Imaging After Thrombolysis and Thrombectomy: Rationale, Modalities and Management Implications

Intracranial aneurysms in patients with acute ischemic stroke prevalence and influence on mechanical thrombectomy over 14 years in a tertiary-care center

INTRODUCTION

The prevalence of intracranial aneurysms (IA) in patients with acute ischemic stroke (AIS) requiring mechanical thrombectomy (MT) is unclear.

OBJECTIVE

To describe the prevalence of IA in patients with AIS and their influence on MT.

MATERIALS & METHODS

This is a retrospective cohort study on all patients admitted with a diagnosis of AIS from January 2008 to March 2022 at a tertiary academic center. The records were reviewed for demographic, clinical, imaging, and outcomes data. Only patients who had CTA at admission were included in this analysis.

RESULTS

Among 2265 patients admitted with AIS, this diagnosis was confirmed in 2113 patients (93.3 %). We included 1111 patients (52.6 %) who had head CTA and 321 (28.9 %) who underwent MT. The observed prevalence of aneurysms on CTA was 4.5 % (50/1111 patients), and 8 (16 %) had multiple aneurysms. MT was performed in 7 patients harboring IAs: 6 ipsilateral (5 proximal and 1 distal to the occlusion)and 1 contralateral aneurysm.. The patient with a contralateral aneurysm had a TICI 2B score In patients with ipsilateral aneurysms, TICI 2B or 3 was achieved in 3 cases (50 %), which is significantly lower than historical control of MT (91.6 %) without IA (p = 0.01). No aneurysms ruptured during MT. The aneurysm noted distal to the occlusion was mycotic.

CONCLUSION

In this analysis, the observed prevalence of IA in patients with AIS was 4.5%. Ipsilateral aneurysms (proximal or distal to the occlusion site) deserve particular attention, given the potential risk of rupture during MT. Aneurysms located distal to the occlusion were mycotic and the rate of recanization in patients with ipsilateral aneurysms was low compared to historical controls. Further studies are needed to improve the outcomes in patients with IA requiring MT.

Evolution pattern estimated by computed tomography perfusion post-thrombectomy predicts outcome in acute ischemic stroke

OBJECTIVES

Computed tomography perfusion (CTP) and computed tomography angiography (CTA) have been recommended to select acute ischemic stroke (AIS) patients for endovascular thrombectomy (EVT) but are not widely used for post-treatment evaluation. We aimed to observe abnormalities in CTP and CTA before and after EVT and evaluate post-EVT CTP and CTA as potential tools for improving clinical outcome prediction.

METHODS

Patients with AIS who underwent EVT and received CTP and CTA before and after EVT were retrospectively evaluated. The ischemic core was defined as the volume of relative cerebral blood flow <30% and hypoperfusion as the volume of Tmax >6 s. A reduction in hypoperfusion volume >90% between baseline and post-EVT CTP was defined as tissue optimal reperfusion (TOR). The 90-day modified Rankin scale was used to evaluate the clinical outcome.

RESULTS

Eighty-three patients were included. Patients with an absent ischemic core or with TOR after EVT had a higher rate of modified Thrombolysis in Cerebral Ischemia score 2c-3 and recanalization of post-treatment vessel condition based on follow-up CTA. Multivariable logistic regression revealed that the baseline ischemic core volume (OR:0.934, p=0.009), TOR (OR:8.322, p=0.029) and immediate NIHSS score after EVT (OR:0.761, p=0.012) were factors significantly associated with good clinical outcome. Combining baseline ischemic core volume and TOR with immediate NIHSS score after EVT showed greatest performance for good outcome prediction after EVT(AUC=0.921).

CONCLUSIONS

The addition of pretreatment and post-treatment CTP information to purely clinical NIHSS scores might help to improve the efficacy for good outcome prediction after EVT.

