The Relationship between CT Angiography Collateral Score and Biochemical Parameters during Acute Ischemic Stroke Caused by Middle Cerebral Artery Infarct

Background/Objectives: Collateral development after AIS is important for prognosis and treatment. In this study, we aimed to investigate the relationship and correlation between biochemical parameters and CT angiography collateral score within the first 9 h and its effect on the neurological outcomes of patients with AIS due to MCA infarction. Methods: A total of 98 patients with MCA infarction were hospitalized for diagnosis and treatment after undergoing CT angiography within 9 h of suffering a stroke. Demographic data, admission biochemical parameters, hospitalization data, and discharge NIHSS scores were recorded. Souza's scoring system for collateral distribution was used to evaluate collaterals. Souza CS system and clinical disability comparison outcomes identified. Results: According to the Souza CS system, 13 patients were in the malignant profile category, and 85 patients were in the good profile category. The NIHSS value of patients with a malignant profile was 27, while the mean NIHSS value of patients with a good profile was 9. There was a statistically significant difference in uric acid, total cholesterol, triglyceride, HDL cholesterol, CRP, hsCRP, D-Dimer, troponin I, vitamin B12, fibrinogen, NSE, homocysteine, aPTT, and INR levels according to collateral distribution. Conclusions: This study demonstrates that biochemical parameters can influence the distribution of malignant and benign collaterals in AIS independent of age and gender.

The impact of leptomeningeal collaterals in acute ischemic stroke: a systematic review and meta-analysis

OBJECTIVES

Leptomeningeal collaterals provide an alternate pathway to maintain cerebral blood flow in stroke to prevent ischemia, but their role in predicting the outcome is still unclear. So, our study aims at assessing the significance of collateral blood flow (CBF) in acute stroke.

METHODS

Electronic databases were searched under different MeSH terms from January 2000 to February 2019. Studies were included if there was available data on good and poor CBF in acute ischemic stroke (AIS). The clinical outcomes included were modified Rankin scale (mRS), recanalization, mortality, and symptomatic intracranial hemorrhage (sICH) at 90 days. Data was analyzed using a random-effect model.

RESULTS

A total of 47 studies with 8194 patients were included. Pooled meta-analysis revealed that there exist twofold higher likelihood of favorable clinical outcome (mRS ≤ 2) at 90 days with good CBF compared with poor CBF (RR: 2.27; 95% CI: 1.94-2.65; p < 0.00001) irrespective of the thrombolytic therapy [RR with IVT: 2.90; 95% CI: 2.14-3.94; p < 0.00001, and RR with IAT/EVT: 1.99; 95% CI: 1.55-2.55; p < 0.00001]. Moreover, there exists onefold higher probability of successful recanalization with good CBF (RR: 1.31; 95% CI: 1.15-1.49; p < 0.00001). However, there was 54% and 64% lower risk of sICH and mortality respectively in patients with good CBF in AIS (p < 0.00001).

CONCLUSIONS

The relative risk of favorable clinical outcome is more in patients with good pretreatment CBF. This could be explained due to better chances of recanalization combined with a lesser risk of intracerebral hemorrhage with good CBF status.

Circle of Willis variation and outcome after intra-arterial treatment

Background

Intra-arterial treatment (IAT) improves outcomes in acute ischaemic stroke. Presence of collaterals increases likelihood of good outcome. We investigated whether variations in the circle of Willis (CoW) and contributing carotid arteries influence outcome in patients who had a stroke treated with IAT.

Methods

CT angiography data on patients who had an acute stroke treated with IAT were retrospectively collected. CoW was regarded complete if the contralateral A1 segment, anterior communicating artery and ipsilateral posterior communicating artery were fully developed, and the P1 segment was visible. Carotid artery contribution was studied with a self-developed carotid artery score ranging from 0 to 2 depending on the number of arteries supplying the occluded side of the CoW. Good clinical outcome was defined as modified Rankin Score ≤2 and measured at discharge and 3 months. We calculated risk ratios for the relation between completeness of the CoW, carotid score and good outcome, and performed a trend analysis for good outcome according to the carotid score.

Results

126 patients were included for analysis. Patients with a complete and incomplete CoW had a comparable risk for good outcome at discharge and 3 months. A higher carotid score was associated with a higher likelihood of good clinical outcome (p for trend 0.24 at discharge and 0.05 at 3 months).

Conclusion

In patients with acute ischaemic stroke treated with IAT, chances of good clinical outcome tended to improve with number of carotid arteries supplying the cerebral circulation. Completeness of the CoW was not related to clinical outcome.

Leukoaraiosis Distribution and Cerebral Collaterals: A Systematic Review and Meta-Analysis

Background and Objective

Microvascular failure might result in the collapse of cerebral collaterals. However, controversy remains regarding the role of leukoaraiosis (LA) in collateral recruitment. We, therefore, performed a systematic review and meta-analysis of the association between LA and cerebral collaterals.

Methods

Ovid Medline, PubMed, Embase, Web of Science, and three Chinese databases were searched from inception to August 2021. Two types of cerebral collaterals, including Circle of Willis (CoW) and leptomeningeal collaterals (LC), were investigated separately. Random effect models were used to calculate the pooled odds ratio (OR). Meta-regression and subgroup analyses were performed to explore the potential sources of heterogeneity.

Results

From 14 studies (n = 2,451) that fulfilled our inclusion criteria, data from 13 could be pooled for analysis. Overall, there was a significant association between severe LA and incomplete CoW (pooled OR 1.66, 95% CI 1.18–2.32, p = 0.003), with low heterogeneity (I² = 5.9%). This association remained significant in deep LA (pooled OR 1.48, 95% CI 1.04–2.11, p = 0.029, I² = 0), but not periventricular LA. Similarly, there was a significant association between LA and LC (pooled OR 1.73, 95% CI 1.03–2.90, p = 0.037), but with high heterogeneity (I² = 67.2%). Meta-regression indicated a negative association of sample size with the effect sizes (p = 0.029). In addition, most of the studies (7/9) included into the analysis of the relationship of severe LA with poor LC enrolled subjects with large vessel occlusion stroke, and this relationship remained significant when pooling the seven studies, but with high heterogeneity.

Conclusion

Severe LA is associated with a higher prevalence of poor collaterals. This association is robust for CoW but weak for LC. Further studies are required to explore the underlying mechanisms.

Topographic Evolution of Anterior Cerebral Artery Infarction and Its Impact on Motor Impairment

INTRODUCTION

Motor deficit is common following anterior cerebral artery (ACA) stroke. This study aimed to determine the impact on the motor outcome, given the location of descending corticofugal fiber tracts (from the primary motor cortex [M1], dorsal and ventral premotor area [PMdv], and supplementary motor area [SMA]) and the regional variations in collateral support of the ACA territory.

METHODS

Patients with ACA vessel occlusion were included. Disruption to corticofugal fibers was inferred by overlap of tracts with a lesion on computed tomography perfusion at the onset and on magnetic resonance imaging (MRI) poststroke. The motor outcome was defined by dichotomized and combined National Institute of Health Stroke Scale (NIHSS) sub-scores for the arm and leg. Multivariate hierarchical partitioning was used to analyze the proportional contribution of the corticofugal fibers to the motor outcome.

