit system on question and exam performance was reflected in a significant decrease in the number of questions flagged and improved overall exam performance in Audit 2. This illustrates the positive impact of Audit 1.

Creating the Black Box: A Primer on Convolutional Neural Network Use in Image Interpretation.

Convolutional neural networks have been shown to demonstrate high diagnostic performance in radiologic image interpretation tasks ranging from recognition of acute stroke on computed tomography to identification of tuberculosis on plain radiographs. To a radiologist not immersed in computer science jargon, it may seem that this inscrutable black box is best treated warily, at arm's length. In this work, we illustrate how a radiologist without a deep background in computer science may be able to set up a state-of-the-art convolutional neural network for image interpretation tasks through transfer learning. This technique is relatively simple to implement, has been shown to demonstrate equivalent performance to neural networks specifically trained on medical image data, and offers a chance for the interested-but-intimidated radiologist to deep her toe in the water without becoming overwhelmed.

Cultivating Meaningful Work in Healthcare: A Paradigm and Practice.

The socioeconomic dynamics of the current healthcare system can challenge physicians to remain engaged with meaningful work, which is problematic given its role in mitigating burnout. In Man's Search For Meaning, Victor Frankl proposes that meaningful work is a prerequisite for a meaningful life. This article provides a road map for radiologists by applying key guiding principles outlined by Frankl as they intersect with current evidence in the field of physician burnout.

A Clinical Paradigm for Classifying Neurologic Symptoms to Screen for Emergent Large Vessel Occlusions.

BACKGROUND: With newly-extended treatment windows for endovascular therapy in emergent large vessel occlusions, it is increasingly important to identify thrombectomy-eligible patients without overwhelming resources dedicated to acute stroke care. We devised a simple paradigm to classify patient's presenting neurologic symptoms to screen for large vessel occlusions. METHODS: We reviewed the presenting symptoms, imaging findings, and final diagnoses of consecutive emergency department stroke alert cases. Patients were classified based on their neurologic exams as focal objective, focal subjective, or nonfocal. Outcomes of final diagnoses of acute ischemic stroke and large vessel occlusions were compared across groups. Comparisons were made to other large vessel occlusion prediction scales. RESULTS: Of 521 patients, 342 (65.6%) were categorized as focal objective, 142 (27.2%) as focal subjective, and 37 (7.1%) as nonfocal. Ischemic stroke and large vessel occlusions were diagnosed in 114 (21.9%) and 27 (5.2%) of patients, respectively. Classification as focal objective significantly predicted stroke (odds ratio 3.77; 95% confidence interval 2.17-6.55) and captured all large vessel occlusions (P = .0001). The focal objective categorization was the only tool which achieved 100% sensitivity for large vessel occlusions (with a specificity of 36%) compared to other large vessel occlusion prediction tools. CONCLUSIONS: Patients who presented as stroke alerts without focal neurologic symptoms were unlikely to have large vessel occlusions. With high sensitivity, classifying patients' neurologic exams into focal objective versus subjective or nonfocal categories may serve as a useful tool to screen for large vessel occlusions and prevent unnecessary emergent workup in patients unlikely to be endovascular candidates.

Lacunar Stroke in Cryptococcal Meningitis: Clinical and Radiographic Features.

OBJECTIVE: Cryptococcal meningitis carries a high mortality, and survivors are left with considerable neurologic sequelae and marked disability. We lack a clear understanding of the pathogenesis of neurologic sequelae and description of stroke features in this population. We aim to describe clinical and radiographic features and predictors of stroke in a cohort of patients with cryptococcal meningitis. METHODS: We collected key information on patients diagnosed with cryptococcal meningitis at the University of Colorado Hospital between 2000 and 2018 (n = 42). Of those, 32 had neuroimaging studies available. Bivariate and risk ratio estimates regression models were performed to identify predictors of stroke. RESULTS: We found a 26% ischemic stroke complication rate in individuals with cryptococcal meningitis. Most strokes were acute (75%), lacunar (100%), multiple (88%), bilateral (63%), and involving the basal ganglia (75%). Presence of malignancy (38% versus 8%, P = .085) was higher in stroke in individuals with cryptococcal meningitis, although not statistically significant. Every unit decrease in hemoglobin and serum sodium were predictors for 1.35 and 1.14 times increase in the risk of ischemic stroke, respectively. The presence of hyponatremia carried a RR of 5.7 (95% confidence interval, 1.7-34, P = .005). Cryptococcal meningitis lead to death in 19% of patients and a considerable rate of neurologic sequela among survivors. CONCLUSIONS: Cryptococcal meningitis carries a high risk of lacunar stroke, particularly in the basal ganglia. Cryptococcal meningitis-associated stroke is common and frequently associated with neurologic disability among survivors. We need to understand the possible role of malignancy, anemia, and hyponatremia in the onset of ischemic stroke.

