Dual-phase 16 slice CT angiography in stroke imaging: a poor man's multiphase study?

Multiphase CT angiography (CTA) in collateral assessment provides time-resolved cerebral angiograms of the intracranial vasculature, requiring a high-speed multidetector CT (MDCT) scanner with ≥ 64 slices. Unfortunately, many hospitals are equipped with lower speed MDCT scanners. Herein, we present our experience performing dual-phase CTA (d-CTA) on a 16 slice MDCT with a biphasic rate injection to grade intracranial collaterals as predictor of clinical outcome. 42 patients were evaluated with both dual-phase CTA (d-CTA) and single-phase CTA (s-CTA) for occluded anterior intracranial circulation and collaterals. They were treated with endovascular reperfusion. Univariate and multivariate analyses were performed to define the independent predictors for favorable outcome at 3 months. Good collateral circulation status on d-CTA was associated with a lower median 24-h (5 vs. 7.5, p = 0.03) and discharge (2 vs. 4.6, p = 0.04) NIHSS. A logistic regression model showed that only age (OR 0.95, 95% CI 0.91-0.98, p = 0.03) and good collateral circulation status at d-CTA (OR 4.3, 95% CI 1.87-11.3, p < 0.01) were independent predictors of favorable functional outcome at 3 months, but that s-CTA was not. The collateral status on d-CTA can be a useful predictor for clinical outcome in acute stroke patients. The proposed protocol adapted to a low-speed MDCT scanner could be of particular interest in hospitals without access to the more up-to-date technology.