RESULTS

Forty-seven patients with a median age of 77.5 (interquartile range 68.0-84.5) years were studied. At the stroke onset, 96% of patients showed evidence of motor deficit on the NIHSS, and the proportional contribution of the corticofugal fibers to motor deficit was M1-33%, SMA-33%, and PMdv-33%. By day 7, motor deficit was present in <50% of patients and contribution of M1 fiber tracts to the motor deficit was reduced (M1-10.2%, SMA-61.0%, PMdv-28.8%). We confirmed our findings using publicly available high-resolution templates created from Human Connectome Project data. This also showed a reduction in involvement of M1 fiber tracts on initial perfusion imaging (33%) compared to MRI at a median time of 7 days poststroke (11%).

CONCLUSION

Improvements in the motor outcome seen in ACA stroke may be due to the relative sparing of M1 fiber tracts from infarction. This may occur as a consequence of the posterior location of M1 fiber tracts and the evolving topography of ACA stroke due to the compensatory capacity of leptomeningeal anastomoses.

Anterior Cerebral Artery Stroke: Role of Collateral Systems on Infarct Topography

[Figure: see text].

Comparison of methods between CT perfusion source images and CT angiography in collateral flow assessment

BACKGROUND

The methods used for grading leptomeningeal collateral flow (LMF) on single-phase computed tomography angiography (CTA) are heterogeneous and limited by temporal resolution.

PURPOSE

To compare the reliability of relative filling time delay (rFTD) on CT perfusion source images (CTP-SI) and the currently used single-phase CTA collateral assessment methods and evaluate their ability to predict clinical outcomes in acute ischemic stroke patients.

MATERIAL AND METHODS

We analyzed consecutive middle cerebral artery or internal carotid artery occlusion patients who received multimodal CT before treatment and within 12 h of stroke symptom onset from October 2015 to December 2018. Patients were dichotomized using the 90-day mRS into good (0-1) versus adverse (2-6) outcomes. CTP-SI was used to identify the rFTD score. CTA images were reconstructed to assess collateral status using the collateral score (Cs) and region leptomeningeal collateral score (rLMCs). Two observers independently assessed images.

RESULTS

The baseline characteristics (n = 54) were median age of 67 years and 68.5% of the participants were men. The baseline median NIHSS was 14. Good clinical outcomes were observed in 19 (35.2%) patients. The k value was higher for rFTDs (k = 0.779, P < 0.001) than Cs (k = 0.666, P < 0.001) and rLMCs (k = 0.763, P < 0.001). Higher rFTDs were correlated with lower rLMCs (Spearman's rho -0.68, P < 0.001) and Cs (rho -0.66, P < 0.001). In multivariate logistic regression, rFTD was associated with functional outcomes (P = 0.044).

CONCLUSION

The rFTDs method is comparable to single-phase CTA-based assessments in assessing LMFs in acute ischemic stroke patients. Higher rFTDs is independently associated with adverse long-term functional outcomes.

Hemodynamics in acute stroke: Cerebral and cardiac complications

Hemodynamics is the study of blood flow, where parameters have been defined to quantify blood flow and the relationship with systemic circulatory changes. Understanding these perfusion parameters, the relationship between different blood flow variables and the implications for ischemic injury are outlined in the ensuing discussion. This chapter focuses on the hemodynamic changes that occur in ischemic stroke, and their contribution to ischemic stroke pathophysiology. We discuss the interaction between cardiovascular response and hemodynamic changes in stroke. Studying hemodynamic changes has a key role in stroke prevention, therapeutic implications and prognostic importance in acute ischemic stroke: preexisting hemodynamic and autoregulatory impairments predict the occurrence of stroke. Hemodynamic failure predisposes to the formation of thromboemboli and accelerates infarction due to impairing compensatory mechanisms. In ischemic stroke involving occlusion of a large vessel, persistent collateral circulation leads to preservation of ischemic penumbra and therefore justifying endovascular thrombectomy. Following thrombectomy, impaired autoregulation may lead to reperfusion injury and hemorrhage.

Severe Leukoaraiosis Is Associated with Poor Outcome after Successful Recanalization of M1 Middle Cerebral Artery Occlusion Strokes

BACKGROUND

Severe leukoaraiosis (LA) is an established risk factor for poor outcome after mechanical thrombectomy (MT) for large vessel occlusion stroke. There is uncertainty whether this association also applies to successfully recanalized patients with M1 segment middle cerebral artery (MCA) occlusions.

METHODS

A retrospective single-centre study of patients with successful reperfusion (thrombolysis in cerebral infarction, TICI 2b or 3) after MT for an M1 MCA occlusion was performed over a 7-year period. LA score (LAS) was assessed using the age-related white matter change scale on pre-interventional brain imaging.

RESULTS

A total of 209 patients (median age 75.0 years) were included. LAS was assessed on pre-interventional imaging by computed tomography in 177 (84.7%) patients and magnetic resonance imaging in 32 (15.3%) patients. The median LAS was 1 (IQR 0-8), and severe LA consisted of the top 25 percentile, ranging from 9 to 24. Multivariable analysis demonstrated an association of severe LA (OR 0.32, 95% CI 0.12-0.88, p = 0.023), higher NIHSS on admission (OR 0.89, 95% CI 0.84-0.94, p < 0.001), advanced age (OR 0.97, 95% CI 0.95-1.00, p = 0.039), good leptomeningeal collaterals (OR 3.65, 95% CI 1.46-8.15, p = 0.001), and TICI 3 score (OR 3.26, 95% CI 10.52-7.01) with good clinical outcome after 3 months as measured with the modified Rankin scale.

CONCLUSION

Severe LA is associated with poor clinical outcome at 3 months in acute stroke patients undergoing MT due to emergent M1 MCA occlusion.

Optimizing Outcome Prediction Scores in Patients Undergoing Endovascular Thrombectomy for Large Vessel Occlusions Using Collateral Grade on Computed Tomography Angiography

BACKGROUND

Although several outcome prediction scores incorporated with pretreatment variables have been developed for acute ischemic stroke (AIS) patients, there is not currently a prediction score that includes pretreatment imaging that can show salvageable brain tissue.

OBJECTIVE

To evaluate whether addition of the collateral grade on computed tomography angiography to previously published prediction scores could increase accuracy of clinical outcome prediction in endovascular thrombectomy (EVT) for AIS.

METHODS

This study used a retrospective multicenter registry for patients undergoing EVT for anterior circulation large vessel occlusion. Three previously published outcome prediction scores (Houston intra-arterial therapy 2, HIAT2; totaled health risks in vascular events, THRIVE; and Pittsburgh response to endovascular therapy, PRE scores) were tested in this study. Using 482 deprivation cohorts, areas under the receiver operating characteristic curves (AUC-ROCs) were compared between prediction scores with/without collateral grades in predicting the poor outcomes (modified Rankin Scale 4-6 at 3-mo follow-up) after EVT. We developed modified prediction scores by adding the collateral grade, and their advancement of outcome prediction was validated using 208 independent validation cohorts.

