Use of Thick Maximum-Intensity Projection Brain Computed Tomography Angiography for Evaluation of Baseline Collateral...

In acute ischemic stroke caused by large-vessel occlusion, tissue viability is dependent on the blood supply from leptomeningeal collaterals until reperfusion is achieved. Rapid and accurate evaluation of baseline collateral status is a key marker of eligibility for endovascular therapy but can be challenging to interpret using source images of the computed tomography angiography (SI-CTA). Our objective was to assess whether the use of thick maximum-intensity projection computed tomography angiography (MIP-CTA) improves interrater agreement for evaluation of baseline collaterals status between stroke trainees and an expert stroke neurologist.

An expert stroke neurologist and 2 stroke trainees independently reviewed images from 40 brain CTA scans with anterior circulation large-vessel occlusion and assessed collateral status using the Tan collateral scoring system using SI-CTA in the first reading and then using MIP-CTA in the second reading. We calculated interrater agreement and recorded the total time needed in each reading.

Interrater agreement was fair between the 2 stroke fellows and stroke expert when using SI-CTA (κ=0.45 with 52.5% agreement). After using MIP-CTA, interrater agreement improved to moderate (κ=0.69 with 70% agreement). The median reading time was 1.89 minutes per scan using SI-CTA and 1.00 minute per scan using MIP-CTA (P<0.0001).

We show that using MIP-CTA, when compared with SI-CTA, shortens interpretation time and improves interrater agreement between stroke trainees and a stroke imaging expert for the evaluation of baseline collaterals in patients presenting with anterior circulation large-vessel occlusion.