Radiology - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 10
-
ItemAssociation between hemorrhagic transformation after endovascular therapy and poststroke seizures(WILEY, 2018-02)OBJECTIVE: Endovascular therapy has recently become standard therapy for select patients with acute ischemic stroke. Infarcted brain tissue may undergo hemorrhagic transformation (HT) after endovascular therapy. We investigated the association between HT and occurrence of poststroke seizures in patients treated with endovascular therapy. METHODS: Consecutive patients treated with endovascular therapy for acute anterior circulation ischemic stroke were included. HT was assessed with computed tomography/magnetic resonance imaging (CT/MRI) at 24 h after stroke onset. Patients were followed for up to 2 years for seizure occurrence. RESULTS: A total of 205 (57.1% male) patients were analyzed. Median age was 69 years (interquartile range [IQR] 57-78). Among patients with HT, 17.9% (10/56) developed poststroke seizures compared with 4.0% (6/149) among those without HT (hazard ratio [HR] 5.52; 95% confidence interval [CI] 2.00-15.22; P = .001). The association remained significant after adjustment for cortical involvement, baseline National Institutes of Health Stroke Scale score, age and use of intravenous tissue plasminogen activator and clot retrieval (HR 4.85; 95% CI 1.60-14.76; P = .005). In patients who developed seizures within the follow-up period, median time to first seizure was 111 days (IQR 28-369) in patients with HT and 36 days (IQR 0.5-183) in patients without HT. SIGNIFICANCE: A patient who develops HT following endovascular therapy for acute ischemic stroke had a nearly 5 times higher rate of developing poststroke seizures within 2 years. HT may be used as an imaging biomarker for poststroke seizures.
-
ItemEndovascular clot retrieval in acute stroke with large ischaemic core is not always associated with poor outcomes(WILEY, 2019-04)BACKGROUND: The benefits of endovascular clot retrieval (ECR) for anterior circulation stroke with large ischaemic cores remain uncertain. In spite of recent pooled analysis of randomised controlled studies, conclusions regarding the fate of large ischaemic cores cannot be reached given the small number of included patients. AIM: To evaluate outcomes of ECR in acute stroke with large ischaemic core. METHODS: This was a single centre retrospective study of patients treated with ECR in the period 2012-2017. The inclusion criteria were anterior circulation stroke with symptom onset less than 6 h, baseline computed tomography perfusion and a 90-day clinical follow up defined by the modified Rankin score. RESULTS: Two hundred and sixty-one patients were included. Median age of 72 (interquartile range: 61-78) and 59% were male. The mean ischaemic core volume was 27.6 mL (SD: 34.9 mL). There were 235 patients with an ischaemic core volume of <70 mL and 26 patients with an ischaemic core volume of ≥70 mL. There was no statistically significant difference; however, in a 90-day functional independence with 66% (154/235) in the <70 mL core group and 54% (14/26) in the ≥70 mL core group reaching a 90-day modified Rankin score ≤2. CONCLUSIONS: We found that patients selected for ECR with ischaemic core size ≥70 mL had clinical outcomes not significantly different compared with those with smaller ischaemic cores. We recommend that large ischaemic core size alone does not necessarily constitute an absolute contraindication for ECR. Randomised controlled studies are needed to define better the benefits for this group of patients.
-
ItemAntiplatelet resistance and thromboembolic complications in neurointerventional procedures.(Frontiers Media SA, 2011)Antiplatelet resistance is emerging as a significant factor in effective secondary stroke prevention. Prevalence of aspirin and clopidogrel resistance is dependent upon laboratory test and remains contentious. Large studies in cardiovascular disease populations have demonstrated worse ischemic outcomes in patients with antiplatelet resistance, particularly in patients with coronary stents. Thromboembolism is a complication of neurointerventional procedures that leads to stroke. Stroke rates related to aneurysm coiling range from 2 to 10% and may be higher when considering silent ischemia. Stroke associated with carotid stenting is a major cause of morbidity. Antiplatelet use in the periprocedure setting varies among different centers. No guidelines exist for use of antiplatelet regimens in neurointerventional procedures. Incidence of stroke in patients post procedure may be partly explained by resistance to antiplatelet agents. Further research is required to establish the incidence of stroke in patients with antiplatelet resistance undergoing neurointerventional procedures.
