K Irie

Nagoya University, Nagoya-shi, Aichi-ken, Japan

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Publications (38)42.41 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: The development of new diagnostic technologies for cerebrovascular diseases requires an understanding of the mechanism behind the growth and rupture of cerebral aneurysms. To provide a comprehensive diagnosis and prognosis of this disease, it is desirable to evaluate wall shear stress, pressure, deformation and strain in the aneurysm region, based on information provided by medical imaging technologies. METHODS: In this research, we propose a new cyber-physical system composed of in vitro dynamic strain experimental measurements and computational fluid dynamics (CFD) simulation for the diagnosis of cerebral aneurysms. A CFD simulation and a scaled-up membranous silicone model of a cerebral aneurysm were completed, based on patient-specific data recorded in August 2008. In vitro blood flow simulation was realized with the use of a specialized pump. A vision system was also developed to measure the strain at different regions on the model by way of pulsating blood flow circulating inside the model. RESULTS: Experimental results show that distance and area strain maxima were larger near the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and finally the main blood vessel section (0.01 and 0.014). These results were complemented by a CFD simulation for the addition of wall shear stress, oscillatory shear index and aneurysm formation index. Diagnosis results using imaging obtained in August 2008 are consistent with the monitored aneurysm growth in 2011. CONCLUSION: The presented study demonstrates a new experimental platform for measuring dynamic strain within cerebral aneurysms. This platform is also complemented by a CFD simulation for advanced diagnosis and prediction of the growth tendency of an aneurysm in endovascular surgery. Copyright © 2013 John Wiley & Sons, Ltd.
    International Journal of Medical Robotics and Computer Assisted Surgery 03/2013; · 1.49 Impact Factor
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    ABSTRACT: Computer-based simulation is necessary to clarify the hemodynamics in brain aneurysm. Specifically for endovascular treatments, the effects of indwelling intravascular devices on blood stream need to be considered. The most recent technology used for cerebral aneurysm treatment is related to the use of flow diverters to reduce the amount of flow entering the aneurysm. To verify the differences of flow reduction, we analyzed multiple Enterprise stents and two kinds of flow diverters. In this research, we virtually modeled three kinds of commercial intracranial stents (Enterprise, Silk, and Pipeline) and mounted to fit into the vessel wall, and deployed across the neck of an IC-ophthalmic artery aneurysm. Also, we compared the differences among multiple Enterprise stents and two flow diverters in a standalone mode. From the numerical results, the values of wall shear stress and pressure are reduced in proportion to the size of mesh, especially in the inflow area. However, the reduced velocity within the aneurysm sac by the multiple stents is not as significant as the flow diverters. This is the first study analyzing the flow alterations among multiple Enterprise stents and flow diverters. The placement of small meshed stents dramatically reduced the aneurysmal fluid movement. However, compared to the flow diverters, we did not observe the reduction of flow velocity within the aneurysm by the multiple stents.
    Asian journal of neurosurgery. 10/2012; 7(4):159-65.
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    ABSTRACT: Hemodynamic factors are thought to play important role in the initiation, growth, and rupture of cerebral aneurysms. However, hemodynamic features in the residual neck of incompletely occluded aneurysms and their influences on recanalization are rarely reported. This study characterized the hemodynamics of incompletely occluded aneurysms that had been confirmed to undergo recanalization during long-term follow-up using computational fluid dynamic analysis. A ruptured left basilar-SCA aneurysm was incompletely occluded and showed recanalization during 11 years follow-up period. We retrospectively characterized on three-dimensional MR angiography. After subtotal occlusion, the flow pattern, wall shear stress (WSS), and velocity at the remnant neck changed during long-term follow-up period. Specifically, high WSS region and high blood flow velocity were found near the neck. Interestingly, these area of the remnant neck coincided with the location of aneurysm recanalization. High WSS and blood flow velocity were consistently observed near the remnant neck of incompletely occluded aneurysm, prone to future recanalization. It will suggest that hemodynamic factors may play important roles in aneurismal recurrence after endovascular treatment.
    Asian journal of neurosurgery. 07/2012; 7(3):109-15.
