with interest the article by Di Napoli et al, 1 who reported the first-ever ischemic stroke to fu... more with interest the article by Di Napoli et al, 1 who reported the first-ever ischemic stroke to further analyze the relationship between C-reactive protein (CRP) values measured immediately and at different times after stroke, and the 1-year outcome. The important message of this article is that the relationship between CRP and prognosis after cerebral ischemia could be of greater utility for risk stratification and may predict future cardiovascular events or death. Ischemic cerebrovascular disease accounts for a substantial proportion of all strokes. Although the proximate cause of most brain infarcts is thrombus formation, atherosclerosis is the chief underlying cause. 2 CRP, one of the acute-phase reactants, is an indicator of underlying systemic inflammation and a novel plasma marker of atherothrombotic disease. 3 Furthermore, elevated plasma levels of CRP are not disease specific but are sensitive markers produced in response to tissue injury, infectious agents, immunologic stimuli, and inflammation. 4,5 Plasma CRP levels are known to be higher in smokers, obese individuals, individuals with abnormal fibrinolytic activity (plasmin-antiplasmin complex), and individuals with subclinical atherosclerosis. We believed that the use of plasma CRP levels may aid in identifying a potentially large number of men and women who are at risk for cerebrovascular events, as described by Rost et al. 5 Our clinical prospective data 6 from a large community-based cohort of men and women of stroke and transient ischemic attack demonstrate a strong association between CRP and fibrinogen in both sexes. In our cases, 25.3% of patients have normal levels of CRP after stroke, and our data indicate that 21.6% of patients with ischemic stroke who have CRP levels Ն1.5 mg/dL have died, as Di Napoli et al described. We have also detected that some of the ischemic stroke patients have history of the trauma. 6 As a result, the detection of especially CRP and fibrinogen is very important in patients with ischemic stroke and transient ischemic attack in determination of possible risk factors, subsequent vascular events or death, and severe neurological deficit and disability, and stratify poststroke patients into relatively high-risk groups.
Objective and importance: A patient with pituitary apoplexy resulting from lymphocytic adenohypop... more Objective and importance: A patient with pituitary apoplexy resulting from lymphocytic adenohypophysitis, which caused visual disturbance during pregnancy, is described. This is the first report of such case. Clinical presentation: A 23-year-old primigravida in her 25th week of gestation experienced headache and bitemporal hemianopsia of sudden onset. Magnetic resonance imaging (MRI) revealed a large pituitary mass with intratumoral hemorrhage. Although conservative treatment with intravenous glycerol improved the symptoms partially, the visual symptoms worsened again 6 weeks later. After delivering a girl by scheduled caesarean section her visual symptoms improved. Despite the symptomatic improvement, MRI showed the chiasmatic compression by the enlarged pituitary gland had not changed. Therefore, trans-sphenoidal surgery to decompress the chiasm was performed. Necrotic tissue was seen exuding behind the enlarged pituitary gland and adenohypophysitis with bleeding (apoplexy) was diagnosed histologically. After follow-up for 40 months, she was doing well without any visual or neurological deficits. Conclusion: Although relatively rare, pituitary apoplexy as a consequence of lymphocytic adenohypophysitis should be borne in mind when a pregnant woman presents with headache and visual disturbance of sudden onset.
Clinical statistics show that the cerebral aneurysm are frequently generated at some specific are... more Clinical statistics show that the cerebral aneurysm are frequently generated at some specific areas. The abruptly curved shape of the artery shown in this figure is called "carotid siphon" and here is the area with high risk of generation of the cerebral aneurysms. We have developed a numerical analysis system which includes pre-processing, numerical simulation and post-processing. In the procedure of pre-processing, computed tomographic angiography is used. These figures show the results of numerical simulation. Complex secondary flow exists in the flow field and the wall shear stress concentrates on some specific areas in the artery.
