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101 result(s) for "Kadirvel, Ramanathan"
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Comparison of citation rates between Covid-19 and non-Covid-19 articles across 24 major scientific journals
Covid-19 has been front and center in the global landscape since the beginning of 2020. In response, the scientific field has dedicated enormous amounts of resources to researching the virus and its effects. The number of times Covid-19 publications are being cited throughout the literature appears remarkably high but has not been directly compared to non-Covid-19 papers in the same journals over an extended period. In our study, we use Clarivate’s Web of Science—Science Citation Index Expanded™ database to identify Covid-19 papers published in 24 major scientific journals over a period of 24 months from January 1, 2020 to December 31, 2021. We conduct our search using keywords “Covid-19”, “coronavirus”, and “sars-cov-2” to locate publications with these words in the title. We then quantify the number of citations these papers have received and compare rates to non-Covid-19 papers in the same journals over the same timeframe. We find that, across 24 open-access and subscription-based scientific journals, Covid-19 papers published in the past 2 years currently have a median citation rate of 120.79 compared to 21.63 for non-Covid-19 papers. When negative binomial regression is used to minimize the influence of other variables such as article number variation and field of research, Covid-19 papers have still experienced more than 80% increase in citations relative to non-Covid-19 papers. These novel findings demonstrate that Covid-19 papers are being cited at remarkably higher rates than non-Covid-19 articles contained within the same journals. This suggests that journal impact factor, which is a product of the number of citations that recently published articles receive, will likely be drastically influenced by the number of Covid-19 papers that a journal has included within its pages in the previous years.
Early neurological improvement as a predictor of outcomes after endovascular thrombectomy for stroke: a systematic review and meta-analysis
BackgroundEarly neurological improvement (ENI) is a potential predictor for 90-day outcomes following mechanical thrombectomy for acute ischemic stroke (AIS). We performed a systematic review and meta-analysis to better understand whether ENI can be used as a surrogate for long-term outcomes following mechanical thrombectomy for AIS.MethodsFollowing the PRISMA guidelines, a systematic literature review of the English language literature was conducted using PubMed, MEDLINE, and Embase. ENI definition, including timing and degree of improvement on the National Institutes of Health Stroke Scale (NIHSS), was catalogued for each included study. Outcomes of interest included 90-day modified Rankin Scale (mRS) 0–2, symptomatic intracranial hemorrhage (sICH), and mortality. We calculated pooled ORs and their corresponding 95% confidence intervals (CI) for all definitions of ENI.ResultsWe included nine studies with 2355 patients in our analysis. ENI definitions included improvement in NIHSS of 8 points, 4 points, 12%, and 30% or greater. There was a significant association between ENI and mRS 0–2 rates (OR 8.62, 95% CI 4.86 to 15.29; p<0.001). Significance of the association was maintained across all definitions (p<0.001). Moreover, achieving ENI was a significant predictor of reduced odds for reported sICH rates (OR 0.11, 95% CI 0.06 to 0.21; p<0.001). There was a significant association between ENI and reduction in mortality rates (OR 0.09, 95% CI 0.05 to 0.15; p<0.001).ConclusionsBroadly defined, ENI is a promising predictor of good functional outcome at 90 days and is associated with lower rates of mortality and sICH.
Delayed hemorrhagic complications after flow diversion for intracranial aneurysms: a literature overview
Introduction Delayed aneurysm rupture and delayed intraparenchymal hemorrhages (DIPH) are poorly understood and often fatal complications of flow diversion (FD) for intracranial aneurysms. The purpose of this study was to identify risk factors for these complications. Methods We performed a systematic review on post-FD delayed aneurysm rupture and DIPH. For each reported case, we collected the following information: aneurysm location, size and rupture status, type of flow diverter used, timing of the hemorrhage, and neurological outcome. We reported descriptive statistics of patients suffering DIPH and delayed aneurysm rupture to determine if there were any characteristics consistently present among patients with these complications. Results We identified 81 delayed aneurysm ruptures and 101 DIPH. Of the delayed ruptures, 76.6 % (45/58) occurred within 1 month. The prognosis of delayed ruptures was poor, with 81.3 % (61/75) experiencing death or poor neurological outcome. Giant aneurysms accounted for 46.3 % of ruptures (31/67). Of these aneurysms, 80.9 % (55/68) were initially unruptured. Of the delayed ruptured aneurysms, 17.8 % (13/73) had prior or concomitant coiling. DIPHs were ipsilateral to the treated aneurysm in 82.2 % (60/73) of cases. Of the DIPH, 86.0 % (43/50) occurred within 1 month after FDS. Combined morbidity/mortality rate was 68.5 % (50/73) following DIPH. Of DIPHs, 23.0 % (14/61) occurred in patients with giant aneurysms. Conclusions Our study demonstrates that giant aneurysms represent almost 50 % of delayed aneurysm ruptures in the flow diverter literature. About 20 % of delayed ruptures occurred despite associated coiling. A substantial proportion of DIPHs occur early following FDS treatment of giant aneurysms.
