gms | German Medical Science

Objective: Delayed cerebral ischemia (DCI) is a major contributor for poor neurological outcome in patients with aneurysmal subarachnoid hemorrhage (SAH). Even though only 36% of patients with angiographic vasospasm present with clinical features of DCI, angiographic vasospasm remains an important radiological surrogate for DCI. Since, catheter angiography (CA) for detection of angiographic vasospasm carries a risk for procedure-related stroke, CT-Angiography combined with CT-Perfusion (PCT) imaging is increasingly facilitated to detect macro-and/or microvascular spasm. We investigated the potential of our PCT imaging algorithm using dynamic 4D CT angiography (dCTA) for detection of macrovascular spasm and its correlation with CA.

Methods: A prospective cohort of 26 consecutive SAH patients was subjected to a standardized screening protocol for DCI: Here, CA on admission and on day 7 after SAH ictus was combined with PCT measurements routinely performed 6 to 12 hours after aneurysm treatment, on days 3 to 4 as well as 9 to 11 after SAH ictus or in case of secondary neurological deterioration, that is, occurrence of clinical features of DCI. DCTA images were extracted from the whole-brain PCT dataset and were independently reviewed by a neuoradiologist and a vascular neurosurgeon with respect to presence and degree of macrovascular spasm. Agreement between CTA and CA for the presence of macrovascular spasm was calculated using kappa-coefficients. Sensitivity, specificity, positive and negative predictive values of CTA to detect macrovascular spasm were calculated considering CA as the gold standard.

Results: 26 aSAH patients with a mean age of 56 ± 11 years and Fisher grades 2-4 and WFNS grades 1-5 were prospectively enrolled in this study. Aneurysm sites were middle cerebral (n=12), anterior communicating (n=6), posterior communicating (n=3), internal carotid (n=2), superior cerebellar (n=2), and basilar artery (n=1). 9 patients revealed PCT values suggestive for DCI (defined as a 1.5-fold prolongation of the mean transit time (MTT)); 6 of these patients presented with macrovascular spasm in the subsequent CA. Macrovascular spasm were seen in four more patients on CA without prior MTT prolongation. A high agreement (k= 0.75) was found between dCTA and CA for the detection of macrovascular spasm. Sensitivity, specificity, positive and negative predictive values were, 80%, 94%, 89%, and 88%, respectively. Using dCTA as a screening method CA may have been avoided in 94%.

Conclusion: Our data highlight that dCTA derived from PCT imaging data reveals good agreement with CA and may serve as the initial modality to rule out macrovascular spasm so that CA for mere diagnostic purposes may be unnecessary. However, CA may be required to rule out microvascular spasm in the presence of clinical features of DCI and absence of macrovascular spasm in dCTA.