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  • 1
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    Imaging-based outcome prediction in posterior circulation stroke
    Springer Science and Business Media LLC ; 2022
    In:  Journal of Neurology Vol. 269, No. 7 ( 2022-07), p. 3800-3809
    Details
    In: Journal of Neurology, Springer Science and Business Media LLC, Vol. 269, No. 7 ( 2022-07), p. 3800-3809
    Kurzfassung: We developed a machine learning model to allow early functional outcome prediction for patients presenting with posterior circulation (pc)-stroke based on CT-imaging and clinical data at admission. The proposed algorithm utilizes quantitative information from automated multidimensional assessments of posterior circulation Acute Stroke Prognosis Early CT-Score (pc-ASPECTS) regions. Discriminatory power was compared to predictions based on conventional pc-ASPECTS ratings. Methods We retrospectively analyzed non-contrast CTs and clinical data of 172 pc-stroke patients. 90 days outcome was dichotomized into good and poor using modified Rankin Scale (mRS) cut-offs. Predictive performance was assessed for outcome differentiation at mRS 2, 3, 4 and survival prediction (mRS ≤ 5) using random forest algorithms. Results were compared to conventional pc-ASPECTS and clinical parameters. Models were evaluated in a nested fivefold cross-validation approach. Results Receiver operating characteristic areas under the curves (ROC-AUCs) of the test sets using conventionally rated pc-ASPECTS reached 0.63 for mRS ≤ 4 to 0.68 for mRS ≤ 5 and 0.73 for mRS ≤ 5 to 0.85 for mRS ≤ 2 if clinical data were considered. Pure imaging-based machine learning classifier ROC-AUCs were lowest for mRS ≤ 4 (0.81) and highest for mRS ≤ 5 (0.87). The combined clinical data and machine learning-based model had the highest predictive performance with ROC-AUCs reaching 0.90 for mRS ≤ 2. Conclusion Machine learning-based evaluation of pc-ASPECTS regions predicts functional outcome of pc-stroke patients with higher accuracy than conventional assessments. This could optimize triage for additional diagnostics and allocation of best possible medical care and might allow required arrangements of the social environment at an early point of time.
    Materialart: Online-Ressource
    ISSN: 0340-5354 , 1432-1459
    URL: Article
    DOI: 10.1007/s00415-022-11010-4
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2022
    ZDB Id: 1421299-7
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  • 2
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    Association Between Net Water Uptake and Functional Outcome in Patients With Low ASPECTS Brain Lesions : Results From the I-LAST Study
    Ovid Technologies (Wolters Kluwer Health) ; 2023
    In:  Neurology Vol. 100, No. 9 ( 2023-02-28), p. e954-e963
    Details
    In: Neurology, Ovid Technologies (Wolters Kluwer Health), Vol. 100, No. 9 ( 2023-02-28), p. e954-e963
    Kurzfassung: The effect of mechanical thrombectomy (MT) on functional outcome in patients with ischemic stroke with low ASPECTS is still uncertain. ASPECTS rating is based on the presence of ischemic hypoattenuation relative to normal; however, the degree of hypoattenuation, which directly reflects net uptake of water, is currently not considered an imaging biomarker in stroke triage. We hypothesized that the effect of thrombectomy on functional outcome in low ASPECTS patients depends on early lesion water uptake. Methods For this multicenter observational study, patients with anterior circulation stroke with ASPECTS ≤5 were consecutively analyzed. Net water uptake (NWU) was assessed as a quantitative imaging biomarker in admission CT. The primary end point was the rate of favorable functional outcome defined as modified Rankin Scale score 0–3 at day 90. The effect of recanalization on functional outcome was analyzed according to the degree of NWU within the early infarct lesion. Results A total of 254 patients were included, of which 148 (58%) underwent MT. The median ASPECTS was 4 (interquartile range [IQR] 3–5), and the median NWU was 11.4% (IQR 8.9%–15.1%). The rate of favorable outcome was 27.6% in patients with low NWU ( 〈 11.4%) vs 6.3% in patients with high NWU (≥11.4%; p 〈 0.0001). In multivariable logistic regression analysis, NWU was an independent predictor of outcome, whereas vessel recanalization (modified thrombolysis in cerebral infarction ≥2b) was only significantly associated with better outcomes if NWU was lower than 12.6%. In inverse-probability weighting analysis, recanalization was associated with 20.7% ( p = 0.01) increase in favorable outcome in patients with low NWU compared with 9.1% ( p = 0.06) in patients with high NWU. Discussion Early NWU was independently associated with clinical outcome and might serve as an indicator of futile MT in low ASPECTS patients. NWU could be tested as a tool to select low ASPECTS patients for MT. Trial Registration Information The study is registered within the ClinicalTrials.gov Protocol Registration and Results System (NCT04862507).
