Standards for Detecting, Interpreting, and Reporting Noncontrast Computed Tomographic Markers of Intracerebral Hemorrhage Expansion.

Significant hematoma expansion (HE) affects one-fifth of people within 24 hours after acute intracerebral hemorrhage (ICH), and its prevention is an appealing treatment target. Although the computed tomography (CT)-angiography spot sign predicts HE, only a minority of ICH patients receive contrast injection. Conversely, noncontrast CT (NCCT) is used to diagnose nearly all ICH, so NCCT markers represent a widely available alternative for prediction of HE. However, different NCCT signs describe similar features, with lack of consensus on the optimal image acquisition protocol, assessment, terminology, and diagnostic criteria. In this review, we propose practical guidelines for detecting, interpreting, and reporting NCCT predictors of HE. ANN NEUROL 2019;86:480-492.

Endovascular thrombectomy for tandem acute ischemic stroke associated with cervical artery dissection: a systematic review and meta-analysis.

PURPOSE: Strokes associated with cervical artery dissection have been managed primarily with antithrombotics with poor outcomes. The additive role of endovascular thrombectomy remains unclear. The objective was to perform systematic review and meta-analysis to compare endovascular thrombectomy and medical therapy for acute ischemic stroke associated with cervical artery dissection. METHODS: Studies from six electronic databases included outcomes of patient cohorts with acute ischemic stroke secondary to cervical artery dissection who underwent treatment with endovascular thrombectomy. A meta-analysis of proportions was conducted with a random effects model. Modified Rankin score at 90 days (mRS 0-2) was the primary outcome. Other outcomes included proportion of patients with thrombolysis in cerebral infarction (TICI) 2b-3 flow, 90-day mortality rate, and 90-day symptomatic intracerebral hemorrhage (sICH) rate. RESULTS: Six studies were included, comprising 193 cases that underwent thrombectomy compared with 59 cases that were managed medically. Successful recanalization with a pooled proportion of thrombolysis in cerebral infarction (TICI) 2b-3 flow in the thrombectomy group was 74%. Favorable outcome (mRS 0-2) was superior in the pooled thrombectomy group (62.9%, 95% CI 55.8-69.5%) compared with medical management (41.5%, 95% CI 29.0-55.1%, P = 0.006). The pooled rate of 90-day mortality was similar for endovascular vs medical (8.6% vs 6.3%). The pooled rate of symptomatic intracranial haemorrhage (sICH) did not significantly differ (5.9% vs 4.2%, P = 0.60). CONCLUSIONS: Current data suggest that endovascular thrombectomy may be an option in patients with acute ischemic stroke due to cervical artery dissection. This requires further confirmation in higher quality prospective studies.

Endovascular clot retrieval for M2 segment middle cerebral artery occlusion: a systematic review and meta-analysis.

BACKGROUND: Endovascular clot retrieval (ECR) is the standard of care for acute ischaemic stroke due to large vessel occlusion. However, isolated occlusion of the M2 segment of the middle cerebral artery (MCA) was underrepresented in the landmark trials. AIMS: Given the potential treatment benefit associated with M2 MCA occlusions, we aimed to evaluate the outcome of patients undergoing ECR for M2 occlusion. METHODS: We conducted a systematic review and meta-analysis of the available literature that included patients with M2 MCA occlusions who underwent ECR. Successful reperfusion was defined as a treatment in cerebral ischaemia score of 2b-3. Good outcome was defined as a modified Rankin Scale score ≤ 2. We also analysed complications such as post-procedure symptomatic intracranial haemorrhage and mortality at 3 months. RESULTS: Fifteen studies including 1105 patients with isolated M2 occlusions were analysed. Successful reperfusion occurred in 75.4% (95% confidence interval (CI) 67.7-84.1%) of patients; good outcome was observed in 58.3% (95% CI 51.7-63.8% of patients. The rate of symptomatic intracranial haemorrhage was 5.1% (95% CI 4.2-8.3%), and 3-month mortality rate was 12.2% (95% CI 10.4-16.3%). CONCLUSION: The outcomes of ECR treatment of M2 occlusions are favourable, with good safety profile. Comparison to medical management from large registries or randomised controlled trials is warranted.

