ASPECTS

• the Alberta Stroke Program Early CT Score (ASPECTS) is used to standardize and increase the reliability of early signs of ischemia detection 
• ASPECTS can be assessed on:
  • non-contrast CT (NCCT) – width/level adjustment can be helpful
  • CT perfusion (CTP)  [Aviv, 2007]
  • CTA source images (CTA-SI)   [Puetz, 2009]
• ASPECTS primarily evaluates the MCA territory
  
• PC-ASPECTS was designed to evaluate changes in the posterior circulation
• there are commercial programs available for the automatic evaluation of ASPECTS  (e.g., BRAINOMIX)  

MCA territory

• a 10-point quantitative CT scan score used for patients with stroke in MCA territory
  
• 10 points are normal; 1 point is subtracted from the initial score of 10 for each region with early signs of ischemia
  • C – caudate nucleus
  • L – lentiform nucleus
  • IC – internal capsule (any portion)
  • I – the insular cortex
  • M1-3 are at the level of the basal ganglia
    • M1 – anterior MCA cortex corresponding to the frontal operculum
    • M2 – MCA cortex lateral to insular ribbon corresponding to the anterior temporal lobe
    • M3 – posterior MCA cortex corresponding to the posterior temporal lobe
  • M4-5 are above the basal ganglia at the level of the ventricles
    • M4 – anterior MCA territory immediately superior to M1
    • M5 – lateral MCA territory immediately superior to M2
    • M6 – posterior MCA territory immediately superior to M3
• ASPECTS is a valuable technique for the evaluation of the prognosis in acute ischemic stroke (thresholds are slightly different for NCCT a CTP)
  • patients with high ASPECTS values are more likely to have favorable outcomes
  • an NCCT ASPECTS score of ≤ 7 predicts a worse functional outcome at three months  [Esmael, 2021]
  • patients with CTP ASPECTS score of < 8 treated with thrombolysis mainly did not achieve a good clinical outcome  [Aviv, 2007]

Posterior circulation

PC-ASPECTS (The posterior circulation Acute Stroke Prognosis Early CT score)

• normal brain scores 10 points; points are subtracted for each affected region
  • thalami (1 point each)
  • occipital lobes (1 point each)
  • midbrain (2 points – uni- and bilateral)
  • pons (2 points – uni- and bilateral)
  • cerebellar hemispheres (1 point each)
• pc-ASPECTS < 8 points ⇒ poor prognosis   [Puetz, 2009]