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Featured researches published by Housei Etou.


Radiation Medicine | 2008

Intraprocedural plaque protrusion resulting in cerebral embolism during carotid angioplasty with stenting

Hiroshi Aikawa; Tomonobu Kodama; Kouhei Nii; Masanori Tsutsumi; Masanari Onizuka; Minoru Iko; Shuko Matsubara; Housei Etou; Kimiya Sakamoto; Kiyoshi Kazekawa

An 82-year-old man with an asymptomatic left high-grade carotid stenosis was treated with carotid artery stenting (CAS) under distal protection. The procedure consisted with predilation with a 5 × 40 mm percutaneous transluminal angioplasty (PTA) balloon, deployment of a 10 × 20 mm self-expandable stent, post-dilation with a 7 × 20 mm PTA balloon, and aspiration of debris with 60 ml of blood. The cervical carotid angiogram immediately after deflation of the distal blocking balloon demonstrated a small in-stent filling defect of the contrast medium that protruded from the anterior wall of the carotid artery. The following cranial carotid angiogram showed abrupt occlusion of the left middle cerebral artery (MCA). Because the in-stent lesion had vanished in the repeat study after recognition of this embolic event, it was suggested that an embolus had been liberated from the in-stent lesion, reaching the left MCA and obliterating it. In this case, the embolus was speculated to originate in the ruptured plaque, which protruded into the stent through the cells of the device and became liberated into the bloodstream. Attention should be paid so as not to overlook any plaque protrusion, which may be seen subsequently as a cerebral embolism on the angiogram obtained immediately after CAS.


American Journal of Neuroradiology | 2008

Carotid Artery Stenting for Calcified Lesions

Masanori Tsutsumi; Hiroshi Aikawa; Masanari Onizuka; Minoru Iko; Tomonobu Kodama; Kouhei Nii; Shuko Hamaguchi; Housei Etou; Kimiya Sakamoto; Kiyoshi Kazekawa

BACKGROUND AND PURPOSE: Our aim was to assess the feasibility of carotid artery stent placement (CAS) for calcified lesions. MATERIALS AND METHODS: Using embolic protection devices (EPDs), we performed 51 CAS procedures in 43 patients with severe carotid artery stenosis accompanied by plaque calcification. Before intervention, all lesions were subjected to multidetector-row CT. The arc of the circumferential plaque calcification was measured on axial source images at the site of maximal luminal stenosis, and the total volume of the plaque calcification was determined. The angiographic outcome immediately after CAS, and intra- and postoperative complications were recorded. RESULTS: The mean arc of calcification was 201.1 ± 72.3° (range, 76–352°), and the mean of the total calcification volume was 154.9 ± 35.4 mm3 (range, 92–2680 mm3). Balloon rupture occurred in 1 procedure (2.0%) at predilation angioplasty; all 51 CAS procedures were successful without clinical adverse effects. Although there was a correlation between the arc of plaque calcification and residual stenosis (r = 0.6, P < .001), excellent dilation with residual stenosis ≤30% was achieved in all lesions. There was no correlation between the total volume of calcification and residual stenosis. None of the patients developed stroke or death within 30 days of the CAS procedure. CONCLUSION: CAS by using EPDs to treat lesions with plaque calcification is feasible even in patients with near-total circumferential plaque calcification.


Neuroradiology | 2007

Accordion effect during carotid artery stenting: report of two cases and review of the literature.

Masanori Tsutsumi; Kiyoshi Kazekawa; Masanari Onizuka; Hiroshi Aikawa; Minoru Iko; Tomonobu Kodama; Kouhei Nii; Shuko Matsubara; Housei Etou; Akira Tanaka

IntroductionThe term “accordion effect” is used to describe a mechanical distortion of tortuous arteries mimicking spasm or dissection. This phenomenon has been reported in patients undergoing percutaneous coronary intervention. To our knowledge, this is the first documentation of the accordion effect during carotid artery intervention.MethodsTwo patients who developed the accordion effect during carotid artery stenting (CAS) are described.ResultsAngiograms obtained just after CAS showed a stenosing lesion with wall irregularity at the distal part of the stent. This lesion disappeared and tortuosity of the internal carotid artery developed after withdrawing the guidewire until its floppy segment rested equally on the lesion. In another patient, the lesion did not disappear completely until the guiding catheter had been withdrawn to the proximal portion of the common carotid artery. We conclude that these stenosing lesions reflected the accordion effect.ConclusionIt is essential to differentiate the accordion effect from dissection, spasm, and thrombosis because the management is importantly different. We report our findings and present a review of the literature.