Carotid artery stenting: Current state of evidence and future directions.

Both carotid endarterectomy (CEA) and carotid artery stenting (CAS) are common treatments for carotid artery stenosis. Several randomized controlled trials (RCTs) have compared CEA to CAS in the treatment of carotid artery stenosis. These studies have suggested that CAS is more strongly associated with periprocedural stroke; however, CEA is more strongly associated with myocardial infarction. Published long-term outcomes report that CAS and CEA are similar. A reduction in complications associated with CAS has also been demonstrated over time. The symptomatic status of the patient and history of previous CEA or cervical radiotherapy are significant factors when deciding between CEA or CAS. Numerous carotid artery stents are available, varying in material, shape and design but with minimal evidence comparing stent types. The role of cerebral protection devices is unclear. Dual antiplatelet therapy is typically prescribed to prevent in-stent thrombosis, and however, evidence comparing periprocedural and postprocedural antiplatelet therapy is scarce, resulting in inconsistent guidelines. Several RCTs are underway that will aim to clarify some of these uncertainties. In this review, we summarize the development of varying techniques of CAS and studies comparing CAS to CEA as treatment options for carotid artery stenosis.

Outcomes of endovascular thrombectomy with and without bridging thrombolysis for acute large vessel occlusion ischaemic stroke.

BACKGROUND: Endovascular thrombectomy (EVT) for management of large vessel occlusion (LVO) acute ischaemic stroke is now current best practice. AIM: To determine if bridging intravenous (i.v.) alteplase therapy confers any clinical benefit. METHODS: A retrospective study of patients treated with EVT for LVO was performed. Outcomes were compared between patients receiving thrombolysis and EVT with EVT alone. Primary end-points were reperfusion rate, 90-day functional outcome and mortality using the modified Rankin Scale (mRS) and symptomatic intracranial haemorrhage (sICH). RESULTS: A total of 355 patients who underwent EVT was included: 210 with thrombolysis (59%) and 145 without (41%). The reperfusion rate was higher in the group receiving i.v. tissue plasminogen activator (tPA) (unadjusted odds ratio (OR) 2.2, 95% confidence interval (CI): 1.29-3.73, P = 0.004), although this effect was attenuated when all variables were considered (adjusted OR (AOR) 1.22, 95% CI: 0.60-2.5, P = 0.580). The percentage achieving functional independence (mRS 0-2) at 90 days was higher in patients who received bridging i.v. tPA (AOR 2.17, 95% CI: 1.06-4.44, P = 0.033). There was no significant difference in major complications, including sICH (AOR 1.4, 95% CI: 0.51-3.83, P = 0.512). There was lower 90-day mortality in the bridging i.v. tPA group (AOR 0.79, 95% CI: 0.36-1.74, P = 0.551). Fewer thrombectomy passes (2 versus 3, P = 0.012) were required to achieve successful reperfusion in the i.v. tPA group. Successful reperfusion (modified thrombolysis in cerebral infarction ≥2b) was the strongest predictor for 90-day functional independence (AOR 10.4, 95% CI:3.6-29.7, P < 0.001). CONCLUSION: Our study supports the current practice of administering i.v. alteplase before endovascular therapy.

Cerebral embolic protection in thoracic endovascular aortic repair.

