Clinical/perfusion CT CBV mismatch as prognostic factor in intraarterial thrombectomy in acute anterior circulation stroke

Flat Detector CT with Cerebral Pooled Blood Volume Perfusion in the Angiography Suite: From Diagnostics to Treatment Monitoring

C-arm flat-panel detector computed tomographic (CT) imaging in the angiography suite increasingly plays an important part during interventional neuroradiological procedures. In addition to conventional angiographic imaging of blood vessels, flat detector CT (FD CT) imaging allows simultaneous 3D visualization of parenchymal and vascular structures of the brain. Next to imaging of anatomical structures, it is also possible to perform FD CT perfusion imaging of the brain by means of cerebral blood volume (CBV) or pooled blood volume (PBV) mapping during steady state contrast administration. This enables more adequate decision making during interventional neuroradiological procedures, based on real-time insights into brain perfusion on the spot, obviating time consuming and often difficult transportation of the (anesthetized) patient to conventional cross-sectional imaging modalities. In this paper we review the literature about the nature of FD CT PBV mapping in patients and demonstrate its current use for diagnosis and treatment monitoring in interventional neuroradiology.

Outcomes and CT Perfusion Thresholds of Mechanical Thrombectomy for Patients With Large Ischemic Core Lesions

Objective

To explore the clinical prognosis and factors after mechanical thrombectomy (MT) in patients with large cerebral infarction assessed by computed tomographic perfusion (CTP)and the optimal threshold of cerebral blood flow (CBF) for estimating ischemic core.

Methods

We analyzed data from the anterior circulation database of our hospital (August 2018-June 2021). Multivariate logistic regression analyses identified the predictors of clinical outcomes for patients with large baseline infarcts (>50 ml) assessed by the MIStar software. The receiver operating characteristic (ROC) analysis was used to explore the cutoff value of factors.

Results

The present study included one hundred thirty-seven patients with large baseline infarcts. Moreover, 23 (16.8%) patients achieved functionally independent outcomes, and 50 (36.5%) patients died at 90 days. A total of 20 (14.7%) patients had symptomatic intracranial hemorrhage (sICH). The multivariable analysis showed that higher age and larger core volume were independent of poor outcomes. The cutoff value of core volume was 90 ml, and the age was 76 years. Hypertension and rt-PA treatment were independent factors of sICH. Higher age and larger ischemic volume were independent risk factors of mortality.

Conclusions

Mechanical thrombectomy can be applied in patients with large ischemic core volumes. Patients older than 76 years with large cores (>90 ml) are unlikely to benefit from MT. These findings may be helpful in selecting patients with large baseline infarcts to be treated by MT. The threshold of CBF < 30% is the independent factor, and this is worth evaluating in future studies to find the optimal threshold of CBF.

Topographic correlation of infarct area on CT perfusion with functional outcome in acute ischemic stroke

OBJECTIVE

The role of CT perfusion (CTP) in the management of patients with acute ischemic stroke (AIS) remains a matter of debate. The primary aim of this study was to evaluate the correlation between the areas of infarction and penumbra on CTP scans and functional outcome in patients with AIS.

METHODS

This was a retrospective review of 100 consecutively treated patients with acute anterior circulation ischemic stroke who underwent CT angiography (CTA) and CTP at admission between February 2011 and October 2014. On CTP, the volume of ischemic core and penumbra was measured using the Alberta Stroke Program Early CT Score (ASPECTS). CTA findings were also noted, including the site of occlusion and regional leptomeningeal collateral (rLMC) score. Functional outcome was defined by modified Rankin Scale (mRS) score obtained at discharge. Associations of CTP and CTA parameters with mRS scores at discharge were assessed using multivariable proportional odds logistic regression models.

RESULTS

The median age was 67 years (range 19-95 years), and the median NIH Stroke Scale score was 16 (range 2-35). In a multivariable analysis adjusting for potential confounding variables, having an infarct on CTP scans in the following regions was associated with a worse mRS score at discharge: insula ribbon (p = 0.043), perisylvian fissure (p < 0.001), motor strip (p = 0.007), M2 (p < 0.001), and M5 (p = 0.023). A worse mRS score at discharge was more common in patients with a greater volume of infarct core (p = 0.024) and less common in patients with a greater rLMC score (p = 0.004).

CONCLUSIONS

The results of this study provide evidence that several CTP parameters are independent predictors of functional outcome in patients with AIS and have potential to identify those patients most likely to benefit from reperfusion therapy in the treatment of AIS.