RESULTS

AUC-ROCs of HIAT2, THRIVE, and PRE scores that incorporated with collateral grade were superior in predicting poor outcomes when compared to that of the unmodified scores (P < 0.001). In modified prediction models, 3, 3, and 10 points were added for poor collateral grade to HIAT2, THRIVE, and PRE score. Modified models outperformed unmodified models in testing of the validation cohorts (P < 0.001).

CONCLUSION

The addition of the collateral grade to outcome prediction scores resulted in better prediction of poor outcome after EVT for AIS compared to the prediction scores alone.

Intracranial atherosclerotic disease

Intracranial atherosclerosis (ICAS) is a progressive pathological process that causes progressive stenosis and cerebral hypoperfusion and is a major cause of stroke occurrence and recurrence around the world. Multiple factors contribute to the development of ICAS. Angiography imaging techniques can improve the diagnosis of and the selection of appropriate treatment regimens for ICAS. Neither aggressive medication nor endovascular interventions can eradicate stroke recurrence in patients with ICAS. Non-pharmacological therapies such as remote ischemic conditioning and hypothermia are emerging. Comprehensive therapy with medication in combination with endovascular intervention and/or non-pharmacological treatment may be a potential strategy for ICAS treatment in the future. We summarized the epidemiology, pathophysiological mechanisms, risk factors, biomarkers, imaging and management of ICAS.

Influence of the circle of Willis on leptomeningeal collateral flow in anterior circulation occlusive stroke: Friend or foe?

BACKGROUND

Clinical outcome after large vessel occlusion (LVO) stroke depends on collateral integrity. We aimed to evaluate whether the completeness of the circle of Willis (CoW) and anterior temporal artery (ATA) determines the status of leptomeningeal collaterals (LC) in patients with acute LVO (internal carotid artery (ICA) and middle cerebral artery M1 (MCA) occlusion) treated with endovascular thrombectomy.

PATIENTS AND METHODS

LC, cross-flow through the anterior communicating artery (ACoA), presence of the ipsilateral posterior communicating artery (IpsiPCoA) and presence of the ATA were evaluated using CT angiography. LC was graded as good when ≥50% collateral filling was noted compared to the unaffected hemisphere.

RESULTS

We included 159 patients with a median age of 75 years (IQR 63-82), MCA M1 occlusion in 96 (60%) and good outcome in 68 (45.6%). The LC were good in 129 (81.1%) patients. Complete IpsiPCoA and incomplete ACoA status was inversely associated with good LC in LVO (OR 0.51 (95% CI 0.02-0.07)). A complete CoW was associated with good LC in ICA occlusions, OR 8.4 (p = .025). Good outcome (modified Rankin scale 0-2 at 3 months) was associated with good LC (OR 5.63 (95% CI 1.11-28.4)), small ischemic lesion volume (OR 0.94 (95% CI 0.97-0.98)) and absence of the ACoA and IpsiPCoA (OR 4.47 (95% CI 1.09-18.3)).

CONCLUSIONS

ATA presence was associated with good leptomeningeal collaterals in LVO (OR 8.13 (95% CI 1.69-39.0)) and in MCA M1 patients (OR 7.9 (95% CI 1.7-36.4)). The effect of ATA was most pronounced in MCA M1 occlusions, and that of ACoA was most pronounced in ICA occlusions.

Autoregulating Cerebral Tissue Selfishly Exploits Collateral Flow Routes Through the Circle of Willis

OBJECTIVE

Ischemic stroke is a leading cause of death and disability. Autoregulation and collateral blood flow through the circle of Willis both play a role in preventing tissue infarction. A steady-state model of the cerebral arterial network was used to investigate the interaction of these mechanisms when autoregulation is impaired ipsilateral to an occluded artery.

MATERIALS AND METHODS

Twelve structural variants of the circle of Willis were modelled with left internal carotid artery occlusion and coupled with (1) a passive model of the cerebral vascular bed, (2) a steady-state model of an autoregulating cerebral vascular bed, and (3) a model in which the contralateral hemisphere autoregulates and the ipsilateral hemisphere does not.

RESULTS

Results showed that if the autoregulatory response is impaired ipsilaterally, then, in the autoregulating hemisphere, cerebral flows are preserved at the expense of those on the ipsilateral side.

CONCLUSIONS

Thus, although autoregulation is an essential facilitator of collateral flow through the circle of Willis, contralateral autoregulation can exacerbate flow reductions if not balanced by the same response in the vascular beds on the ipsilateral side. The status of the autoregulatory response in both hemispheres can strongly influence cerebral blood flows and tissue survival and should, therefore, be monitored in stroke.

Impact of collateral circulation status on favorable outcomes in thrombolysis treatment: A systematic review and meta-analysis

Collateral circulation affects the prognosis of patients with acute ischemic stroke (AIS) treated by thrombolysis. The present study performed a systematic assessment of the impact of the collateral circulation status on the outcomes of patients receiving thrombolysis treatment. Relevant full-text articles from the Cochrane Library, Ovid, Medline, Embase and PubMed databases published from January 1, 2000 to November 1, 2016 were retrieved. The quality of the studies was assessed and data were extracted by 2 independent investigators. The random-effects model was used to estimate the impact of good vs. poor collateral circulation, as well as baseline characteristics, on the outcome within the series presented as risk ratios. Subgroup analyses explored the potential factors that may interfere with the effects of the collateral circulation status on the outcome. A total of 29 studies comprising 4,053 patients were included in the present meta-analysis. A good collateral circulation status was revealed to have a beneficial effect on favorable functional outcome (modified Rankin scale, 0–3 at 3–6 months; P<0.001) and a higher rate of recanalization (P<0.001) compared with poor collateral circulation. Good collateral circulation was also associated with a lower rate of symptomatic intracranial hemorrhage (P<0.01), a lower rate of mortality (P<0.01) and a smaller infarct size (P<0.01). In conclusion, good collateral circulation was demonstrated to have a favorable prognostic value regarding the outcome for patients with AIS receiving thrombolysis treatment. Assessment of collateral circulation and penumbra area during pre-treatment imaging within an appropriate time-window prior to thrombolytic therapy will therefore improve the identification of AIS patients who may benefit from thrombolysis treatment.

Aldehyde Dehydrogenase 2 (ALDH2) Glu504Lys Polymorphism Affects Collateral Circulation and Short-Term Prognosis of Acute Cerebral Infarction Patients

Background

Acute cerebral infarction is a major clinical subtype of ischemic stroke that has become a leading cause of death and disability worldwide. Aldehyde dehydrogenase 2 (ALDH2) is an important oxidative enzyme in alcohol metabolism. The polymorphism of ALDH2 Glu504Lys polymorphism modifies the activity of this enzyme. However, the potential association between the allelic variation of ALDH2 Glu504Lys with collateral circulation and short-term prognosis of acute cerebral infarction remains unclear.

Material/Methods

A total of 394 patients with acute cerebral infarction were recruited for ALDH2 genotyping using direct sequencing. Cerebrovascular stenosis and collateral circulation were evaluated by digital subtraction angiography (DSA). Short-term prognosis was assessed in accordance with the modified Ranking Scale (mRS).

Results

We identified 297 as EAS and 394 as IAS. There were more patients with occluded blood vessel in the opened group and far fewer in the unopened group. ALDH2 polymorphism was significantly different among the primary, secondary, and tertiary opened groups. ALDH2 gene Glu504Lys was significantly associated with short-term prognosis. The genotype GA+AA of ALDH2 gene Glu504Lys locus was an independent risk factor of poor 90-day prognosis.