The paper aims to investigate effects of blood vessel geometry on hemodynamics of the cerebral ar... more The paper aims to investigate effects of blood vessel geometry on hemodynamics of the cerebral artery, particularly the internal carotid artery using computer graphics. The medical statistics show that generation and rupture of the cerebral aneurysms is strongly correlated with the wall shear stress and flow patterns in the blood vessel. In order to provide better understanding of phenomena, the paper presents the numerical analysis system, which consists of pre-processing, simulation and postprocessing. In the pre-processing, the medical imaging data, mainly CT (Computerized Tomographic) angiography, are used to construct the three-dimensional geometry of the artery. Various simulations are carried out varying curvature or location of bifurcation, and the results are visualized to investigate geometry effect.
✓ In most cases of pituitary cyst there are no clinical symptoms and the lesions are found incide... more ✓ In most cases of pituitary cyst there are no clinical symptoms and the lesions are found incidentally. The authors report the case of a 60-year-old man with a pituitary cyst causing visual disturbance and hyponatremia. The patient presented with appetite loss and general fatigue. On admission, blood workup showed severe hyponatremia (112 mEq/L), and bitemporal hemianopsia was observed on neurological examination. Magnetic resonance imaging revealed an intra- and suprasellar region cystic mass extending to the frontal base and hypothalamic area. The serum level of brain natriuretic peptide (BNP) was elevated (92 pg/ml) with polyuria and excessive Na excretion. Transsphenoidal surgery was performed to drain the cyst. The cyst wall was partially excised and the cystic fluid was aspirated. The secretion of BNP normalized postoperatively, and the hyponatremia and visual symptoms resolved. Histological examination, including an electron microscopy study, confirmed the diagnosis of a sim...
The present study was carried out to compare the neuroprotective effect of the novel noncompetiti... more The present study was carried out to compare the neuroprotective effect of the novel noncompetitive NMDA antagonist, FR115427, with that of (+)MK-801 in rat focal cerebral ischemia. Focal cerebral ischemia was produced by permanent occlusion of the left middle cerebral artery (MCA). Drugs were administered intraperitoneally immediately after ischemia and once a day for 6 successive days. FR115427 (10 mg/kg, i.p.) significantly improved neurologic deficit at 1 day after ischemia and reduced total infarct volume (54%) at 7 days after ischemia. Although FR115427 (10 mg/kg, s.c.) produced neuronal vacuolization similar to (+)MK-801, FR115427 did not produce adverse effects such as a loss of body weight, mortality, and hypothermia, in contrast to (+)MK-801. These results suggest that FR115427 may be useful in the treatment of stroke.
We simultaneously measured neurotransmitter amino acids by the microdialysis technique and cortic... more We simultaneously measured neurotransmitter amino acids by the microdialysis technique and cortical CBF by laser-Doppler flowmetry in the ischemic penumbral cortex of rats subjected to 2-h normothermic (36.5–37.5°C) transient middle cerebral artery (MCA) clipocclusion. Brains were perfusion-fixed 3 days later and infarct volume measured. CBF (% of preischemic values) fell to 32 ± 2% (mean ± SD) during ischemia and rose to 157 ± 68% during recirculation. Extracellular glutamate levels increased from a baseline value of 7 ± 3 μ M to a peak value of 180 ± 247 μ M 20–30 min following onset of ischemia but subsequently returned to near baseline levels after 70 min of ischemia despite ongoing MCA occlusion. The threshold CBF for moderate glutamate release was 48%. Massive glutamate release was seen during the first 60 min of MCA occlusion in the two animals showing the largest infarcts and occurred at CBF values ≤20% of control levels. Mean CBF during ischemia exhibited an inverse relatio...
International Journal for Numerical Methods in Fluids, 2007
... Ryo Torii1,∗, , Marie Oshima2, Toshio Kobayashi3, Kiyoshi Takagi4 and Tayfun E. Tezduyar5 ..... more ... Ryo Torii1,∗, , Marie Oshima2, Toshio Kobayashi3, Kiyoshi Takagi4 and Tayfun E. Tezduyar5 ... of Neurosurgery, Ogura Hospital, 4-2-5 Nakamachi, Setagaya, Tokyo 158-8585, Japan 5Mechanical Engineering, Rice UniversityMS 321, 6100 Main Street, Houston, TX 77005 ...
