Malignant CTA collateral profile is highly specific for large admission DWI infarct core and poor outcome in acute stroke

Abstract

Background and purpose: Large admission DWI lesion volumes are associated with poor outcomes despite acute stroke treatment. The primary aims of our study were to determine whether CTA collaterals correlate with admission DWI lesion volumes in patients with AIS with proximal occlusions, and whether a CTA collateral profile could identify large DWI volumes with high specificity.

Materials and methods: We studied 197 patients with AIS with M1 and/or intracranial ICA occlusions. We segmented admission and follow-up DWI lesion volumes, and categorized CTA collaterals by using a 5-point CS system. ROC analysis was used to determine CS accuracy in predicting DWI lesion volumes >100 mL. Patients were dichotomized into 2 categories: CS = 0 (malignant profile) or CS>0. Univariate and multivariate analyses were performed to compare imaging and clinical variables between these 2 groups.

Results: There was a negative correlation between CS and admission DWI lesion volume (ρ = -0.54, P < .0001). ROC analysis revealed that CTA CS was a good discriminator of DWI lesion volume >100 mL (AUC = 0.84, P < .001). CS = 0 had 97.6% specificity and 54.5% sensitivity for DWI volume >100 mL. CS = 0 patients had larger mean admission DWI volumes (165.8 mL versus 32.7 mL, P < .001), higher median NIHSS scores (21 versus 15, P < .001), and were more likely to become functionally dependent at 3 months (95.5% versus 64.0%, P = .003). Admission NIHSS score was the only independent predictor of a malignant CS (P = .007).

Conclusions: In patients with AIS with PAOs, CTA collaterals correlate with admission DWI infarct size. A malignant collateral profile is highly specific for large admission DWI lesion size and poor functional outcome.

Fig 1.

CS system: 0 = absent collaterals >50% of an M2 territory; 1 = diminished collaterals >50% M2 territory; 2 = diminished collaterals <50% M2 territory; 3 = collaterals equal to contralateral side; 4 = increased collaterals.

Fig 2.

There is progressive decrease in admission (A) DWI lesion volumes (P < .001) and (B) NIHSS (P < .001) as CS increases. Error bars represent 95% confidence intervals.

Fig 3.

ROC curves for CS versus DWI volumes (A) >100 mL (AUC = 0.84, P < .001) and (B) >70 mL (AUC = 0.78, P < .001). Tables display test characteristics for various scores, including optimal operating points (*), and positive (PPV) and negative predictive values (NPV).

Fig 4.

Scatterplot of DWI volumes versus CSs. Most CS = 0 patients have lesion volumes >70–100 mL (horizontal lines). There is great overlap between the other CS categories.

Fig 5.

Distribution of mRS scores between patients with CS = 0 versus >0.