Conclusions

ALDH2 Glu504Lys could be a risk factor for collateral circulation and a negative predictor for short-term prognosis in acute cerebral infarction in Han Chinese. ALDH2 Glu504Lys could be a new therapeutic target for patients with acute cerebral infarction.

The Dual Role of Cerebral Autoregulation and Collateral Flow in the Circle of Willis After Major Vessel Occlusion

OBJECTIVE

Ischaemic stroke is a leading cause of death and disability. Autoregulation and collateral blood flow through the circle of Willis both play a role in preventing tissue infarction. To investigate the interaction of these mechanisms a one-dimensional steady-state model of the cerebral arterial network was created.

METHODS

Structural variants of the circle of Willis that present particular risk of stroke were recreated by using a network model coupled with: 1) a steady-state physiological model of cerebral autoregulation; and 2) one wherein the cerebral vascular bed was modeled as a passive resistance. Simulations were performed in various conditions of internal carotid and vertebral artery occlusion.

RESULTS

Collateral flow alone is unable to ensure adequate blood flow ([Formula: see text] normal flow) to the cerebral arteries in several common variants during internal carotid artery occlusion. However, compared to a passive model, cerebral autoregulation is better able to exploit available collateral flow and maintain flows within [Formula: see text] of baseline. This is true for nearly all configurations.

CONCLUSION

Hence, autoregulation is a crucial facilitator of collateral flow through the circle of Willis.

SIGNIFICANCE

Impairment of this response during ischemia will severely impact cerebral blood flows and tissue survival, and hence, autoregulation should be monitored in this situation.

Expanding the concept of neuroprotection for acute ischemic stroke: The pivotal roles of reperfusion and the collateral circulation

This review surveys the efforts taken to achieve clinically efficacious protection of the ischemic brain and underscores the necessity of expanding our purview to include the essential role of cerebral perfusion and the collateral circulation. We consider the development of quantitative strategies to measure cerebral perfusion at the regional and local levels and the application of these methods to elucidate flow-related thresholds of ischemic viability and to characterize the ischemic penumbra. We stress that the modern concept of neuroprotection must consider perfusion, the necessary substrate upon which ischemic brain survival depends. We survey the major mechanistic approaches to neuroprotection and review clinical neuroprotection trials, focusing on those phase 3 multicenter clinical trials for acute ischemic stroke that have been completed or terminated. We review the evolution of thrombolytic therapies; consider the lessons learned from the initial, negative multicenter trials of endovascular therapy; and emphasize the highly successful positive trials that have finally established a clinical role for endovascular clot removal. As these studies point to the brain's collateral circulation as key to successful reperfusion, we next review the anatomy and pathophysiology of collateral perfusion as it relates to ischemic infarction, as well as the molecular and genetic influences on collateral development. We discuss the current MR and CT-based diagnostic methods for assessing the collateral circulation and the prognostic significance of collaterals in ischemic stroke, and we consider past and possible future therapeutic directions.

Intravenous Thrombolysis and Passes of Thrombectomy as Predictors for Endovascular Revascularization in Ischemic Stroke

BACKGROUND

Patient selection for endovascular revascularization treatment (ERT) in acute ischemic stroke depends on the expected benefit-risk ratio. As rapid revascularization is a major determinant of good functional outcome, we aimed to identify its predictors after ERT.

METHODS

Consecutive stroke patients from a single stroke center with distal internal carotid artery-, proximal middle cerebral artery- or T-occlusions treated with ERT were retrospectively selected. We assessed admission noncontrast computed tomography and computed tomography angiography for thrombus location, thrombus load (clot burden score), and collateral status. Clinical data were extracted from medical charts. Univariate and multivariate regression analyses were performed to identify predictors of revascularization (thrombolysis in cerebral infarction ≥2b) after ERT.

RESULTS

A total of 63 patients were identified (median age, 73 years; interquartile range: 62-77; 40 females). Sixteen patients (25.4%) underwent intravenous thrombolysis (ivT) before ERT. Twenty-two patients (34.9%) had additional intra-arterial application of recombinant tissue plasminogen activator. The overall recanalization rate was 66.7%, and 9.5% had symptomatic intracranial bleeding. In-hospital mortality was 15%, and 30% reached good functional outcome at discharge. In the univariate analysis, preceding ivT and the number of passes for thrombectomy (dichotomized ≤2 versus >2) were associated with recanalization. There was a trend for number of thrombectomy passes (as continuous variable) and multimodal ERT. In the multivariate regression analysis, ivT prior to ERT and passes of thrombectomy were identified as independent predictors for recanalization.

CONCLUSION

ivT and lower passes of thrombectomy are associated with recanalization after ERT for ischemic stroke with proximal vessel occlusions.

Determinants of leptomeningeal collateral flow in stroke patients with a middle cerebral artery occlusion

Introduction

Poor leptomeningeal collateral flow is related to worse clinical outcome in acute ischemic stroke, but the factors that determine leptomeningeal collateral patency are largely unknown. We explored the determinants of leptomeningeal collateral flow and assessed their effect on the relation between leptomeningeal collateral flow and clinical outcome.

Methods

We included 484 patients from the Dutch acute stroke study (DUST) with a middle cerebral artery (MCA) occlusion. The determinants of poor leptomeningeal collateral flow (≤50 % collateral filling) were identified with logistic regression. We calculated the relative risk (RR) of poor leptomeningeal collateral flow in relation to poor clinical outcome (90-day modified Rankin Scale 3–6) using Poisson regression and assessed whether the determinants of leptomeningeal collateral flow affected this relation.

Results

Leptomeningeal collateral flow was poor in 142 patients (29 %). In multivariable analyses, higher admission glucose level (odds ratio (OR) 1.1 per mmol/L increase (95 % CI 1.0–1.2)), a proximal MCA occlusion (OR 1.9 (95 % CI 1.3–3.0)), and an incomplete posterior circle of Willis (OR 1.7 (95 % CI 1.1–2.6)) were independently related to poor leptomeningeal collateral flow. Poor leptomeningeal collateral flow was related to poor clinical outcome (unadjusted RR 1.7 (95 % CI 1.4–2.0)), and this relation was not affected by the determinants of leptomeningeal collateral flow.

Conclusion

Our study shows that admission glucose level, a proximal MCA occlusion, and an incomplete ipsilateral posterior circle of Willis are determinants of leptomeningeal collateral flow that represent a combination of congenital, acquired, and acute factors. After adjustment for these determinants, leptomeningeal collateral flow remains related to clinical outcome.

Impact of collaterals on the efficacy and safety of endovascular treatment in acute ischaemic stroke: a systematic review and meta-analysis

OBJECTIVE

We aimed to investigate the role of pretreatment collateral status in predicting the efficacy and safety of endovascular treatment (EVT) in acute ischaemic stroke due to cervical and/or cerebral arterial occlusions.

METHODS

Relevant full-text articles published since 1 January 2000, investigating correlations between collateral status and any efficacy or safety outcome in patients undergoing EVT in cohort or case-control studies, or randomised clinical trials, were retrieved by PubMed and manual search. Two authors extracted data from eligible studies and assessed study quality. Risk ratios (RR) were pooled for good versus poor collaterals for outcomes based on a random-effects model. Sensitivity and subgroup analyses were conducted.

