Comparison of CT angiography collaterals for predicting target perfusion profile and clinical outcome in patients with acute ischemic stroke

Eur Radiol. 2019 Sep;29(9):4922-4929. doi: 10.1007/s00330-019-06027-9. Epub 2019 Feb 14.


Objectives: To compare collateral status on single-phase CT angiography (sCTA) and multiphase CT angiography (mCTA) and their ability to predict a target mismatch on CT perfusion (CTP) and clinical outcome in patients with acute ischemic stroke (AIS).

Methods: Seventy-three AIS patients with stroke onset between 5 and 15 h or with unclear onset time and occlusions in the M1/M2 segment of the middle cerebral artery and/or intracranial internal carotid artery underwent head non-contrast CT and CTP. Simulated sCTA and mCTA were reconstructed from CTP data and were compared for collaterals assessment. The ability to predict target mismatch on CTP (an ischemic core < 70 ml, a mismatch ratio ≥ 1.8, and an absolute difference ≥ 15 ml) and 90-day modified Rankin Scale (mRS) score of 0-2 was compared between sCTA and mCTA by using receiver operating curve analysis.

Results: sCTA underestimated the collateral status when compared with mCTA (p < 0.01). The ability of mCTA to predict target mismatch (AUC = 0.902, 95% confidence interval [CI] 0.809, 0.959) and clinical outcome (AUC = 0.771; 95% CI, 0.655, 0.864) was better than that of sCTA (p < 0.05 overall). A mCTA collateral score of > 3 best identified the target mismatch (sensitivity, 78.4%; specificity, 90.9%) and predicted 90-day mRS score of 0-2 (sensitivity, 84.8%; specificity, 69.4%).

Conclusions: The collaterals were better estimated by mCTA compared with sCTA. A mCTA collateral score of > 3 optimized the prediction of a target mismatch on CTP and a good clinical outcome in patients with AIS.

Key points: • Collateral circulation is a key determinant of ischemic core and penumbra. Better collaterals are associated with smaller ischemic core volumes and larger mismatch ratios on CT perfusion. • The collaterals can be better estimated by multiphase CTA compared with single-phase CTA. • A collateral score of > 3 on multiphase CTA best identifies patients with target mismatch on CT perfusion and predicts 90-day mRS score of 0-2.

Keywords: CT angiography; Collateral circulation; Perfusion imaging; Stroke.

MeSH terms

  • Aged
  • Brain Ischemia / diagnostic imaging*
  • Brain Ischemia / physiopathology*
  • Carotid Artery, Internal / diagnostic imaging
  • Carotid Artery, Internal / physiopathology
  • Cerebral Angiography
  • Collateral Circulation*
  • Computed Tomography Angiography / methods*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Middle Cerebral Artery / diagnostic imaging
  • Middle Cerebral Artery / physiopathology
  • Perfusion Imaging
  • Sensitivity and Specificity
  • Stroke / diagnostic imaging*
  • Stroke / physiopathology*