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    ABSTRACT: For the development of artificial intelligent diagnosis for cerebrovascular intervention, it is desirable to forecast the growth of cerebral aneurysms. In order to achieve such purpose, it is needed to evaluate wall shear stress, strain, pressure, deformation and flow velocity in the aneurysm region. In this research, we focus on in-vitro strain and deformation measurements of cerebral aneurysm models, and propose a cyber-physical system, in which a scaled-up membranous silicone model of cerebral aneurysm was built and integrated with a specialized pump for the pulsatile blood flow simulation, and a vision system was constructed to measure the strain on different regions on the model with pulsatile blood flow circulated inside. Experimental results show that both distance and area strain maxima were larger for the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and then by the main blood vessel section (0.01 and 0.014), which were complemented with computer fluid dynamics simulation for the inclusion of wall shear stress, oscillatory shear index and aneurysm formation index. Medical imaging data of the cerebral aneurysm in 2008 and 2011 was obtained. Diagnosis results have concordance with the aneurysm growth in 2011. The presented measurement method offers an option for measuring strain and deformation to be complementary with computer fluid dynamics and photoelastic stress analysis for advanced diagnostic in the endovascular surgery.
    Intelligent Robots and Systems (IROS), 2012 IEEE/RSJ International Conference on; 01/2012
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    ABSTRACT: Computer based simulation is important for clarifying the hemodynamics in brain aneurysm. Specifically, for endovascular treatments, the effect of indwelling intravascular devices on blood stream needs to be considered. Most recent technology for cerebral aneurysm treatment is related with the use of flow diverters to reduce the amount of flow entering to the aneurysms. In this research, we present a new method for design of flow diverters and fitting them to patient specific vasculature models. This methodology enables to change porosity of the flow diverters as well as their location in the blood vessel. One coiling assist stent and two flow diverters were compared to estimate the effect of flow alteration in aneurysm for treatment of a cerebral aneurysm. From the numerical result, we can conclude that pore density and size of mesh affect the hemodynamics in aneurysm and high density and small size of pore produce reduction effect of pressure and wall shear stress on an aneurysm.
    Complex Medical Engineering (CME), 2012 ICME International Conference on; 01/2012
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    ABSTRACT: Carotid cavernous fistula (CCF) is an abnormal arteriovenous communication in the cavernous sinus. Direct CCF results from a tear in the intracavernous carotid artery. Typically, it has a high flow and usually presents with oculo-orbital venous congestive features such as exophthalmos, chemosis, and sometimes oculomotor or abducens cranial nerve palsy. Indirect CCF generally occurs spontaneously with subtle signs. We report a rare case of spontaneous direct CCF in childhood who did not have the usual history of craniofacial trauma or connective tissue disorder but presented with progressive chemosis and exophthalmos of the right eye. This report aims also to describe the safety and success of transvenous embolization with coils of the superior ophthalmic vein and cavernous sinus through the inferior petrosal sinus.
    Asian journal of neurosurgery. 01/2011; 6(1):45-8.
  • Journal of The Neurological Sciences - J NEUROL SCI. 01/2009; 285.
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    ABSTRACT: Our objective was to set up a management-oriented classification for paraclinoid aneurysms, and then design and apply a simplified management scheme according to each group defined by this classification. Paraclinoid aneurysms were classified as group I (supraophthalmic artery), group II (ophthalmic artery) and group III (infraophthalmic artery) aneurysms intradurally. Between January 2005 and December 2006, 86 cases with 89 paraclinoid aneurysms were treated. There were 35 (40.2%) aneurysms in group I (20 in group Ia, 15 in group Ib), 32 (36.8%) in group II and 20 (23%) in group III. In group I aneurysms, 20 (57.1%) were treated by clipping or/and wrapping, while 15 (42.9%) were managed by coiling. In group II aneurysms, 20 (62.5%) were treated by clipping and 12 (37.5%) by coiling. The contralateral approach was performed for 4 (6%) aneurysms in groups I and II. All 20 group III aneurysms were treated by coiling. The overall rate of permanent complications was 4.6%. The rate of complete occlusion was 92.5% in surgical cases and 55.6% in endovascular ones. The overall outcomes in the treatment of paraclinoid aneurysms were excellent (GOS = 5, 95.4%). Based on our modified classification of paraclinoid aneurysms, a simplified management scheme was designed and applied. For group I (supraophthalmic artery) and group II (ophthalmic artery) aneurysms, surgical clipping or/and wrapping should be the first choice of treatment, while for group III (infraophthalmic artery) aneurysms, endovascular coiling should be the best modality. Additionally, individualizing the treatment planning might contribute to better results.
