Comparing perfusion CT evaluation algorithms for predicting outcome after endovascular treatment in anterior circulation ischaemic stroke

Effect of different thresholds for CT perfusion volumetric analysis on estimated ischemic core and penumbral volumes

Purpose

This single-center study compared three threshold settings for automated analysis of the ischemic core (IC) and penumbral volumes using computed tomographic perfusion, and their accuracy for predicting final infarct volume (FIV) in patients with anterior circulation acute ischemic stroke (AIS).

Methods

Fifty-two consecutive AIS patients undergoing mechanical thrombectomy (November 2015–March 2018) were included. Perfusion images were retrospectively analyzed using a single CT Neuro perfusion application (syngo.via 4.1, Siemens Healthcare GmbH). Three threshold values (S1–S3) were derived from another commercial package (RAPID; iSchema View) (S1), up-to-date syngo.via default values (S2), and adapted values for syngo.via from a reference study (S3). The results were compared with FIV determined by non-contrast CT.

Results

The median IC volume (mL) was 24.6 (interquartile range: 13.7–58.1) with S1 and 30.1 (20.1–53.1) with S2/S3. After removing the contralateral hemisphere from the analysis, the median IC volume decreased by 1.33(0–3.14) with S1 versus 9.13 (6.24–14.82) with S2/S3. The median penumbral volume (mL) was 74.52 (49.64–131.91), 77.86 (46.56–99.23), and 173.23 (125.86–200.64) for S1, S2, and S3, respectively. Limiting analysis to the affected hemisphere, the penumbral volume decreased by 1.6 (0.13–9.02), 19.29 (12.59–26.52), and 58.33 mL (45.53–74.84) for S1, S2, and S3, respectively. The correlation between IC and FIV was highest in patients with successful recanalization (n = 34, r = 0.784 for S1; r = 0.797 for S2/S3).

Conclusion

Optimizing thresholds significantly improves the accuracy of estimated IC and penumbral volumes. Current recommended values produce diversified results. International guidelines based on larger multicenter studies should be established to support the standardization of volumetric analysis in clinical decision-making.

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.