RESULTS

In total, 35 (3542 participants) and 23 (2652 participants) studies were included in qualitative review and quantitative meta-analysis, respectively. Overall, good pretreatment collaterals increased the rate of favourable functional outcome at 3 months (RR=1.98, 95% CI 1.64 to 2.38; p<0.001), and reduced the risks of periprocedural symptomatic intracranial haemorrhage (RR=0.59, 95% CI 0.43 to 0.81; p=0.001) and 3-month mortality (RR=0.49, 95% CI 0.38 to 0.63; p<0.001), as compared with poor collaterals, in patients with acute ischaemic stroke under EVT. No individual study could alter the estimate of overall effect of collateral status, but there were moderate to significant heterogeneities between subgroups of studies with different modes of EVT, different arterial occlusions and different collateral grading methods.

CONCLUSIONS

Good pretreatment collateral status is associated with higher rates of favourable functional outcome, and lower rates of symptomatic intracranial haemorrhage and mortality, in patients with acute ischaemic stroke receiving endovascular therapies.

Inter-rater Agreement in Three Perfusion-Computed Tomography Evaluation Methods before Endovascular Therapy for Acute Ischemic Stroke

PURPOSE

There is ongoing debate on which method of perfusion computed tomography (PCT) evaluation in ischemic stroke is the most appropriate for improved selection of patients for endovascular treatment. We sought to test different assessment methods for inter-rater reliability.

METHODS

Twenty-six patients were enrolled prospectively before endovascular therapy for acute anterior circulation ischemic stroke. Three raters experienced in stroke imaging and blinded to other imaging and clinical information independently analyzed 22 technically successful PCT scans according to 3 prespecified assessment methods applied to cerebral blood flow (CBF)/cerebral blood volume (CBV) and time-to-peak (TTP) maps: (1) visual mismatch estimate (VME), (2) Alberta Stroke Program Early CT Score perfusion method (ASPECTS-PCT), and (3) quantitative perfusion ratios (qPRs): RCBF, RCBV, RTTP. Inter-rater agreement was assessed with Cohen's kappa, intraclass correlation coefficients (ICC), Bland-Altman plots, and global and descriptive statistics.

RESULTS

Significant differences between raters were found with VME and ASPECTS-PCT (P < .001) but with qPRs only for CBV (P = .03). Inter-rater agreement for VME was at best moderate by kappa statistics (.51); moderate by ICC for all parametric maps of ASPECTS-PCT (.56-.62), strong for RTTP (.76), and excellent for RCBF (.92) and RCBV (.86). Pairwise comparisons revealed less scattering of individual values with qPRs and less deviation of mean differences from 0, suggesting minor systematic deviation by any 1 rater as compared with VME or ASPECTS-PCT.

CONCLUSION

PCT evaluation methods used before endovascular therapy for acute anterior circulation stroke are subject to substantial inter-rater disagreement. QPRs in PCT evaluation had better inter-rater reliability than the often used VME and ASPECTS-PCT assessment.

CT angiography and CT perfusion improve prediction of infarct volume in patients with anterior circulation stroke

Introduction

We investigated whether baseline CT angiography (CTA) and CT perfusion (CTP) in acute ischemic stroke could improve prediction of infarct presence and infarct volume on follow-up imaging.

Methods

We analyzed 906 patients with suspected anterior circulation stroke from the prospective multicenter Dutch acute stroke study (DUST). All patients underwent baseline non-contrast CT, CTA, and CTP and follow-up non-contrast CT/MRI after 3 days. Multivariable regression models were developed including patient characteristics and non-contrast CT, and subsequently, CTA and CTP measures were added. The increase in area under the curve (AUC) and R² was assessed to determine the additional value of CTA and CTP.

Results

At follow-up, 612 patients (67.5 %) had a detectable infarct on CT/MRI; median infarct volume was 14.8 mL (interquartile range (IQR) 2.8–69.6). Regarding infarct presence, the AUC of 0.82 (95 % confidence interval (CI) 0.79–0.85) for patient characteristics and non-contrast CT was improved with addition of CTA measures (AUC 0.85 (95 % CI 0.82–0.87); p < 0.001) and was even higher after addition of CTP measures (AUC 0.89 (95 % CI 0.87–0.91); p < 0.001) and combined CTA/CTP measures (AUC 0.89 (95 % CI 0.87–0.91); p < 0.001). For infarct volume, adding combined CTA/CTP measures (R² = 0.58) was superior to patient characteristics and non-contrast CT alone (R² = 0.44) and to addition of CTA alone (R² = 0.55) or CTP alone (R² = 0.54; all p < 0.001).

Conclusion

In the acute stage, CTA and CTP have additional value over patient characteristics and non-contrast CT for predicting infarct presence and infarct volume on follow-up imaging. These findings could be applied for patient selection in future trials on ischemic stroke treatment.

Electronic supplementary material

The online version of this article (doi:10.1007/s00234-015-1636-z) contains supplementary material, which is available to authorized users.

Effect of Collaterals on Clinical Presentation, Baseline Imaging, Complications, and Outcome in Acute Stroke

BACKGROUND AND PURPOSE

Good CTA collaterals independently predict good outcome in acute ischemic stroke. Our aim was to evaluate the role of collateral circulation and its added benefit over CTP-derived total ischemic volume as a predictor of baseline NIHSS score, total ischemic volume, hemorrhagic transformation, final infarct size, and a modified Rankin Scale score >2.

MATERIALS AND METHODS

This was a retrospective study of 395 patients with stroke dichotomized by recanalization (recanalization positive/recanalization negative) and collateral status. Clot burden score was quantified on baseline CTA. Total ischemic volumes were derived from thresholded CTP maps. Final infarct size was assessed on follow-up CT/MRI. We performed uni-/multivariate analyses for each outcome, adjusting for rtPA status, using general linear (continuous variables) and logistic (binary variables) regression. Model comparison with collateral score and total ischemic volume was performed using the F or likelihood ratio test.

RESULTS

Collateral presence independently and inversely predicted all outcomes except hemorrhagic transformation in patients who were recanalization negative and mRS >2 in patients who were recanalization positive. The greatest collateral benefit occurred in patients who were recanalization negative, contributing 16.5% and 19.2% of the variability for final infarct size and mRS >2. The collateral score model is superior to the total ischemic volume for mRS >2 prediction, but a combination of total ischemic volume and collateral score is superior for mRS >2 and final infarct prediction (24% and 28% variability, respectively). In patients who were recanalization positive, a model including collateral score and total ischemic volume was superior to that of total ischemic volume for hemorrhagic transformation and final infarct prediction but was muted compared with patients who were recanalization negative (11.3% and 16.9% variability).

CONCLUSIONS

Collateral circulation is an independent predictor of all outcomes, but the magnitude of significance varies, greater in patients who were recanalization negative versus recanalization positive. Total ischemic volume assessment is complementary to collateral score in many cases.