Launchpad for Onboarding New Faculty Into Academic Life.

We developed a faculty professional development seminar series in order to facilitate the integration of our numerous new faculty into academics. The changing nature of the healthcare system, increasing clinical and administrative responsibility, and lack of access to senior mentors can hinder junior faculty productivity and possibly increase attrition. Given that no ready-made resources existed to address these issues we established a Professional Development Committee, developed a curriculum that covers relevant topics including promotion, mentorship, conflict management and feedback, and effective presentation of scientific data, and instituted changes iteratively based upon feedback. We used surveys from successive years of this seminar series to assess effectiveness, and our data demonstrate that our Professional Development Seminar Series was valued by its participants and that individual lectures improved from year to year. While it is too early to determine whether our efforts will lead to long-term changes in promotion success or faculty retention, our initial data are promising.

Beyond the embolus: "do not miss" diffusion abnormalities of ischaemic and non-ischaemic neurological disease.

Given the rapid evolution and technological advances in the diagnosis and treatment of acute ischaemic stroke (AIS), including the proliferation of comprehensive stroke centres and increasing emphasis on interventional stroke therapies, the need for prompt recognition of stroke due to acute large vessel occlusion has received significant attention in the recent literature. Diffusion-weighted imaging (DWI) is the gold standard for the diagnosis of acute ischaemic stroke, as images appear positive within minutes of ischaemic injury, and a high signal-to-noise ratio enables even punctate infarcts to be readily detected. DWI lesions resulting from a single arterial embolic occlusion or steno-occlusive lesion classically lateralise and conform to a specific arterial territory. When there is a central embolic source (e.g. left atrial thrombus), embolic infarcts are often found in multiple vascular territories. However, ischaemic disease arising from aetiologies other than arterial occlusion will often not conform to an arterial territory. Furthermore, there are several important entities unrelated to ischaemic disease that can present with abnormal DWI and which should not be confused with infarct. This pictorial review explores the scope and typical DWI findings of select neurologic conditions beyond acute arterial occlusion, which should not be missed or misinterpreted. TEACHING POINTS: • DWI abnormalities due to acute arterial occlusion must be promptly identified. • DWI abnormalities not due to arterial occlusion will often not conform to an arterial territory. • Several important non-ischaemic entities can present on DWI and should not be confused with infarct.

The Addition of Endovascular Intervention for Dural Venous Sinus Thrombosis: Single-Center Experience and Review of Literature.

BACKGROUND: Dural venous sinus thrombosis (DVST) is a cause of infarction and intracranial hemorrhage (ICH) that can lead to significant morbidity. Endovascular therapy has emerged as an adjunctive therapy in select cases but has been associated with increased hemorrhagic complications. We present our experience with a large single-center cohort of DVST cases treated with current-generation thrombectomy devices. MATERIALS AND METHODS: In this retrospective cohort study, a chart review was performed to compare presentations and outcomes of patients treated with anticoagulation alone with those treated with additional interventional therapy, using the modified Rankin Scale (mRS) score at discharge and at 90 days' follow-up. RESULTS: A total of 66 patients were included; 37 were treated with anticoagulation alone, and 29 underwent additional interventional therapy. Patients presenting with ICH or infarction had a significantly greater likelihood of disability at the time of discharge (odds ratio [OR] of 64.5 and 45.8, respectively; P < .0001) and at 90 days (OR of 28.4 and 22.8, respectively; P < .0001). Patients presenting with ICH or infarction were more likely to be selected for endovascular therapy (P < .05). Endovascular therapy was typically performed within 24 hours of admission; 9 patients (31%) had post-treatment hemorrhage, with 2 being (6.9%) symptomatic. There were fewer patients with slight disability (mRS score ≤1) in the endovascular group compared with the anticoagulation group at discharge (P = .05), but outcomes were not significantly different at 90 days (P = .19). CONCLUSIONS: Despite a higher rate of ICH or infarction at presentation in the endovascular group and an increased risk of postprocedural ICH, both treatment groups had similarly good functional outcomes at 90 days.

Imaging of Laser Therapy in Epilepsy.

