Identification of imaging selection patterns in acute ischemic stroke patients and the influence on treatment and clinical trial enrollment decision making

Follow-up Imaging After Thrombolysis: FIAT, A Randomized Trial

TRIAL DESIGN

Current protocols for treatment of acute ischemic stroke with intravenous thrombolytics, such as alteplase (tPA) and tenecteplase (tNK), recommend the completion of a routine non-contrast head CT at 24 hours post treatment to evaluate for hemorrhage prior to the initiation of antiplatelet therapy for secondary stroke prevention. This guideline was instituted because it had been part of the protocol in the NINDS multicenter randomized placebo-controlled trial that showed the benefit of IV thrombolytics within 3 hours of stroke onset. Recent observational studies indicate that the repeat (stability) head CT rarely alters clinical management, in the absence of neurological worsening or evidence of clinical signs of hemorrhagic conversion, such as seizures, severe headache, or novel acute deficits. A solitary CT carries with it a non-negligible dose of radiation with additive cost to the medical system at large.

METHODS

We aimed to identify, with a randomized, blinded outcome assessment trial, if a routine head CT at 24 hours, in the absence of clinical indication, negatively influences clinical outcomes. We enrolled 58 patients, and evaluated differences between groups with t-tests. We also evaluated differences between outcomes (90 day modified Rankin Scale, mRS and change in National Institutes of Health Stroke Scale, NIHSS) from pretreatment to discharge using multivariable logistic regression, including age, baseline NIHSS, and group as independent variables.

RESULTS

We found no added benefit of routine CT on either outcome measure.

CONCLUSION

It is likely safe to forgo follow up imaging after thrombolysis in the absence of clinical decompensation.

Early Brain Imaging Shows Increased Severity of Acute Ischemic Strokes With Large Vessel Occlusion in COVID-19 Patients

BACKGROUND AND PURPOSE

Reports are emerging regarding the association of acute ischemic strokes with large vessel occlusion and coronavirus disease 2019 (COVID-19). While a higher severity of these patients could be expected from the addition of both respiratory and neurological injury, COVID-19 patients with strokes can present with mild or none respiratory symptoms. We aimed to compare anterior circulation large vessel occlusion strokes severity between patients with and without COVID-19.

METHODS

We performed a comparative cohort study between patients with COVID-19 who had anterior circulation large vessel occlusion and early brain imaging within 3 hours from onset, in our institution during the 6 first weeks of the COVID-19 outbreak and a control group admitted during the same calendar period in 2019.

RESULTS

Twelve COVID-19 patients with anterior circulation large vessel occlusion and early brain imaging were included during the study period and compared with 34 control patients with anterior circulation large vessel occlusion and early brain imaging in 2019. Patients in the COVID-19 group were younger (P=0.032) and had a history of diabetes mellitus more frequently (P=0.039). Patients did not significantly differ on initial National Institutes of Health Stroke Scale nor time from onset to imaging (P=0.18 and P=0.6, respectively). Patients with COVID-19 had more severe strokes than patients without COVID-19, with a significantly lower clot burden score (median: 6.5 versus 8, P=0.016), higher rate of multivessel occlusion (50% versus 8.8%, P=0.005), lower DWI-ASPECTS (Diffusion-Weighted Imaging-Alberta Stroke Program Early CT Scores; median: 5 versus 8, P=0.006), and higher infarct core volume (median: 58 versus 6 mL, P=0.004). Successful recanalization rate was similar in both groups (P=0.767). In-hospital mortality was higher in the COVID-19 patients' group (41.7% versus 11.8%, P=0.025).

CONCLUSIONS

Early brain imaging showed higher severity large vessel occlusion strokes in patients with COVID-19. Given the massive number of infected patients, concerns should be raised about the coming neurovascular impact of the pandemic worldwide.

The Effect of Scan Length on the Assessment of BOLD Delay in Ischemic Stroke

Objectives: To evaluate the impact of resting-state functional MRI scan length on the diagnostic accuracy, image quality and lesion volume estimation of BOLD delay maps used for brain perfusion assessment in acute ischemic stroke.

Methods: Sixty-three acute ischemic stroke patients received a 340 s resting-state functional MRI within 24 h of stroke symptom onset. BOLD delay maps were calculated from the full scan and four shortened versions (68 s, 136 s, 204 s, 272 s). The BOLD delay lesions on these maps were compared in terms of spatial overlap and volumetric agreement with the lesions derived from the full scans and with time-to-maximum (Tmax) lesions derived from DSC-MRI in a subset of patients (n = 10). In addition, the interpretability and quality of these maps were compared across different scan lengths using mixed models.