BACKGROUND: Stroke occurs in 3% to 8% and silent cerebral infarction in >60% of patients undergoing thoracic endovascular aortic repair (TEVAR). We investigated the utility of a filter cerebral embolic protection device (CEPD) to reduce diffusion-weighted magnetic resonance imaging (DW-MRI) detected cerebral injury and gaseous and solid embolization during TEVAR. METHODS: Patients anatomically suitable underwent TEVAR with CEPD, together with intraoperative transcranial Doppler to detect gaseous and solid high-intensity transient signals (HITSs), pre- and postoperative DW-MRI, and clinical neurologic assessment ≤6 months after the procedure. RESULTS: Ten patients (mean age, 68 years) underwent TEVAR with a CEPD. No strokes or device-related complications developed. The CEPD added a median of 7 minutes (interquartile range [IQR], 5-16 minutes) to the procedure, increased the fluoroscopy time by 3.3 minutes (IQR, 2.4-3.9 minutes), and increased the total procedural radiation by 2.2%. The dose area product for CEPD was 1824 mGy·cm2 (IQR, 1235-3392 mGy·cm2). The average contrast volume used increased by 23 mL (IQR, 24-35 mL). New DW-MRI lesions, mostly in the hindbrain, were identified in seven of nine patients (78%). The median number was 1 (IQR, 1-3), with a median surface area of 6 mm2 (IQR, 3-16 mm2). A total of 2835 HITSs were detected in seven patients: 91% gaseous and 9% solid. The maximum number of HITSs were detected during CEPD manipulation: 142 (IQR, 59-146; 95% gaseous and 5% solid). The maximum number of HITSs during TEVAR occurred during stent deployment: 82 (IQR, 73-142; 81% gas and 11% solid). Solid HITSs were associated with an increase in surface area of new DW-MRI lesions (rs = 0.928; P = .01). Increased gaseous HITSs were associated with new DW-MRI lesions (rs = 0.912; P = .01), which were smaller (<3 mm; r = 0.88; P = .02). Embolic debris was captured in 95% of the filters. The median particle count was 937 (IQR, 146-1687), and the median surface area was 2.66 mm2 (IQR, 0.08-9.18 mm2). CONCLUSIONS: The use of a CEPD with TEVAR appeared to be safe and feasible in this first pilot study and could serve as a useful adjunct to reduce cerebral injury. The significance of gaseous embolization and its role in cerebral injury in TEVAR warrants further investigation.

Functional magnetic resonance imaging in clinical practice: State of the art and science.

BACKGROUND: Functional magnetic resonance imaging (fMRI) has become a mainstream neuroimaging modality in the assessment of patients being evaluated for brain tumour and epilepsy surgeries. Thus, it is important for doctors in primary care settings to be well acquainted with the present and potential future applications, as well as limitations, of this modality. OBJECTIVE: The objective of this article is to introduce the theoretical principles and state-of-the-art clinical applications of fMRI in brain tumour and epilepsy surgery, with a focus on the implications for clinical primary care. DISCUSSION: fMRI enables non-invasive functional mapping of specific cortical tasks (eg motor, language, memory-based, visual), revealing information about functional localisation, anatomical variation in cortical function, and disease effects and adaptations, including the fascinating phenomenon of brain plasticity. fMRI is currently ordered by specialist neurologists and neurosurgeons for the purposes of pre-surgical assessment, and within the context of an experienced multidisciplinary team to prepare, conduct and interpret the scan. With an increasing number of patients undergoing fMRI, general practitioners can expect questions about the current and emerging role of fMRI in clinical care from these patients and their families.

Evaluation of techniques to improve a deep learning algorithm for the automatic detection of intracranial haemorrhage on CT head imaging.