International Journal for Numerical Methods in Biomedical Engineering, 2010
Fluid-structure interaction (FSI) analyses of cerebral aneurysm using patient-specific geometry w... more Fluid-structure interaction (FSI) analyses of cerebral aneurysm using patient-specific geometry with uniform and pathological aneurysmal wall thickness models are carried out. The objective is to assess the influence of the wall thickness on the FSI and hemodynamics in aneurysms. Two aneurysm models that were reconstructured based on CT images are used. The arterial wall thickness is set to 0.3 mm for the non-aneurysmal artery and to 0.05 mm for the aneurysmal wall based on experimental findings. Another set of aneurysm models with a uniform wall thickness of 0.3 mm for the entire model is used for comparison. The FSI simulations are carried out using the deforming-spatial-domain/stabilized space-time method with physiological inflow and pressure profiles. Computations with different aneurysmal wall thicknesses depict considerable differences in displacement, flow velocity and wall shear stress (WSS). The wall displacement for the pathological wall model is 61% larger than that of the uniform wall model. Consequently, the flow velocities in the aneurysm with the pathological wall model are lower, and that results in a 51% reduction in WSS on the aneurismal wall. Because low WSS on the aneurymal wall is linked to growth and rupture risk of aneurysm, the results suggest that using uniform wall thickness for the aneurysmal wall could underestimate risk in aneurysms.
In this paper, we retrospectively analyzed the effect of cisternal washing therapy using urokinas... more In this paper, we retrospectively analyzed the effect of cisternal washing therapy using urokinase combined with head shaking in preventing vasospasm in patients of high subarachnoid hemorrhage (SAH) grades. Since 1988, a total of 250 consecutive cases in Fisher group 3 were retrospectively analyzed. Of these patients, 56 were diagnosed as grade 4 or 5 according to WFNS grading. Thirty cases had cisternal washing therapy and 26 cases, not. All of these patients had clipping operations within 3 days following SAH, ventricular or cisternal drainage during the clipping operation, and postoperative management with normovolemia and normo-mild hypertension. In these two groups, the incidence of symptomatic vasospasm (transiently symptomatic vasospasm without infarction), cerebral infarction on CT, and mortality and morbidity (M&M) (below moderately disabled) due to vasospasm was analyzed. In the group without cisternal washing, the incidence of symptomatic vasospasm, cerebral infarction on CT, and M&M due to vasospasm was 0%, 30.7%, and 23.1%, respectively. On the other hand, in the group with cisternal washing, the incidence of symptomatic vasospasm, cerebral infarction on CT, and M&M due to vasospasm was 13.3%, 0%, and 3.33%, respectively. Cisternal washing therapy was, therefore, effective to prevent cerebral infarction due to vasospasm.
Computer Methods in Applied Mechanics and Engineering, 2009
... Ryo Torii a , Corresponding Author Contact Information , E-mail The Corresponding Author , Ma... more ... Ryo Torii a , Corresponding Author Contact Information , E-mail The Corresponding Author , Marie Oshima b , Toshio Kobayashi c , Kiyoshi Takagi b , d and Tayfun E. Tezduyar e. ... e Mechanical Engineering, Rice University MS 321, 6100 Main Street, Houston, 77005 TX, USA. ...