BACKGROUND AND PURPOSE: MR-guided laser interstitial thermal therapy (MRgLITT) is an increasingly popular neuroablative method for the surgical treatment of epilepsy patients. This article intends to demonstrate the utility and pitfalls of imaging in the context of patient care with MRgLITT. MATERIAL AND METHODS: A retrospective review of the medical records and imaging database with six illustrative cases selected to demonstrate the use of imaging throughout patient management with MRgLITT in diverse clinical situations and pathologies. A review of the knowledge in the literature was applied to the relevant points discussed. RESULTS: Imaging findings were described in the setting of laser therapy in nonlesional epilepsy, mesial temporal sclerosis, dual pathology, periventricular nodular heterotopia, and schizencephaly. Discussion of imaging principles, potential pitfalls, as well as its use in the patient work-up and follow-up, is shown. CONCLUSIONS: MRgLITT is an alternative minimally invasive therapy for refractory epilepsy, which is becoming widely sought for. Imaging plays a crucial role prior to, during, and after the procedure.

Cement technique correlates with tuberosity healing in hemiarthroplasty for proximal humeral fracture.

BACKGROUND: Tuberosity healing correlates with clinical outcomes after hemiarthroplasty for 4-part proximal humeral fractures (4PHFs). We seek to examine variables that affect tuberosity healing. METHODS: This was a retrospective comparative study. At 1 year postoperatively, patients who underwent hemiarthroplasty for 4PHFs were divided into 2 groups: those with anatomically healed tuberosities and those with tuberosity nonunion. The primary variables included time between injury and surgery, prosthesis fenestration, cement mantle classification, and both vertical and horizontal tuberosity reduction. Secondary demographic factors included age, gender, osteoporosis status, diabetes status, and smoking status. RESULTS: There were 84 individuals who met the inclusion criteria: 37 (44%) had anatomically healed tuberosities, and 47 (56%) did not. Individuals with anatomic healing had cement near or under the tuberosities 32% of the time, whereas individuals with nonunion or resorption had cement near the tuberosities 66% of the time (P = .002). There was no association between tuberosity healing and fenestration of the humeral stem (P = .84). Anatomic reduction between tuberosities was associated with healing (P <.001), whereas greater tuberosity-to-head height was not (P = .25). There were no significant differences in age, osteoporosis status, smoking status, diabetes status, or time to surgery between groups. Male patients had nearly double the rate of healing (P = .03). DISCUSSION AND CONCLUSION: The classification and effect of cement technique on tuberosity healing have not previously been described. We suggest limiting cementation to a minimum of 5 mm below the level of the tuberosity fracture. The ideal candidate for hemiarthroplasty for a 4PHF is a male patient with anatomic tuberosity reduction and limited use of cement.

Arterial spin labeling: Pathologically proven superiority over conventional MRI for detection of high-grade glioma progression after treatment.

BACKGROUND: Standard of care for high-grade gliomas (HGGs) includes surgical debulking and adjuvant chemotherapy and radiation. Patients under treatment require frequent clinical and imaging monitoring for therapy modulation. Differentiating tumor progression from treatment-related changes can be challenging on conventional MRI, resulting in delayed recognition of tumor progression. Arterial spin labeling (ASL) may be more sensitive for tumor progression. MATERIALS AND METHODS: ASL and associated conventional MR images obtained in patients previously treated for HGGs and before biopsy or re-resection were reviewed by three neuroradiologists who were blinded to the histopathologic results. Regions of interest (ROIs) of greatest perfusion were chosen by consensus, and mirror-image contralateral ROIs were also placed. Sensitivity of ASL for tumor progression was compared with those of contrast-enhanced T1-weighted (T1W-CE) and fluid-attenuated inversion recovery (FLAIR) images using McNemar's test. We tested for an association between cerebral blood flow (CBF) and apparent diffusion correlation (ADC) using a Hotelling-Lawley trace. Finally, we used a Pearson's analysis to test for a correlation between CBF and percentage of tumor within each resection. RESULTS: Twenty-two patients were studied. ASL demonstrated hyperperfusion in all cases with mean CBF ratio 3.37 (±1.71). T1W-CE and FLAIR images were positive in 15 (p = 0.0233) and 16 (p = 0.0412) cases, respectively. There was no association between ADC and CBF (p = 0.687). There was a correlation between CBF and percentage of tumor (p = 0.048). CONCLUSION: ASL may be more sensitive than conventional MR sequences for the detection of tumor progression in patients treated for HGGs.

Postoperative Risk of Hepatic Decompensation after Orthopedic Surgery in Patients with Cirrhosis.