    Materialart: Online-Ressource
    ISSN: 0028-3878 , 1526-632X
    URL: Article
    DOI: 10.1212/WNL.0000000000201601
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2023
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  • 3
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    Thrombectomy of Mild Stroke : An Analysis of the Nationwide Registry of the German Society for Neuroradiology
    Springer Science and Business Media LLC ; 2023
    In:  Clinical Neuroradiology Vol. 33, No. 3 ( 2023-09), p. 687-694
    Details
    In: Clinical Neuroradiology, Springer Science and Business Media LLC, Vol. 33, No. 3 ( 2023-09), p. 687-694
    Kurzfassung: Whether patients presenting with mild stroke (NIHSS at admission 〈  6) should be treated with mechanical thrombectomy (MT) is the subject of an ongoing debate. This retrospective study based on large-scale clinical data aims to identify factors associated with favorable outcome (FO) in patients with mild stroke. Methods A total of 761 patients with mild stroke enrolled between 1 January 2020 and 31 December 2020 in the Quality Registry of the German Society for Neuroradiology were analyzed. The FO was defined as stable or improved NIHSS at discharge vs. admission. Descriptive statistics and multivariable logistic regression analyses were performed to identify factors associated with FO. Furthermore, a subgroup analysis of mild stroke based on distal vessel occlusion was conducted. Results In this study 610 patients had FO with a median NIHSS at discharge of 1 (interquartile range, IQR, 0-2) and 151 had an unfavorable outcome (UO) with median NIHSS at discharge of 10 (IQR 13). Patients with FO had a slightly higher NIHSS at admission (4 vs. 3, p   〈  0.001), lower mTICI 0 (2.7% vs. 14.2%, p   〈  0.001), higher mTICI 3 (61.3% vs. 34.5%, p   〈  0.001) and a lower number of passes (1 vs. 2, p   〈  0.001). No statistically significant difference was observed for MT-related adverse events. Multivariable logistic regression suggested that NIHSS at admission (adjusted odds ratio (aOR) = 1.28, 95% confidence interval (CI) = 1.10–1.48), mTICI 2b (aOR = 5.44, CI = 2.06–15.03), mTICI 2c (aOR = 10.81, CI = 3.65–34.07) and mTICI 3 (aOR = 11.56, CI = 4.49–31.10) as well as number of passes (aOR 0.76, CI = 0.66–0.88) were significantly associated with FO. No MT-related adverse events were observed for distal vessel occlusions. Conclusion The FO in patients with mild stroke undergoing MT was associated with successful recanalization. No significant differences between patients with FO and UO were found for MT-related adverse events, suggesting that MT complications have no significant effects on the outcome of these patients. MT might improve the prognosis also in patients with mild stroke based on distal vessel occlusions without significantly increasing the risk of adverse events.