Computer Methods in Applied Mechanics and Engineering, 2001
The purpose of the paper is to develop a numerical simulation system for the clinical study of a ... more The purpose of the paper is to develop a numerical simulation system for the clinical study of a cerebral aneurysm. This paper presents the system, which consists of three processes: pre-processing, numerical simulation and post-processing. In the pre-processing process, the three-dimensional solid model was constructed from the computed tomography (CT) angiography raw data. The finite element method (FEM) is used
Patient-specific simulations based on medical images such as CT and MRI offer information on the ... more Patient-specific simulations based on medical images such as CT and MRI offer information on the hemodynamic and wall tissue stress in patient-specific aneurysm configurations. These are considered important in predicting the rupture risk for individual aneurysms but are not possible to measure directly. In this paper, fluid-structure interaction (FSI) analyses of a cerebral aneurysm at the middle cerebral artery (MCA) bifurcation are presented. A 0D structural recursive tree model of the peripheral vasculature is incorporated and its impedance is coupled with the 3D FSI model to compute the outflow through the two branches accurately. The results are compared with FSI simulation with prescribed pressure variation at the outlets. The comparison shows that the pressure at the two outlets are nearly identical even with the peripheral vasculature model and the flow division to the two branches is nearly the same as what we see in the simulation without the peripheral vasculature model. This suggests
We evaluated acute alterations of local cerebral perfusion following 30 min of transient right pr... more We evaluated acute alterations of local cerebral perfusion following 30 min of transient right proximal middle cerebral artery (MCA) clip-occlusion in the rat and following two intervals of postischemic reperfusion. Local cerebral blood flow (ICBF) was assessed by [14C]iodoantipyrine autoradiography. Brain temperature was controlled at 35.5-36.5°C throughout the experiment. We measured ICBF in four groups of rats: (a) sham-operated controls (n = 5), (b) following 30 min MCA occlusion (n = 5), (c) following 30 min of MCA occlusion with 15-min reperfusion (n = 6) and (d) following 30 min of MCA with 120-min reperfusion (n = 6). ICBF was measured in seven regions of the ischemic and non-ischemic hemispheres. MCA occlusion induced an ipsilateral reduction of ICBF, which was most severe in the parietal cortex (8.4 + 4.0% of control, mean + S.D.), and dorsolateral caudoputamen (20.0 + 13.4% of control). ICBF in the non-ischemic hemisphere and in ipsilateral regions lying outside the MCA territory also decreased significantly. ICBF recovery was incomplete when assessed following only 15 min of reperfusion. Reperfusion of 120 min led to return of cortical CBF to control levels, but 1CBF in the caudoputamen remained depressed (50-55% of control values). Caudoputaminal CBF and cortical CBF values were highly correlated with one another under normal and ischemic conditions, but this correlation was disrupted following reperfusion. On the basis of these results, we speculate that, if a means were found to enhance the early recovery of 1CBF following transient ischemia, this might expand the therapeutic window of opportunity for the institution of other neuroprotective strategies.
with interest the article by Di Napoli et al, 1 who reported the first-ever ischemic stroke to fu... more with interest the article by Di Napoli et al, 1 who reported the first-ever ischemic stroke to further analyze the relationship between C-reactive protein (CRP) values measured immediately and at different times after stroke, and the 1-year outcome. The important message of this article is that the relationship between CRP and prognosis after cerebral ischemia could be of greater utility for risk stratification and may predict future cardiovascular events or death. Ischemic cerebrovascular disease accounts for a substantial proportion of all strokes. Although the proximate cause of most brain infarcts is thrombus formation, atherosclerosis is the chief underlying cause. 2 CRP, one of the acute-phase reactants, is an indicator of underlying systemic inflammation and a novel plasma marker of atherothrombotic disease. 3 Furthermore, elevated plasma levels of CRP are not disease specific but are sensitive markers produced in response to tissue injury, infectious agents, immunologic stimuli, and inflammation. 4,5 Plasma CRP levels are known to be higher in smokers, obese individuals, individuals with abnormal fibrinolytic activity (plasmin-antiplasmin complex), and individuals with subclinical atherosclerosis. We believed that the use of plasma CRP levels may aid in identifying a potentially large number of men and women who are at risk for cerebrovascular events, as described by Rost et al. 5 Our clinical prospective data 6 from a large community-based cohort of men and women of stroke and transient ischemic attack demonstrate a strong association between CRP and fibrinogen in both sexes. In our cases, 25.3% of patients have normal levels of CRP after stroke, and our data indicate that 21.6% of patients with ischemic stroke who have CRP levels Ն1.5 mg/dL have died, as Di Napoli et al described. We have also detected that some of the ischemic stroke patients have history of the trauma. 6 As a result, the detection of especially CRP and fibrinogen is very important in patients with ischemic stroke and transient ischemic attack in determination of possible risk factors, subsequent vascular events or death, and severe neurological deficit and disability, and stratify poststroke patients into relatively high-risk groups.