-
ItemMachine Learning for Outcome Prediction of Acute Ischemic Stroke Post Intra-Arterial Therapy(PUBLIC LIBRARY SCIENCE, 2014-02-10)INTRODUCTION: Stroke is a major cause of death and disability. Accurately predicting stroke outcome from a set of predictive variables may identify high-risk patients and guide treatment approaches, leading to decreased morbidity. Logistic regression models allow for the identification and validation of predictive variables. However, advanced machine learning algorithms offer an alternative, in particular, for large-scale multi-institutional data, with the advantage of easily incorporating newly available data to improve prediction performance. Our aim was to design and compare different machine learning methods, capable of predicting the outcome of endovascular intervention in acute anterior circulation ischaemic stroke. METHOD: We conducted a retrospective study of a prospectively collected database of acute ischaemic stroke treated by endovascular intervention. Using SPSS®, MATLAB®, and Rapidminer®, classical statistics as well as artificial neural network and support vector algorithms were applied to design a supervised machine capable of classifying these predictors into potential good and poor outcomes. These algorithms were trained, validated and tested using randomly divided data. RESULTS: We included 107 consecutive acute anterior circulation ischaemic stroke patients treated by endovascular technique. Sixty-six were male and the mean age of 65.3. All the available demographic, procedural and clinical factors were included into the models. The final confusion matrix of the neural network, demonstrated an overall congruency of ∼ 80% between the target and output classes, with favourable receiving operative characteristics. However, after optimisation, the support vector machine had a relatively better performance, with a root mean squared error of 2.064 (SD: ± 0.408). DISCUSSION: We showed promising accuracy of outcome prediction, using supervised machine learning algorithms, with potential for incorporation of larger multicenter datasets, likely further improving prediction. Finally, we propose that a robust machine learning system can potentially optimise the selection process for endovascular versus medical treatment in the management of acute stroke.
-
ItemProximal Hyperdense Middle Cerebral Artery Sign Predicts Poor Response to Thrombolysis(PUBLIC LIBRARY SCIENCE, 2014-05-07)The aim of our study was to compare the rapid neurological improvement after intravenous recombinant tissue-type plasminogen activator (rtPA) in patients with proximal hyperdense middle cerebral artery sign (p-HMCAS) to those without the sign and those with the distal hyperdense middle cerebral artery sign (d-HMCAS). Admission and 24 hour non-contrast CT scans of 120 patients with middle cerebral artery (MCA) territory stroke who were treated with intravenous rtPA were assessed for the presence of p-HMCAS and d-HMCAS. The sign was classified according to the site of occlusion. Rapid neurological improvement was defined as ≥ 50% improvement in the NIHSS score at 24 hours after thrombolysis. Rapid neurological recovery after thrombolysis was assessed and compared between the subgroups. Rapid neurological recovery was less common in the pooled group of patients with either p-HMCAS or d-HMCAS than those without the sign (p<0.01). Patients with p-HMCAS were less likely to have rapid neurological recovery than those with d-HMCAS (p<0.01). However, there was no difference in early neurological recovery between patients with d-HMCAS and those without any hyperdense sign. Our study showed that poor neurological recovery post rtPA was confined to p-HMCAS and not to d-HMCAS, indicating that these signs have quite different prognostic significance.
-
ItemAdvances in medical revascularisation treatments in acute ischemic stroke.(Hindawi Limited, 2014)Urgent reperfusion of the ischaemic brain is the aim of stroke treatment and there has been ongoing research to find a drug that can promote vessel recanalisation more completely and with less side effects. In this review article, the major studies which have validated the use and safety of tPA are discussed. The safety and efficacy of other thrombolytic and anticoagulative agents such as tenecteplase, desmoteplase, ancrod, tirofiban, abciximab, eptifibatide, and argatroban are also reviewed. Tenecteplase and desmoteplase are both plasminogen activators with higher fibrin affinity and longer half-life compared to alteplase. They have shown greater reperfusion rates and improved functional outcomes in preliminary studies. Argatroban is a direct thrombin inhibitor used as an adjunct to intravenous tPA and showed higher rates of complete recanalisation in the ARTTS study with further studies which are now ongoing. Adjuvant thrombolysis techniques using transcranial ultrasound are also being investigated and have shown higher rates of complete recanalisation, for example, in the CLOTBUST study. Overall, development in medical therapies for stroke is important due to the ease of administration compared to endovascular treatments, and the new treatments such as tenecteplase, desmoteplase, and adjuvant sonothrombolysis are showing promising results and await further large-scale clinical trials.
-
ItemEvolution of Endovascular Therapy in Acute Stroke: Implications of Device Development(KOREAN STROKE SOC, 2015-05)Intravenous thrombolysis is an effective treatment for acute ischaemic stroke. However, vascular recanalization rates remain poor especially in the setting of large artery occlusion. On the other hand, endovascular intra-arterial therapy addresses this issue with superior recanalization rates compared with intravenous thrombolysis. Although previous randomized controlled studies of intra-arterial therapy failed to demonstrate superiority, the failings may be attributed to a combination of inferior intra-arterial devices and suboptimal selection criteria. The recent results of several randomized controlled trials have demonstrated significantly improved outcomes, underpinning the advantage of newer intra-arterial devices and superior recanalization rates, leading to renewed interest in establishing intra-arterial therapy as the gold standard for acute ischaemic stroke. The aim of this review is to outline the history and development of different intra-arterial devices and future directions in research.