Long-term outcomes of flow diversion for unruptured intracranial aneurysms: a systematic review and meta-analysis
BackgroundFlow diverters have been widely used in clinical practice for more than a decade. However, most outcome data are limited to 1 year timepoints. This study aims to offer meta-analysis data on long-term (>1 year) safety and effectiveness results for patients with aneurysms treated with flow diverters.MethodsPubMed, Web of Science, Embase, and SCOPUS were searched up to February 24, 2022 using the AutoLit platform. We included primary studies assessing the long-term outcomes for flow diverter devices to manage unruptured internal carotid artery aneurysms with a follow-up period of >1 year. The meta-analysis was carried out using Comprehensive Meta-Analysis software (CMA).ResultsEleven studies were included in the meta-analysis. The pooled occlusion rates after flow diversion treatment for unruptured intracranial brain aneurysms were 77%, 87.4%, 84.5%, 89.4%, 96% for 1 year, 1–2 years, 2 years, 3 years, and 5 years follow-up, respectively. The in-stent stenosis rate was 4.8% and the retreatment rate for the long-term follow-up period was 5%. No delayed rupture of the aneurysm was reported, and there was one case of delayed ischemic stroke. The sensitivity analysis of the prospective studies showed a complete occlusion rate of 83.5% and 85.2% for 1 and 3 years of follow-up, respectively.ConclusionFlow diverters are safe and effective in short- and long-term follow-up and rarely cause serious delayed side effects.
Orbit image analysis machine learning software can be used for the histological quantification of acute ischemic stroke blood clots
Our aim was to assess the utility of a novel machine learning software (Orbit Image Analysis) in the histological quantification of acute ischemic stroke (AIS) clots. We analyzed 50 AIS blood clots retrieved using mechanical thrombectomy procedures. Following H&E staining, quantification of clot components was performed by two different methods: a pathologist using a reference standard method (Adobe Photoshop CC) and an experienced researcher using Orbit Image Analysis. Following quantification, the clots were categorized into 3 types: RBC dominant (≥60% RBCs), Mixed and Fibrin dominant (≥60% Fibrin). Correlations between clot composition and Hounsfield Units density on Computed Tomography (CT) were assessed. There was a significant correlation between the components of clots as quantified by the Orbit Image Analysis algorithm and the reference standard approach (ρ = 0.944**, p < 0.001, n = 150). A significant relationship was found between clot composition (RBC-Rich, Mixed, Fibrin-Rich) and the presence of a Hyperdense artery sign using the algorithmic method (X2(2) = 6.712, p = 0.035*) but not using the reference standard method (X2(2) = 3.924, p = 0.141). Orbit Image Analysis machine learning software can be used for the histological quantification of AIS clots, reproducibly generating composition analyses similar to current reference standard methods.