BACKGROUND: Deep learning (DL) algorithms are playing an increasing role in automatic medical image analysis. PURPOSE: To evaluate the performance of a DL model for the automatic detection of intracranial haemorrhage and its subtypes on non-contrast CT (NCCT) head studies and to compare the effects of various preprocessing and model design implementations. METHODS: The DL algorithm was trained and externally validated on open-source, multi-centre retrospective data containing radiologist-annotated NCCT head studies. The training dataset was sourced from four research institutions across Canada, the USA and Brazil. The test dataset was sourced from a research centre in India. A convolutional neural network (CNN) was used, with its performance compared against similar models with additional implementations: (1) a recurrent neural network (RNN) attached to the CNN, (2) preprocessed CT image-windowed inputs and (3) preprocessed CT image-concatenated inputs. The area under the receiver operating characteristic curve (AUC-ROC) and microaveraged precision (mAP) score were used to evaluate and compare model performances. RESULTS: The training and test datasets contained 21,744 and 491 NCCT head studies, respectively, with 8,882 (40.8%) and 205 (41.8%) positive for intracranial haemorrhage. Implementation of preprocessing techniques and the CNN-RNN framework increased mAP from 0.77 to 0.93 and increased AUC-ROC [95% confidence intervals] from 0.854 [0.816-0.889] to 0.966 [0.951-0.980] (p-value = 3.91 × 10-12). CONCLUSIONS: The deep learning model accurately detected intracranial haemorrhage and improved in performance following specific implementation techniques, demonstrating clinical potential as a decision support tool and an automated system to improve radiologist workflow efficiency. KEY POINTS: • The deep learning model detected intracranial haemorrhages on computed tomography with high accuracy. • Image preprocessing, such as windowing, plays a large role in improving deep learning model performance. • Implementations which enable an analysis of interslice dependencies can improve deep learning model performance. • Visual saliency maps can facilitate explainable artificial intelligence systems. • Deep learning within a triage system may expedite earlier intracranial haemorrhage detection.

Sustainability in interventional radiology: are we doing enough to save the environment?

BACKGROUND: Healthcare waste contributes substantially to the world's carbon footprint. Our aims are to review the current knowledge of Interventional Radiology (IR) waste generation and ways of reducing waste in practice, to quantify the environmental and financial impact of waste generated and address green initiatives to improve IR waste management. METHODS: A systematic literature search was conducted in July 2022 using the Medline and Embase literature databases. The scope of the search included the field of IR as well as operating theatre literature, where relevant to IR practice. RESULTS: One-hundred articles were reviewed and 68 studies met the inclusion criteria. Greening initiatives include reducing, reusing and recycling waste, as well as strict waste segregation. Interventional radiologists can engage with suppliers to reformulate procedure packs to minimize unnecessary items and packaging. Opened but unused equipment can be prevented if there is better communication within the team and increased staff awareness of wasted equipment cost. Incentives to use soon-to-expire equipment can be offered. Power consumption can be reduced by powering down operating room lights and workstations when not in use, changing to Light Emitting Diode (LED) and motion sensor lightings. Surgical hand wash can be replaced with alcohol-based hand rubs to reduce water usage. Common barriers to improving waste management include the lack of leadership, misconceptions regarding infectious risk, lack of data, concerns about increased workload, negative staff attitudes and resistance to change. Education remains a top priority to engage all staff in sustainable healthcare practices. CONCLUSION: Interventional radiologists have a crucial role to play in improving healthcare sustainability. By implementing small, iterative changes to our practice, financial savings, greater efficiency and improved environmental sustainability can be achieved.

Radiologic Mimics of Osteomyelitis and Septic Arthritis: A Pictorial Essay.

Various imaging techniques may be employed in the investigation of suspected bone and joint infections. These include ultrasound, radiography, functional imaging such as positron emission tomography (PET) and nuclear scintigraphy, and cross-sectional imaging, including computed tomography (CT) and magnetic resonance imaging (MRI). The cross-sectional modalities represent the imaging workhorse in routine practice. The role of imaging also extends to include assessment of the anatomical extent of infection, potentially associated complications, and treatment response. The imaging appearances of bone and joint infections are heterogeneous and depend on the duration of infection, an individual patient's immune status, and virulence of culprit organisms. To add to the complexity of radiodiagnosis, one of the pitfalls of imaging musculoskeletal infection is the presence of other conditions that can share overlapping imaging features. This includes osteoarthritis, vasculopathy, inflammatory, and even neoplastic processes. Different pathologies may also coexist, for example, diabetic neuropathy and osteomyelitis. This pictorial review aims to highlight potential mimics of osteomyelitis and septic arthritis that are regularly encountered, with emphasis on specific imaging features that may aid the radiologist and clinician in distinguishing an infective from a noninfective aetiology.