Pupillometry in the follow-up of patients undergoing EVT - prediction of space-occupying hemispheric infarction

BACKGROUND

Despite benefits of endovascular treatment (EVT) for large vessel occlusion (LVO) ischemic stroke, space-occupying brain edema (BE) represents a detrimental complication. In critical-care settings, CT-imaging is needed for monitoring these patients. Yet, bed-side techniques with the potential to predict whether patients develop BE or not would facilitate a time- and cost-efficient patient care. We assessed clinical significance of automated pupillometry in the follow-up of patients undergoing EVT.

METHODS

From 10/2018 to 10/2021, neurocritical-care-unit patients were retrospectively enrolled after EVT of anterior circulation LVO. We monitored parameters of pupillary reactivity [light-reflex-latency (Lat), constriction- and redilation-velocities (CV, DV), percentage-change-of-apertures (per-change); NeurOptics-pupilometer®] up to every hour on day 1-3 of ICU stay. BE was defined as midline shift ≥ 5 mm on follow-up imaging 3-5 days after EVT. We calculated mean values of intra-individual differences between successive pairs of parameters (mean-deltas), determined best discriminative cut-off values for BE development (ROC-analyses), and evaluated prognostic performance of pupillometry for BE development (sensitivity/specificity/positive-/negative-predictive-values).

RESULTS

3241 pupillary assessments of 122 patients [67 women, 73 years (61.0-85.0)] were included. 13/122 patients developed BE. Patients with BE had significantly lower CVs, DVs, and smaller per-changes than patients without BE. On day 1 after EVT mean-deltas of CV, DV, and per-changes were significantly lower in patients with than without BE. Positive-predictive-values of calculated thresholds to discriminate both groups were considerably low, yet, we found high negative-predictive-values for CV, DV, per-changes, and mean-deltas (max.: 98.4%).

CONCLUSION

Our data suggest associations between noninvasively detected changes in pupillary reactivity and BE early after LVO-EVT. Pupillometry may identify patients who are unlikely to develop BE and may not need repetitive follow-up-imaging or rescue-therapy.

Post-ischemic hyperemia following endovascular therapy for acute stroke is associated with lesion growth

A substantial proportion of acute stroke patients fail to recover following successful endovascular therapy (EVT) and injury to the brain and vasculature secondary to reperfusion may be a contributor. Acute stroke patients were included with: i) large vessel occlusion of the anterior circulation, ii) successful recanalization, and iii) evaluable MRI early after EVT. Presence of hyperemia on MRI perfusion was assessed by consensus using a modified ASPECTS. Three different approaches were used to quantify relative cerebral blood flow (rCBF). Sixty-seven patients with median age of 66 [59-76], 57% female, met inclusion criteria. Hyperemia was present in 35/67 (52%) patients early post-EVT, in 32/65 (49%) patients at 24 hours, and in 19/48 (40%) patients at 5 days. There were no differences in incomplete reperfusion, HT, PH-2, HARM, severe HARM or symptomatic ICH rates between those with and without early post-EVT hyperemia. A strong association (R2 = 0.81, p < 0.001) was found between early post-EVT hyperemia (p = 0.027) and DWI volume at 24 hours after adjusting for DWI volume at 2 hours (p < 0.001) and incomplete reperfusion at 24 hours (p = 0.001). Early hyperemia is a potential marker for cerebrovascular injury and may help select patients for adjunctive therapy to prevent edema, reperfusion injury, and lesion growth.

Evaluation and Prediction of Post-stroke Cerebral Edema Based on Neuroimaging

Cerebral edema is a common complication of acute ischemic stroke that leads to poorer functional outcomes and substantially increases the mortality rate. Given that its negative effects can be reduced by more intensive monitoring and evidence-based interventions, the early identification of patients with a high risk of severe edema is crucial. Neuroimaging is essential for the assessment and prediction of edema. Simple markers, such as midline shift and hypodensity volume on computed tomography, have been used to evaluate edema in clinical trials; however, advanced techniques can be applied to examine the underlying mechanisms. In this study, we aimed to review current imaging tools in the assessment and prediction of cerebral edema to provide guidance for using these methods in clinical practice.

