| 11. |
- Abbasi, R., et al.
(författare)
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A Search for Coincident Neutrino Emission from Fast Radio Bursts with Seven Years of IceCube Cascade Events
- 2023
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Ingår i: Astrophysical Journal. - : Institute of Physics (IOP). - 1538-4357 .- 0004-637X. ; 946:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of a search for neutrinos that are spatially and temporally coincident with 22 unique, nonrepeating fast radio bursts (FRBs) and one repeating FRB (FRB 121102). FRBs are a rapidly growing class of Galactic and extragalactic astrophysical objects that are considered a potential source of high-energy neutrinos. The IceCube Neutrino Observatory's previous FRB analyses have solely used track events. This search utilizes seven years of IceCube cascade events which are statistically independent of track events. This event selection allows probing of a longer range of extended timescales due to the low background rate. No statistically significant clustering of neutrinos was observed. Upper limits are set on the time-integrated neutrino flux emitted by FRBs for a range of extended time windows.
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| 12. |
- Abbasi, Rasha, et al.
(författare)
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IceCube search for neutrinos from GRB 221009A
- 2023
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Ingår i: Proceedings of 38th International Cosmic Ray Conference (ICRC 2023). - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- GRB 221009A is the brightest Gamma Ray Burst (GRB) ever observed. The observed extremelyhigh flux of high and very-high-energy photons provide a unique opportunity to probe the predictedneutrino counterpart to the electromagnetic emission. We have used a variety of methods to searchfor neutrinos in coincidence with the GRB over several time windows during the precursor, promptand afterglow phases of the GRB. MeV scale neutrinos are studied using photo-multiplier ratescalers which are normally used to search for galactic core-collapse supernovae neutrinos. GeVneutrinos are searched starting with DeepCore triggers. These events don’t have directionallocalization, but instead can indicate an excess in the rate of events. 10 GeV - 1 TeV and >TeVneutrinos are searched using traditional neutrino point source methods which take into accountthe direction and time of events with DeepCore and the entire IceCube detector respectively. The>TeV results include both a fast-response analysis conducted by IceCube in real-time with timewindows of T0 − 1 to T0 + 2 hours and T0 ± 1 day around the time of GRB 221009A, as well asan offline analysis with 3 new time windows up to a time window of T0 − 1 to T0 + 14 days, thelongest time period we consider. The combination of observations by IceCube covers 9 ordersof magnitude in neutrino energy, from MeV to PeV, placing upper limits across the range forpredicted neutrino emission.
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| 13. |
- Cruz-Rojas, Agneta, et al.
(författare)
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Prevalence and incidence of Carotid-Fetal-Posterior syndrome
- 2023
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Ingår i: Cerebrovascular Diseases. - : S. Karger. - 1015-9770 .- 1421-9786. ; 52:6, s. 643-650
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Carotid-Fetal-Posterior (CFP) syndrome is a posterior cerebral artery (PCA) territory ischemic stroke/TIA caused by symptomatic >= 50% carotid stenosis or occlusion via fetal posterior communicating artery. We aimed to assess the incidence of CFP syndrome and prevalence of CFP syndrome among symptomatic >= 50% carotid stenosis or occlusion as these are unknown.Methods: We reassessed consecutive CTAs from 4042 persons, and included locally admitted patients with >= 50% carotid stenosis or occlusion. These were assessed for symptoms and signs of possible posterior circulation stroke/TIA (suspicion of CFP syndrome). Among these, those with unilateral PCA territory stroke/TIA, ipsilateral stenosis and fetal/fetal type PCA were considered CFP syndrome.Results: We included 208 locally admitted patients with >= 50% carotid stenosis or occlusion, 33 (16%) patients had suspicion of CFP syndrome, of which 3 (9%) had CFP syndrome. The prevalence of CFP syndrome was 2.9% of symptomatic >= 50% carotid stenosis or occlusion; incidence was 4.23 per 1 000 000 person-years. Also, we found a lower prevalence of CFP-syndrome (0.9%, p=0.047) among referred patients with symptomatic >= 50% carotid stenosis or occlusion than among locally admitted patients with symptomatic >= 50% carotid stenosis or occlusion.Discussion/Conclusion: CFP syndrome has a low incidence and low prevalence among symptomatic carotid stenosis cases. Given lower prevalence of CFP syndrome among referred cases than local, CFP-syndrome seems susceptible to underdiagnosis. On the other hand, few cases with suspicion of CFP syndrome had CFP syndrome, why CFP syndrome also seems susceptible to overdiagnosis if detailed assessment is not employed.
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| 14. |
- Gu, Thomas, et al.