Utility of perfusion imaging in acute stroke treatment: a systematic review and meta-analysis

BACKGROUND

Variability in imaging protocols and techniques has resulted in a lack of consensus regarding the incorporation of perfusion imaging into stroke triage and treatment. The objective of our study was to evaluate the available scientific evidence regarding the utility of perfusion imaging in determining treatment eligibility in patients with acute stroke and in predicting their clinical outcome.

METHODS

We performed a systematic review of the literature using PubMed, Web of Science, and Cochrane Library focusing on themes of medical imaging, stroke, treatment, and outcome (CRD42016037817). We included randomized controlled trials, cohort studies, and case-controlled studies published from 2011 to 2016. Two independent reviewers conducted the study appraisal, data abstraction, and quality assessments of the studies.

RESULTS

Our literature search yielded 13 studies that met our inclusion criteria. In total, 994 patients were treated with the aid of perfusion imaging compared with 1819 patients treated with standard care. In the intervention group 51.1% of patients had a favorable outcome at 3 months compared with 45.6% of patients in the control group (p=0.06). Subgroup analysis of studies that used multimodal therapy (IV tissue plasminogen activator, endovascular thrombectomy) showed a significant benefit of perfusion imaging (OR 1.89, 95% CI 1.43 to 2.51, p<0.01).

CONCLUSIONS

Perfusion imaging may represent a complementary tool to standard radiographic assessment in enhancing patient selection for reperfusion therapy, with a subset of patients having up to 1.9 times the odds of achieving independent functional status at 3 months. This is particularly important as patients selected based on perfusion status often included individuals who did not meet the current treatment eligibility criteria.

Angiographic and Clinical Factors Related with Good Functional Outcome after Mechanical Thrombectomy in Acute Cerebral Artery Occlusion

Objective

The aim of this study is to investigate good prognostic factors for an acute occlusion of a major cerebral artery using mechanical thrombectomy.

Methods

Between January 2013 to December 2014, 37 consecutive patients with acute occlusion of a major cerebral artery treated by mechanical thrombectomy with stent retrievers were conducted. We analyzed clinical and angiographic factors retrospectively. The collateral flow and the result of recanalization were sorted by grading systems. Outcome was assessed by National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) at 90 days. We compared the various parameters between good and poor angiographic and clinical results.

Results

Twenty seven patients demonstrated good recanalization [Thrombolysis in Cerebral Infarction (TICI) 2b or 3] after thrombectomy. At the 90-day follow up, 19 patients had good (mRS, 0-2), 14 had moderate (3-4) and four had poor outcomes (5-6). The mRS of older patients (≥75 years) were poor than younger patients. Early recanalization, high Thrombolysis in Myocardial Infarction risk score, and low baseline NIHSS were closely related to 90-day mRS, whereas high TICI was related to both mRS and the decrease in the NIHSS.

Conclusion

NIHSS decreased markedly only when recanalization was successful. A good mRS was related to low initial NIHSS, good collateral, and early successful recanalization.

Dynamic Angiography and Perfusion Imaging Using Flat Detector CT in the Angiography Suite: A Pilot Study in Patients with Acute Middle Cerebral Artery Occlusions

BACKGROUND AND PURPOSE

Perfusion and angiographic imaging using intravenous contrast application to evaluate stroke patients is now technically feasible by flat detector CT performed by the angiographic system. The aim of this pilot study was to show the feasibility and qualitative comparability of a novel flat detector CT dynamic perfusion and angiographic imaging protocol in comparison with a multimodal stroke MR imaging protocol.

MATERIALS AND METHODS

In 12 patients with acute stroke, MR imaging and the novel flat detector CT protocol were performed before endovascular treatment. Perfusion parameter maps (MTT, TTP, CBV, CBF) and MIP/volume-rendering technique images obtained by using both modalities (MR imaging and flat detector CT) were compared.

RESULTS

Comparison of MIP/volume-rendering technique images demonstrated equivalent visibility of the occlusion site. Qualitative comparison of perfusion parameter maps by using ASPECTS revealed high Pearson correlation coefficients for parameters CBF, MTT, and TTP (0.95-0.98), while for CBV, the coefficient was lower (0.49).

CONCLUSIONS

We have shown the feasibility of a novel dynamic flat detector CT perfusion and angiographic protocol for the diagnosis and triage of patients with acute ischemic stroke. In a qualitative comparison, the parameter maps and MIP/volume-rendering technique images compared well with MR imaging. In our opinion, this flat detector CT application may substitute for multisection CT imaging in selected patients with acute stroke so that in the future, patients with acute stroke may be directly referred to the angiography suite, thereby avoiding transportation and saving time.

