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 3months. 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 3months, 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.