Aspects Score Calculator

ASPECTS is a topographic scoring system that converts a non-contrast head CT into a single number describing how much of the middle cerebral artery territory has already infarcted. The MCA territory is divided into ten regions read across two standardized axial levels: at the basal ganglia level the caudate, lentiform nucleus, insular ribbon, and internal capsule; at the supraganglionic level six cortical zones labelled M1 through M6. A normal scan scores 10, and one point is deducted for each region showing early ischemic change, meaning loss of grey-white differentiation, parenchymal hypoattenuation, or focal swelling with sulcal effacement. The ten regions are weighted equally even though they differ substantially in tissue volume and functional importance, which is a deliberate simplification in favour of speed and reproducibility. Scores of 7 to 10 indicate a small established core and correlate with good functional outcome after reperfusion. A score of 6 was the entry threshold for most of the pivotal thrombectomy trials, and below 6 the infarct core is large and the risk of hemorrhagic transformation rises. Several practical limits are worth knowing. The score applies only to the anterior circulation and says nothing about posterior circulation or anterior cerebral artery strokes. Early ischemic change is genuinely subtle within the first 3 to 6 hours, so scans read early tend to yield scores that are too high and underestimate the infarct. Inter-rater agreement is moderate, with reported kappa values commonly between 0.4 and 0.7, better for deep structures than cortical zones and better on diffusion-weighted MRI than on CT.

ASPECTS was introduced in 2000 by Philip Barber, Andrew Demchuk, Jianjian Zhang, and Alastair Buchan of the Calgary Stroke Programme in Alberta, published in The Lancet as a validity and reliability study in hyperacute stroke. The motivation was practical. The earlier European Cooperative Acute Stroke Study had used a rule excluding thrombolysis when early ischemic change exceeded one third of the MCA territory, but estimating a one-third threshold by eye proved unreliable between readers and difficult to audit. A ten-region tally was easier to teach, faster to apply under time pressure, and reproducible enough to serve as a trial entry criterion. Its role expanded sharply with the arrival of effective mechanical thrombectomy. The 2015 trials, including MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, and REVASCAT, used ASPECTS thresholds around 6 for enrolment, and the HERMES pooled analysis published by Mayank Goyal and colleagues in 2016 confirmed benefit across that range, embedding the score in American Heart Association stroke guidelines. The boundary has since moved. Trials reported in 2023, including SELECT2 and ANGEL-ASPECT, found that patients with large cores and ASPECTS values in the 3 to 5 range still derived benefit from thrombectomy, prompting a reassessment of who should be excluded on imaging grounds. Automated scoring software has been developed in parallel to reduce the reader variability that has dogged the score since its introduction.