Objective and importance: A patient with pituitary apoplexy resulting from lymphocytic adenohypop... more Objective and importance: A patient with pituitary apoplexy resulting from lymphocytic adenohypophysitis, which caused visual disturbance during pregnancy, is described. This is the first report of such case. Clinical presentation: A 23-year-old primigravida in her 25th week of gestation experienced headache and bitemporal hemianopsia of sudden onset. Magnetic resonance imaging (MRI) revealed a large pituitary mass with intratumoral hemorrhage. Although conservative treatment with intravenous glycerol improved the symptoms partially, the visual symptoms worsened again 6 weeks later. After delivering a girl by scheduled caesarean section her visual symptoms improved. Despite the symptomatic improvement, MRI showed the chiasmatic compression by the enlarged pituitary gland had not changed. Therefore, trans-sphenoidal surgery to decompress the chiasm was performed. Necrotic tissue was seen exuding behind the enlarged pituitary gland and adenohypophysitis with bleeding (apoplexy) was diagnosed histologically. After follow-up for 40 months, she was doing well without any visual or neurological deficits. Conclusion: Although relatively rare, pituitary apoplexy as a consequence of lymphocytic adenohypophysitis should be borne in mind when a pregnant woman presents with headache and visual disturbance of sudden onset.
Clinical statistics show that the cerebral aneurysm are frequently generated at some specific are... more Clinical statistics show that the cerebral aneurysm are frequently generated at some specific areas. The abruptly curved shape of the artery shown in this figure is called "carotid siphon" and here is the area with high risk of generation of the cerebral aneurysms. We have developed a numerical analysis system which includes pre-processing, numerical simulation and post-processing. In the procedure of pre-processing, computed tomographic angiography is used. These figures show the results of numerical simulation. Complex secondary flow exists in the flow field and the wall shear stress concentrates on some specific areas in the artery.
The paper aims to investigate effects of blood vessel geometry on hemodynamics of the cerebral ar... more The paper aims to investigate effects of blood vessel geometry on hemodynamics of the cerebral artery, particularly the internal carotid artery using computer graphics. The medical statistics show that generation and rupture of the cerebral aneurysms is strongly correlated with the wall shear stress and flow patterns in the blood vessel. In order to provide better understanding of phenomena, the paper presents the numerical analysis system, which consists of pre-processing, simulation and postprocessing. In the pre-processing, the medical imaging data, mainly CT (Computerized Tomographic) angiography, are used to construct the three-dimensional geometry of the artery. Various simulations are carried out varying curvature or location of bifurcation, and the results are visualized to investigate geometry effect.
✓ In most cases of pituitary cyst there are no clinical symptoms and the lesions are found incide... more ✓ In most cases of pituitary cyst there are no clinical symptoms and the lesions are found incidentally. The authors report the case of a 60-year-old man with a pituitary cyst causing visual disturbance and hyponatremia. The patient presented with appetite loss and general fatigue. On admission, blood workup showed severe hyponatremia (112 mEq/L), and bitemporal hemianopsia was observed on neurological examination. Magnetic resonance imaging revealed an intra- and suprasellar region cystic mass extending to the frontal base and hypothalamic area. The serum level of brain natriuretic peptide (BNP) was elevated (92 pg/ml) with polyuria and excessive Na excretion. Transsphenoidal surgery was performed to drain the cyst. The cyst wall was partially excised and the cystic fluid was aspirated. The secretion of BNP normalized postoperatively, and the hyponatremia and visual symptoms resolved. Histological examination, including an electron microscopy study, confirmed the diagnosis of a sim...
The present study was carried out to compare the neuroprotective effect of the novel noncompetiti... more The present study was carried out to compare the neuroprotective effect of the novel noncompetitive NMDA antagonist, FR115427, with that of (+)MK-801 in rat focal cerebral ischemia. Focal cerebral ischemia was produced by permanent occlusion of the left middle cerebral artery (MCA). Drugs were administered intraperitoneally immediately after ischemia and once a day for 6 successive days. FR115427 (10 mg/kg, i.p.) significantly improved neurologic deficit at 1 day after ischemia and reduced total infarct volume (54%) at 7 days after ischemia. Although FR115427 (10 mg/kg, s.c.) produced neuronal vacuolization similar to (+)MK-801, FR115427 did not produce adverse effects such as a loss of body weight, mortality, and hypothermia, in contrast to (+)MK-801. These results suggest that FR115427 may be useful in the treatment of stroke.