Fronto-parietal involvement in chronic stroke motor performance when corticospinal tract integrity is compromised.

BACKGROUND: Preserved integrity of the corticospinal tract (CST) is a marker of good upper-limb behavior and recovery following stroke. However, there is less understanding of neural mechanisms that might help facilitate upper-limb motor recovery in stroke survivors with extensive CST damage. OBJECTIVE: The purpose of this study was to investigate resting state functional connectivity in chronic stroke survivors with different levels of CST damage and to explore neural correlates of greater upper-limb motor performance in stroke survivors with compromised ipsilesional CST integrity. METHODS: Thirty chronic stroke survivors (24 males, aged 64.7 ± 10.8 years) participated in this study. Three experimental sessions were conducted to: 1) obtain anatomical (T1, T2) structural (diffusion) and functional (resting state) MRI sequences, 2) determine CST integrity with transcranial magnetic stimulation (TMS) and conduct assessments of upper-limb behavior, and 3) reconfirm CST integrity status. Participants were divided into groups according to the extent of CST damage. Those in the extensive CST damage group did not show TMS evoked responses and had significantly lower ipsilesional fractional anisotropy. RESULTS: Of the 30 chronic stroke survivors, 12 were categorized as having extensive CST damage. Stroke survivors with extensive CST damage had weaker functional connectivity in the ipsilesional sensorimotor network and greater functional connectivity in the ipsilesional fronto-parietal network compared to those with preserved CST integrity. For participants with extensive CST damage, improved motor performance was associated with greater functional connectivity of the ipsilesional fronto-parietal network and higher fractional anisotropy of the ipsilesional rostral superior longitudinal fasciculus. CONCLUSIONS: Stroke survivors with extensive CST damage have greater resting state functional connectivity of an ipsilesional fronto-parietal network that appears to be a behaviorally relevant neural mechanism that improves upper-limb motor performance.

Artificial intelligence in clinical decision support and outcome prediction - applications in stroke.

Artificial intelligence (AI) is making a profound impact in healthcare, with the number of AI applications in medicine increasing substantially over the past five years. In acute stroke, it is playing an increasingly important role in clinical decision-making. Contemporary advances have increased the amount of information - both clinical and radiological - which clinicians must consider when managing patients. In the time-critical setting of acute stroke, AI offers the tools to rapidly evaluate and consolidate available information, extracting specific predictions from rich, noisy data. It has been applied to the automatic detection of stroke lesions on imaging and can guide treatment decisions through the prediction of tissue outcomes and long-term functional outcomes. This review examines the current state of AI applications in stroke, exploring their potential to reform stroke care through clinical decision support, as well as the challenges and limitations which must be addressed to facilitate their acceptance and adoption for clinical use.

CaRotid Artery Filtering Technique (CRAFT): A Technique for Carotid Artery Stenting with Intrinsic Embolic Protection.

PURPOSE: Carotid artery stenting (CAS) is an established treatment for symptomatic carotid artery stenosis as an alternative to carotid endarterectomy. A variety of techniques and devices have been devised to minimise periprocedural stroke risk using either proximal or distal embolic protection. This study presents a method of embolic protection during CAS-the CaRotid Artery Filtering Technique (CRAFT). MATERIALS AND METHODS: The CRAFT technique employs aspects of both proximal and distal embolic protection. The CASPER RX stent (MicroVention, Tustin, CA, USA), which is a double-layered, closed-cell, micromesh nitinol stent, is deployed across the carotid artery stenosis with the assistance of a FlowGate balloon guide catheter (Stryker Neurovascular, Fremont, CA, USA). The partially deployed stent acts as a distal filter while the balloon guide is deflated midway during stent deployment to prevent distal plaque embolisation, followed by completion of stent deployment and angioplasty. RESULTS: A total of 94 patients underwent CAS using the CRAFT technique between June 2016 and March 2021. Successful stent deployment was achieved in all patients. Preliminary results demonstrated acute stent occlusion in 6 patients (6.4%) and distal embolic stroke in 5 patients (5.3%). The median procedural fluoroscopy time was 34 minutes with an interquartile range of 22 to 55 minutes. CONCLUSION: The CRAFT technique of CAS presented by this study can be applied in the treatment of symptomatic carotid artery stenosis in both emergency and elective procedure settings with a high technical success and low distal embolic stroke risk.