Efficacy and safety of surpass evolve flow diverters: A systematic review and meta-analysis
To provide cumulative evidence on the safety and efficacy of the Surpass Evolve Flow Diverters (SE-FDs) in treating intracranial aneurysms. PubMed, Scopus, Embase, and Web of Science were searched until May, 2024. The primary efficacy endpoint was complete occlusion rate, and the safety endpoints included rate of different complications and mortality. Data is pooled and reported with 95 % confidence intervals (CIs) using random-effect models. A meta-regression analysis was performed to assess the potential effects of confounding factors on study endpoints. Eleven studies with 690 patients and 757 aneurysms were included. There was moderate risk of bias in all studies. With a median follow-up of 243 days, the complete occlusion rate was 67.1 % (95 %CI: 57.3–75.5 %, I2=72 %), with no difference between ruptured and unruptured aneurysms (p = 0.97). Stent stenosis was the most frequent complication which occurred in 18.2 % (95 %CI: 10.3–30.1 %, I2=71 %) of aneurysms at a median follow-up of 306 days. The rate of thromboembolic complications was 6.6 % (95 %CI: 3.8–11 %, I2=50 %), including ischemic stroke in 1.9 % (95 %CI: 1.1–3.4 %, I2=0 %) of patients. Device-related mortality rate was 0.5 % (95 %CI: 0.2–1.5 %, I2=0 %). Meta-regression showed that diameter of aneurysm was significantly associated with complete occlusion rate (coefficient: - 0.11, p < 0.001). SE-FD is effective for treating intracranial aneurysms, with moderate efficacy compared to other devices and an acceptable rate of complications. Larger aneurysm size predicts lower occlusion rates. The lack of controlled trials warrants further research to explore the efficacy and safety of SE-FDs in clinical practice. •The Surpass Evolve (SE) is an emerging flow diverter to treat intracranial aneurysms.•Rate of complete occlusion was ∼70 % for both acutely ruptured and unruptured aneurysms.•Meta-regression showed that larger aneurysm size predicts lower occlusion rates.•Complication rates (∼7 %), including ischemic stroke (∼2 %) and mortality (∼2 %), were acceptable.•The lack of trials and low quality of evidence highlight the need for further studies.
Clot permeability and histopathology: is a clot’s perviousness on CT imaging correlated with its histologic composition?
BackgroundClot perviousness in large vessel occlusion has been shown to be associated with improved recanalization outcomes with mechanical thrombectomy and intravenous thrombolysis.ObjectiveTo evaluate the association between clot perviousness based on thrombus attenuation increase (TAI) on CT, and histologic composition of clots in acute ischemic stroke (AIS).MethodsA retrospective review was completed of patients with AIS secondary to large vessel occlusion, non-contrast CT (NCCT) and CT angiography (CTA) images, and histologic analysis of the retrieved clot. TAI was measured by subtracting clot attenuation on NCCT from the attenuation on CTA. Up to 3 regions of interest (ROIs) were evaluated on each clot; the average attenuation was used for analysis if multiple ROIs were assessed. Pervious clots were defined as TAI ≥10 Hounsfield units (HUs); impervious clots had TAI <10 HU. Histopathologic analyses of clots were assessed for relative compositions of red blood cells (RBCs), white blood cells (WBCs), fibrin, and platelets/other.Results57 patients were included. Pervious clots were more likely to be RBC rich (p=0.04); impervious clots were more likely to be fibrin and WBC rich (p=0.01 for both). Pervious clots also had greater RBC density than impervious clots (49.8% and 33.0%, respectively; p=0.006); fibrin density of pervious clots was lower than that of impervious clots (17.8% and 23.2%, respectively; p=0.02).ConclusionClot perviousness, assessed on NCCT and CTA imaging, is associated with higher RBC density and lower fibrin density, offering a possible explanation for the higher rates of successful thrombectomy and favorable clinical outcome seen in such patients.
Neck apposition is a key factor for aneurysm occlusion after Woven EndoBridge device embolization
BackgroundSealing of the aneurysm neck with a Woven EndoBridge (WEB) device is recommended for disrupting the blood flow inside the aneurysm. This study investigates the relationship between WEB neck apposition and aneurysm occlusion rates.MethodsAneurysms treated with a WEB from March 2017 to May 2022 at a single center were included. WEB neck apposition (poor/good) and WEB protrusion (yes/no) were evaluated on post-detachment high resolution cone beam CT images. Angiographic occlusion was assessed with the Bicêtre Occlusion Scale score (BOSS). Univariate and multivariable analysis tested the association between neck apposition and occlusion rates.ResultsThe study included 159 aneurysms in 141 patients (mean age 55.8±11.2 years; 64.2% women). Good neck apposition and protrusion were noted in 123 (77.4%) and 30 (18.9%) cases, respectively. Inter-rater agreements were good for neck apposition (κ=0.75) and protrusion (κ=0.78). Complete and adequate occlusion was achieved in 104 (65%) and 130 (82%) cases, respectively (median follow-up 18 months). Good neck apposition was a strong independent predictor for both adequate (adjusted OR (aOR)=5.9, 95% CI 2.4 to 14.9; P<0.001) and complete occlusion (aOR=7.1, 95% CI 3.0 to 18.1; P<0.001). Protrusion was more frequent in the adequate occlusion group versus the aneurysm recurrence group without reaching statistical significance (P=0.06), but was associated with more thromboembolic complications (9/30 (30%) vs 12/129 (9%); P<0.01). WEB shape modification was significantly greater in poor apposition cases (P=0.03).ConclusionsAchieving good neck apposition of the WEB strongly predicts aneurysm occlusion during follow-up. WEB protrusion should be minimized due to the increase in thromboembolic risk with limited impact on aneurysm occlusion.
