Large Vessel Occlusion Stroke due to Intracranial Atherosclerotic Disease: Identification, Medical and Interventional Treatment, and Outcomes.

Large vessel occlusion stroke due to underlying intracranial atherosclerotic disease (ICAD-LVO) is prevalent in 10 to 30% of LVOs depending on patient factors such as vascular risk factors, race and ethnicity, and age. Patients with ICAD-LVO derive similar functional outcome benefit from endovascular thrombectomy as other mechanisms of LVO, but up to half of ICAD-LVO patients reocclude after revascularization. Therefore, early identification and treatment planning for ICAD-LVO are important given the unique considerations before, during, and after endovascular thrombectomy. In this review of ICAD-LVO, we propose a multistep approach to ICAD-LVO identification, pretreatment and endovascular thrombectomy considerations, adjunctive medications, and medical management. There have been no large-scale randomized controlled trials dedicated to studying ICAD-LVO, therefore this review focuses on observational studies.

High-resolution vessel wall imaging after mechanical thrombectomy.

OBJECTIVES: High-resolution magnetic resonance imaging has the potential of characterising arterial wall changes after endovascular mechanical thrombectomy. The purpose of this study is to evaluate high-resolution magnetic resonance imaging features of large intracranial arteries following mechanical thrombectomy. METHODS: Patients who presented with acute ischaemic stroke due to large vessel occlusion and underwent mechanical thrombectomy were prospectively recruited. Subjects underwent high-resolution magnetic resonance imaging within 24 hours of the procedure. Magnetic resonance imaging sequences included whole brain T1 pre and post-contrast black-blood imaging, three-dimensional T2, contrast-enhanced magnetic resonance angiography and susceptibility-weighted imaging. Arterial wall enhancement was objectively assessed after normalisation with the pituitary stalk. The contrast ratio of target vessels was compared with non-affected reference vessels. RESULTS: Twenty patients with 22 target vessels and 20 reference vessels were included in the study. Sixteen patients were treated with stentriever with or without aspiration, and four with contact aspiration only. Significantly higher arterial wall enhancement was identified on the target vessel when compared to the reference vessel (U = 22.5, P < 0.01). The stentriever group had an 82% increase in the contrast ratio of the target vessel (x̄ = 0.75 ± 0.21) when compared to the reference vessel (x̄ = 0.41 ± 0.13), whereas the contact aspiration group had a 64% increase of the contrast ratio difference between target (x̄ = 0.62 ± 0.07) and reference vessels (x̄ = 0.38 ± 0.12). Approximately 65% of patients in the stentriever group had a positive parenchymal susceptibility-weighted imaging versus 25% in the contact aspiration group. There was no statistically significant correlation between susceptibility-weighted imaging volume and the percentage increase in the contrast ratio (rs = 0.098, P = 0.748). CONCLUSIONS: This prospective pilot study used the objective quantification of arterial wall enhancement in determining arterial changes after mechanical thrombectomy. Preliminary data suggest that the use of stentrievers is associated with a higher enhancement as compared to reperfusion catheters.

Impact of Procedure Time on Outcomes of Thrombectomy for Stroke.

BACKGROUND: Endovascular thrombectomy (ET) for acute ischemic stroke is the current standard of care. Although successful ET has high efficacy in improving functional outcomes, the decision to abort a long procedure remains a challenge. Longer procedure time (PT) has been associated with lower rates of functional independence. OBJECTIVES: The objective of this study was to evaluate the impact of PT on outcomes and complications after ET using different techniques at a multicenter level and to define the risk of procedure extension in different patient cohorts. METHODS: Patients undergoing ET with a stent retriever (SR) or a direct aspiration at first pass technique at 7 U.S. centers between June 2013 and February 2018 were reviewed from prospectively maintained databases that include baseline variables and technical and clinical outcomes. Multivariate analyses were used to assess impact of PT on 90-day modified Rankin scores, successful recanalization, post-procedural symptomatic hemorrhage (sICH), and complications. RESULTS: The study included 1,359 patients and demonstrated a decreased likelihood of good functional outcomes (modified Rankin score 0 to 2) when PT extended beyond 30 min (p < 0.01). Rates of sICH and complications increased exponentially with PT (doubling rates of 26 and 50 min, respectively). The cumulative rate of successful recanalization and good outcomes plateaued after 60 min of PT. In patients with PT >30 min, fewer attempts predicted the success of ET and good outcomes (p < 0.01). Successful recanalization was achieved faster with the direct aspiration at first pass technique than in SR. The direct aspiration technique was more sensitive to PT than SR, and posterior stroke was more sensitive to PT than anterior stroke. CONCLUSIONS: Longer ET procedures lead to lower rates of functional independence and higher rates of sICH and complications. Exceeding 60 min or 3 attempts should trigger careful assessment of futility and risks of continuing the procedure.

Comparative evaluation in nonhuman primates of five PET radiotracers for imaging the serotonin transporters: [11C]McN 5652, [11C]ADAM, [11C]DASB, [11C]DAPA, and [11C]AFM.

The recent introduction of a number of new radiotracers suitable for imaging the serotonin transporters (SERT) has radically changed the field of SERT imaging. Whereas, until recently, only one selective SERT radiotracer was available ([11C]McN 5652) for SERT imaging with positron emission tomography (PET), several new C-11-labeled radiotracers of the -dimethyl-2-(arylthio)benzylamine class have been described as appropriate imaging agents for the SERT. The aim of this study was to conduct a comparative evaluation of four of the most promising agents in this class ([11C]ADAM, [11C]DASB, [11C]DAPA, and [11C]AFM) with the reference tracer [11C]McN 5652 under standardized experimental conditions. This evaluation included in vitro measurements of affinity and lipophilicity, and in vivo PET imaging experiments in baboons. In vitro, DASB displayed significantly lower affinity for SERT than the other four tracers. In the blood, [11C]DASB and [11C]AFM display faster clearance and higher free fractions. Brain uptake was analyzed with kinetic modeling using a one-tissue compartment model and the metabolite-corrected arterial input function. The kinetic uptake of [11C]DASB was significantly faster compared with the other compounds, and the scan duration required to derive time-independent estimates of regional distribution volumes was shorter. [11C]DAPA exhibited the slowest brain kinetic. Regional-specific-to-nonspecific equilibrium partition coefficient (V3") was the highest for [11C]AFM, followed by [11C]DASB and [11C]DAPA, which in turn provided higher V3" values than [11C]ADAM and [11C]McN 5652. From these experiments, two ligands emerged as superior radiotracers that provide a significant improvement over [11C]McN 5652 for PET imaging of SERT: [11C]DASB, because it enables the measurement of SERT availability in a shorter scanning time, and [11C]AFM, because its higher signal-to-noise ratios provide a more reliable measurement of SERT availability in brain regions with relatively low density of SERT, such as in the limbic system.