Influence of Recanalization and Time of Cerebral Ischemia on Tissue Outcome after Endovascular Stroke Treatment on Computed Tomography Perfusion

BACKGROUND

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) has been proposed as a straightforward alternative to the less reliable visual estimation of tissue at risk. We evaluated the association between admission ASPECTS on computed tomography perfusion (CTP) parameter maps and final infarct ASPECTS in patients with acute ischemic stroke who were treated by endovascular therapy (eT) and compared the results with thrombolysis candidates treated conservatively.

METHODS

eT was performed in 26 consecutive ischemic stroke patients within 6 hours of symptom onset. The control group was matched for age and admission National Institutes of Health Stroke Scale having the same admission imaging protocol and a transcranial Doppler sonography within 24 hours. ASPECTS determined from CTP maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and time to peak (TTP) were compared with final infarct ASPECTS on day 5 noncontrast CT.

RESULTS

Recanalization rate was 73% in treatment and 50% in control group. ASPECTS for all CTP parameters were significantly lower than ASPECTS-CT in both groups (P < .005). In the treatment group, this applied to patients with successful recanalization. Only controls without recanalization showed a strong correlation between ASPECTS-CTP parameters and ASPECTS-CT (CBV: P = .005; CBF and TTP: P = .028). Patients with early recanalization (≤4 hours) had greater differences between ASPECTS-CTP and ASPECTS-CT than patients with late recanalization (>4 hours; CBF: P = .056; CBV: P = .095; TTP: P = .048).

CONCLUSIONS

The initial ASPECTS-CTP lesion was significantly larger than the final infarct determined by ASPECTS in case of recanalization. Initial perfusion lesion, including CBV, is reversible in case of reperfusion, especially in early reperfusion.

The cortical contrast accumulation from brain computed tomography after endovascular treatment predicts symptomatic hemorrhage

BACKGROUND AND PURPOSE

The prognostic value of contrast accumulation from non-contrast brain computed tomography taken immediately after endovascular reperfusion treatment in acute ischaemic stroke patients to predict symptomatic hemorrhage was studied.

METHODS

Between July 2007 and August 2014, acute anterior circulation ischaemic stroke patients who were treated by intra-arterial thrombolysis or thrombectomy were included. Contrast accumulation was defined as a high attenuation area from non-contrast brain computed tomography immediately taken after endovascular reperfusion treatment, and patients were categorized into three groups according to the presence and location of contrast: (i) negative, (ii) cortical involvement and (iii) non-cortical involvement. The rates of symptomatic hemorrhage after 24 h and functional outcome at discharge were compared between patients with and without cortical involvement.

RESULTS

Of 64 patients who were treated by endovascular intervention, contrast accumulation was detected in 56, including 33 patients with cortical involvement and 23 patients without cortical involvement. The cortical involvement pattern was more frequently associated with symptomatic hemorrhage (13 vs. 1 patient, P = 0.003) and with grave outcome at discharge with modified Rankin Scale 5 or 6 (14 vs. 4, P = 0.048) than the non-cortical involvement group. Multivariate logistic regression analysis including initial collateral status and occlusion site disclosed that cortical involvement pattern independently predicted symptomatic hemorrhage after endovascular treatment (odds ratio 19.0, confidence interval 1.6-227.6, P = 0.020).

CONCLUSION

Our study provides evidence that the cortical involvement of contrast accumulation is associated with symptomatic hemorrhage after endovascular reperfusion treatment.

Degree of Collaterals and Not Time Is the Determining Factor of Core Infarct Volume within 6 Hours of Stroke Onset

BACKGROUND AND PURPOSE

Growth of the core infarct during the first hours of ischemia onset is not well-understood. We hypothesized that factors other than time from onset of ischemia contribute to core infarct volume as measured by MR imaging.

MATERIALS AND METHODS

Prospectively collected clinical and imaging data of consecutive patients with stroke presenting between March 2008 and April 2013 with anterior circulation large-vessel occlusion and MR imaging performed within 6 hours from the time of onset were reviewed. The association of time from onset, clinical, and radiographic features with DWI volume was assessed by using χ(2) and Mann-Whitney U tests.

RESULTS

Of 91 patients, 21 (23%) underwent MR imaging within 0-3 hours from onset, and 70 (76%), within 3-6 hours. Median MR imaging infarct volume was similar in both timeframes, (24.7 versus 29.4 mL, P = .906), and there was no difference in the proportion of patients with large infarct volumes (≥70 mL, 23.8% versus 22.8%, P = .928). Using receiver operating characteristic analysis, we detected no association between the time from onset and MR imaging infarct volume (area under the curve = 0.509). In multivariate analysis, CTA collaterals (>50% of the territory) (adjusted OR, 0.192; 95% CI, 0.04-0.9; P = .046), CTA ASPECTS (adjusted OR, 0.464; 95% CI, 0.3-0.8; P = .003), and a history of hyperlipidemia (adjusted OR, 11.0; 95% CI, 1.4-88.0; P = .023) (but not time from stroke onset to imaging) were independent predictors of MR imaging infarct volume.

CONCLUSIONS

Collateral status but not time from stroke onset to imaging was a predictor of the size of core infarct in patients with anterior circulation large-vessel occlusion presenting within 6 hours from onset.

Imaging Patterns and Management Algorithms in Acute Stroke: An Update for the Emergency Radiologist

Neuroimaging plays a key role in the initial work-up of patients with symptoms of acute stroke. Understanding the advantages and limitations of available CT and MR imaging techniques and how to use them optimally in the emergency setting is crucial for accurately making the diagnosis of acute stroke and for rapidly determining appropriate treatment.

Effect of the Interaction between Recanalization and Collateral Circulation on Functional Outcome in Acute Ischaemic Stroke

Identification of patients with acute ischaemic stroke who could most benefit from arterial recanalization after endovascular treatment remains an unsettled issue. Although several classifications of collateral circulation have been proposed, the clinical role of collaterals is still debated. We evaluated the effect of the collateral circulation in relation to recanalization as a predictor of clinical outcome. Data were prospectively collected from 103 patients consecutively treated for proximal middle cerebral or internal carotid artery occlusion. The collateral circulation was evaluated with a novel semiquantitative-qualitative score, the Careggi collateral score (CCS), in six grades. Both CCS and recanalization grades (TICI) were analysed in relation to clinical outcome. A statistical analysis was performed to evaluate the effect of interaction between recanalization and collateral circulation on clinical outcome. Out of the 103 patients, 37 (36.3%) had poor collaterals, and 65 (63.7%) had good collaterals. Patients with good collaterals had lower basal National Institute of Health Stroke Scale (NIHSS), more distal occlusion, smaller lesions at 24h CT scan and better functional outcome. After multivariate analysis, the interaction between recanalization and collateral grades was significantly stronger as a predictor of good outcome (OR 6.87, 95% CI 2.11-22.31) or death (OR 4.66, 95%CI 1.48-14.73) compared to the effect of the single variables. Collaterals showed an effect of interaction with the recanalization grade in determining a favourable clinical outcome. Assessment of the collateral circulation might help predict clinical results after recanalization in patients undergoing endovascular treatment for acute ischaemic stroke.

Collateral flow and brain changes on computed tomography angiography predict infarct volume on early diffusion-weighted imaging

BACKGROUND

We investigated whether a computed tomography (CT)-based score could predict a large infarct (≥ 80 mL) on early diffusion-weighted magnetic resonance imaging (DWI).

