Association of Intravenous Thrombolysis with Delayed Reperfusion After Incomplete Mechanical Thrombectomy.

PURPOSE: Treatment of distal vessel occlusions causing incomplete reperfusion after mechanical thrombectomy (MT) is debated. We hypothesized that pretreatment with intravenous thrombolysis (IVT) may facilitate delayed reperfusion (DR) of residual vessel occlusions causing incomplete reperfusion after MT. METHODS: Retrospective analysis of patients with incomplete reperfusion after MT, defined as extended thrombolysis in cerebral infarction (eTICI) 2a-2c, and available perfusion follow-up imaging at 24 ± 12 h after MT. DR was defined as absence of any perfusion deficit on time-sensitive perfusion maps, indicating the absence of any residual occlusion. The association of IVT with the occurrence of DR was evaluated using a logistic regression analysis adjusted for confounders. Sensitivity analyses based on IVT timing (time between IVT start and the occurrence incomplete reperfusion following MT) were performed. RESULTS: In 368 included patients (median age 73.7 years, 51.1% female), DR occurred in 225 (61.1%). Atrial fibrillation, higher eTICI grade, better collateral status and longer intervention-to-follow-up time were all associated with DR. IVT did not show an association with the occurrence of DR (aOR 0.80, 95% CI 0.44-1.46, even in time-sensitive strata, aOR 2.28 [95% CI 0.65-9.23] and aOR 1.53 [95% CI 0.52-4.73] for IVT to incomplete reperfusion following MT timing <80 and <100 min, respectively). CONCLUSION: A DR occurred in 60% of patients with incomplete MT at ~24 h and did not seem to occur more often in patients receiving pretreatment IVT. Further research on potential associations of IVT and DR after MT is required.

A perfusion phantom for ASL MRI based on impinging jets.

PURPOSE: We present a novel perfusion phantom for validation of arterial spin labeled (ASL) perfusion MRI methods and protocols. METHODS: Impinging jets, driven by a peristaltic pump, were used to achieve perfusion-like mixing of magnetically labeled inflowing fluid within a perfusion compartment. The phantom was validated by varying pump rates and obtaining ASL-MRI data at multiple postlabeling delays using a pseudo-continuous ASL sequence with a 3D stack-of-spirals readout. An additional data set was acquired using a pseudo-continuous ASL sequence with a 2D EPI readout. Phantom sensitivity to pseudo-continuous ASL labeling efficiency was also tested. RESULTS: Fluid dynamics simulations predicted that maximum mixing would occur near the central axis of the perfusion compartment. Experimentally observed signal changes within this region were reproducible and well fit by the standard Buxton general kinetic model. Simulations and experimental data showed no label outflow from the perfusion chamber and calculated perfusion rates, averaged over the entire phantom volume, agreed with the expected volumetric flow rates provided by the flow pump. Phantom sensitivity to pseudo-continuous ASL labeling parameters was also demonstrated. CONCLUSION: Perfusion-like signal can be simulated using impinging jets to create a well-mixed compartment. Observed perfusion and transit time values were reproducible and within the physiological range for brain perfusion. This phantom design has a broad range of potential applications in both basic and clinical research involving ASL MRI.

Frequency, aetiology, and impact of vestibular symptoms in the emergency department: a neglected red flag.

OBJECTIVE: We aimed to determine the incidence of all vestibular symptoms in a large interdisciplinary tertiary emergency department (ED) and to assess stroke prevalence, and frequency of other life-threatening aetiologies. METHODS: In this 1-year retrospective study, we manually screened all medical records of 23,608 ED visits for descriptions of vestibular symptoms. Symptoms were classified according to the International Classification of Vestibular Disorders of the Bárány Society. We evaluated all patients older than 16 years in whom vestibular symptoms were the main or accompanying complaint. We extracted clinical, radiological, and laboratory findings as well as aetiologies from medical records. RESULTS: We identified a total of 2596 visits by 2464 patients (11% of ED visits) who reported at least one vestibular symptom. In 1677/2596 visits (64.6%), vestibular symptoms were the main reason for the ED consultation. Vestibular symptoms were classified as dizziness (43.8%), vertigo (33.9%), postural symptoms (6.5%), or more than one symptom (15.8%). In 324/2596 visits (12.5%), cerebrovascular events were the aetiology of vestibular symptoms, and in 355/2596 visits (13.7%), no diagnosis could be established. In 23.8% of visits with vestibular symptoms as the main complaint, the underlying condition was life-threatening. CONCLUSION: Frequency and impact of vestibular symptoms in patients visiting the ED were higher than previously reported, and life-threatening aetiologies such as strokes are common. Therefore, awareness among physicians regarding the importance of vestibular symptoms has to be improved.