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1.
Neuroimage ; 271: 119985, 2023 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-36933627

RESUMO

We present an annotated dataset for the purposes of creating a benchmark in Artificial Intelligence for automated clot detection. While there are commercial tools available for automated clot detection on computed tomographic (CT) angiographs, they have not been compared in a standardized manner whereby accuracy is reported on a publicly available benchmark dataset. Furthermore, there are known difficulties in automated clot detection - namely, cases where there is robust collateral flow, or residual flow and occlusions of the smaller vessels - and it is necessary to drive an initiative to overcome these challenges. Our dataset contains 159 multiphase CTA patient datasets, derived from CTP and annotated by expert stroke neurologists. In addition to images where the clot is marked, the expert neurologists have provided information about clot location, hemisphere and the degree of collateral flow. The data is available on request by researchers via an online form, and we will host a leaderboard where the results of clot detection algorithms on the dataset will be displayed. Participants are invited to submit an algorithm to us for evaluation using the evaluation tool, which is made available at together with the form at https://github.com/MBC-Neuroimaging/ClotDetectEval.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Humanos , Inteligência Artificial , Benchmarking , Angiografia Cerebral/métodos
2.
Stroke ; 52(1): 339-343, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33370180

RESUMO

BACKGROUND AND PURPOSE: Lacunar syndromes correlate with a lacunar stroke on imaging in 50% to 60% of cases. Computed tomography perfusion (CTP) is becoming the preferred imaging modality for acute stroke triage. We aimed to estimate the sensitivity, specificity, and predictive values for noncontrast computed tomography and CTP in lacunar syndromes, and for cortical, subcortical, and posterior fossa regions. METHODS: A retrospective analysis of confirmed ischemic stroke patients who underwent acute CTP and follow-up magnetic resonance imaging between 2010 and 2018 was performed. Brain noncontrast computed tomography and CTP were assessed independently by 2 stroke neurologists. Receiver operating characteristic curve analysis was performed to estimate sensitivity, specificity, and area under the curve (AUC) for the detection of strokes in patients with lacunar syndromes using different CTP maps. RESULTS: We found 106 clinical lacunar syndromes, but on diffusion-weighted imaging, these consisted of 59 lacunar, 33 cortical, and 14 posterior fossa strokes. The discrimination of ischemia identification was very poor using noncontrast computed tomography in all 3 regions, but good for cortical (AUC, 0.82) and poor for subcortical and posterior regions (AUCs, 0.55 and 0.66) using automated core-penumbra maps. The addition of delay time and mean transient time maps substantially increased subcortical (AUC, 0.80) and slightly posterior stroke detection (AUC, 0.69). CONCLUSIONS: Analysis of mean transient time and delay time maps in combination with core-penumbra maps improves detection of subcortical and posterior strokes.


Assuntos
Imagem de Perfusão/métodos , Acidente Vascular Cerebral Lacunar/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Idoso , Mapeamento Encefálico , Córtex Cerebral/diagnóstico por imagem , Diagnóstico Diferencial , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Curva ROC , Estudos Retrospectivos , Sensibilidade e Especificidade , Acidente Vascular Cerebral Lacunar/diagnóstico , Síndrome , Triagem/métodos , Triagem/tendências
3.
Stroke ; 50(3): 602-609, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30777001

RESUMO

Background and Purpose- Poststroke fatigue affects a large proportion of stroke survivors and is associated with a poor quality of life. In a recent trial, modafinil was shown to be an effective agent in reducing poststroke fatigue; however, not all patients reported a significant decrease in fatigue with therapy. We sought to investigate clinical and radiological predictors of fatigue reduction with modafinil therapy in a stroke survivor cohort. Methods- Twenty-six participants with severe fatigue (multidimensional fatigue inventory-20 ≥60) underwent magnetic resonance imaging at baseline and during the last week of a 6-week treatment period of 200 mg modafinil taken daily. Resting-state functional magnetic resonance imaging and high-resolution structural imaging data were obtained, and functional connectivity and regional brain volumes within the fronto-striato-thalamic network were obtained. Linear regression analysis was used to identify predictors of modafinil-induced fatigue reduction. Results- Multiple regression analysis showed that baseline multidimensional fatigue inventory-20 score (ß=0.576, P=0.006) and functional connectivity between the dorsolateral prefrontal cortex and the caudate nucleus (ß=-0.424, P=0.008) were significant predictors of modafinil-associated decreases in poststroke fatigue (adjusted r2=0.52, area under the receiver operator characteristic curve=0.939). Conclusions- Fronto-striato-thalamic functional connectivity predicted modafinil response for poststroke fatigue. Fatigue in other neurological disease has been attributed to altered function of the fronto-striato-thalamic network and may indicate that poststroke fatigue has a similar mechanism to other neurological injury related fatigue. Self-reported fatigue in patients with normal fronto-striato-thalamic functional connectivity may have a different mechanism and require alternate therapeutic approaches. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: ACTRN12615000350527.


