As advancements are made in the treatment of acute infarcts, it becomes increasingly important to develop ways to assist in the prediction of the final infarct size and overall prognosis. The ability to predict patient outcomes has been investigated over many years through various methods. The idea of using a grading system for collateral flow was originally described back in 2004 and was applied to baseline conventional cerebral angiograms [1]. Tan et al. [2] was subsequently the first to apply this collateral flow grading scale to CTA examinations. 

The Alberta Stroke Programme Early CT Score (ASPECTS) was the first study to demonstrate a reliable grading system to assess early ischemic changes on noncontrast CT examinations [3,4]. This study divided the middle cerebral artery (MCA) territory into ten anatomic regions of interest. Kim et al. [1] further expanded this idea by documenting a collateral flow score for each of the anatomic locations of the affected hemisphere. 

Neurointerventional procedures, like any procedure, inherently contain risks which must be outweighed by the benefits. Neurointerventionalists often use a combination of information to determine if a patient is a candidate for treatment including, but not limited to: clinical examination, CT, CTA, CTP, MRI, etc. Any additional information that can be gleaned from these studies to assist in targeting a patient population who most likely will benefit from intervention can help reduce unnecessary risk of disability and death.

The aim of our study was to evaluate the use of a CTA collateral flow score (CTACFS) in patients with an acute thrombus in the MCA, as well as its correlation with the NIH Stroke Scale (NIHSS).