Computer Aided Diagnosis in Stroke

Stroke is the second leading cause of disability worldwide. In order to minimize disability, the goal of stroke treatment is to preserve tissue in the area where blood supply is decreased but sufficient to stave off cell death. Thrombectomy has been shown to offer fast and efficient reperfusion with high recanalization rates. However, due to the inherent risks of thrombectomy, indications including evidence of good collateral circulation should be present. Currently, methods for evaluating collateral circulation are limited. We are working on developing automated techniques to compute a collateral circulation score based on differences seen in mean intensities between left and right cerebral hemispheres in 4D angiography images.

Automatic Collateral Circulation Evaluation in Ischemic Stroke (ACCESS)

Sufficient collateral blood supply is crucial for favorable outcomes with endovascular treatment. The current practice of collateral scoring relies on visual inspection and thus can suffer from inter and intra-rater inconsistency. We present a robust and automatic method to score cerebral collateral blood supply to aid ischemic stroke treatment decision making.
Our proposed method, ACCESS estimates a target patient’s unfilled cerebrovasculature in contrast-enhanced CTA using the lack of contrast agent due to clotting. To do so, the fast Robust Matrix Completion (fRMC) algorithm with in-face extended Frank-Wolfe optimization is applied on a cohort of healthy subjects and a target patient, to model the patient’s unfilled vessels and the estimated full vasculature as sparse and low-rank components respectively. The collateral score is computed as the ratio of the unfilled vessels to the full vasculature, mimicking existing clinical protocols. ACCESS was tested with 46 stroke patients and obtained a mean AUC of 85.39%.
ACCESS automates collateral scoring to mitigate the shortcomings of the standard clinical practice. It is a robust approach, which resembles how radiologists score clinical scans, and can be used to help radiologists in clinical decisions of stroke treatment.

Figure: The overall workflow of the ACCESS method