Assuntos
Encéfalo/diagnóstico por imagem , Fadiga/tratamento farmacológico , Fadiga/etiologia , Modafinila/uso terapêutico , Vias Neurais/diagnóstico por imagem , Acidente Vascular Cerebral/complicações , Promotores da Vigília/uso terapêutico , Adulto , Idoso , Núcleo Caudado/diagnóstico por imagem , Estudos de Coortes , Estudos Cross-Over , Método Duplo-Cego , Fadiga/diagnóstico por imagem , Feminino , Previsões , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Córtex Pré-Frontal/diagnóstico por imagem , Qualidade de Vida , Acidente Vascular Cerebral/diagnóstico por imagem , Tálamo/diagnóstico por imagem
4.
Front Neurol ; 15: 1359775, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38426177

RESUMO

Introduction: In acute stroke, identifying early changes (parenchymal hypodensity) on non-contrast CT (NCCT) can be challenging. We aimed to identify whether the accuracy of clinicians in detecting acute hypodensity in ischaemic stroke patients on a non-contrast CT is improved with the use of an Artificial Intelligence (AI) based, automated hypodensity detection algorithm (HDT) using MRI-DWI as the gold standard. Methods: The study employed a case-crossover within-clinician design, where 32 clinicians were tasked with identifying hypodensity lesions on NCCT scans for five a priori selected patient cases, before and after viewing the AI-based HDT. The DICE similarity coefficient (DICE score) was the primary measure of accuracy. Statistical analysis compared DICE scores with and without AI-based HDT using mixed-effects linear regression, with individual NCCT scans and clinicians as nested random effects. Results: The AI-based HDT had a mean DICE score of 0.62 for detecting hypodensity across all NCCT scans. Clinicians' overall mean DICE score was 0.33 (SD 0.31) before AI-based HDT implementation and 0.40 (SD 0.27) after implementation. AI-based HDT use was associated with an increase of 0.07 (95% CI: 0.02-0.11, p = 0.003) in DICE score accounting for individual scan and clinician effects. For scans with small lesions, clinicians achieved a mean increase in DICE score of 0.08 (95% CI: 0.02, 0.13, p = 0.004) following AI-based HDT use. In a subgroup of 15 trainees, DICE score improved with AI-based HDT implementation [mean difference in DICE 0.09 (95% CI: 0.03, 0.14, p = 0.004)]. Discussion: AI-based automated hypodensity detection has potential to enhance clinician accuracy of detecting hypodensity in acute stroke diagnosis, especially for smaller lesions, and notably for less experienced clinicians.

5.
Front Neurol ; 14: 1098562, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36908587

RESUMO

Introduction: Computed tomography perfusion (CTP) imaging is widely used in cases of suspected acute ischemic stroke to positively identify ischemia and assess suitability for treatment through identification of reversible and irreversible tissue injury. Traditionally, this has been done via setting single perfusion thresholds on two or four CTP parameter maps. We present an alternative model for the estimation of tissue fate using multiple perfusion measures simultaneously. Methods: We used machine learning (ML) models based on four different algorithms, combining four CTP measures (cerebral blood flow, cerebral blood volume, mean transit time and delay time) plus 3D-neighborhood (patch) analysis to predict the acute ischemic core and perfusion lesion volumes. The model was developed using 86 patient images, and then tested further on 22 images. Results: XGBoost was the highest-performing algorithm. With standard threshold-based core and penumbra measures as the reference, the model demonstrated moderate agreement in segmenting core and penumbra on test images. Dice similarity coefficients for core and penumbra were 0.38 ± 0.26 and 0.50 ± 0.21, respectively, demonstrating moderate agreement. Skull-related image artefacts contributed to lower accuracy. Discussion: Further development may enable us to move beyond the current overly simplistic core and penumbra definitions using single thresholds where a single error or artefact may lead to substantial error.