Neurosurgery | 2011

Early ceasing of intra-aneurysmal contrast opacification during coil embolization in ruptured aneurysms compared with unruptured aneurysms.

Masanori Tsutsumi; Hiroshi Aikawa; Kouhei Nii; Shuko Hamaguchi; Housei Etou; Kimiya Sakamoto; Hidenori Yoshida; Yoshihisa Matsumoto; Kiyoshi Kazekawa

BACKGROUND:The difference between coil-embolized ruptured and unruptured aneurysms with respect to intra-aneurysmal thrombus formation remains to be determined. OBJECTIVE:We examined whether there was a difference between ruptured and unruptured coil-embolized aneurysms in the rate and timing of thrombus formation in the aneurysmal sac and discuss the effect of thrombus on the treatment outcome. METHODS:We evaluated 209 aneurysms with an aneurysmal dome smaller than 10 mm and a neck size less than 4 mm. Of these, 91 (43.5%) were ruptured. We assessed intra-aneurysmal thrombus formation by the coil-packing ratio (CPR): the percentage of coil volume occupying the aneurysmal sac. The initial CPR was defined as the CPR at which contrast influx into the sac ceased and the final CPR as that at the end of the procedure. ΔCPR was calculated as the difference between initial and final CPRs. Embolized aneurysms were evaluated on follow-up angiograms. RESULTS:The initial CPR was significantly lower in ruptured aneurysms (P < .01), and there was not a significant difference in the final CPR between ruptured and unruptured aneurysms (P = .05). ΔCPR was significantly higher in ruptured aneurysms (P < .01). The rate of aneurysmal recanalization was significantly higher in ruptured aneurysms (P < .05). The incidence of recanalization was high in ruptured aneurysms with low initial CPR and ΔCPR values. CONCLUSION:In ruptured aneurysms, intra-aneurysmal thrombus formation tends to occur in the earlier stages of coil embolization. In some cases, thrombus formation may inhibit dense coil packing and result in recanalization.


Neuroradiology | 2007

Stent fracture in revascularization for symptomatic ostial vertebral artery stenosis

Masanori Tsutsumi; Kiyoshi Kazekawa; Masanari Onizuka; Tomonobu Kodama; Shuko Matsubara; Hiroshi Aikawa; Minoru Iko; Kouhei Nii; Housei Etou; Akira Tanaka


Neuroradiology | 2008

Endovascular treatment of tiny ruptured anterior communicating artery aneurysms

Masanori Tsutsumi; Hiroshi Aikawa; Masanari Onizuka; Tomonobu Kodama; Kouhei Nii; Shuko Matsubara; Minoru Iko; Housei Etou; Kimiya Sakamoto; Kiyoshi Kazekawa


Neurologia Medico-chirurgica | 2007

Rebleeding after endovascular embolization of ruptured cerebral aneurysms.

Hiroshi Aikawa; Kiyoshi Kazekawa; Shun-ichi Nagata; Masanari Onizuka; Minoru Iko; Masanori Tsutsumi; Tomonobu Kodama; Kouhei Nii; S. Matsubara; Housei Etou; Akira Tanaka


Neurologia Medico-chirurgica | 2007

Development of Unusual Collateral Channel From the Posterior Meningeal Artery After Endovascular Proximal Occlusion of the Posterior Inferior Cerebellar Artery

Masanori Tsutsumi; Kiyoshi Kazekawa; Hiroshi Aikawa; Minoru Iko; Tomonobu Kodama; Kouhei Nii; Shuko Matsubara; Housei Etou; Kimiya Sakamoto; Akira Tanaka


Neurologia Medico-chirurgica | 2011

Incidence of Hemodynamic Depression After Carotid Artery Stenting Using Different Self-Expandable Stent Types

Kouhei Nii; Masanori Tsutsumi; Hiroshi Aikawa; Shuko Hamaguchi; Housei Etou; Kimiya Sakamoto; Kiyoshi Kazekawa


Neurologia Medico-chirurgica | 2013

Histological Examination of Expanded Polytetrafluoroethylene Artificial Dura Mater at 14 Years After Craniotomy

Yoshihisa Matsumoto; Hiroshi Aikawa; Masanori Tsutsumi; Sumito Narita; Hidenori Yoshida; Housei Etou; Kimiya Sakamoto; Kiyoshi Kazekawa

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