We simultaneously measured neurotransmitter amino acids by the microdialysis technique and cortic... more We simultaneously measured neurotransmitter amino acids by the microdialysis technique and cortical CBF by laser-Doppler flowmetry in the ischemic penumbral cortex of rats subjected to 2-h normothermic (36.5–37.5°C) transient middle cerebral artery (MCA) clipocclusion. Brains were perfusion-fixed 3 days later and infarct volume measured. CBF (% of preischemic values) fell to 32 ± 2% (mean ± SD) during ischemia and rose to 157 ± 68% during recirculation. Extracellular glutamate levels increased from a baseline value of 7 ± 3 μ M to a peak value of 180 ± 247 μ M 20–30 min following onset of ischemia but subsequently returned to near baseline levels after 70 min of ischemia despite ongoing MCA occlusion. The threshold CBF for moderate glutamate release was 48%. Massive glutamate release was seen during the first 60 min of MCA occlusion in the two animals showing the largest infarcts and occurred at CBF values ≤20% of control levels. Mean CBF during ischemia exhibited an inverse relatio...
International Journal for Numerical Methods in Fluids, 2007
... Ryo Torii1,∗, , Marie Oshima2, Toshio Kobayashi3, Kiyoshi Takagi4 and Tayfun E. Tezduyar5 ..... more ... Ryo Torii1,∗, , Marie Oshima2, Toshio Kobayashi3, Kiyoshi Takagi4 and Tayfun E. Tezduyar5 ... of Neurosurgery, Ogura Hospital, 4-2-5 Nakamachi, Setagaya, Tokyo 158-8585, Japan 5Mechanical Engineering, Rice UniversityMS 321, 6100 Main Street, Houston, TX 77005 ...
International Journal for Numerical Methods in Biomedical Engineering, 2010
Fluid-structure interaction (FSI) analyses of cerebral aneurysm using patient-specific geometry w... more Fluid-structure interaction (FSI) analyses of cerebral aneurysm using patient-specific geometry with uniform and pathological aneurysmal wall thickness models are carried out. The objective is to assess the influence of the wall thickness on the FSI and hemodynamics in aneurysms. Two aneurysm models that were reconstructured based on CT images are used. The arterial wall thickness is set to 0.3 mm for the non-aneurysmal artery and to 0.05 mm for the aneurysmal wall based on experimental findings. Another set of aneurysm models with a uniform wall thickness of 0.3 mm for the entire model is used for comparison. The FSI simulations are carried out using the deforming-spatial-domain/stabilized space-time method with physiological inflow and pressure profiles. Computations with different aneurysmal wall thicknesses depict considerable differences in displacement, flow velocity and wall shear stress (WSS). The wall displacement for the pathological wall model is 61% larger than that of the uniform wall model. Consequently, the flow velocities in the aneurysm with the pathological wall model are lower, and that results in a 51% reduction in WSS on the aneurismal wall. Because low WSS on the aneurymal wall is linked to growth and rupture risk of aneurysm, the results suggest that using uniform wall thickness for the aneurysmal wall could underestimate risk in aneurysms.
In this paper, we retrospectively analyzed the effect of cisternal washing therapy using urokinas... more In this paper, we retrospectively analyzed the effect of cisternal washing therapy using urokinase combined with head shaking in preventing vasospasm in patients of high subarachnoid hemorrhage (SAH) grades. Since 1988, a total of 250 consecutive cases in Fisher group 3 were retrospectively analyzed. Of these patients, 56 were diagnosed as grade 4 or 5 according to WFNS grading. Thirty cases had cisternal washing therapy and 26 cases, not. All of these patients had clipping operations within 3 days following SAH, ventricular or cisternal drainage during the clipping operation, and postoperative management with normovolemia and normo-mild hypertension. In these two groups, the incidence of symptomatic vasospasm (transiently symptomatic vasospasm without infarction), cerebral infarction on CT, and mortality and morbidity (M&M) (below moderately disabled) due to vasospasm was analyzed. In the group without cisternal washing, the incidence of symptomatic vasospasm, cerebral infarction on CT, and M&M due to vasospasm was 0%, 30.7%, and 23.1%, respectively. On the other hand, in the group with cisternal washing, the incidence of symptomatic vasospasm, cerebral infarction on CT, and M&M due to vasospasm was 13.3%, 0%, and 3.33%, respectively. Cisternal washing therapy was, therefore, effective to prevent cerebral infarction due to vasospasm.