6.
Eur J Radiol ; 164: 110845, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37148842

RESUMO

INTRODUCTION: Stroke is a leading cause of adult disability and death worldwide. Automated detection of stroke on brain imaging has promise in a time critical environment. We present a method for the automated detection of intracranial occlusions on dynamic CT Angiography (CTA) causing acute ischemic stroke. METHODS: We derived dynamic CTA images from CT Perfusion (CTP) data and utilised advanced image processing to enhance and display major cerebral blood vessels for symmetry analysis. We reviewed the performance of the algorithm on a cohort of 207 patients from the International Stroke Perfusion Imaging Registry (INSPIRE), with Large Vessel Occlusion (LVO) and non-LVO strokes. Included in the data were images with chronic stroke, various artefacts, incomplete vessel occlusions, and images of poorer quality. All images were annotated by stroke experts. In addition, each image was graded in terms of the difficulty of the task of occlusion detection. Performance was evaluated on the overall cohort, and with respect to occlusion location, collateral grade, and task difficulty. We also evaluated the impact of including additional perfusion data. RESULTS: Images with a rating of lower difficulty achieved a sensitivity and specificity of 96% and 90%, respectively, while images with a moderate difficulty rating achieved 88% and 50%, respectively. For cases of high difficulty, where more than two experts or additional data were required to reach consensus, sensitivity and specificity was 53% and 11%. The addition of perfusion data to the dCTA images increased the specificity by 38%. CONCLUSION: We have provided an unbiased interpretation of algorithm performance. Further developments include generalising to conventional CTA and employing the algorithm in a clinical setting for prospective studies.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Adulto , Humanos , Isquemia Encefálica/diagnóstico por imagem , Angiografia Cerebral/métodos , Angiografia por Tomografia Computadorizada/métodos , Estudos Prospectivos , Estudos Retrospectivos , Acidente Vascular Cerebral/diagnóstico por imagem
7.
Int Orthop ; 35(5): 767-76, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-20544197

RESUMO

The purpose of this study was to investigate the influence of body function, activities and pain on the level of activity in adults with Kashin Beck Disease (KBD). Seventy-five KBD patients with a mean age of 54.8 years (SD 11.3) participated. Anthropometrics, range of joint motion (ROM) and muscle strength were measured as well as the time-up-and-go test and functional tests for the lower and upper extremities. Activity was assessed with the participation scale and the WHO DAS II. In the shoulder, elbow, hip and knee joints, a severe decrease in ROM and bilateral pain was noted. A decrease in muscle strength was observed in almost all muscles. The timed-up-and-go test scores decreased. No or mild restriction in activity was found in 35%, and 33% experienced a moderate restriction whereas 32% had severe to extreme restriction. Activities in the lower extremities were mildly to moderately correlated to ROM and muscle strength, whereas in the upper extremities activities were correlated to range of joint motion. Activity was significantly associated with ROM after correction for muscle strength, gender and age. Participation was borderline significantly associated with ROM after correction for muscle strength, gender, age and the activity time-up-and-go. In KBD adults, a severe decrease in activity is primarily caused by decrease in ROM. These findings have strong influence on rehabilitation and surgical intervention.


Assuntos
Articulações/fisiopatologia , Doença de Kashin-Bek/fisiopatologia , Força Muscular/fisiologia , Osteoartrite/fisiopatologia , Atividades Cotidianas , Estudos Transversais , Teste de Esforço , Feminino , Humanos , Doença de Kashin-Bek/complicações , Doença de Kashin-Bek/reabilitação , Masculino , Pessoa de Meia-Idade , Atividade Motora , Debilidade Muscular , Osteoartrite/complicações , Dor , Amplitude de Movimento Articular , Índice de Gravidade de Doença
8.
Front Neurol ; 12: 612177, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34163417