METHODS

Acute stroke patients considered for endovascular therapy within 8 hours of the onset of symptoms were included. The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) was determined on noncontrast CT and computed tomography angiography source images (CTA-SI). Limited collateral flow was defined as less than 50% collateral filling on CTA-SI.

RESULTS

Fifty-six patients were analyzed. National Institutes of Health Stroke Scale score was 20 (15-24) in the large infarct group and 16 (11-20) in the small infarct group (P = .049). ASPECTS on noncontrast CT and CTA-SI was 5 (3-8) and 3 (2-6) in the large infarct group and 9 (8-10) and 8 (7-9) in the small infarct group (both P < .001), respectively. Limited collateral flow was frequent in the large infarct group than in the small infarct group (92% vs. 11%, P < .001). Multivariate analysis found that CTA-SI ASPECTS less than or equal to 5 (odds ratio [OR], 40.55; 95% confidence interval [CI], 1.10-1493.44; P = .044) and limited collateral flow (OR, 114.64; 95% CI, 1.93-6812.79; P = .023) were associated with a large infarct. Absence of ASPECTS less than or equal to 5 and limited collateral flow on CTA-SI predicted absence of a large infarct with a sensitivity of .89, specificity of 1.00, positive predictive value of 1.00, and negative predictive value of .71.

CONCLUSIONS

Assessment of ASPECTS and collateral flow on CTA-SI may be able to exclude a patient with large infarct on early DWI.

Computer modeling of anterior circulation stroke: proof of concept in cerebrovascular occlusion

BACKGROUND

Current literature emphasizes the role of the Circle of Willis (CoW) in salvaging ischemic brain tissue but not that of leptomeningeal anastomoses (LA). We developed a computational model of the cerebral circulation to (1) evaluate the roles of the CoW and LA in restoring flow to the superficial compartment of the middle cerebral artery (MCA) territory and (2) estimate the size of the LA required to maintain flow above the critical ischemic threshold (>30% of baseline) under simulated occlusion.

METHODS

Cerebral vasculature was modeled as a network of junctions connected by cylindrical pipes. The experiments included occlusion of successive distal branches of the intracranial arteries while the diameters of LA were varied.

RESULTS

The model showed that the region of reduced flow became progressively smaller as the site of occlusion was moved from the large proximal to the smaller distal arteries. There was no improvement in flow in the MCA territory when the diameters of the inter-territorial LA were varied from 0.0625 to 0.5 mm while keeping the intra-territorial LA constant. By contrast, the diameter of the inter-territorial LA needed to be >1.0 mm in order to provide adequate (>30%) flow to selected arteries in the occluded MCA territory.

CONCLUSION

The CoW and inter-territorial LA together play important supportive roles in intracranial artery occlusion. Computational modeling provides the ability to experimentally investigate the effect of arterial occlusion on CoW and LA function.

[Vascular assessment in stroke codes: role of computed tomography angiography]

Advances in imaging studies for acute ischemic stroke are largely due to the development of new efficacious treatments carried out in the acute phase. Together with computed tomography (CT) perfusion studies, CT angiography facilitates the selection of patients who are likely to benefit from appropriate early treatment. CT angiography plays an important role in the workup for acute ischemic stroke because it makes it possible to confirm vascular occlusion, assess the collateral circulation, and obtain an arterial map that is very useful for planning endovascular treatment. In this review about CT angiography, we discuss the main technical characteristics, emphasizing the usefulness of the technique in making the right diagnosis and improving treatment strategies.

The impact of arterial collateralization on outcome after intra-arterial therapy for acute ischemic stroke

BACKGROUND AND PURPOSE

Although intra-arterial therapy for acute ischemic stroke is associated with superior recanalization rates, improved clinical outcomes are inconsistently observed following successful recanalization. There is emerging concern that unfavorable arterial collateralization, though unproven, predetermines poor outcome. We hypothesized that poor leptomeningeal collateralization, assessed by preprocedural CTA, is associated with poor outcome in patients with acute ischemic stroke undergoing intra-arterial therapy.

MATERIALS AND METHODS

We retrospectively analyzed patients with acute ischemic stroke with intracranial ICA and/or MCA occlusions who received intra-arterial therapy. The collaterals were graded on CTA. Univariate and multivariate analyses were used to investigate the association between the dichotomized leptomeningeal collateral score and functional outcomes at 3-months mRS ≤2, mortality, and intracranial hemorrhages.

RESULTS

Eighty-seven patients were included. The median age was 66 years (interquartile range, 54-76 years) and the median NIHSS score at admission was 18 (interquartile range, 14-20). The leptomeningeal collateral score 3 was found to have significant association with the good functional outcome at 3 months: OR = 3.13; 95% CI, 1.25-7.825; P = .016. This association remained significant when adjusted for the use of IV tissue plasminogen activator: alone, OR = 2.998; 95% CI, 1.154-7.786; P = .024; and for IV tissue plasminogen activator and other confounders (age, baseline NIHSS score, and Thrombolysis in Cerebral Infarction grades), OR = 2.985; 95% CI, 1.027-8.673; P = .045.

CONCLUSIONS

We found that poor arterial collateralization, defined as a collateral score of <3, was associated with poor outcome, after adjustment for recanalization success. We recommend that future studies include collateral scores as one of the predictors of functional outcome.

Diffusion-weighted imaging volume as the best predictor of the diffusion-perfusion mismatch in acute stroke patients within 8 hours of onset

BACKGROUND

Diagnostic accuracies of standard NCCT, CTA, CTA-SI, FLAIR, and DWI to detect the diffusion-perfusion mismatch (DPM) were compared.

METHODS

Stroke patients considered for endovascular therapy within 8 hours of onset were enrolled. DPM was defined as at least 160% mismatch between DWI and PWI volume.

RESULTS

DPM was seen in 35 (71%) of 49 patients. ASPECTS on NCCT, CTA-SI, and DWI was 9 (8-9), 8 (6-9), and 7 (5-9) in mismatch group, and 6 (4-9), 6 (2-7), 5 (2-6) in nonmismatch group, respectively (P = .027, .006, and .001). Ischemic volume on CTA-SI and DWI was 4.6 (.2-13.0) cm(3) and 21.5 (9.7-44.0) cm(3) in mismatch group, and 61.5 (6.6-101.1) cm(3) and 94.9 (45.7-139.8) cm(3) in nonmismatch group (P = .003 and <.001). Significant collateralization on CTA-SI and FLAIR was seen in 80% and 88% in mismatch group, and 42% and 58% in nonmismatch group (P = .026 and .039). Odds ratios (95% CI) of DWI volume of ≤ 70 cm(3) to predict the mismatch was 30.17 (2.06-442.41) after adjusting for ASPECTSs on NCCT, CTA-SI, and DWI, 44.90 (2.75-732.73) for ischemic volume on CTA-SI, and 42.80 (3.05-601.41) for significant collateralization on CTA-SI and FLAIR (P = .013, .008, and .005).

CONCLUSIONS

DWI volume was the best predictor of DPM.

Patient body weight-tailored contrast medium injection protocol for the craniocervical vessels: a prospective computed tomography study

OBJECTIVES

To evaluate body weight-tailored contrast medium (CM) administration for computed tomography angiography (CTA) of the craniocervical vessels.