Computer Methods in Applied Mechanics and Engineering, 2009
... Ryo Torii a , Corresponding Author Contact Information , E-mail The Corresponding Author , Ma... more ... Ryo Torii a , Corresponding Author Contact Information , E-mail The Corresponding Author , Marie Oshima b , Toshio Kobayashi c , Kiyoshi Takagi b , d and Tayfun E. Tezduyar e. ... e Mechanical Engineering, Rice University MS 321, 6100 Main Street, Houston, 77005 TX, USA. ...
Computer Methods in Applied Mechanics and Engineering, 2001
The purpose of the paper is to develop a numerical simulation system for the clinical study of a ... more The purpose of the paper is to develop a numerical simulation system for the clinical study of a cerebral aneurysm. This paper presents the system, which consists of three processes: pre-processing, numerical simulation and post-processing. In the pre-processing process, the three-dimensional solid model was constructed from the computed tomography (CT) angiography raw data. The finite element method (FEM) is used
Patient-specific simulations based on medical images such as CT and MRI offer information on the ... more Patient-specific simulations based on medical images such as CT and MRI offer information on the hemodynamic and wall tissue stress in patient-specific aneurysm configurations. These are considered important in predicting the rupture risk for individual aneurysms but are not possible to measure directly. In this paper, fluid-structure interaction (FSI) analyses of a cerebral aneurysm at the middle cerebral artery (MCA) bifurcation are presented. A 0D structural recursive tree model of the peripheral vasculature is incorporated and its impedance is coupled with the 3D FSI model to compute the outflow through the two branches accurately. The results are compared with FSI simulation with prescribed pressure variation at the outlets. The comparison shows that the pressure at the two outlets are nearly identical even with the peripheral vasculature model and the flow division to the two branches is nearly the same as what we see in the simulation without the peripheral vasculature model. This suggests
We evaluated acute alterations of local cerebral perfusion following 30 min of transient right pr... more We evaluated acute alterations of local cerebral perfusion following 30 min of transient right proximal middle cerebral artery (MCA) clip-occlusion in the rat and following two intervals of postischemic reperfusion. Local cerebral blood flow (ICBF) was assessed by [14C]iodoantipyrine autoradiography. Brain temperature was controlled at 35.5-36.5°C throughout the experiment. We measured ICBF in four groups of rats: (a) sham-operated controls (n = 5), (b) following 30 min MCA occlusion (n = 5), (c) following 30 min of MCA occlusion with 15-min reperfusion (n = 6) and (d) following 30 min of MCA with 120-min reperfusion (n = 6). ICBF was measured in seven regions of the ischemic and non-ischemic hemispheres. MCA occlusion induced an ipsilateral reduction of ICBF, which was most severe in the parietal cortex (8.4 + 4.0% of control, mean + S.D.), and dorsolateral caudoputamen (20.0 + 13.4% of control). ICBF in the non-ischemic hemisphere and in ipsilateral regions lying outside the MCA territory also decreased significantly. ICBF recovery was incomplete when assessed following only 15 min of reperfusion. Reperfusion of 120 min led to return of cortical CBF to control levels, but 1CBF in the caudoputamen remained depressed (50-55% of control values). Caudoputaminal CBF and cortical CBF values were highly correlated with one another under normal and ischemic conditions, but this correlation was disrupted following reperfusion. On the basis of these results, we speculate that, if a means were found to enhance the early recovery of 1CBF following transient ischemia, this might expand the therapeutic window of opportunity for the institution of other neuroprotective strategies.
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