治療大血管阻塞所引起的缺血性腦中風，在特定條件下，目前的標準治療包含動脈内取栓。除臨床的嚴重度及發生的時間外，其中一項很重要的評估是影像檢查。這些檢查包含了沒有施打顯影劑的腦部電腦斷層、單時間點電腦斷層血管攝影、多時間點電腦斷層血管攝影、動態顯影電腦斷層腦灌流檢查、及磁振造影。因為選擇條件越嚴格，病人的預後就越好，但符合條件的比例會降低，也就是能實際接受治療的病人會變少。這些被排除的病人，雖然預期神經功能恢復的程度較低，卻也不是完全沒有機會因為動脈内取栓而獲益。所以治療指引建議發作時間在六個小時内的病患，採取較寬鬆的條件來選擇適合治療的病患；而發作時間在六到二十四小時或時間不明確的病患，則採取比較進階的影像來評估。但是不是所有醫院都隨時有適當的影像工具可以立刻進行評估，在此對於影像工具有限時，如何進行影像評估也給予簡單的建議。

Intra-arterial endovascular thrombectomy is currently recommended in treating patients with acute ischemic stroke caused by large vessel occlusion. Clinical severity and time after onset are two key points to evaluate such patients. Imaging study plays an important role in patient selection for thrombectomy. The imaging modalities include non-contrast CT, single-phase CT angiography, multi-phase CT angiography, dynamic contrast-enhanced CT perfusion, and MRI. When the selection criteria are strict, the patient outcome is usually better. However, some patients out of the inclusion criteria may benefit from thrombectomy, but they would not be treated. Therefore, in current guideline, loose selection criteria are used for patients with onset less than 6 hours. Advanced imaging criteria are used for patients with onset more than 6 hours or unknown duration. In general practice, the advanced imaging modality may not always available in all hospital. Simple practical criteria are suggested in this article.