What can we learn from machine learning studies on flow diverter aneurysm embolization? A systematic review
BackgroundAs the use of flow diverters has expanded in recent years, predicting successful outcomes has become more challenging for certain aneurysms.ObjectiveTo provide neurointerventionalists with an understanding of the available machine learning algorithms for predicting the success of flow diverters in occluding aneurysms.MethodsThis study followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the four major medical databases (PubMed, Embase, Scopus, Web of Science) were screened. The study included original research articles that evaluated the predictive abilities of various machine learning algorithms for determining the success of flow diverters in achieving aneurysm occlusion.ResultsFive studies out of 217 were included based on our criteria. The included studies used various variables (patient demographics, aneurysm and parent artery characteristics, flow diverter and hemodynamic-related features, and angiographic parametric imaging) to predict flow diverter treatment outcomes. The machine learning algorithms used, along with their respective accuracy rates, were as follows: logistic regression (61% and 85%), support vector machine (88%), Gaussian support vector machine (90%), linear support vector machine (85%), decision tree (80%), random forest (87%), k-nearest neighbors (83% and 85%), XGBoost (87%), CatBoost (86%), deep neural networks (77.9%), and recurrent neural networks (74%).Two studies trained the machine learning models with both all features and the most significant features. Both studies observed that the accuracy of machine learning models decreased by removing the insignificant features.ConclusionThe current literature indicates that machine learning algorithms can be trained to predict the success of flow diverters with an accuracy of up to 90%.
Endovascular Therapy for Stroke Presenting Beyond 24 Hours
Previous randomized clinical trials (RCTs) have supported the use of endovascular therapy (EVT) in late-window acute ischemic stroke (AIS; 6-24 hours). However, little is known about the use of EVT in very late-window AIS (>24 hours). To examine outcomes following EVT for very late-window AIS. A systematic review of the English language literature was conducted using Web of Science, Embase, Scopus, and PubMed to search for articles published from database inception until December 13, 2022. This systematic review and meta-analysis included published studies regarding very late-window AIS treated with EVT. Multiple reviewers screened studies, and an extensive manual search of the references of included articles was performed to identify any missed articles. Of the 1754 initially retrieved studies, 7 published between 2018 and 2023 were ultimately included. Data were extracted independently by multiple authors and evaluated for consensus. Data were pooled using a random-effects model. This study is reported per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guideline, and the protocol was prospectively registered with PROSPERO. The primary outcome of interest was functional independence, as assessed with 90-day modified Rankin Scale (mRS) scores (0-2). Secondary outcomes included thrombolysis in cerebral infarction (TICI) scores (2b-3 or 3), symptomatic intracranial hemorrhage (sICH), 90-day mortality, early neurological improvement (ENI), and early neurological deterioration (END). Frequencies and means were pooled with the corresponding 95% CIs. This review included 7 studies involving a total of 569 patients. The mean baseline National Institutes of Health Stroke Scale score was 13.6 (95% CI, 11.9-15.5), and the mean Alberta Stroke Program Early CT Score was 7.9 (95% CI, 7.2-8.7). The mean time from last known well and/or onset to puncture was 46.2 hours (95% CI, 32.4-65.9 hours). Frequencies for the primary and secondary outcomes were 32.0% (95% CI, 24.7%-40.2%) for functional independence (90-day mRS scores of 0-2) and 81.9% (95% CI, 78.5%-84.9%) for TICI scores of 2b to 3, 45.3% (95% CI, 36.6%-54.4%) for TICI scores of 3, 6.8% (95% CI, 4.3%-10.7%) for sICH, and 27.2% (95% CI, 22.9%-31.9%) for 90-day mortality. In addition, frequencies were 36.9% (95% CI, 26.4%-48.9%) for ENI and 14.3% (95% CI, 7.1%-26.7%) for END. In this review, EVT for very late-window AIS was associated with favorable frequencies of 90-day mRS scores of 0 to 2 and TICI scores of 2b to 3 and with low frequencies of 90-day mortality and sICH. These results suggest that EVT may be safe and associated with improved outcomes for very late-window AIS, although RCTs and prospective, comparative studies are needed to determine which patients may benefit from very late intervention.