    Materialart: Online-Ressource
    ISSN: 1869-1439 , 1869-1447
    URL: Article
    DOI: 10.1007/s00062-023-01262-6
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2023
    ZDB Id: 2232347-8
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
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    Impact of intravenous alteplase on sub-angiographic emboli in high-resolution diffusion-weighted imaging following successful thrombectomy
    Springer Science and Business Media LLC ; 2021
    In:  European Radiology Vol. 31, No. 11 ( 2021-11), p. 8228-8235
    Details
    In: European Radiology, Springer Science and Business Media LLC, Vol. 31, No. 11 ( 2021-11), p. 8228-8235
    Kurzfassung: Thrombus microfragmentation causing peripheral emboli (PE) during mechanical thrombectomy (MT) may modulate treatment effects, even in cases with successful reperfusion. This study aims to investigate whether intravenous alteplase is of potential benefit in reducing PE after successful MT. Methods Patients from a prospective study treated at a tertiary care stroke center between 08/2017 and 12/2019 were analyzed. The main inclusion criterion was successful reperfusion after MT (defined as expanded thrombolysis in cerebral infarction (eTICI) scale ≥ 2b50) of large vessel occlusion anterior circulation stroke. All patients received a high-resolution diffusion-weighted imaging (DWI) follow-up 24 h after MT for PE detection. Patients were grouped as “direct MT” (no alteplase) or as MT plus additional intravenous alteplase. The number and volume of ischemic core lesions and PE were then quantified and analyzed. Results Fifty-six patients were prospectively enrolled. Additional intravenous alteplase was administered in 46.3% (26/56). There were no statistically significant differences of PE compared by groups of direct MT and additional intravenous alteplase administration regarding mean numbers (12.1, 95% CI 8.6–15.5 vs. 11.1, 95% CI 7.0–15.1; p = 0.701), and median volume (0.70 mL, IQR 0.21–1.55 vs. 0.39 mL, IQR 0.10–1.62; p = 0.554). In uni- and multivariable linear regression analysis, higher eTICI scores were significantly associated with reduced PE, while the administration of alteplase was neither associated with numbers nor volume of peripheral emboli. Additional alteplase did not alter reperfusion success. Conclusions Intravenous alteplase neither affects the number nor volume of sub-angiographic DWI-PE after successful endovascular reperfusion. In the light of currently running randomized trials, further studies are warranted to validate these findings. Key Points • Thrombus microfragmentation during endovascular stroke treatment may cause peripheral emboli that are only detectable on diffusion-weighted imaging and may directly compromise treatment effects. • In this prospective study, the application of intravenous alteplase did not influence the occurrence of peripheral emboli detected on high-resolution diffusion-weighted imaging. • A higher degree of recanalization was associated with a reduced number and volume of peripheral emboli and better functional outcome, while contrariwise, peripheral emboli did not modify the effect of recanalization on modified Rankin Scale scores at day 90.
    Materialart: Online-Ressource
    ISSN: 0938-7994 , 1432-1084
    URL: Article
    DOI: 10.1007/s00330-021-07980-0
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2021
    ZDB Id: 1472718-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
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    Sub-angiographic peripheral emboli in high resolution DWI after endovascular recanalization
    Springer Science and Business Media LLC ; 2020
    In:  Journal of Neurology Vol. 267, No. 5 ( 2020-05), p. 1401-1406
    Details
    In: Journal of Neurology, Springer Science and Business Media LLC, Vol. 267, No. 5 ( 2020-05), p. 1401-1406
    Kurzfassung: To analyze the incidence of peripheral emboli after successful mechanical thrombectomy (MT) of intracranial large vessel occlusions (LVO). Methods We performed a prospective analysis of patients with intracranial LVO who underwent successful MT and received a 1.5 T MRI including diffusion-weighted imaging (DWI) in standard- and high-resolution as well as susceptibility-weighted imaging (SWI) on the day following the intervention. Reperfusion grade was assessed on post-thrombectomy digital subtraction angiography (DSA) using the expanded thrombolysis in cerebral infarction (eTICI) scale. Punctuate DWI lesions distal to the DWI core lesion were classified as peripheral emboli. DWI lesions outside the primary affected vascular territory were classified as emboli into new territories. Additionally, SWI and post-thrombectomy DSA were analyzed and correlated to findings on DWI. Results Twenty-eight patients undergoing successful MT met the inclusion criteria. In 26/28 patients (93%), a total of 324 embolic lesions were detected in DWI representing 2.1% of the cumulated ischemic core volume. 151 peripheral emboli were detected in standard-resolution DWI, 173 additional emboli were uncovered in high-resolution DWI. Eight out of nine patients with an eTICI 3 reperfusion had embolic lesions (29 DWI lesions). 9.6% (31/324) of peripheral emboli were observed in vascular territories not affected by the LVO. SWI lesions were observed in close proximity to 10.2% (33/324) of DWI lesions. Conclusions Peripheral emboli are frequent after MT even after complete reperfusion. These emboli occur rather in the vascular territory of the occluded vessel than in other territories. A large proportion of peripheral emboli is only detected by high-resolution DWI.
