**3. CT perfusion may predict patients' outcome in patients with carotid arterial stenosis**

Except for a history of hypertension, an otherwise healthy 72‐year‐old male was planned for an elective surgery for his cervical disc hernia. His preoperative evaluation of carotid ultraso‐ nography revealed total occlusion of the left internal carotid artery (**Figure 1A**). Since we have experienced a similar case in which stroke has developed shortly after the diagnosis of total occlusion of the left internal carotid artery (**Figure 1B**), we planned to evaluate the potential risks of developing neurological complications perioperatively by CT perfusion. In the latter case in which stroke has been confirmed soon after the diagnosis of total left internal carotid artery occlusion, simultaneous evaluation of CT perfusion revealed clear laterality of cerebral blood flow imaging, suggesting that the left intracranial hypoperfusion was apparent owing to the total occlusion of the left internal carotid artery (**Figure 1C**). By contrast, in the former case, no laterality of the intracranial cerebral flow was observed, suggesting that the collateral circulation may have compensated the total occlusion of the left internal carotid artery (**Figure 1D**). To further confirm that there is no laterality of cerebral blood flow between the right and the left hemispheres, we calculated the cerebral blood flow (CBF), mean transit time (MTT), and the cerebral blood volume (CBV) in his both hemispheres. The right cerebral blood flow was 34.4 mL/100 g/min and the left CBF was 34.5 mL/100 g/min. The cerebral blood volume (CBV) of his right hemisphere was 2.7 mL/100 g and the CBV of his left hemisphere was 2.9 mL/100 g. The mean transit time (MTT) of his right hemisphere was 4.9 s and the left was 5.3 s. The results clearly showed that there was no difference between his right and left hemi‐ spheres with respect to the dynamics of cerebral blood flow, although prolonged MTT was equally observed in both hemispheres to some degree. Based on the results of CT perfusion, the patient was given the consent that if his neurological symptoms relating to his cervical disc hernia would further worsen, he is going to be scheduled for an elective surgery. During the 2‐year follow‐up period, he has not developed any cerebrovascular complications and has remained otherwise healthy.

**Figure 1.** (**A**) A 72‐year‐old male presented to our hospital complaining the pain in the left upper extremity. He was diagnosed as having cervical disc hernia. Simultaneous evaluation of cervical MR angiography together with ultra‐ sound imaging revealed total occlusion of the left internal carotid artery. (**B**) A 65‐year‐old male presented to our hos‐ pital because of transient gait instability and dysarthria. CT angiography together with ultrasound imaging revealed total occlusion of the left internal carotid artery. (**C**) CT perfusion imaging revealed an apparent decrease of CBF and prolonged MTT in his left hemisphere. (**D**) CT perfusion imaging of the 72‐year‐old male revealed no apparent laterali‐ ty of CBF, CBV, and MTT between the right and the left hemispheres.

After obtaining Institutional Review Board's approval, we have further surveyed all the medical charts of 58 patients who have been examined by CT perfusion in our facility between 2012 and 2014. Among the 58 cases, we have identified 11 individuals who have been diag‐ nosed as having carotid arterial stenosis by ultrasonography. Among 11 patients with carotid arterial stenosis, 7 patients had no apparent CBF laterality or CBV laterality. Except for one case in whom bilateral carotid arterial stenosis (77% stenosis in the right internal carotid artery and 85% stenosis in the left carotid artery) was noted by ultrasonography who subsequently was found dead at his home, all the six cases have remained otherwise healthy without any cerebrovascular complications during the 2‐year follow‐up period, which suggests that the intact CT perfusion findings may predict favorable outcome in patients with carotid arterial stenosis (**Table 1**). By contrast, the rest of four patients with an apparent CBF decrease either with maintained CBV or with decreased CBV developed irreversible cerebrovascular compli‐ cations either at the time of evaluation of CT perfusion or during the 2‐year follow‐up period (**Table 1**). The incidence of development of cerebrovascular complication was significantly higher in whom an abnormal CT perfusion finding was observed (*p* = 0.006, chi‐squared test).

s. The results clearly showed that there was no difference between his right and left hemi‐ spheres with respect to the dynamics of cerebral blood flow, although prolonged MTT was equally observed in both hemispheres to some degree. Based on the results of CT perfusion, the patient was given the consent that if his neurological symptoms relating to his cervical disc hernia would further worsen, he is going to be scheduled for an elective surgery. During the 2‐year follow‐up period, he has not developed any cerebrovascular complications and has

**Figure 1.** (**A**) A 72‐year‐old male presented to our hospital complaining the pain in the left upper extremity. He was diagnosed as having cervical disc hernia. Simultaneous evaluation of cervical MR angiography together with ultra‐ sound imaging revealed total occlusion of the left internal carotid artery. (**B**) A 65‐year‐old male presented to our hos‐ pital because of transient gait instability and dysarthria. CT angiography together with ultrasound imaging revealed total occlusion of the left internal carotid artery. (**C**) CT perfusion imaging revealed an apparent decrease of CBF and prolonged MTT in his left hemisphere. (**D**) CT perfusion imaging of the 72‐year‐old male revealed no apparent laterali‐

After obtaining Institutional Review Board's approval, we have further surveyed all the medical charts of 58 patients who have been examined by CT perfusion in our facility between 2012 and 2014. Among the 58 cases, we have identified 11 individuals who have been diag‐ nosed as having carotid arterial stenosis by ultrasonography. Among 11 patients with carotid arterial stenosis, 7 patients had no apparent CBF laterality or CBV laterality. Except for one

ty of CBF, CBV, and MTT between the right and the left hemispheres.

remained otherwise healthy.

122 Current Topics in Anesthesiology


Among 11 patients who were diagnosed as having carotid arterial stenosis by ultrasonography, 4 patients showed an apparent decreased CBF at the ipsilateral hemisphere, and 7 patients showed normal CT perfusion findings. All the four patients developed irreversible cerebrovascular complications either at the time when CT perfusion was evaluated or during the 2‐year follow‐up period.

\* Bilateral carotid arterial stenosis (77% stenosis in the right internal carotid artery and 85% stenosis in the left carotid artery) was noted by ultrasonography, and the patient was subsequently found dead at his home. \*\*Although the sample power is not strong enough, the likelihood of the patients with carotid arterial stenosis to remain healthy appeared to have correlated with their intact CT perfusion findings (*p* = 0.006, chi‐squared test).

**Table 1.** The outcome of the patients with carotid arterial stenosis (with 2‐year follow‐up) and its correlation to their findings of CT perfusion.
