Additional Value of Brain CT Perfusion in The Detection of Intracranial Vessel Occlusion in Acute Ischemic Stroke: A (Multi Experience Level) Inter-Observer Study

R. Becks, M. Meijs, R. Manniesing, J. Vister, S. Schalekamp, R. Mann, S. Steens, E. Smit, E. van Dijk, M. Prokop and F. Meijer

Annual Meeting of the Radiological Society of North America 2016.

PURPOSE: We aimed to evaluate the additional value of brain CT perfusion (CTP) for intracranial vessel occlusion detection in acute ischemic stroke for observers with different levels of experience.

METHOD AND MATERIALS: We retrospectively included all patients with symptoms of acute ischemic stroke (onset of less than 9 hours) who were scanned with non-enhanced CT (NECT), CT angiography (CTA) and CTP in the year 2015. Four observers with different levels of experience (neuroradiologist, non-neuroradiologist, two radiology residents) evaluated the imaging data with 2 imaging strategies. Method 1 included NECT and CTA. For method 2, additional CTP maps were provided for the evaluation of intracranial vessel occlusion on CTA. The observers were blinded to patient identity and clinical outcome. Receiver operating characteristic (ROC) was used for the evaluation of accuracy in intracranial vessel occlusion detection. The reference standard of vessel occlusion was set based on the evaluation by the four observers, and the judgment of an independent neuroradiologist serving as a referee in case of discrepancy.

RESULTS: In total 110 patients were included, preliminary analyses included 94 patients. There was an increase of AUC in the overall detection of intracranial vessel occlusion for observer 1, 3 and 4, though only for observer 1 the increase in AUC was statistically significant (p=0.041). Increase of intracranial vessel occlusion detection mainly concerned distal vessel occlusions. No significant added value of CTP was found for proximal vessel occlusions, with already a high accuracy based on NECT and CTA for all experience levels with sensitivity ranging between 86-94% and specificity between 92-100%.

CONCLUSION: Our study demonstrates that the use of CTP can aid in the detection of distal intracranial vessel occlusions on CTA in case CTP is integrated in the reading strategy. It is also demonstrated that CTP was not of added value for the detection of proximal intracranial vessel occlusions. Finally, there was no major difference in the diagnostic accuracy of intracranial vessel occlusion detection for the different levels in experience of the observers.

CLINICAL RELEVANCE/APPLICATION: Our study demonstrated that brain CT perfusion can aid in the detection of distal intracranial vessel occlusions, which is clinically relevant for optimizing the imaging strategy in acute ischemic stroke.