(författare)
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Symptomatic carotid near-occlusion causes a high risk of recurrent ipsilateral ischemic stroke
- 2020
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Ingår i: Journal of Neurology. - : Springer. - 0340-5354 .- 1432-1459. ; 267, s. 522-530
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To assess the risk of recurrent ipsilateral ischemic stroke in patients with symptomatic near-occlusion with and without full collapse.Methods: Included were consecutive patients eligible for revascularization, grouped into symptomatic conventional ≥ 50% carotid stenosis (n = 266), near-occlusion without full collapse (n = 57) and near-occlusion with full collapse (n = 42). The risk of preoperative recurrent ipsilateral ischemic stroke was analyzed, or, for cases not revascularized within 90 days, 90-day risk was analyzed.Results: The risk of a preoperative recurrent ipsilateral ischemic stroke or ipsilateral retinal artery occlusion was 15% (95% CI 9–20%) for conventional ≥ 50% stenosis, 22% (95% CI 6–38%) among near-occlusion without full collapse and 30% (95% CI 16–44%) among near-occlusion with full collapse (p = 0.01, log rank test). In multivariate analysis, near-occlusion with full collapse had a higher risk of recurrent ipsilateral ischemic stroke (adjusted HR 2.6, 95% CI 1.3–5.3) and near-occlusion without full collapse tended to have a higher risk (adjusted HR 2.0, 95% CI 0.9–4.5) than conventional ≥ 50% stenosis. Only 24% of near-occlusion with full collapse underwent revascularization, common causes for abstaining were misdiagnosis as occlusion (31%), deemed surgically unfeasible (21%) and low perceived benefit (10%).Conclusions: Symptomatic carotid near-occlusion has a high short-term risk of recurrent ipsilateral ischemic stroke, especially near-occlusion with full collapse.
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| 15. |
- Henze, Alexander, et al.
(författare)
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High risk of early recurrent stroke in patients with near-occlusion with full collapse of the internal carotid artery
- 2024
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Ingår i: Neuroradiology. - : Springer Science+Business Media B.V.. - 0028-3940 .- 1432-1920. ; 66:3, s. 349-352
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to validate the prognostic ability and assess interrater reliability of a recently suggested measurement-based definition of near-occlusion with full collapse (distal ICA diameter ≤ 2.0mm and/or ICA ratio ≤ 0.42). 118 consecutive patients with symptomatic near-occlusion were prospectively included and assessed on computed tomography angiography by 2 blinded observers, 26 (22%) had full collapse. At 2days after presenting event, the risk of preoperative stroke was 3% for without full collapse and 16% for with full collapse (p = 0.01). At 28days, this risk was 16% for without full collapse and 22% for with full collapse (p = 0.22). Interrater reliability was perfect (kappa 1.0). Thus, near-occlusion with full collapse should be defined as distal ICA ≤ 2.0mm and/or ICA ratio ≤ 0.42 in order to detect cases with very high risk of early stroke recurrence.
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| 16. |
- Holmgren, Madelene, et al.
(författare)
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Diagnostic separation of conventional ⩾50% carotid stenosis and near-occlusion with phase-contrast MRI
- 2024
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Ingår i: European Stroke Journal. - : Sage Publications. - 2396-9873 .- 2396-9881. ; 9:1, s. 135-143
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The aim of this study was to assess sensitivity, specificity and interrater reliability of phase-contrast MRI (PC-MRI) for diagnosing carotid near-occlusion. Patients and methods: Prospective cross-sectional study conducted between 2018 and 2021. We included participants with suspected 50%–100% carotid stenosis on at least one side, all were examined with CT angiography (CTA) and PC-MRI and both ICAs were analyzed. Degree of stenosis on CTA was the reference test. PC-MRI-based blood flow rates in extracranial ICA and intracranial cerebral arteries were assessed. ICA-cerebral blood flow (CBF) ratio was defined as ICA divided by sum of both ICAs and Basilar artery. Results: We included 136 participants. The ICAs were 102 < 50% stenosis, 88 conventional ⩾50% stenosis (31 with ⩾70%), 49 near-occlusion, 12 occlusions, 20 unclear cause of small distal ICA on CTA and one excluded. For separation of near-occlusion and conventional stenoses, ICA flow rate and ICA-CBF ratio had the highest area under the curve (AUC; 0.98–0.99) for near-occlusion. ICA-CBF ratio ⩽0.225 was 90% (45/49) sensitive and 99% (188/190) specific for near-occlusion. Inter-rater reliability for this threshold was excellent (kappa 0.98). Specificity was 94% (29/31) for cases with ⩾70% stenosis. PC-MRI had modest performance for separating <50% and conventional ⩾50% stenosis (highest AUC 0.74), and eight (16%) of near-occlusions were not distinguishable from occlusion (no visible flow). Conclusion: ICA-CBF ratio ⩽0.225 on PC-MRI is an accurate and reliable method to separate conventional ⩾50% stenosis and near-occlusion that is feasible for routine use. PC-MRI should be considered further as a potential standard method for near-occlusion detection, to be used side-by-side with established modalities as PC-MRI cannot separate other degrees of stenosis.
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| 17. |
- Holmgren, Madelene, et al.
