Fig 1.
Typical time-intensity curve from indocyanine green (ICG) measurement in patient with carotid artery stenosis.
TPP; time to peak.
Fig 2.
Case 1 (non-HP): A 64-year-old male presented with severe symptomatic right internal carotid artery stenosis.
Right common carotid angiography showed severe right internal carotid artery stenosis (A). Balloon angioplasty for post-dilatation was performed after stent placement with filter protection (B). Right common carotid angiography after CAS confirmed stent patency (C). Time-intensity curve from ICG-NIRS monitoring before (D), just after (E), 6 hours after (F), and 1 day after CAS (G). No remarkable change was seen in the time-intensity curve time course throughout the measurement. Yellow curve; affected side, Orange curve; unaffected side. We found no remarkable differences between preoperative rCBF in the right hemisphere with 123I-IMP SPECT in the resting state between before (H) and 1 day after CAS (I). MRI showed no additional ischemic lesions. He was discharged without any neurological deficits.
Fig 3.
Case 2 (HPS case): A 70-year-old male presented with symptomatic right internal carotid artery stenosis.
Magnetic resonance angiography showed reduction in the right internal carotid artery signal before (A) and after CAS (B). He underwent right-side CAS with NIRS monitoring. Right common carotid angiography showed right internal carotid artery nearly occlusion (C). Balloon angioplasty for post-dilatation was performed after stent placement with filter protection (D). Right common carotid angiography after CAS confirmed stent patency (E). MRI showed no additional ischemic lesions, and hence, he was diagnosed with postoperative HPS. The patient’s systolic blood pressure was strictly controlled between 100–140 mmHg, and sedation was induced with dexmedetomidine. Seven days after CAS, he recovered from the symptoms and he was discharged without any neurological deficits. Time-intensity curve from ICG-NIRS monitoring before (F), just after (G), 6 hours after (H), 1 day after (I), and 7 days after CAS (J). A remarkable change in the time-intensity curve time just after CAS was observed; the difference disappeared 7 days after CAS. Yellow curve; affected side, Orange curve; unaffected side. Preoperative 123I-IMP SPECT in the resting state showed a decrease in rCBF in the right hemisphere (K). One day after CAS, hyperperfusion was seen in the ipsilateral hemisphere (L). One week after CAS, hyperperfusion in the ipsilateral hemisphere had normalized (M).
Fig 4.
Preoperative cerebrovascular reactivity (CVR) and postoperative asymmetry index (AI) the day after stent placement.
A CVR value lower than the mean + 2 SD (i.e., 23.8%) was defined as reduced CVR (vertical line), and an AI value higher than the mean + 3 SD (i.e., 104.6%) was defined as increase in AI (horizontal line). Open circles indicate patients with HPS after CAS.
Fig 5.
The BFI ratio was correlated with preoperative CVR (A). The BFI ratio was also correlated with the postoperative AI (B). Open circles indicate patients with HPS after CAS.
Table 1.
Patient and lesion characteristics.
Table 2.
Treatment and clinical results.
Table 3.
Comparison of ICG kinetics between the groups.
Fig 6.
The time course of BFI between the hyperperfusion (HP) group and the non-hyperperfusion (non-HP) group.
Black circles indicate the HP group, and gray squares indicate the non-HP group. *P < 0.05.