Results: Shortened BOLD delay scans showed a small volumetric bias (ranging from 0.05 to 5.3 mL; between a 0.13% volumetric underestimation and a 7.7% overestimation relative to the mean of the volumes, depending on scan length) compared to the full scan. Decreased scan length was associated with decreased spatial overlap with both the BOLD delay lesions derived from the full scans and with Tmax lesions. Only the two shortest scan lengths (68 and 136 s) were associated with substantially decreased interpretability, decreased structure clarity, and increased noisiness of BOLD delay maps.

Conclusions: BOLD delay maps derived from resting-state fMRI scans lasting 272 and 204 s provide sufficient diagnostic quality and adequate assessment of perfusion lesion volumes. Such shortened scans may be helpful in situations where quick clinical decisions need to be made.

Clinical Results of the Intra-Arterial Thrombolysis with Stent Retriever Device Weather Perfusion Diffusion Mismatching and Intravenous Tissue Plasminogen Activator Administration

Objective

Intraarterial thrombolysis (IA-Tx) with stent retriever is accepted as an additional treatment for selected patients and the clinical benefit is well reported. Each intravenous tissue plasminogen activator administration (IV-tPA) and perfusion diffusion mismatching (P/D-mismatching) is well known the beneficial effects for recanalization and clinical outcomes. In this report, authors analyzed the clinical outcomes of additional IA-Tx with retrieval stent device, according to the combined IV-tPA and P/D-mismatching or not.

Methods

Eighty-one treated IA-Tx with the Solitaire stent retriever device, diagnosed as anterior circulation larger vessel occlusion were included in this study. Computed tomography-angiography (CTA) was done as an initial diagnostic image and acute stroke magnetic resonance image (MRI) followed after the IV-tPA. Forty-two patients were in the tPA group and 39 patients were in the non-tPA group. Recanalization rate, clinically significant hemorrhagic (sICH) and clinical outcomes were recorded according to the IV-tPA and P/D-mismatching.

Results

Recanalization rate was 81.0% in IV-tPA group, and it was 69.2% in non-tPA group (p = 0.017). While sICH were 19.9% and 25.6%, respectively (p = 0.328). Neurologic outcomes did not influence by IV-tPA administration or not. But according to the P/D-mismatching, the recanalization rate and sICH were 91.9% and 16.7% in the mismatched group and 46.7% and 46.7% in the matched group (p = 0.008 and p = 0.019, respectively).

Conclusion

For patients treated with IA-Tx with retrieval stent, IV-tPA infusion does not influence on the sICH, recanalization rate and neurologic outcomes. But P/D-mismatching was correlated well with sICH, recanalization rate and clinical outcomes.

Determinants of the impact of blood pressure variability on neurological outcome after acute ischaemic stroke

INTRODUCTION

Increased blood pressure variability (BPV) is detrimental after acute ischaemic stroke, but the interaction between BPV and neuroimaging factors that directly influence stroke outcome has not been explored.

METHODS

We retrospectively reviewed inpatients from 2007 to 2014 with acute anterior circulation ischaemic stroke, CT perfusion and angiography at hospital admission, and a modified Rankin Scale (mRS) 30-365 days after stroke onset. BPV indices included SD, coefficient of variation and successive variation of the systolic blood pressure between 0 and 120 hours after admission. Ordinal logistic regression models were fitted to mRS with predictor variables of BPV indices. Models were further stratified by CT perfusion volumetric measurements, proximal vessel occlusion and collateral score.

RESULTS

110 patients met the inclusion criteria. The likelihood of a 1-point rise in the mRS increased with every 10 mm Hg increase in BPV (OR for the 3 BPV indices ranged from 2.27 to 5.54), which was more pronounced in patients with larger ischaemic core volumes (OR 8.37 to 18.0) and larger hypoperfused volumes (OR 6.02 to 15.4). This association also held true for patients with larger mismatch volume, proximal vessel occlusion and good collateral vessels.

CONCLUSIONS

These results indicate that increased BPV is associated with worse neurological outcome after stroke, particularly in patients with a large lesion core volume, concurrent viable ischaemic penumbra, proximal vessel occlusion and good collaterals. This subset of patients, who are often not candidates for or fail acute stroke therapies such as intravenous tissue plasminogen activator or endovascular thrombectomy, may benefit from interventions aimed at reducing BPV.