-
ItemBlood Pressure May Be Associated with Arterial Collateralization in Anterior Circulation Ischemic Stroke before Acute Reperfusion Therapy(KOREAN STROKE SOC, 2017-05)BACKGROUND AND PURPOSE: Leptomeningeal collaterals maintain arterial perfusion in acute arterial occlusion but may fluctuate subject to arterial blood pressure (ABP). We aim to investigate the relationship between ABP and collaterals as assessed by computer tomography (CT) perfusion in acute ischemic stroke. METHODS: We retrospectively analyzed acute anterior circulation ischemic stroke patients with CT perfusion from 2009 to 2014. Collateral status using relative filling time delay (rFTD) determined by time delay of collateral-derived contrast opacification within the Sylvian fissure, from 0 seconds to unlimited count. The data were analyzed by zero-inflated negative binomial regression model including an appropriate interaction examining in the model in terms of occlusion location and onset-to-CT time (OCT). RESULTS: Two hundred and seventy patients were included. We found that increment of 10 mm Hg in BP, the odds that a patient would have rFTD equal to 0 seconds increased by 27.9% in systolic BP (SBP) (p=0.001), by 73.9% in diastolic BP (DBP) (p<0.001) and by 68.5% in mean BP (MBP) (p<0.001). For patients with rFTD not necessarily equal to 0 seconds, every 10 mm Hg increase in BP, there was a 7% decrease in expected count of seconds for rFTD in SBP (p=0.002), 10% decrease for rFTD in DBP and 11% decrease for rFTD in MBP. The arterial occlusion location and OCT showed no significant interaction in the BP-rFTD relationship (p>0.05). CONCLUSIONS: In acute ischemic stroke, higher ABP is possibly associated with improved leptomeningeal collaterals as identified by decreased rFTD.
-
ItemIs general anaesthesia preferable to conscious sedation in the treatment of acute ischaemic stroke with intra-arterial mechanical thrombectomy? A review of the literature(SPRINGER, 2013-01)INTRODUCTION: Intra-arterial mechanical thrombectomy (IAMT) is an endovascular technique that allows for the acute retrieval of intravascular thrombi and is increasingly being used for the treatment of acute ischaemic stroke (AIS). There are currently two anaesthetic options during IAMT: general anaesthesia (GA) and conscious sedation (CS). The decision to use GA versus CS is the source of controversy, as it requires careful balance between patient pain, movement and airway protection whilst minimising time delay and haemodynamic fluctuations. This review examines and summarises the evidence for the use of GA versus CS in the treatment of AIS by IAMT. METHODS: Studies were identified using systematic bibliographic searches. The five applicable studies were analysed with reference to overall outcomes and the key parameters that govern the decision to use GA or CS. The key parameters included the impact of GA and CS on pain, complication rates, time delays, airway protection and haemodynamic stability. RESULTS: Several retrospective analyses have shown that the use of GA is associated with adverse outcomes. CONCLUSION: Intra-arterial mechanical thrombectomy under general anaesthesia is associated with poor outcomes in observational studies. It is reasonable to offer conscious sedation as the preferred option where adverse patient factors such as agitation are lacking.
-
ItemEndovascular Thrombectomy for Ischemic Stroke Increases Disability-Free Survival, Quality of Life, and Life Expectancy and Reduces Cost(FRONTIERS MEDIA SA, 2017-12-14)BACKGROUND: Endovascular thrombectomy improves functional outcome in large vessel occlusion ischemic stroke. We examined disability, quality of life, survival and acute care costs in the EXTEND-IA trial, which used CT-perfusion imaging selection. METHODS: Large vessel ischemic stroke patients with favorable CT-perfusion were randomized to endovascular thrombectomy after alteplase versus alteplase-only. Clinical outcome was prospectively measured using 90-day modified Rankin scale (mRS). Individual patient expected survival and net difference in Disability/Quality-adjusted life years (DALY/QALY) up to 15 years from stroke were modeled using age, sex, 90-day mRS, and utility scores. Level of care within the first 90 days was prospectively measured and used to estimate procedure and inpatient care costs (US$ reference year 2014). RESULTS: There were 70 patients, 35 in each arm, mean age 69, median NIHSS 15 (IQR 12-19). The median (IQR) disability-weighted utility score at 90 days was 0.65 (0.00-0.91) in the alteplase-only versus 0.91 (0.65-1.00) in the endovascular group (p = 0.005). Modeled life expectancy was greater in the endovascular versus alteplase-only group (median 15.6 versus 11.2 years, p = 0.02). The endovascular thrombectomy group had fewer simulated DALYs lost over 15 years [median (IQR) 5.5 (3.2-8.7) versus 8.9 (4.7-13.8), p = 0.02] and more QALY gained [median (IQR) 9.3 (4.2-13.1) versus 4.9 (0.3-8.5), p = 0.03]. Endovascular patients spent less time in hospital [median (IQR) 5 (3-11) days versus 8 (5-14) days, p = 0.04] and rehabilitation [median (IQR) 0 (0-28) versus 27 (0-65) days, p = 0.03]. The estimated inpatient costs in the first 90 days were less in the thrombectomy group (average US$15,689 versus US$30,569, p = 0.008) offsetting the costs of interhospital transport and the thrombectomy procedure (average US$10,515). The average saving per patient treated with thrombectomy was US$4,365. CONCLUSION: Thrombectomy patients with large vessel occlusion and salvageable tissue on CT-perfusion had reduced length of stay and overall costs to 90 days. There was evidence of clinically relevant improvement in long-term survival and quality of life. CLINICAL TRIAL REGISTRATION: http://www.ClinicalTrials.gov NCT01492725 (registered 20/11/2011).