(författare)
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Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion
- 2024
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Ingår i: NEURORADIOLOGY. - : Springer Nature. - 0028-3940 .- 1432-1920.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Compare extracranial internal carotid artery flow rates and intracranial collateral use between conventional >= 50% carotid stenosis and carotid near-occlusion, and between symptomatic and asymptomatic carotid near-occlusion. Methods We included patients with >= 50% carotid stenosis. Degree of stenosis was diagnosed on CTA. Mean blood flow rates were assessed with four-dimensional phase-contrast MRI. Results We included 110 patients of which 83% were symptomatic, and 38% had near-occlusion. Near-occlusions had lower mean internal carotid artery flow (70 ml/min) than conventional >= 50% stenoses (203 ml/min, P < .001). Definite use of >= 1 collateral was found in 83% (35/42) of near-occlusions and 10% (7/68) of conventional stenoses (P < .001). However, there were no differences in total cerebral blood flow (514 ml/min vs. 519 ml/min, P = .78) or ipsilateral hemispheric blood flow (234 vs. 227 ml/min, P = .52), between near-occlusions and conventional >= 50% stenoses, based on phase-contrast MRI flow rates. There were no differences in total cerebral or hemispheric blood flow, or collateral use, between symptomatic and asymptomatic near-occlusions. Conclusion Near-occlusions have lower internal carotid artery flow rates and more collateral use, but similar total cerebral blood flow and hemispheric blood flow, compared to conventional >= 50% carotid stenosis.
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| 18. |
- Johansson, Elias, et al.
(författare)
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Atherosclerotic ICA stenosis coinciding with ICA asymmetry associated with Circle of Willis variations can mimic near-occlusion
- 2020
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Ingår i: Neuroradiology. - : Springer. - 0028-3940 .- 1432-1920. ; 62, s. 101-104
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Tidskriftsartikel (refereegranskat)abstract
- Differentiating carotid near-occlusion (tight atherosclerotic stenosis causing distal artery size reduction) from conventional stenosis is the first step when grading carotid stenoses with NASCET method. The internal carotid artery (ICA) can be asymmetrically associated with Circle of Willis variations. When such ICA asymmetry coincides with stenosis, it may mimic near-occlusion. We studied ICA anatomical variant prevalence in 4042 consecutive CTA exams from all indications, 53 excluded due to carotid occlusion, 814 with any >= 50% steno-occlusive disease intra- or extracranially, 3228 without. Of the 3989 included cases, 568 (14%) had ICA asymmetry, of which 335 (59%) were from associated with Circle of Willis variations. Of 3228 patients without >= 50% stenosis or other steno-occlusive disease intra- and extracranially; 257 (8.0%) demonstrated ICA asymmetry associated with Circle of Willis variations, equally common among sexes and age unrelated and most frequently attributed to an ipsilateral A1 hypoplasia/aplasia, less often attributed to large contralateral posterior communicating artery. As ICA asymmetry associated with Circle of Willis variations are common, caution should be exercised diagnosing near-occlusion on asymmetry alone.
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| 19. |
- Johansson, Elias, et al.
(författare)
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Carotid near-occlusion is often overlooked when CT angiography is assessed in routine practice
- 2020
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Ingår i: European Radiology. - : Springer. - 0938-7994 .- 1432-1084. ; 30:5, s. 2543-2551
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Assess the sensitivity and specificity of computed tomography angiography (CTA) for carotid near-occlusion diagnosis interpreted in clinical practice against expert assessment.Methods: CTAs were graded by two expert interpreters for near-occlusion. Findings were compared with clinical reports in 383 consecutive cases with symptomatic ≥ 50% carotid stenosis. In addition, 14 selected CTA exams (8 near-occlusions and 6 controls) were analyzed in a national effort by 13 radiologists experienced with carotid CTA.Results: In clinical practice, imaging reports were 20% (95% CI 12–28%) sensitive for near-occlusion, ranging 0–58% between different radiologists; specificity was 99%. Among the 13 radiologists reviewing the same 8 near-occlusions, the average sensitivity was 8%, ranging 0–75%; specificity was 100%.Conclusions: Carotid near-occlusion is systematically under-reported in clinical routine practice, caused by limited application of grading criteria when assessing CTA.
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| 20. |
- Johansson, Elias, et al.
(författare)
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Defining carotid near-occlusion with full collapse: a pooled analysis
- 2022
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Ingår i: Neuroradiology. - : Springer-Verlag New York. - 0028-3940 .- 1432-1920. ; 64, s. 59-67
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Create a new definition of near-occlusion with full collapse to predicting recurrent stroke.Methods: Pooled analysis of two studies. Patients with symptomatic ≥ 50% carotid stenoses were included. Outcome was preoperative recurrent ipsilateral ischemic stroke or retinal artery occlusion within 28 days of presenting event. We analyzed several artery diameters on computed tomography angiography and stenosis velocity on ultrasound.Results: A total of 430 patients with symptomatic ≥ 50% carotid stenosis were included, 27% had near-occlusion. By traditional definition, 27% with full collapse and 11% without full collapse reached the outcome (p = 0.047). Distal internal carotid artery (ICA) diameter, ICA ratio, and ICA-to-external carotid artery ratio were associated with the outcome. Best new definition of full collapse was distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42. With this new definition, 36% with full collapse and 4% without full collapse reached the outcome (p < 0.001).Conclusions: Defining near-occlusion with full collapse as distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42 seems to yield better prognostic discrimination than the traditional appearance-based definition. This novel definition can be used in prognostic and treatment studies of near-occlusion with full collapse.
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