Biomedical subjects

Satoshi Tateshima

Publications and source records attributed to Satoshi Tateshima.

9 recordsLinked to original sources

PubMed2006

Stereotactic radiosurgery of the rete mirabile in swine: a longitudinal study of histopathological changes.

OBJECTIVE: Stereotactic radiosurgery is an established, effective treatment for brain arteriovenous malformations. The mechanisms of vessel occlusion in arteriovenous malformations has not been extensively evaluated. To better understand these mechanisms, we report histopathological changes in the swine rete mirabile after stereotactic radiosurgery. METHODS: Thirty-five swine were used, 15 as nonradiated controls and 20 as radiated. Two in the control group and five in the radiated group were sacrificed before the study endpoint. Tissue was obtained from 13 nonradiated (4 at 3 mo, 5 at 6 mo, 4 at 9 mo) and 15 radiated swine (2 at 3 mo, 3 at 6 mo, 10 at 9 mo) for histological, immunohistochemical, and morphometric analysis. RESULTS: Radiated vessels showed increasing intimal hyperplasia over the follow-up period. Histometrical analysis confirmed this with evidence of progressive luminal narrowing over the follow-up period. Immunohistochemical analysis showed intimal cells to be proliferating smooth muscle cells with surrounding extracellular collagen Type IV. Adventitial fibrosis composed of collagen Type IV was also seen with smooth muscle cells interspersed within the collagen matrix. The nonradiated animals showed no intimal hyperplasia or change in the appearance or size of the vessels over the same follow-up period. Adventitial fibrosis was minimal in the nonradiated animals. CONCLUSION: The vessels show an intimal response to radiation with progressive occlusion caused by migrating, proliferating smooth muscle cells, a likely source of the extracellular collagen in the intima. Cytokine mediated pathways likely produce these morphological changes. Future studies will be directed toward elucidating these underlying molecular mechanisms.

Animals↗

PubMed2006

Visualization and quantification of flow and velocity fields in intracranial arteriovenous malformations using phase-contrast MR angiography.

OBJECTIVE: The objective of this study was to describe postprocessing tools for MR phase-contrast flow quantification images and apply those tools to cerebral arteriovenous malformations (AVMs) to visualize blood flow dynamics noninvasively. CONCLUSION: Inflow and outflow zones were clearly depicted at different regions in the AVM. The processed images showed flow patterns including vortical flow and variations in velocity over the cardiac cycle. Particle tracking gave an impression of the overall flow state and of the venous drainage system in particular.

Blood Flow Velocity↗

PubMed2005

[Paradoxical worsening of cavernous sinus dural arteriovenous fistula: case report with serial angiograms].

We report, with serial angiograms, a case worsening of dural arteriovenous fistulae (DAVFs) located at the hypoplastic right cavernous sinus and draining into the left superior ophthalmic vein across the inter-cavernous sinus. The patient presented with sudden onset of external ophthalmoplegia and deterioration of visual acuity on the left. An imaging work-up at the day of admission included contrast-enhanced computed tomography and conventional catheter angiography, which demonstrated complete thrombosis of the left cavernous sinus. There was no strong evidence to suggest DAVFs other than small faint opacification of the posterior cavernous sinus on the right at the late arterial phase. For this reason a diagnosis of left cavernous sinus thrombosis was made, followed by aggressive anticoagulation therapy with intravenous administration of antibiotics. Although the patient's eye symptoms improved significantly after the anticoagulation therapy, the follow-up angiogram obtained 5 days after admission demonstrated small right cavernous sinus DAVFs, which drained into the left superior ophthalmic vein. The patient was followed up conservatively at the out-patient clinic. Three-month follow up angiograms demonstrated spontaneous cure of the DAVF. Also noted was a complete recovery of external ophthalmoplegia with significant improvement of left visual acuity. The alternation of clinical and angiographic findings in this case may help to understand the etiology of paradoxical worsening of cavernous sinus DAVF. In selected cases, anticoagulation therapy may help to improve the prognosis of paradoxical worsening.

Aged↗

PubMed2004

Intraaneurysmal flow visualization by using phase-contrast magnetic resonance imaging: feasibility study based on a geometrically realistic in vitro aneurysm model.