BACKGROUND AND AIMS: Previous studies have shown increased hepatic decompensation in patients with cirrhosis undergoing surgery. However, there are little data available in cirrhotics undergoing orthopedic surgery compared to cirrhotics who did not undergo surgery. The aim of this study was to examine the demographics, comorbid conditions, and clinical factors associated with hepatic decompensation within 90 days in cirrhotics who underwent orthopedic surgery. METHODS: This is a retrospective matched cohort study. Inclusion criteria were cirrhosis diagnosis, age > 18 years, ≥ 6 months continuous health plan membership, and a procedure code for orthopedic surgery. Up to five cirrhotic controls without orthopedic surgery were matched on age, gender, and cirrhosis diagnosis date. Data abstraction was performed for demographics, socioeconomics, clinical, and decompensation data. Chart review was performed for validation. Multivariable analysis estimated relative risk of decompensation. RESULTS: Eight hundred fifty-three orthopedic surgery cases in cirrhotics were matched with 4,263 cirrhotic controls. Among the cases and matched controls, the mean age was 60.5 years, and 52.2% were female. Within 90 days after surgery, cases had more decompensation compared to matched controls (12.8% vs 4.9%). Using multivariable analysis, orthopedic surgery, a 0.5 g/dL decrease in serum albumin, and a 1-unit increase in Charlson Comorbidity Index were associated with a significant increase in decompensation within 90 days of surgery. Diabetes, chronic obstructive pulmonary disease, and chronic kidney disease were seen with increased frequency in cases vs. matched controls. CONCLUSIONS: Cirrhotics who underwent orthopedic surgery had a significant increase in hepatic decompensation within 90 days of surgery compared to matched controls. An incremental decrease in serum albumin and an incremental increase in the Charlson Comorbidity Index were significantly associated with hepatic decompensation after surgery.

Diagnostic, treatment, and surgical imaging in epilepsy.

Dedicated epilepsy centers are growing in hospitals throughout the USA and abroad, with a continuously increasing role of imaging in multidisciplinary meetings. Imaging is paramount in diagnosis, treatment, and surgical decision-making in lesional and nonlesional epileptic disease. Besides being up-to-date with technical developments in imaging that may make an impact in patient care, familiarity with clinical and surgical aspects of epilepsy is fundamental to better understanding of patient management. The present article intends to revisit diagnostic, therapeutic, and surgical imaging in epilepsy. Finally, with the increase in frequency of epilepsy management-related procedures and their hardware, MRI safety issues are discussed.

Neuroimaging of Concussion.

In this review, we discuss the literature regarding both concussion and mild traumatic brain injury. We focus on the role for neuroimaging in the concussed patient and describe the recommended practices related to imaging in concussion. This discussion first focuses on the exclusion of severe injuries and is followed by a discussion of the potential utility of various advanced imaging techniques in research and clinical practice.

The Dotter method revisited: early experience with a novel method of rapid internal carotid artery revascularization in the setting of acute ischemic stroke.

BACKGROUND: Tandem occlusive disease in the setting of acute ischemic stroke involving cervical and cerebral arteries has been associated with poor neurological outcome and poses significant challenges to neurointerventionists. Previously described endovascular methods typically involve carotid revascularization with stent placement prior to or following intracranial thrombectomy. Stent-based approaches, however, require the use of antiplatelet therapy which may increase the risk of hemorrhagic transformation. We describe a novel modified Dotter technique which may be used for carotid revascularization in lieu of stenting. This technique can eliminate the need for antiplatelet therapy, reduce procedure times, and possibly reduce hemorrhagic conversion rates. METHODS: Seven patients presenting between April 2013 and January 2014 were treated with this technique. All patients had carotid stenosis of 65-100% and tandem middle cerebral artery occlusions. National Institutes of Health (NIH) Stroke Scale scores as well as clinical and procedural times were recorded. Pre- and post-Dotter stenosis was measured using the NASCET criteria. Follow-up imaging and clinical data were reviewed. RESULTS: The mean age was 64 years and mean initial NIH Stroke Scale score was 11.7. Mean groin to recanalization time was 26 min. Thrombolysis In Cerebral Infarction grade 2b-3 was achieved in all patients. The mean stenosis was 88% preoperatively and 61% postoperatively. There were no intracranial hemorrhages. The modified Rankin Scale score was 0 in six patients (86%) and 6 in one patient (14%). CONCLUSIONS: The Dotter stroke technique is a feasible and safe alternative to carotid stenting in the setting of acute ischemic stroke and may reduce the risk of hemorrhagic conversion. No re-occlusion occurred during follow-up in patients with post-Dotter stenosis ≤65%.