Twelve-Month Clinical and Quality-of-Life Outcomes in the Interventional Management of Stroke III Trial

BACKGROUND AND PURPOSE

Randomized trials have indicated a benefit for endovascular therapy in appropriately selected stroke patients at 3 months, but data regarding outcomes at 12 months are currently lacking.

METHODS

We compared functional and quality-of-life outcomes at 12 months overall and by stroke severity in stroke patients treated with intravenous tissue-type plasminogen activator followed by endovascular treatment as compared with intravenous tissue-type plasminogen activator alone in the Interventional Management of Stroke III Trial. The key outcome measures were a modified Rankin Scale score ≤2 (functional independence) and the Euro-QoL EQ-5D, a health-related quality-of-life measure.

RESULTS

656 subjects with moderate-to-severe stroke (National Institutes of Health Stroke Scale ≥8) were enrolled at 58 centers in the United States (41 sites), Canada (7), Australia (4), and Europe (6). There was an interaction between treatment group and stroke severity in the repeated measures analysis of modified Rankin Scale ≤2 outcome (P=0.039). In the 204 participants with severe stroke (National Institutes of Health Stroke Scale ≥20), a greater proportion of the endovascular group had a modified Rankin Scale ≤2 (32.5%) at 12 months as compared with the intravenous tissue-type plasminogen activator group (18.6%, P=0.037); no difference was seen for the 452 participants with moderately severe strokes (55.6% versus 57.7%). In participants with severe stroke, the endovascular group had 35.2 (95% confidence interval: 2.1, 73.3) more quality-adjusted-days over 12 months as compared with intravenous tissue-type plasminogen activator alone.

CONCLUSIONS

Endovascular therapy improves functional outcome and health-related quality-of-life at 12 months after severe ischemic stroke.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00359424.

Effect of extended CT perfusion acquisition time on ischemic core and penumbra volume estimation in patients with acute ischemic stroke due to a large vessel occlusion

BACKGROUND AND PURPOSE

It has been suggested that CT Perfusion acquisition times <60 seconds are too short to capture the complete in and out-wash of contrast in the tissue, resulting in incomplete time attenuation curves. Yet, these short acquisitions times are not uncommon in clinical practice. The purpose of this study was to investigate the occurrence of time attenuation curve truncation in 48 seconds CT Perfusion acquisition and to quantify its effect on ischemic core and penumbra estimation in patients with acute ischemic stroke due to a proximal intracranial arterial occlusion of the anterior circulation.

MATERIALS AND METHODS

We analyzed CT Perfusion data with 48 seconds and extended acquisition times, assuring full time attenuation curves, of 36 patients. Time attenuation curves were classified as complete or truncated. Ischemic core and penumbra volumes resulting from both data sets were compared by median paired differences and interquartile ranges. Controlled experiments were performed using a digital CT Perfusion phantom to investigate the effect of time attenuation curve truncation on ischemic core and penumbra estimation.

RESULTS

In 48 seconds acquisition data, truncation was observed in 24 (67%) cases for the time attenuation curves in the ischemic core, in 2 cases for the arterial input function and in 5 cases for the venous output function. Analysis of extended data resulted in smaller ischemic cores and larger penumbras with a median difference of 13.2 (IQR: 4.3-26.0) ml (P<0.001) and; 12.4 (IQR: 4.1-25.7) ml (P<0.001), respectively. The phantom data showed increasing ischemic core overestimation with increasing tissue time attenuation curve truncation.

CONCLUSIONS

Truncation is common in patients with large vessel occlusion and results in repartitioning of the area of hypoperfusion into larger ischemic core and smaller penumbra estimations. Phantom experiments confirmed that truncation results in overestimation of the ischemic core.

Multimodal imaging in acute ischemic stroke

OPINION STATEMENT

Recent years have seen the development of novel neuroimaging techniques whose roles in the management of acute stroke are sometimes confusing and controversial. This may be attributable in part to a focus on establishing simplified algorithms and terminology that omit consideration of the basic pathophysiology of cerebral ischemia and, consequently, of the full potential for optimizing patients' care based upon their individual imaging findings. This review begins by discussing cerebral hemodynamic physiology and of the effects of hemodynamic disturbances upon the brain. Particular attention will be paid to the hemodynamic measurements and markers of tissue injury that are provided by common clinical imaging techniques, with the goal of enabling greater confidence and flexibility in understanding the potential uses of these techniques in various clinical roles, which will be discussed in the remainder of the review.