OBJECT: The aim of this study was to evaluate the feasibility of complex intraaneurysmal flow visualization with the currently available phase-contrast magnetic resonance (MR) imaging modality. METHODS: A geometrically realistic in vitro aneurysm model, in which detailed flow velocity analysis had already been conducted using laser Doppler velocimetry was used for this in vitro hemodynamic simulation, so that the results of phase-contrast velocity measurements could be compared with the previous reliable results. On a 1.5-tesla unit, three orthogonal components of velocity were obtained using a standard two-dimensional fast low-angle shot flow quantification sequence. Three-dimensional (3D) intraaneurysmal flow structures recorded during one cardiac cycle were depicted in one midsagittal and three axial cross-sectional planes with the aid of gray scale phase-contrast velocity maps. Isovelocity contour maps and secondary flow vectors were also created based on the phase-contrast velocity maps by using MATLAB software. The isovelocity contours in those three axial sections could demonstrate the shapes of inward and outward flow areas and their alternation over one cardiac cycle. The secondary flow vectors demonstrated twin vortices within the outward flow area adjacent to the boundary layer of inward and outward flow in all axial planes. CONCLUSIONS: The phase-contrast MR imaging method was able to depict the complex 3D intraaneurysmal flow structures in the in vitro aneurysm model. Detailed 3D intraaneurysmal flow information will be obtainable in vivo after improvements are made in spatial resolution, which is expected in the near future. The capability to visualize intraaneurysmal flow structures directly with the use of noninvasive MR imaging technology will have a positive impact on future clinical practice.

Hemodynamics↗

PubMed2003

Matrix and bioabsorbable polymeric coils accelerate healing of intracranial aneurysms: long-term experimental study.

BACKGROUND AND PURPOSE: Acceleration of intra-aneurysmal clot organization and fibrosis may be a solution to preventing aneurysm recanalization after endovascular treatment. The purpose of this study was to evaluate the short-term efficacy and long-term safety of the new Matrix coil system. METHODS: Matrix coils consist of thin platinum coils covered with a bioabsorbable, polymeric material (polyglycolic acid/lactide). Fifty-two experimental aneurysms were created in 26 swine. All of the aneurysms were tightly packed with Matrix or Guglielmi detachable coils (GDC). Comparative angiographic and histopathologic data were analyzed at 2 weeks (n=14), 3 months (n=6), and 6 months (n=6) after embolization. RESULTS: Three aneurysms treated with GDC ruptured despite tight packing. No recanalization or rupturing was observed in the aneurysms embolized with Matrix coils. At 14 days after embolization, the aneurysms treated with Matrix coils exhibited a more extensive area of organized thrombus when compared with the aneurysms treated with GDC (87% versus 75%, P=0.008, n=11). At 3 months, both Matrix and GDC-treated aneurysms demonstrated complete clot organization. Neck tissue thickness was higher in Matrix-treated aneurysms at 14 days and 3 months, but not at 6 months. No untoward parent artery stenosis was observed in aneurysms treated with Matrix during follow-up. The angiographic cross-sectional area of the Matrix-treated aneurysms was smaller than those treated with GDC at the 3 months. CONCLUSIONS: Matrix accelerated aneurysm fibrosis and neointima formation without parent artery stenosis. The Matrix system might prevent aneurysmal recanalization after endovascular treatment of cerebral aneurysms.

Absorbable Implants↗

PubMed2003

In vitro measurement of fluid-induced wall shear stress in unruptured cerebral aneurysms harboring blebs.

BACKGROUND AND PURPOSE: Little attention has been focused on the role of fluid-induced wall shear stress in fully developed cerebral aneurysms. The purpose of this study is to evaluate the alternation and distribution of wall shear stress over 1 cardiac cycle in patients' aneurysms. METHODS: A middle cerebral artery aneurysm and a basilar tip aneurysm with localized outpouching (blebs) in their domes were selected for this study. With the use of a stereo lithography machine, geometrically realistic aneurysm models were created on the basis of 3-dimensional CT angiograms. In vitro shearing velocity measurement was conducted with the use of laser-Doppler velocimetry at multiple points on the aneurysmal wall to calculate the value of wall shear stress. The wall shear stress was documented at multiple points in the aneurysm inflow zone, dome, and outflow zone. RESULTS: Distribution of wall shear stress was not uniform in the aneurysm walls, and particular regions were exposed to relatively high wall shear stress. The wall shear stress changed dynamically throughout 1 cardiac cycle at the point where a high value of wall shear stress was noted. The blebs of both aneurysms were exposed to high wall shear stress. Unlike previous reports in which an ideal spherical aneurysm model was used, the aneurysm inflow zone was not exposed to high shear stress. CONCLUSIONS: In vitro aneurysm models based on the patients' angiograms allowed us to conduct a more realistic evaluation of wall shear stress in the aneurysms harboring blebs. These results provide us with further indications of the correlation of wall shear stress with the natural history of cerebral aneurysms.

Angiography↗

PubMed2003

Three-dimensional blood flow analysis in a wide-necked internal carotid artery-ophthalmic artery aneurysm.