METHODS

Institutional review board approval was obtained, and all patients gave written informed consent. Sixty patients were consecutively assigned to one of three dose groups (20 patients per group) with CM doses of Visipaque 270® (iodixanol 270 mg/ml) tailored to body weight at doses of 1.5, 1.0, or 0.5 ml/kg. Region-of-interest (ROI) analysis of maximum enhancement (ME) was conducted, and signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were calculated. Retrospective comparison was performed with three matched control groups examined with a standard CM dose (80 ml of Visipaque 270®). Image quality was rated by two neuroradiologists blinded to the CM dose used. Interrater reliability was calculated using kappa statistics.

RESULTS

Body weight/BMI and ME were inversely correlated in the three control groups receiving the standard dose (r = -0.544/-0.597/-0.542/r = -0.358/r = -0.424/r = -0.280). Compared to standard dose, 1.5 ml/kg produced higher ME, SNR, and CNR in the anterior circulation (p≤0.038), 1.0 ml/kg had higher ME in cervical and medium-sized cerebral arteries (p≤0.034), and 0.5 ml/kg had lower ME, SNR and CNR for medium-sized cerebral arteries (p≤0.049). ME, SNR, and CNR were the same for 1.5 ml/kg and 1.0 ml/kg (p≥0.24), and both had higher values compared to 0.5 ml/kg (p≤0.043/p≤0.028). In patients with BMI>25, 1.5 ml/kg and 1.0 ml/kg produced higher ME than standard dose (p<0.001/p = 0.008), but ME in patients with BMI>25 did not differ between group 1 and group 2 (p = 0.673). In patients with BMI≤25, 1.5 ml/kg and 1.0 ml/kg produced ME comparable to standard dose (p = 0.132/p = 0.403). Regardless of patient weight, 0.5 ml/kg yielded lower ME than standard dose (p = 0.019/0.002).

CONCLUSIONS

Craniocervical CTA with a body weight-tailored CM dose of 1.0 ml/kg (270 mg iodine/ml) reduces iodine load in patients weighing <80 kg while producing ME similar to standard dose and improves ME in patients with BMI>25.

Update on acute endovascular and surgical stroke treatment

Emergency stroke care has become a natural part of the emerging discipline of neurocritical care and demands close cooperation between the neurologist and neurointerventionists, neurosurgeons, and anesthesiologists. Endovascular treatment (EVT), including intra-arterial thrombolysis, mechanical thrombectomy and angioplasty/stenting, is under rapid development. Although EVT has yet to be shown in randomized controlled trials to improve clinical outcome compared to intravenous thrombolysis, it is far better in achieving recanalization of occluded large cerebral vessels, which is crucial for rescuing the penumbra. Moreover, decompressive craniectomy is now a well-established treatment option for malignant middle cerebral artery infarction and cerebellar stroke. Using a case-based approach, this article reviews recent achievements in advanced treatment options for patients with acute ischemic stroke.

Perfusion-weighted imaging-derived collateral flow index is a predictor of MCA M1 recanalization after i.v. thrombolysis

BACKGROUND AND PURPOSE

Recent studies highlight the role of CC in preserving ischemic penumbra. Some authors suggested the quality of CC could also impact recanalization. The purpose of this study is to test this hypothesis in patients who were treated with i.v. thrombolysis for MCA-M1 occlusion.

MATERIALS AND METHODS

A normalized index derived from Tmax maps (MR-PWI) was defined to quantify the CC deficit (nCCD) in 64 patients with stroke who underwent i.v. thrombolysis. Correlations between nCCD and parameters that may be altered by CC quality were tested (baseline NIHSS, volume of diffusion abnormalities, modified Rankin Scale at 3 months). The correlation between baseline nCCD and MCA-M1 recanalization rate at 24 hours was tested.

RESULTS

The nCCD is significantly correlated with NIHSS and with lesional volume (Pearson correlation test, positive correlations, respectively, 0.40, 0.57; P = .00089, P = 8.7e-07). The nCCD also has a significant predictive value on the full recanalization at 24 hours that decreases as TTT increases (logistic regression, P = .021). Furthermore, among patients who were treated within 3 hours, nCCD and recanalization are significantly correlated (correlation ratio test, eta2 = 0.23, P = .0023): Patients who did not achieve full recanalization have significantly higher nCCD than fully recanalized patients (Mann-Whitney U test, P = .007). In addition, the probability of full recanalization decreases as the nCCD increases (P = .021). nCCD (OR 0.988, 95% CI 0.977-0.999, P = .042) and full recanalization at 24 hours (OR 4.539, 95% CI 1.252-16.456, P = .021) are independent predictors of functional independence at 3 months.

CONCLUSIONS

The nCCD index is a predictor of full MCA-M1 recanalization in patients treated with i.v. thrombolysis.

Characteristics of cerebral ischemia in major rat stroke models of middle cerebral artery ligation through craniectomy

BACKGROUND

The refinement of experimental stroke models is important for further development of neuroprotective interventions.

AIMS AND/OR HYPOTHESIS

Our goal was to study the reproducibility of outcomes obtained in five rat models of middle cerebral artery (MCA) ligation in order to identify the optimal model for the preclinical studies.

METHODS

In Part 1 of the experiments, systolic blood flow velocity (sBFV) and cerebral area at risk (AR) were determined immediately after the onset of brain ischemia induced in different ways in Wistar rats. After that, another set of experiments was performed (Part 2 of the experiments), now aimed at the assessment of the delayed outcome of five different models of cerebral ischemia designated as Versions 1-5. The versions were: Version 1 - 40-minute left MCA (LMCA) occlusion with reperfusion; Version 2 - permanent LMCA ligation; Version 3 - permanent ligation of both LMCA and left common carotid artery (CCA); Version 4 - permanent LMCA and bilateral CCA (bCCA) ligation; Version 5 - permanent LMCA ligation and 40-minute bCCA occlusion. The infarct size (IS) was quantified using triphenyltetrazolium chloride staining. The severity of neurological deficit was assessed by the Garcia score. The extent of brain edema was determined by calculating the difference in volumes of affected and contralateral hemispheres.

RESULTS

Within a relatively big AR, Versions 1 and 2 resulted in a small IS [0·2 (0·0; 0·4)% and 0·3 (0·0; 0·7)%, respectively, P > 0·05]. Unlike that and comparable with AR, Version 3 resulted in a greater, albeit more variable IS [5·9 (2·1; 8·3)%, P < 0·0001 vs. Version 2]. Also comparable with AR, Versions 4 and 5 produced greatest values of IS [14·5 (11·4; 17·9)% and 11·3 (10·1; 14·2)%, respectively]; this parameter was most reproducible in Version 5. A significant decrease in neurological deficit score was found in Versions 4 and 5. Again, the reproducibility of the data on neurological outcome was higher in Version 5 versus Version 4.

CONCLUSIONS

Comparative analysis of several Versions of focal cerebral ischemia within a single study might be helpful in better understanding of the mechanisms underlying the development and aftermath of stroke. Permanent LMCA ligation plus transient bilateral CCA occlusion produced most consistent results and might be recommended for preclinical studies.