Antiplatelet Drugs for Neurointerventions: Part 2 Clinical Applications.

Endovascular techniques have expanded to include balloon and stent-assistance, flow diversion and individualized endovascular occlusion devices, to widen the treatment spectrum for more complex aneurysm morphologies. While usually well-tolerated by patients, endovascular treatment of intracranial aneurysms carries the risk of complications, with procedure-related ischemic complications being the most common. Several antiplatelet agents have been studied in a neurointerventional setting for both prophylaxis and in the setting of intraprocedural thrombotic complications. Knowledge of these antiplatelet agents, evidence for their use and common dosages is important for the practicing neurointerventionist to ensure the proper application of these agents.Part one of this two-part review focused on basic platelet physiology, pharmacology of common antiplatelet medications and future directions and therapies. Part two focuses on clinical applications and evidence based therapeutic regimens.

Review of deep learning algorithms for the automatic detection of intracranial hemorrhages on computed tomography head imaging.

Artificial intelligence is a rapidly evolving field, with modern technological advances and the growth of electronic health data opening new possibilities in diagnostic radiology. In recent years, the performance of deep learning (DL) algorithms on various medical image tasks have continually improved. DL algorithms have been proposed as a tool to detect various forms of intracranial hemorrhage on non-contrast computed tomography (NCCT) of the head. In subtle, acute cases, the capacity for DL algorithm image interpretation support might improve the diagnostic yield of CT for detection of this time-critical condition, potentially expediting treatment where appropriate and improving patient outcomes. However, there are multiple challenges to DL algorithm implementation, such as the relative scarcity of labeled datasets, the difficulties in developing algorithms capable of volumetric medical image analysis, and the complex practicalities of deployment into clinical practice. This review examines the literature and the approaches taken in the development of DL algorithms for the detection of intracranial hemorrhage on NCCT head studies. Considerations in crafting such algorithms will be discussed, as well as challenges which must be overcome to ensure effective, dependable implementations as automated tools in a clinical setting.

Application of a computational model in simulating an endovascular clot retrieval service system within regional Australia.

INTRODUCTION: The global demand for endovascular clot retrieval (ECR) has grown rapidly in recent years creating challenges to healthcare system planning and resource allocation. This study aims to apply our established computational model to predict and optimise the performance and resource allocation of ECR services within regional Australia, and applying data from the state of South Australia as a modelling exercise. METHOD: Local geographic information obtained using the Google Maps application program interface and real-world data was input into the discrete event simulation model we previously developed. The results were obtained after the simulation was run over 5 years. We modelled and compared a single-centre and two-centre ECR service delivery system. RESULTS: Based on the input data, this model was able to simulate the ECR delivery system in the state of South Australia from the moment when emergency services were notified of a potential stroke patient to potential delivery of ECR treatment. In the model, ECR delivery improved using a two-centre system compared to a one-centre system, as the percentage of stroke patients requiring ECR was increased. When 15% of patients required ECR, the proportion of 'failure to receive ECR' cases for a single-centre system was 17.35%, compared to 3.71% for a two-centre system. CONCLUSIONS: Geolocation and resource utilisation within the ECR delivery system are crucial in optimising service delivery and patient outcome. Under the model assumptions, as the number of stroke cases requiring ECR increased, a two-centre ECR system resulted in increased timely ECR delivery, compared to a single-centre system. This study demonstrated the flexibility and the potential application of our DES model in simulating the stroke service within any location worldwide.