OBJECT: The aim of this study was to evaluate axial and secondary flow structures in a wide-necked internal carotid artery-ophthalmic artery aneurysm, one of the most common locations for endovascular coil placement. METHODS: A clear acrylic aneurysm model was manufactured from a three-dimensional computerized tomography angiogram. Intraaneurysm blood flow analysis was conducted using an acrylic aneurysm model together with laser Doppler velocimetry and particle imaging velocimetry. The maximal axial blood flow velocities in the inflow and outflow zones at the aneurysm orifice were noted at the peak systolic phase, measuring 46.8 and 24.9% of that in the parent artery, respectively. The mean size of the inflow zone during one cardiac cycle was 44.3 +/- 9.8% (range 35.6-58.7%) the size of the axial section at the aneurysm orifice. In the lower and upper planes of the aneurysm dome, the mean size of inward and outward flow areas were 43.3 +/- 6.7% and 43.8 +/- 6.8% the size of the axial cross-sectional plane, respectively. The axial flow velocity structures were dynamically altered throughout the cardiac cycle, particularly at the aneurysm orifice. The fastest secondary flow at the opening was also noted at the peak systolic and early diastolic phases. Axial blood flow velocity was slower in the upper axial plane of the aneurysm dome than in the lower one. Conversely, the secondary flow component was faster in the upper plane. CONCLUSIONS: The side-wall aneurysm in this study did not demonstrate a simple flow pattern as was previously seen in ideally shaped experimental aneurysms in vitro and in vivo. The flow patterns of inflow and outflow zones were very difficult to predict based on the limited flow information provided on standard digital subtraction angiography, even in an aneurysm with a relatively simple dome shape.

Aneurysm↗

PubMed2003

Combined endovascular treatment for both intracranial aneurysm and symptomatic vasospasm.

BACKGROUND AND PURPOSE: The best strategy for treatment of subarachnoid hemorrhage due to ruptured cerebral aneurysm is obliteration of the aneurysm as soon as possible. Early surgery is desirable if the patient does not develop severe vasospasm or is clinically stable. However, if the patient has already developed severe vasospasm on admission, surgery may carry the risk of increasing the severity. We evaluated the safety and effectiveness of combined Guglielmi detachable coil (GDC) embolization and angioplasty in a single session for the treatment of ruptured aneurysms associated with symptomatic vasospasm. METHODS: From January 1992 to January 2001, 12 consecutive patients with ruptured aneurysms associated with symptomatic vasospasm were treated. Patients were classified as Hunt and Hess grade 2 (n = 1), 3 (n = 6), 4 (n = 4), or 5 (n = 1) and Fisher CT group 2 (n = 1), 3 (n = 10), or 4 (n = 1). They underwent GDC aneurysm occlusion and balloon angioplasty (n = 6), intraarterial papaverine infusion (n = 2), or both (n = 4) in a single session. In nine patients, aneurysm coil occlusion was performed first. RESULTS: Complete GDC occlusion was achieved in eight patients, a small neck remnant persisted in three, and embolization was incomplete in one patient. In all patients, angiographic improvement of vasospasm was obtained. In one patient, a thromboembolic complication occurred and was treated with urokinase. Clinical outcomes at discharge were good recovery in six, moderate disability in two, severe disability in three, or death in one. CONCLUSION: Endovascular treatment can be the first therapeutic option for ruptured aneurysms associated with severe vasospasm on admission. It offers some advantages over surgery in this setting, but these are balanced by the risk of thromboembolism.

Adult↗

PubMed2002

Cellular responses of bioabsorbable polymeric material and Guglielmi detachable coil in experimental aneurysms.

BACKGROUND AND PURPOSE: Acceleration of healing mechanisms is a promising approach to improve current limitations of endovascular aneurysm therapy with the use of platinum coils. We evaluated a new endovascular therapeutic, bioabsorbable polymeric material (BPM), which may promote cellular reaction in the aneurysms. METHODS: Four different concentrations of lactide/glycolic acid copolymer [poly(D-L-lactic-co-glycolic acid)] (PLGA), 85/15, 75/25, 65/35, and 50/50, were used as BPMs. Sixteen experimental aneurysms were created in 8 swine. Eight-millimeter-long spiral-shaped BPMs were surgically implanted in the aneurysms without tight packing (n=3 for each BPM). Guglielmi detachable coils (GDCs) were used as control (n=4). The animals were killed 14 days after embolization, and angiographic, histological, and immunohistochemical analyses were performed. RESULTS: Despite loose packing of aneurysms with BPMs, faster BPMs such as 50/50 or 65/35 PLGA demonstrated more mature collagen formation and fibrosis in the sac and neck of the aneurysm. One aneurysm treated with 65/35 PLGA, 1 treated with 75/25 PLGA, and all 3 treated with 85/15 PLGA showed a neck remnant on angiography. There was a linear relationship between collagen levels and polymer degradation properties (r=-0.9513). CONCLUSIONS: This preliminary animal study indicates that acceleration of aneurysm healing with the use of BPM is feasible. This concept can be applied to decrease and perhaps prevent aneurysmal recanalization after endovascular treatment of cerebral aneurysms.

Absorbable Implants↗