Chronic constipation is widespread. It is believed that between 10% and 15% of the population are treated for constipation on an ongoing basis.

Before the introduction of modern treatments, acute ischemic stroke (AIS) resulted in 10% early mortality, around 50% of survivors left with moderate-to-severe neurologic deficits, and 25% left dependent on others. This drastically improved with the introduction of intravenous tissue plasminogen activators and later with endovascular treatment (EVT). Patient selection for EVT relies on dedicated multimodality neuroimaging conducted with four main goals – 1) exclude a hemorrhagic stroke and identify early ischemic changes, 2) identify a proximal large vessel occlusion, 3) determine the volume of ‘ischemic core’, and 4) determine the volume of ‘ischemic penumbra’. This comparative narrative review aims to discuss in detail how different imaging modalities are used in the context of AIS to select patients for EVT. This includes computed tomography (CT) and magnetic resonance imaging (MRI), including their role in angiographic and perfusion imaging. Based on the success of EVT trials from 2015 and 2018, the updated American Heart Association - American Stroke Association guidelines state that non-contrast head CT and CT angiography are sufficient to identify patients who are fit to undergo EVT in the early window (