    Materialart: Online-Ressource
    ISSN: 0340-5354 , 1432-1459
    URL: Article
    DOI: 10.1007/s00415-020-09719-1
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2020
    ZDB Id: 1421299-7
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  • 6
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    Output Saturation in Electric Motor Systems: Identification and Controller Design
    ASME International ; 2010
    In:  Journal of Dynamic Systems, Measurement, and Control Vol. 132, No. 5 ( 2010-09-01)
    Details
    In: Journal of Dynamic Systems, Measurement, and Control, ASME International, Vol. 132, No. 5 ( 2010-09-01)
    Kurzfassung: Input saturation is a well-known nonlinearity in mechanical control systems; it constrains the maximum acceleration, which results in the limitation of the system response time. Input saturation has been considered in controller design in various ways, e.g., antiwindup control. In addition to the input, the state variables of mechanical systems are often subjected to saturation. For example, the maximum angular velocity of electric motor systems is limited by the maximum voltage provided to the motor windings. In the case of electronically commutated motors (i.e., brushless dc motors), the maximum speed is additionally constrained by limitations of the servo amplifier output. If gears are utilized, further constraints are introduced due to resonances in ball bearings and/or velocity dependent friction. Although such factors are significant in practice, they have not been fully considered in controller design. This paper investigates the input and output saturations, and presents how they may be considered in the controller design; a Kalman filter, a PID controller, and a disturbance observer are designed, taking input/output saturations into consideration. A case study is provided to verify the proposed methods.
    Materialart: Online-Ressource
    ISSN: 0022-0434 , 1528-9028
    URL: Article
    DOI: 10.1115/1.4001792
    Sprache: Englisch
    Verlag: ASME International
    Publikationsdatum: 2010
    ZDB Id: 240760-7
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  • 7
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    Posterior circulation stroke: machine learning-based detection of early ischemic changes in acute non-contrast CT scans
    Springer Science and Business Media LLC ; 2020
    In:  Journal of Neurology Vol. 267, No. 9 ( 2020-09), p. 2632-2641
    Details
    In: Journal of Neurology, Springer Science and Business Media LLC, Vol. 267, No. 9 ( 2020-09), p. 2632-2641
    Kurzfassung: Triage of patients with basilar artery occlusion for additional imaging diagnostics, therapy planning, and initial outcome prediction requires assessment of early ischemic changes in early hyperacute non-contrast computed tomography (NCCT) scans. However, accuracy of visual evaluation is impaired by inter- and intra-reader variability, artifacts in the posterior fossa and limited sensitivity for subtle density shifts. We propose a machine learning approach for detecting early ischemic changes in pc-ASPECTS regions (Posterior circulation Alberta Stroke Program Early CT Score) based on admission NCCTs. Methods The retrospective study includes 552 pc-ASPECTS regions (144 with infarctions in follow-up NCCTs) extracted from pre-therapeutic early hyperacute scans of 69 patients with basilar artery occlusion that later underwent successful recanalization. We evaluated 1218 quantitative image features utilizing random forest algorithms with fivefold cross-validation for the ability to detect early ischemic changes in hyperacute images that lead to definitive infarctions in follow-up imaging. Classifier performance was compared to conventional readings of two neuroradiologists. Results Receiver operating characteristic area under the curves for detection of early ischemic changes were 0.70 (95% CI [0.64; 0.75]) for cerebellum to 0.82 (95% CI [0.77; 0.86] ) for thalamus. Predictive performance of the classifier was significantly higher compared to visual reading for thalamus, midbrain, and pons ( P value  〈  0.05). Conclusions Quantitative features of early hyperacute NCCTs can be used to detect early ischemic changes in pc-ASPECTS regions. The classifier performance was higher or equal to results of human raters. The proposed approach could facilitate reproducible analysis in research and may allow standardized assessments for outcome prediction and therapy planning in clinical routine.
