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  • Author or Editor: Koji Iihara x
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Tomohito Hishikawa, Koji Iihara, Naoaki Yamada, Hatsue Ishibashi-Ueda and Susumu Miyamoto

Object

The aim of this study was to assess the histopathological differences between advanced atherosclerotic carotid artery (CA) plaques with signal hyperintensity on T1-weighted MR images and those without, focusing on necrotic core size and intraplaque hemorrhage (IPH).

Methods

Thirty-five patients scheduled for carotid endarterectomy underwent preoperative CA MR imaging using 3D inversion-recovery-based T1-weighted imaging (magnetization-prepared rapid acquisition gradient-echo [MPRAGE]). The signal intensity of the CA plaque on MPRAGE sequences was classified as “high” when the intensity was more than 200% that of adjacent muscle. A total of 96 axial MR images obtained in 35 patients were compared with corresponding histological sections from 36 excised specimens. The area of the necrotic core in histological sections was compared between specimens with and without high signal intensity on MPRAGE sequences. The IPH was histopathologically graded according to the size of the area positive for glycophorin A as revealed by immunohistochemical staining. The difference between plaques with and without high signal intensity was investigated with respect to the degree of IPH. The relationship of the severity of IPH to size of the necrotic core was also evaluated.

Results

The area of the necrotic core in plaques with high signal intensity on MPRAGE sequences was significantly larger than that in plaques without high signal intensity (median 51.2% [interquartile range 43.3–66.8%] vs 49.0% [33.2–57.6%], p = 0.029). Carotid artery plaques with high signal intensity had significantly more severe IPH than plaques with lower signal intensity (p < 0.0001). The severity of IPH was significantly associated with the size of the necrotic core (p < 0.0001).

Conclusions

Atherosclerotic CA plaques with high signal intensity on MPRAGE sequences had large necrotic cores with IPH in patients with high-grade stenosis; MPRAGE is useful for the evaluation of CA plaque progression.

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Koji Iihara, Masakazu Okawa, Tomohito Hishikawa, Naoaki Yamada, Kazuhito Fukushima, Hidehiro Iida and Susumu Miyamoto

The authors report a rare case of slowly progressive neuronal death associated with postischemic hyperperfusion in cortical laminar necrosis after radial artery/external carotid artery–middle cerebral artery bypass graft surgery for an intracavernous carotid artery aneurysm. Under barbiturate protection, a 69-year-old man underwent high-flow bypass surgery combined with carotid artery sacrifice for a symptomatic intracavernous aneurysm. The patient became restless postoperatively, and this restlessness peaked on postoperative Day (POD) 7. Diffusion-weighted and FLAIR MR images obtained on PODs 1 and 7 revealed subtle cortical hyperintensity in the temporal cortex subjected to temporary occlusion. On POD 13, 123I-iomazenil (123I-IMZ) SPECT clearly showed increased distribution on the early image and mildly decreased binding on the delayed image with count ratios of the affected–unaffected corresponding regions of interest of 1.23 and 0.84, respectively, suggesting postischemic hyperperfusion. This was consistent with the finding on 123I-iodoamphetamine SPECT. Of note, neuronal density in the affected cortex on the delayed 123I-IMZ image further decreased to the affected/unaffected ratio of 0.44 on POD 55 during the subacute stage when characteristic cortical hyperintensity on T1-weighted MR imaging, typical of cortical laminar necrosis, was emerging. The affected cortex showed marked atrophy 8 months after the operation despite complete neurological recovery. This report illustrates, for the first time, dynamic neuroradiological correlations between slowly progressive neuronal death shown by 123I-IMZ SPECT and cortical laminar necrosis on MR imaging in human stroke.