RESUMO

Background and Purpose: Altered executive functions and resting-state functional connectivity (rsFC) are common following a minor stroke or transient ischemic attack (TIA). However, the long-term persistence of these abnormalities is not well-studied. We investigated whether there were cognitive and rsFC differences between (a) controls and minor cerebrovascular event (CVE) patients and (b) between CVE patients with and without an imaging confirmed infarct (i.e., minor stroke and TIA, respectively) at an average of 3.8 years following their event. Methods: Structural and resting-state imaging and cognitive assessments including the Montreal Cognitive Assessment, the Trail Making Task and the National Institute of Health (NIH) Cognition Toolbox were conducted on 42 patients (minor stroke = 17, TIA = 25) and 20 healthy controls (total N = 62). Results: Controls performed better than patients on two measures of executive functioning (both p < 0.046) and had reduced rsFC between the frontoparietal and default mode networks (FPN and DMN, respectively; p = 0.035). No cognitive differences were found between minor stroke and TIA patients, however, rsFC differences were found within the FPN and the DMN (both p < 0.013). Specifically, increased connectivity within the FPN was associated with faster performance in the minor stroke group but not the TIA group (p = 0.047). Conclusions: These findings suggest that transient or relatively minor cerebrovascular events are associated with persistent disruption of functional connectivity of neural networks and cognitive performance. These findings suggest a need for novel interventions beyond secondary prevention to reduce the risk of persistent cognitive deficits.

9.
Sci Rep ; 9(1): 9660, 2019 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-31273283

RESUMO

Post-stroke fatigue has a significant impact on stroke survivors' mental and physical well-being. Our recent clinical trial showed significant reduction of post-stroke fatigue with modafinil treatment, however functional connectivity changes in response to modafinil have not yet been explored in stroke survivors with post-stroke fatigue. Twenty-eight participants (multidimensional fatigue inventory-20 ≥ 60) had MRI scans at baseline, and during modafinil and placebo treatment. Resting-state functional MRI data were obtained, and independent component analysis was used to extract functional networks. Resting-state functional connectivity (rsFC) was examined between baseline, modafinil and placebo treatment using permutation testing with threshold-free cluster enhancement. Overall twenty-eight participants (mean age: 62 ± 14.3, mean baseline MFI-20: 72.3 ± 9.24) were included. During modafinil treatment, increased rsFC was observed in the right hippocampus (p = 0.004, 11 voxels) compared to placebo. This coincided with lower rsFC in the left frontoparietal (inferior parietal lobule, p = 0.023, 13 voxels), somatosensory (primary somatosensory cortex; p = 0.009, 32 voxels) and mesolimbic network (temporal pole, p = 0.016, 35 voxels). In conclusion, modafinil treatment induces significant changes in rsFC in post-stroke fatigue. This modulation of rsFC may relate to a reduction of post-stroke fatigue; however, the relationship between sensory processing, neurotransmitter expression and fatigue requires further exploration.


Assuntos
Estimulantes do Sistema Nervoso Central/uso terapêutico , Conectoma , Fadiga/tratamento farmacológico , Modafinila/uso terapêutico , Rede Nervosa/efeitos dos fármacos , Acidente Vascular Cerebral/complicações , Sobreviventes/estatística & dados numéricos , Mapeamento Encefálico , Método Duplo-Cego , Fadiga/etiologia , Fadiga/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Rede Nervosa/patologia
10.
Physiother Res Int ; 24(3): e1775, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30942552

RESUMO

OBJECTIVE: This study examined the feasibility of a parallel-group assessor-blinded randomized controlled trial investigating whether task-specific training preceded by aerobic exercise (AEX + TST) improves upper limb function more than task-specific training (TST) alone. METHODS: People with upper limb motor dysfunction after stroke were allocated to TST or AEX + TST. Both groups were prescribed 60 hr of TST over 10 weeks (3 × 1-hr sessions with a therapist per week and 3 × 1 hr of home-based self-practice per week). The AEX + TST group performed 30 minutes of aerobic exercise immediately prior to the 1 hr of TST with the therapist. Recruitment, adherence, retention, participant acceptability, and adverse events were recorded. Clinical measures were performed prerandomization at baseline, on completion of the intervention, and at 1- and 6-month follow-up. RESULTS: Fifty-nine persons after stroke were screened, 42 met the eligibility criteria, and 20 (11 male; mean [SD] age: 55.4 [16.0] years; time since stroke: 71.7 [91.2] months) were recruited over 17 months. The mean Wolf Motor Function Test Functional Ability Score at baseline was 27.4 (max = 75) and the mean Action Research Arm Test score was 11.2 (max = 57). Nine were randomized to AEX + TST and 11 to TST. There were no adverse events, but there was one drop out. Retention at 1- and 6-month follow-up was 80% and 85%, respectively. Attendance was 93% (6) for the AEX + TST group, and 89% (9) for the TST group. AEX + TST was perceived as acceptable (100%) and beneficial (87.5%). Exertional fatigue (visual analogue scale) prior to TST was worse in the AEX + TST group (3.5 [0.7] out of 10) than the TST group (1.7 [1.4] out of 10). The TST group performed 31% more repetitions per session than the AEX + TST group. CONCLUSION: A subsequent Phase III study is feasible, but modifications to eligibility criteria, outcome measures, and intervention delivery are recommended.


