Synopsis

Keywords: Stroke, Thrombo-Embolic

To investigate the predictive value of baseline DWI-pcASPECTS combined with MRA-collateral circulation score in patients with acute posterior circulation ischemic stroke after mechanical thrombectomy. DWI-pcASPECTS score and MRA-collateral circulation score before treatment were retrospectively analyzed in patients with acute posterior circulation ischemic stroke after mechanical thrombolectomy. Multivariate Logistic regression was used to analyze the independent predictors of functional outcomes 90 days after mechanical thrombectomy. MR-pcASCO score can be used as an important means to predict the prognostic function of patients with acute posterior circulation ischemic stroke after mechanical thrombectomy.

Purpose

To investigate the prognostic value of the composite MR-pcASCO score, which combines the DWI-pcASPECTS and the MRA-collateral circulation score, at baseline among patients with acute posterior circulation ischemic stroke after mechanical thrombectomy.

Methods

We retrospectively analyzed patients with acute posterior circulation ischemic stroke in a comprehensive stroke center in northern China from July 2021 to March 2022 and continuously collected patient information that met the inclusion criteria. The included patients met the diagnostic criteria of acute ischemic stroke in the Chinese guidelines for the diagnosis and treatment of acute ischemic stroke 2020. The inclusion criteria were as follows: (1) age ≥ 18 years old; (2) acute posterior circulation ischemic stroke, DWI and MRA were assessed at baseline; (3) occlusion or severe stenosis of the vertebral basilar artery or its branches; and (4) patients who underwent DSA and mechanical thrombectomy. The exclusion criteria were as follows: (1) intracranial hemorrhage or other intracranial lesions; (2) incomplete imaging data; (3) acute ischemic stroke in the anterior circulation; and (4) scores affected by other factors. All patients underwent an MRI examination after admission and before thrombectomy treatment. The MRI data were acquired on a 1.5T MR scanner (MAGNETOM Avanto, Siemens Healthineers, Erlangen, Germany) with a 32-channel receiver array head coil. A readout-segmented echo-planar DWI sequence were performed with following parameters: TR/TE=3250/77(126) ms, b value =0 ,1000 s/mm2, matrix=192*192, FOV =230*230 mm2, slice thickness=5mm, and slice gap=1.5 mm. The scanning parameters about the 3D-TOF-MRA sequence were as follows: TR/TE=22/7ms, matrix=320*320, FOV=240*240 mm2, and voxel size=0.6mm isotropic scanning. The scan range included the intracranial segment of the posterior circulation.In this study, the DWI-pcASPECTS was combined with the MRA-collateral circulation score to define the composite score, i.e., the MR-pcASCO score, which has a maximum score of 20, including 10 points on the pcASPECTS and 10 points on the collateral circulation score. The scores were determined by two experienced neuroimaging doctors.Statistical analysis was performed using SPSS version 26 (IBM, Armonk, New York, USA). Continuous data are described as the mean ± SD and were compared using independent-samples T-tests or Mann-Whitney U-tests, while categorical variables are presented as a frequencies(percentages) and were compared using the chi-squared test. To minimize overfitting of the regression model, multicollinearity of pretreatment variables (baseline and imaging parameters) in univariate analysis with p<0.05 was assessed using the variance inflation factor (VIF). Variables with a VIF <10 were included in the multivariate binary logistic regression. A nomogram was constructed from the results of the multivariate analysis using the R package Version 3.4.4 (R Package for Statistical Computing; www.r-project.org). Receiver operating characteristic (ROC) analysis and the area under the curve (AUC) were used to assess and compare prognostic models. The Youden index was computed using sensitivity + specificity − 1 to identify the optimal cutoff values. The Delong test was used to compare the diagnostic performance of the ROC curve. A two-tailed p<0.05 was considered statistically significant.

Results

Mechanical thrombectomy was performed in 57 patients; 38 patients had a good prognosis, 19 patients had a poor prognosis, 6 patients died, and 33 patients were successfully recanalized. Multivariate logistic regression showed that the GCS score (OR:2.14, 95% CI: 1.15-3.95, P =0.016) and pcASCO score (OR:0.74, 95% CI: 0.25-2.18, P =0.04) were independent predictors of good functional outcome. Based on ROC curve analysis, the discriminant ability of functional independence classification with the pcASCO score≥14.5 (AUC 0.81, 95% CI: 0.67-0.94) was higher than that of the pcASPECTS (AUC 0.65) and collateral circulation score (AUC 0.79). ROC curve analysis also showed that the diagnostic efficacy of the pcASCO score (AUC 0.80, 95% CI: 0.63-0.97) was slightly higher than that of the GCS score (AUC 0.76, 95% CI: 0.56-0.95) in the group with a low baseline GCS score.

Discussion

We combined DWI-pcASPECTS in brain tissue regional and MRA-collateral circulation scores to comprehensively evaluate the baseline infarction of patients. We have reliable data to confirm that the baseline GCS score and MR-pcASCO score are independent predictors of good functional outcome and have good diagnostic efficacy. ROC curve analysis revealed that the optimal cutoff point of the baseline GCS score is 13.5, and the higher the score is, the better the prognosis of patients. This finding suggests that the baseline status of patients is closely related to the prognosis. DWI-pcASPECTS or MRA-collateral circulation score alone. This research result may improve the prediction of prognosis. It can be used as a simple auxiliary means for the classification of patients with vertebrobasilar artery occlusion, especially when the indication for mechanical thrombectomy is uncertain. In patients with poor baseline GCS scores (GCS<13.5), the MR-pcASCO score was slightly more effective than the GCS score. The MR-pcASCO score may be a practical and easy-to-implement method to predict outcomes.

Conclusion

The composite MR-pcASCO score can be used as an important predictor of the prognosis of patients with acute posterior circulation ischemic stroke after mechanical thrombectomy.

Acknowledgements

All authors made substantial contributions to this manuscript and take responsibility for its content. YL and JY was responsible for the study design. YY, YG, TL, XS, XX, GL, HS, HH contributed to the acquisition of MRI and demographical data. SH and BB performed the data analysis. SW and ZL assisted with data analysis and interpretation of findings. SH drafted the manuscript. BB provided critical revision of the manuscript for important intellectual content. All authors critically reviewed content and approved final version for publication.

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