Complications of Mechanical Thrombectomy in Acute Ischemic Stroke

Multiple randomized clinical trials have supported the use of mechanical thrombectomy (MT) as standard of care in the treatment of large vessel occlusion acute ischemic stroke. Optimal outcomes depend not only on early reperfusion therapy but also on post thrombectomy care. Early recognition of post MT complications including reperfusion hemorrhage, cerebral edema and large space occupying infarcts, and access site complications can guide early initiation of lifesaving therapies that can improve neurologic outcomes. Knowledge of common complications and their management is essential for stroke neurologists and critical care providers to ensure optimal outcomes. We present a review of the available literature evaluating the common complications in patients undergoing MT with emphasis on early recognition and management.

Effects of Magnetic Nanoparticle Drug Delivery Systems on Thrombosis and Neuroprotection in Brain Stroke Model

Nanomaterials refer to solid materials that are composed of ultrafine particles on the order of nanometers. Nanomaterials show broad application prospects in the fields of chemistry, metallurgy, electronics, aerospace, biology and medicine. The incidence of stroke in China ranks first in the world and the mortality rate is much higher than that in European and American countries. Drugs that are sensitive to the internal environment of the living body can be combined in the nuclear department to prevent them from reacting with the biological environment before reaching the target site, thereby reducing the efficacy or causing toxic side effects on other cells, tissues and organs. This project uses transgenic mice as experimental materials to establish an animal model of cerebral stroke. The light-embedded stroke model is used to simulate the pathological state of acute ischemic stroke. In vivo imaging and immunohistochemical techniques are used to analyze the administration of magnetic nanoparticles. Effects of the system on thrombolysis and neurological function protection in cerebral stroke models.

Value of Vascular and Non-Vascular Pattern on Computed Tomography Perfusion in Patients With Acute Isolated Aphasia

Background and Purpose:

Acute onset aphasia may be due to stroke but also to other causes, which are commonly referred to as stroke mimics. We hypothesized that, in patients with acute isolated aphasia, distinct brain perfusion patterns are related to the cause and the clinical outcome. Herein, we analyzed the prognostic yield and the diagnostic usefulness of computed tomography perfusion (CTP) in patients with acute isolated aphasia.

Methods:

From a single-center registry, we selected a cohort of 154 patients presenting with acute isolated aphasia who had a whole-brain CTP study available. We collected the main clinical and radiological data. We categorized brain perfusion studies on CTP into vascular and nonvascular perfusion patterns and the cause of aphasia as ischemic stroke, transient ischemic attack, stroke mimic, and undetermined cause. The primary clinical outcome was the persistence of aphasia at discharge. We analyzed the sensitivity, specificity, positive and negative predictive values of perfusion patterns to predict complete clinical recovery and ischemic stroke on follow-up imaging.

Results:

The cause of aphasia was an ischemic stroke in 58 patients (38%), transient ischemic attack in 3 (2%), stroke mimic in 68 (44%), and undetermined in 25 (16%). CTP showed vascular and nonvascular perfusion pattern in 62 (40%) and 92 (60%) patients, respectively. Overall, complete recovery occurred in 116 patients (75%). A nonvascular perfusion pattern predicted complete recovery (sensitivity 75.9%, specificity 89.5%, positive predictive value 95.7%, and negative predictive value 54.8%), and a vascular perfusion pattern was highly predictive of ischemic stroke (sensitivity 94.8%, specificity 92.7%, positive predictive value 88.7%, and negative predictive value 96.7%). The 3 patients with ischemic stroke without a vascular perfusion pattern fully recovered at discharge.

Conclusions:

CTP has prognostic value in the workup of patients with acute isolated aphasia. A nonvascular pattern is associated with higher odds of full recovery and may prompt the search for alternative causes of the symptoms.