Assuntos
Terapia por Exercício/métodos , Exercício Físico , Reabilitação do Acidente Vascular Cerebral/métodos , Acidente Vascular Cerebral/terapia , Extremidade Superior/fisiopatologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Participação do Paciente/estatística & dados numéricos , Projetos Piloto , Acidente Vascular Cerebral/fisiopatologia , Análise e Desempenho de Tarefas , Resultado do Tratamento
11.
J Neuroimaging ; 29(1): 111-118, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30160814

RESUMO

BACKGROUND AND PURPOSE: Degeneration of gray matter and subcortical structures after ischemic stroke has been well described. However, little is known about white matter degeneration after stroke. It is unclear whether white matter degeneration occurs throughout the whole brain, or whether patterns of degeneration occur more in specific brain areas. METHODS: We prospectively collected National Institutes of Health Stroke Scale (NIHSS) scores and diffusion tensor imaging (DTI) in patients with acute ischemic stroke within the first week after onset (baseline), and at 1 and 3 months. DTI was processed to produce maps of fractional anisotropy, apparent diffusion coefficients, and axial and radial diffusivity. DTI parameters in specified regions-of-interest corresponding to items on the NIHSS were calculated and changes over time were assessed using linear mixed-effect modeling. RESULTS: Seventeen patients were included in the study. Mean age (SD) was 71 (11.7) years, and median (IQR) baseline NIHSS 9 (5-13.3). Changes over time were observed in both visual cortices, contralesional primary motor cortex, premotor cortex, and superior temporal gyrus (P < .05). Changes in the ipsilesional motor cortex and inferior parietal lobule were only seen in patients with scores on the respective NIHSS-items (P < .05). No significant changes in global white matter diffusivity parameters were identified (P > .05). CONCLUSION: White matter changes after stroke may be localized rather than a global phenomenon.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Acidente Vascular Cerebral/diagnóstico por imagem , Substância Branca/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Anisotropia , Encéfalo/patologia , Isquemia Encefálica/patologia , Imagem de Tensor de Difusão/métodos , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/patologia , Substância Branca/patologia
12.
Contemp Clin Trials Commun ; 7: 179-185, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29696183

RESUMO

Motor function may be enhanced if aerobic exercise is paired with motor training. One potential mechanism is that aerobic exercise increases levels of brain-derived neurotrophic factor (BDNF), which is important in neuroplasticity and involved in motor learning and motor memory consolidation. This study will examine the feasibility of a parallel-group assessor-blinded randomised controlled trial investigating whether task-specific training preceded by aerobic exercise improves upper limb function more than task-specific training alone, and determine the effect size of changes in primary outcome measures. People with upper limb motor dysfunction after stroke will be allocated to either task-specific training or aerobic exercise and consecutive task-specific training. Both groups will perform 60 hours of task-specific training over 10 weeks, comprised of 3 × 1 hour sessions per week with a therapist and 3 × 1 hours of home-based self-practice per week. The combined intervention group will also perform 30 minutes of aerobic exercise (70-85%HRmax) immediately prior to the 1 hour of task-specific training with the therapist. Recruitment, adherence, retention, participant acceptability, and adverse events will be recorded. Clinical outcome measures will be performed pre-randomisation at baseline, at completion of the training program, and at 1 and 6 months follow-up. Primary clinical outcome measures will be the Action Research Arm Test (ARAT) and the Wolf Motor Function Test (WMFT). If aerobic exercise prior to task-specific training is acceptable, and a future phase 3 randomised controlled trial seems feasible, it should be pursued to determine the efficacy of this combined intervention for people after stroke.

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