    Cerebrovascular Diseases 09/2008; 26(4):388-96. · 3.70 Impact Factor
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    ABSTRACT: Extracranial vertebral artery aneurysm associated with neurofibromatosis (NF1) is very rare. The aneurysm was successfully treated by endovascular trapping of the aneurysm and proximal vertebral artery with coils.
    Interventional Neuroradiology 03/2007; 13 Suppl 1:90-3. · 0.73 Impact Factor
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    ABSTRACT: A limited series of patients with aneurysm were reviewed retrospectively to analyze strategies for integrating microsurgical and endovascular techniques in the management of complex, surgically intractable aneurysms. Four patients were managed in Fujita Health University with a multimodality approach: intentional reconstruction of the aneurysm neck followed by endovascular coiling. A total of 5 aneurysms were treated, of which 3 were large or giant in size, and 3 were fusiform or multilobulated. Complete angiographic obliteration was confirmed in 4 aneurysms (80%). All patients had a good outcome (Glasgow Outcome Scale score 5; mean follow-up, 64 months). As for complex, surgically intractable aneurysms, the intentional reconstruction of the aneurysm neck followed by endovascular coiling should be considered more often.
    Cerebrovascular Diseases 02/2007; 23(5-6):381-7. · 3.70 Impact Factor
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    ABSTRACT: An in vitro patient-specific vascular model, for simulating endovascular intervention is presented. Proposed vascular model reproduces the 3-dimensional vessel lumen structure using CT/MRI information with 13 mum resolution, and it also reproduce the physical characteristics of arterial tissue (elastic modulus and friction coefficient). Furthermore, in this paper, we propose a novel method to evaluate the stress on vasculature which is applied by surgical operations. This method allows quantitatively evaluating 3-dimensional stress conditions in real-time during surgical simulation. Finally, we constructed a comprehensive surgical simulation system, which reproduces whole human aorta structure (with more than Imm inside diameter), reproduce patient-specific pulsatile blood streaming, allowed to evaluate the stress applied to the aorta structure by surgical operations with almost same manner and environment as the practical endovascular intervention. Consequently proposed model, evaluation method and resultant system provides a very valuable platform for evaluating the performance of surgical robots and instruments developed by developers and researchers, and surgical procedures
    Robotics and Automation, 2006. ICRA 2006. Proceedings 2006 IEEE International Conference on; 02/2006
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    ABSTRACT: An in vitro patient-specific vascular model, for simulating endovascular intervention is presented. Proposed vascular model reproduces the 3-dimensional vessel lumen structure using CT/MRI information with 13 μm resolution, and it also reproduces the physical characteristics of arterial tissue (elastic modulus and friction coefficient). Furthermore, in this paper, we propose a novel method to evaluate the stress on vasculature which is applied by surgical operations. This method allows quantitatively evaluating 3-dimensional stress condition in real-time during surgical simulation. With these techniques, we finally constructed a comprehensive surgical simulation system, which reproduces whole human aorta structure (with more than 1 mm inside diameter), reproduce patient-specific pulsatile blood streaming, allowing interventionalists and developers to evaluate the stress on arterial wall applied by surgical operations with almost the same manner as the practical endovascular intervention. Consequently, the proposed model, stress analysis method and resultant system provides a valuable platform for evaluating the performance of surgical robots and instruments developed by developers and researchers, in addition to surgical procedures.