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Koji Iihara, Kenichi Murao, Nobuyuki Sakai, Naoaki Yamada, Izumi Nagata and Susumu Miyamoto

Object

The authors of this study prospectively compared periprocedural neurological morbidity and the appearance of lesions on diffusion-weighted (DW) magnetic resonance (MR) imaging in patients who had undergone carotid endarterectomy (CEA) or carotid artery stent placement (CASP) with distal balloon protection, based on a CEA risk grading scale.

Methods

Patients undergoing CEA (139 patients) and CASP (92 patients) were classified into Grades I to IV, based on the presence of angiographic (Grade II), medical (Grade III), and neurological (Grade IV) risks. Although not randomized, the CEA and CASP groups were well matched in terms of the graded risk factors except for a greater proportion of neurologically unstable patients in the CEA group (11 compared with 3%, p = 0.037). There were greater proportions of asymptomatic (64 compared with 34%, p = 0.006) and North American Symptomatic Carotid Endarterectomy Trial–ineligible patients (29 compared with 14%, p < 0.0001) in the CASP group. The overall rates of neurological morbidity with ischemic origin and the appearance of lesions on DW MR imaging after CEA were 2.2 and 9.3%, and those after CASP were 7.6 and 35.9% (nondisabling stroke only), respectively. The only disabling stroke was caused by an intracerebral hemorrhage attributable to hyperperfusion in one case (0.7%) of CEA. There were no deaths. There was no significant association between neurological morbidity and the risk grade in patients who had undergone CEA, although the incidence of lesions on DW imaging was significantly greater in the Grade IV risk group compared with that in the other risk groups combined (42.1 compared with 4.2%, p < 0.0001). After CASP, a higher incidence of neurological morbidity and lesions on DW imaging was noted for the Grade II and III risk groups combined as compared with that in the Grade I risk group, regardless of a symptomatic or an asymptomatic presentation (neurological morbidity: 10.5 compared with 3.1%, respectively, p = 0.41; and DW imaging lesions: 47.4 compared with 19.4%, p = 0.01). The incidence of lesions on DW imaging after CEA was significantly lower than that after CASP except for the Grade IV risk groups.

Conclusions

Despite a higher incidence of DW imaging–demonstrated lesions in the Grade IV risk group, there was no significant association between the risk group and neurological morbidity rates after CEA. The presence of vascular and medical risk profiles conferred higher rates of neurological morbidity and an increased incidence of lesions on DW imaging after CASP. Considering that no serious nonneurological complications were noted, CEA and CASP appear to be complementary methods of revascularization for carotid artery stenosis with various risk profiles.

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Koji Iihara, Kenichi Murao, Nobuyuki Sakai, Akio Soeda, Hatsue Ishibashi-Ueda, Chikao Yutani, Naoaki Yamada and Izumi Nagata

✓ A 58-year-old woman harboring a partially thrombosed giant aneurysm of the vertebral artery (VA) presented with lower cranial nerve palsies and cerebellar ataxia. The authors initially attempted to reduce the mass effect by obliterating the lumen of the aneurysm as well as by trapping of the parent artery with coils. Although there was no angiographically demonstrated evidence of filling, the aneurysm continued to enlarge. Magnetic resonance imaging revealed a marked enhancement around the packed coils close to the neck of the aneurysm. Aneurysmectomy and removal of the coils were performed and resulted in an almost complete cure of the patient's symptoms. Interestingly, at the time of resection, a marked development of vasa vasorum on the occluded VA and the neck of the aneurysm was noted. When the occluded VA was cut, there was blood oozing through the coils packed within its lumen on the side where the aneurysm lay. Histological examination showed the presence of inflammatory cells and neovascularization of a partially organized thrombus around the packed coils in both the aneurysm and occluded VA. The proliferation of vasa vasorum was also recognized histologically. This unique case provides insight into the growth mechanisms of a partially thrombosed giant aneurysm after an apparently complete occlusion by endovascular treatment, especially the role of vaso vasorum on the occluded parent artery in the dynamic process of neovascularization in the incomplete organization of thrombus around the packed coils.