Four-Dimensional Magnetic Resonance Imaging Assessment of Intracranial Aneurysms: A State-of-the-Art Review.

Treatment of unruptured intracranial aneurysms can reduce the risk of subarachnoid hemorrhage and its associated morbidity and mortality. However, current methods to predict the risk of rupture and optimize treatment strategies for intracranial aneurysms are limited. Assessment of intra-aneurysmal flow using 4-dimensional magnetic resonance imaging (4D MRI) is a novel tool that could be used to guide therapy. A systematic search of the literature was performed to provide a state-of-the-art review on 4D MRI assessment of unruptured intracranial aneurysms. A total of 18 studies were available for review. Eccentric flow on 4D MRI is associated with a greater aspect ratio and peak wall shear stress (WSS). WSS, vorticity, and peak velocity are greater in saccular than fusiform aneurysms. Unstable aneurysms are associated with greater WSS, peak wall stress, and flow jet angle and may exhibit wall enhancement. In comparison to computational fluid dynamics (CFD), 4D MRI has a lower spatial resolution and reports lower WSS and velocity magnitudes, but these parameters equalize when spatial resolution is matched. 4D MRI demonstrates the intra-aneurysmal hemodynamic changes associated with flow diversion, including significantly decreased flow velocity. Thus, 4D MRI is a novel, noninvasive imaging tool used for the evaluation of hemodynamics within intracranial aneurysms. Hemodynamic indices derived from 4D MRI appear to correlate well with the simulated (CFD) values and may be used to measure the success of endovascular therapies and risk factors for aneurysm growth and rupture.

Antiplatelet Drugs for Neurointerventions: Part 1 Clinical Pharmacology.

The development of endovascular treatment for intracranial aneurysms has established new techniques such as balloon and stent-assistance, flow diversion and endosaccular occlusion devices. Antiplatelet treatment is an important aspect to reduce risk of thrombus formation on microcatheters and implanted devices when utilizing these methods. It is particularly relevant for flow diverting stents to prevent early and late stent thrombosis. Consideration of platelet physiology and appropriate selection of antiplatelet medication is important as platelet dysfunction drives many of the pathological processes and complications of neurointerventional procedures. Part one of this review focuses on basic platelet physiology, pharmacology of common antiplatelet medications and future directions and therapies. Part two focuses on clinical applications and evidence-based therapeutic regimens.

Geographic Service Delivery for Endovascular Clot Retrieval: Using Discrete Event Simulation to Optimize Resources.

BACKGROUND: Endovascular clot retrieval (ECR) is the standard of care for acute ischemic stroke caused by large vessel occlusion. Reducing stroke symptom onset to reperfusion time is associated with improved functional outcomes. This study aims to develop a computational model to predict and identify time-related outcomes of community stroke calls within a geographic area based on variable parameters to support planning and coordination of ECR services. METHODS: A discrete event simulation (DES) model to simulate and predict ECR service was designed using SimPy, a process-based DES framework written in Python. Geolocation data defined by the user, as well as that used by the model, were sourced using the Google Maps application programming interface. Variables were customized by the user on the basis of their local environment to provide more accurate prediction. RESULTS: A DES model can estimate the delay between the time that emergency services are notified of a potential stroke and potential cerebral reperfusion using ECR at a capable hospital. Variables can be adjusted to observe the effect of modifying each parameter input. By varying the percentage of stroke patients receiving ECR, we were able to define the levels at which our existing service begins to fail in service delivery and assess the effect of adding centers. CONCLUSIONS: This novel computational DES model can aid the optimization of delivery of a stroke service within a city, state, or country. By varying geographic, population, and other user-defined inputs, the model can be applied to any location worldwide.