    Micro-NanoMechatronics and Human Science, 2005 IEEE International Symposium on; 12/2005
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    ABSTRACT: In this paper, we propose an in vitro patient-tailored biological model of human cerebral artery, an innovative platform for simulating intravascular neurosurgery to evaluate medical robots and devices. This anatomically accurate model reproduces 3-dimensional configuration of individual arteries with an artery-like thin membranous structure made of silicone elastomer. Its modeling resolution is 13 μm. Presented modeling methodology also allows constructing any hollow structure, which is suitable for robot evaluations, making use of CAD. Presented model also reproduces the physical properties of arterial tissue with errors less than 5% (that include elastic modulus, poisson's ratio and frictional coefficient). Thus the cerebral arterial model reproduces not only the behavior of arteries caused by surgical operations, but also the dynamic behavior of surgical robots and devices (e.g. elastic deformation and slip/stick motion). Furthermore, we also propose a novel method that allows developers to evaluate 3-dimensional stress condition on arterial wall, which is caused by surgical operations, by making use of the photoelastic effect. As there are almost no realistic hardware platform enough to fairly evaluate medical robots and devices, it should provide an advanced testing environment for developing robots and other various medical equipments, especially for intravascular neurosurgery.
    Intelligent Robots and Systems, 2005. (IROS 2005). 2005 IEEE/RSJ International Conference on; 09/2005
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    ABSTRACT: An in vitro patient-tailored reproduction model of cerebral artery, a hardware platform for simulating endovascular intervention for making diagnoses and surgical trainings is presented. 3-D configuration of vessel lumen is reproduced as vessel model with 13 microm modeling resolution, using CT and MRI information. Physical characteristics of cerebral artery, such as elastic modulus and friction coefficient, are also reproduced. We also propose a novel method to visualize stress condition on vessel wall using photoelastic effect. Consequently, it should be helpful for clinical applications, academic researches and other various purposes.
    Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention. 02/2005; 8(Pt 1):925-32.
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    ABSTRACT: Vascular recanalization by the vascular reconstruction method can dramatically improve ischemic symptoms in patients with acute cerebral ischemia. However, this treatment method is frequently associated with haemorrhagic complications. The indications for this therapeutic approach have been described in a number of studies in the literature. The present paper discusses the possibility of assessing the prognosis of ischemic areas using perfusion CT (PCT) by comparing the results obtained before and after thrombolytic therapy. Twenty-six patients underwent vascular reconstruction at our hospital between July 2002 and March 2004. Of these patients, six who underwent PCT before treatment and showed adequate recanalization following vascular reconstruction were included in the present study. PCT images were obtained using the first-pass bolus-tracking method with a 16-row multislice helical CT scanner. Areas of cerebral ischemia were evaluated by CT before and after vascular reconstruction. A region of interest was placed in the area showing low density in CT images before vascular reconstruction. The mean average CBF (mL/min/100 g), CBV (mL/100 g), and MTT (s) values were calculated in areas with and without cerebral infarction after vascular reconstruction. The %CBF, % CBV, and %MTT values relative to the normal side were evaluated with reference to the time until recanalization. Transarterial vascular reconstruction resulted in full recanalization in four patients and partial recanalization in two. The mean time from onset to recanalization was 284.7 +/- 63.27 minutes and was not longer than six hours in any patient. The patient prognosis results in terms of GOS were GR in two patients, MD in three patients, and SD in one patient. Based on comparison of the time after examination to recanalization, the %CBF showed a significant positive correlation in the salvaged area (Y = 47.321 + 2.491 x %CBF:R(2) = 0.792, p < 0.05). A significant correlation was not observed in %CBV, but %MTT showed a significant negative correlation (Y = 269.45 - 0.356 x %MTT:R(2) = 0.794, p < 0.05). The %CBF and %MTT results obtained by PCT performed before transarterial vascular reconstruction suggest that it may be possible to estimate the time before vascular reconstruction and the relationship with prognosis. These findings are expected to help ensure the appropriate application of vascular reconstruction and to provide useful information for developing optimal therapeutic protocols, thus reducing complications. In addition, because the results are based on the time after examination, the appropriate therapeutic approach can be determined even when the time of onset of ischemia is uncertain.
    Interventional Neuroradiology 12/2004; 10 Suppl 2:69-78. · 0.73 Impact Factor
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    ABSTRACT: In vitro patient-tailored anatomical model of human cerebral artery, for presurgical simulation and medical training of intravascular neurosurgery, is presented. Lumens of vasculature are hollowly and precisely reproduced within a transparent elastic silicone structure, based on CT (computed tomography) or MRI (magnetic resonance imaging) angiography. Furthermore, Several material properties (elastic modulus, Poisson's ratio and friction coefficient) of arterial tissue are precisely reproduced. Consequently, proposed anatomical model should serves as an innovative platform for simulating intravascular intervention in purpose of diagnosis, surgical planning, preclinical testing and other various purposes.