    Materialart: Online-Ressource
    ISSN: 0340-5354 , 1432-1459
    URL: Article
    DOI: 10.1007/s00415-020-09859-4
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2020
    ZDB Id: 1421299-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
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    Radiomics of Brain MRI: Utility in Prediction of Metastatic Tumor Type
    Radiological Society of North America (RSNA) ; 2019
    In:  Radiology Vol. 290, No. 2 ( 2019-02), p. 479-487
    Details
    In: Radiology, Radiological Society of North America (RSNA), Vol. 290, No. 2 ( 2019-02), p. 479-487
    Materialart: Online-Ressource
    ISSN: 0033-8419 , 1527-1315
    URL: Article
    DOI: 10.1148/radiol.2018180946
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: Radiological Society of North America (RSNA)
    Publikationsdatum: 2019
    ZDB Id: 80324-8
    ZDB Id: 2010588-5
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  • 9
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    Unfavorable cerebral venous outflow is associated with futile recanalization in acute ischemic stroke patients
    Wiley ; 2023
    In:  European Journal of Neurology Vol. 30, No. 9 ( 2023-09), p. 2684-2692
    Details
    In: European Journal of Neurology, Wiley, Vol. 30, No. 9 ( 2023-09), p. 2684-2692
    Kurzfassung: Mechanical thrombectomy (MT) has proven to be the standard of care for patients with acute ischemic stroke due to large vessel occlusion (AIS‐LVO). However, high revascularization rates do not necessarily result in favorable functional outcomes. We aimed to investigate imaging biomarkers associated with futile recanalization, defined as unfavorable functional outcome despite successful recanalization in AIS‐LVO patients. Methods A retrospective multicenter cohort study was made of AIS‐LVO patients treated by MT. Successful recanalization was defined as modified Thrombolysis in Cerebral Infarction score of 2b–3. A modified Rankin Scale score of 3–6 at 90 days was defined as unfavorable functional outcome. Cortical Vein Opacification Score (COVES) was used to assess venous outflow (VO), and the Tan scale was utilized to determine pial arterial collaterals on admission computed tomography angiography (CTA). Unfavorable VO was defined as COVES ≤ 2. Multivariable regression analysis was performed to investigate vascular imaging factors associated with futile recanalization. Results Among 539 patients in whom successful recanalization was achieved, unfavorable functional outcome was observed in 59% of patients. Fifty‐eight percent of patients had unfavorable VO, and 31% exhibited poor pial arterial collaterals. In multivariable regression, unfavorable VO was a strong predictor (adjusted odds ratio = 4.79, 95% confidence interval = 2.48–9.23) of unfavorable functional outcome despite successful recanalization. Conclusions We observe that unfavorable VO on admission CTA is a strong predictor of unfavorable functional outcomes despite successful vessel recanalization in AIS‐LVO patients. Assessment of VO profiles could help as a pretreatment imaging biomarker to determine patients at risk for futile recanalization.
    Materialart: Online-Ressource
    ISSN: 1351-5101 , 1468-1331
    URL: Issue
    URL: Article
    DOI: 10.1111/ene.v30.9
    DOI: 10.1111/ene.15898
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2023
    ZDB Id: 2020241-6
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  • 10
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    Effect of Balloon Guide Catheter Utilization on the Incidence of Sub-angiographic Peripheral Emboli on High-Resolution DWI After Thrombectomy: A Prospective Observational Study
    Frontiers Media SA ; 2020
    In:  Frontiers in Neurology Vol. 11 ( 2020-5-7)
    Details
    In: Frontiers in Neurology, Frontiers Media SA, Vol. 11 ( 2020-5-7)
    Materialart: Online-Ressource
    ISSN: 1664-2295
    URL: Article
    DOI: 10.3389/fneur.2020.00386
    Sprache: Unbekannt
    Verlag: Frontiers Media SA
    Publikationsdatum: 2020
    ZDB Id: 2564214-5
    Standort Signatur Einschränkungen Verfügbarkeit
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