Use of intravenous (IV) thrombolysis and intra-arterial (IA) recanalization treatment has been rapidly increasing, However, despite of the treatment, recanalization rates are 22.6 - 70% and only 30-50% of patients show meaningful clinical improvements. Mechanisms of futile recanalization may include 1) large ischemic core, 2) poor collateral, and 3) presence of comorbidity. In this regards, developing selection criteria using acute stroke imaging and comorbidity is warranted.

Investigators will recruit the consecutive acute stroke patients who received IV thrombolysis and/or IA recanalization treatment. This study will perform with prospective design to develop CT-based clot, core and collateral scores and a comorbidity index for selecting stroke patients who are at high risks by the treatment. Investigators will firstly establish the CT-based scores and comorbidity index using a pre-existing cohort database. Using these CT-based and comorbidity index, Investigators will validate them in a multi-center prospectively cohort. In addition, Investigators will assess the cost-effectiveness of selecting patients based on the comorbidity index.

Inclusion Criteria:

• Age ≥20 years old
• Acute ischemic stroke patients who underwent CT angiographies before IV thrombolysis and/or IA recanalization treatment
• Patients who give an informed consents for participation in the study or the legal representative or immediate family give informed consent on behalf of patients in case of difficulty to decide study enrollment.

Exclusion Criteria:

• Age <20 years old
• Acute ischemic stroke patients who did not receive IV thrombolysis and/or IA recanalization treatment
• No informed consents from patients

Acute ischemic stroke patients who received intravenous (IV) thrombolysis and/or intra-arterial (IA) recanalization treatment