Endovascular mechanical thrombectomy is the standard of care for treating patients with a large-vessel occlusion acute ischemic stroke. However, in more than half of these patients, remaining distal vessel occlusions limit the benefit of this therapy. Currently the detection of residual vessel occlusions and the decision for further treatment by the operator is based on the 2D digital subtraction angiography (DSA) images. However, this technique has several limitations. Recently, a new imaging technique, with the possibility to acquire 3D time-resolved perfusion images directly in the operating room was introduced (the flat-panel detector computed tomography perfusion imaging, FDCTP). It can overcome the spatial limitations of 2D DSA, but the details on clinical validation and utility of FDCTP are currently lacking.

This clinical investigation is planned as a multi-center, prospective, non-randomized observational study with a primary endpoint to evaluate a potential diagnostic benefit. The diagnostic tool to be studied is clinically indicated 60s Dyna CT Head Perfusion (FDCTP imaging) obtained after or during mechanical thrombectomy for acute ischemic stroke.

The population consists of patients with symptoms of acute ischemic stroke, who were intended to undergo mechanical thrombectomy. This means that patients who did not undergo mechanical thrombectomy and only had diagnostic angiography (e.g. physician team has decided against thrombectomy due to pre-interventional vessel reperfusion), can still be included in the study. Patients can only be included if a FDCTP was acquired immediately after thrombectomy or diagnostic angiography by the treating physician team as part of the standard clinical routine. There is no control group.

The overall objective is to investigate the potential clinical use of FDCTP acquired during or shortly after the endovascular stroke treatment. Primary study objective is to evaluate in how many cases FDCTP maps reveal new, potentially relevant clinical information that may change treatment decisions. The primary research hypothesis is that the proportion of patients where FDCTP reveals new, potentially clinically relevant findings is greater than 25%. Assuming a true proportion of 33% of the primary outcome, we will need 251 patients to reach a power of 80% at a one-sided alpha of 2.5%, based on a one-sample binomial exact test. To account for a drop-out rate of 10%, we plan to recruit 279 patients.

Inclusion Criteria:

• Informed consent as documented by a signature
• The patients received mechanical thrombectomy or there was the intention to perform endovascular treatment, but only diagnostic angiography was performed.
• Patients received FDCTP as clinically indicated by the treating physician.

Exclusion Criteria:

• Inability to give consent due to insufficient knowledge of the project language
• Inability to follow the clinically indicated visit at 90 days after the index stroke (e.g. patients living abroad).

Patients with an acute ischemic stroke with large vessel occlusion who have undergone endovascular mechanical thrombectomy and received a (flat-panel detector computed tomography perfusion imaging (FDCTP) shortly after the treatment.