    Robotics and Automation, 2004. TExCRA '04. First IEEE Technical Exhibition Based Conference on; 12/2004
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    ABSTRACT: In this paper, we propose an in vitro patient-tailored biological model of human cerebral artery, a novel hardware platform for simulating endovascular intervention, in purpose of diagnosis, presurgical simulation and medical training. Proposed biological model precisely reproduces 3-dimensional configuration of vasculature lumen within vasculature-like thin uniform membrane made of silicon elastomer that provides material property closest to arterial tissue (as to elasticity and surface friction). With this patient-tailored precise vasculature model, then we propose a novel technique to visualize and to analyze 3-dimensional stress distribution over 3-dimensional membranous vasculature structure, which arise from surgical treatments or pulsatile blood streaming, using photoelastic stress analysis. Although photoelastic analysis is generally effective only for 2-dimensional problems, we adapted it to our 3-dimensional problem by making use of vasculature-like thin membranous configuration of proposed biological model. Stress distribution is dearly observed at its fringe as rainbow-colored photoelastic stress pattern. Consequently, proposed patient-tailored biological model should be useful for a wide range of applications, such as hemodynamic study and evaluation of medical devices, as well as surgical simulations.
    Micro-Nanomechatronics and Human Science, 2004 and The Fourth Symposium Micro-Nanomechatronics for Information-Based Society, 2004. Proceedings of the 2004 International Symposium on; 01/2004
  • Surgery for Cerebral Stroke 01/2004; 32(1):37-41.
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    ABSTRACT: Arterial dissection is now recognized as an important cause of stroke. Most reported dissections involve the extracranial portion of the internal carotid artery (ICA) and vertebral arteries. Spontaneous dissecting aneurysms of the intracranial ICA are uncommon. Endovascular treatment for cerebral aneurysms has become widespread; however, the dissecting aneurysm is still difficult to treat if the parent artery has to be preserved. More recently, stenting has been advocated for use with endosaccular coiling, with the coils held in place by the stent. We herein report a spontaneous intracranial ICA dissecting aneurysm in a 51-year-old woman who was treated using a new technique of combined stent and coils.
    Neuroradiology 12/2003; 45(11):825-9. · 2.37 Impact Factor
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    ABSTRACT: Stent assisted coil embolization is a useful therapeutic modality for wide-necked and geometrically difficult aneurysms, as the stent provide a buttress that allows for coil deposition while preventing coil haerniation into the parent vessel lumen, and placement of an endovascular stent within the parent artery across the aneurysm neck may divert the blood from the aneurysm inflow tract and promote intra-aneurysm stasis and thrombosis.We report herein a 3 patients treated with endovascular stent-assisted coil embolization for symptomatic or enlarging wide-necked, dissecting, and fusiform aneurysms of the carotid and vertebrobasilar arteries. One patient had intracranial mass effect, the second had subarachnoid haemorrhage, and the third had angiographic evidence of enlarging aneurysm. The aneurysm was located in the petrous segment of internal carotid artery in one patient and in the intracranial vertebral artery in the other two patients. For all patients, we used balloon expandable stent (such as GFX, S-670) in this technique. Complete obliteration of the aneurysms could be achieved in all cases, with preservation of distal circulation.
    Interventional Neuroradiology 09/2003; 9(3):255-61. · 0.73 Impact Factor

Publication Stats

205 Citations
42.41 Total Impact Points

Institutions

  • 2004–2013
    • Nagoya University
      • Department of Micro-Nano Systems Engineering
      Nagoya-shi, Aichi-ken, Japan
  • 2002–2013
    • Fujita Health University
      • Department of Neurosurgery
      Nagoya, Aichi, Japan
  • 2011
    • Angeles University Foundation
      Angeles, Central Luzon, Philippines
  • 2008
    • Xiamen University
      Amoy, Fujian, China
  • 2001
    • Kagawa University
      • Department of Neurological Surgery
      Miki, Hyogo-ken, Japan