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.

The 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. The investigators will firstly establish the CT-based scores and comorbidity index using a pre-existing cohort database. Using these CT-based and comorbidity index, the investigators will validate them in a multi-center prospectively cohort.

1)Full design

1. The study proceeds with a parallel design of retrospective and prospective research.
2. As in the retrospective study, this study aims to establish the ideal screening criteria and to verify the efficacy of the thrombolytic procedure by using the relevant image information, clinical information, and the history of the subjects.
3. This study is an observational study, and there is no intervention for the study.

2) retrospective design

1. Retrospective study was conducted as a multi-center retrospective cohort and intravenous thrombolysis and intraarterial thrombus according to the guidelines for stroke among patients who were admitted to neurology with stroke from January 1, 2012 to December 31, 2015 of participating hospitals. Patients who underwent surgical removal.
2. The retrospective study was performed after 3 months F / U and 6 months after confirming the medical history and clinical information taken before the thrombolysis and the accompanying disease history. Check whether or not.
3. We will establish the most ideal screening criteria and verify the efficacy of predicting the prognosis after thrombolysis using the relevant imaging information, clinical information and the accompanying disease history.
4. All data are collected using e-CRF, and CT angiography images of subjects are anonymized and sent to the host institution. The lead institution quantifies the clinical information, including CT angiographic indicators and accompanying diseases, in the dark.
5. Interim analysis will be conducted once when the retrospective study is completed.

3) prospective design

1. A prospective study is a multicenter prospective observational study, in which intravenous thrombolysis and arteries were already followed in accordance with guidelines for stroke among patients who were admitted to neurology after a stroke on November 1, 2016 (based on hospitalization date). Patients who have undergone internal thrombectomy
2. Obtain a written consent form from a study subject who meets the selection / exclusion criteria (see How to Obtain a Study Participation Consent Form), and collect the medical data including the accompanying diseases of the study subject and images taken before thrombosis (removal) treatment. do.
3. In the same way as retrospective study, confirm and confirm the image and clinical information and the accompanying disease history of the study subjects and confirm the survival after 3 months F / U and 6 months.
4. The observation period in the study is expected to take about 6 months (intravenous thrombolytic therapy and intraarterial reopening therapy, mRS indicator at 3 months after discharge and stroke, and survival at 6 months after stroke).
5. All data are collected using eCRF, and CT angiography images of subjects are anonymized and sent to the host institution. The lead institution quantifies CT angiography and associated disease indicators with blinded clinical information.
6. Screening (time of hospitalization due to stroke) Patients who had cerebrovascular pretreatment prior to intravenous thrombolysis and were able to identify comorbidities.

Inclusion Criteria:

1. Age ≥20 years old
2. Acute ischemic stroke patients who underwent CT angiographies before IV thrombolysis and/or IA recanalization treatment
3. 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:

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

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