**1. Introduction**

Although overall mortality for patients undergoing coronary bypass graft surgery (CABG) has decreased by 23% in 1990s, the incidence of stroke perioperatively has remained un‐ changed [1]. Some report suggests that perioperative neurological complications occur with

<sup>1</sup> This work was in part presented at the 33rd Annual Congress of the Scandinavian Society of Anesthesiology and Intensive Care Medicine, Reykjavik, Iceland, 2015, and the 62nd Annual Congress of Japanese Society of Anesthesiologists, 2015, Kobe, Japan.

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

an overall frequency of 2.8%, and an incidence rate of 0.9% in patients younger than 65 years, 3.6% aged between 65 and 74 years, and 8.9% older than 75 years [2]. Additionally, the patient with a neurological complication has a ninefold increase in mortality [2]. Carotid arterial disease accounts for approximately 10% of perioperative cerebral complications [3]. Although ultrasound imaging is an excellent modality for evaluating the morphology of the carotid arteries with its excellent spatial resolution [3], intracranial cerebral blood flow dynamics cannot be assessed by the use of ultrasound. Here, we report that computed tomography perfusion (CTP) imaging is an efficacious modality for evaluating the intracranial cerebral flow.

In our facility, CTP imaging has been introduced in 2012, and 58 cases underwent its evaluation by the end of 2014. After obtaining an IRB (Institutional Review Board) approval, we have analyzed all the 58 cases, and identified 11 individuals who have been diagnosed as having carotid arterial stenosis/occlusion. We have measured cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) at the ipsilateral as well as at the contrala‐ teral hemisphere, and their correlation to the subsequent development of neurological events during the 2‐year follow‐up period was evaluated.

Of 11 patients, the decreased CBF at the ipsilateral hemisphere was noted in four individuals, and the other seven showed intact CTP findings. All the four patients who showed decreased CBF pattern and the one who showed normal CTP finding developed cerebrovascular diseases during the 2‐year follow‐up period. The rest of six individuals who showed normal CTP findings have remained otherwise healthy. We suggest that the decreased CBF at the ipsilateral side may predict the possible neurological complications in the patients with carotid arterial stenosis/occlusion. In patients with carotid arterial stenosis whose cerebral blood flow (CBF) has remained intact, the patients' outcome has remained favorable, and they have remained otherwise healthy. By contrast, in patients whose CBF is decreased, they have developed severe cerebrovascular complications. The findings described here potentially indicate the possibility that CT perfusion findings may predict the perioperative outcomes in patients with carotid arterial stenosis/occlusion.
