Search

Endoscopic third ventriculostomy (ETV) has been accepted for obstructive hydrocephalus (OH). We herein present a case of OH and optic nerve sheath edema (ONSE). Although ETV was successful, ONSE worsened. Discussion is focused on the relationship among intracranial hypertension (IH), ETV, and ONSE. The patient was a 19-year-old woman with complaints of headache and emesis. Papilledema was prominent. Radiological examination showed OH as an aqueductal tumor. Endoscopic tumorectomy and ETV were accomplished. Although headache and emesis disappeared, papilledema persisted. On the 4th day, the patient lost light perception. On magnetic resonance imaging, the third ventricular stroma and aqueduct were patent. Nevertheless, ONSE was prominent. After lumbar drainage, her vision was restored. Finally, ventriculoperitoneal shunting was performed, following which ONSE disappeared. IH is not always accompanied by ONSE. However, once it occurs, it may act separately from IH, and ETV may even exacerbate ONSE due to alteration of cerebrospinal fluid (CSF) flow into the chiasmatic cistern. In the optic nerve sheath, CSF pressure is not easily transmitted across different areas; this should explain the dissociation between ONSE and other symptoms of IH. Furthermore, we suggest that ONSE and acute optic dysfunction should be considered an independent crisis as “hydronervus opticus.”

Dissolution-dynamic nuclear polarization (d-DNP) is a state-of-the-art technology that can dramatically enhance the detection sensitivity of nuclear magnetic resonance (NMR). DNP NMR has been applied to small molecules with stable isotopes and has been used to obtain metabolic and physiological information in vivo. However, the hyperpolarized state exponentially decays back to the thermal equilibrium state, depending on the spin-lattice relaxation time (T1). This signal decay has remained a major problem associated with this technology. Therefore, DNP NMR molecular probes useful for in vivo analysis have been limited to naturally occurring small molecules that inherently show long T1. While peptides are promising targets for DNP NMR studies, because of the limitation in T1, DNP NMR molecular probes applicable in vivo have been limited to amino acids or dipeptides. Herein we propose a 13C-labeling strategy to utilize the C-terminal [1-13C]Gly-d2 residue for realizing long T1 in peptides. Structure-based T1 relaxation analysis of amino acids and peptides revealed that (1) T1 does not decrease monotonically with increasing molecular weight and (2) T1 is not significantly affected by a side chain on the neighboring amino acid residue. These findings suggest that the C-terminal [1-13C]Gly-d2 residue affords sufficiently long T1 for biological uses, even in oligopeptides, and allowed us to develop 13C-b- casomorphin-5 (Tyr-Pro-Phe-Pro-[1-13C]Gly-d2, T1 = 24 ± 4 s at 3 T in H2O) and 13C-glutathione (g-Glu-Cys-[1-13C]Gly-d2, T1 = 58 ± 3 s at 3 T in H2O) as DNP NMR probes with long T1. We succeeded in in vivo detection of enzymatic conversions of these two probes. These results demonstrate the utility of our strategy and would contribute to further expansion of the substrate scope for DNP applications.

We propose a method for learning temporal data using a parametrized quantum circuit. We use the circuit that has a similar structure as the recurrent neural network which is one of the standard approaches employed for this type of machine learning task. Some of the qubits in the circuit are utilized for memorizing past data, while others are measured and initialized at each time step for obtaining predictions and encoding a new input datum. The proposed approach utilizes the tensor product structure to get nonlinearity with respect to the inputs. Fully controllable, ensemble quantum systems such as an NMR quantum computer is a suitable choice of an experimental platform for this proposal. We demonstrate its capability with Simple numerical simulations, in which we test the proposed method for the task of predicting cosine and triangular waves and quantum spin dynamics. Finally, we analyze the dependency of its performance on the interaction strength among the qubits in numerical simulation and find that there is an appropriate range of the strength. This work provides a way to exploit complex quantum dynamics for learning temporal data., 9 pages, 5 figures

Tumor emboli due to a sarcoma are usually confirmed by an autopsy or operative findings. A sarcoma embolus in an acute stroke patient is rare. We herein report a 37-year-old man with acute stroke caused by internal carotid artery occlusion who underwent embolectomy. A histopathological analysis of an embolus obtained with a mechanical retriever device was diagnosed as undifferentiated sarcoma. This is the first case of extracardiac sarcoma extraction via mechanical retrieval performed during intervention for acute ischemic stroke. A histopathologic evaluation with embolectomy is important for diagnosing tumor emboli.

We demonstrate room-temperature 13C hyperpolarization by dynamic nuclear polarization (DNP) using optically polarized triplet electron spins in two polycrystalline systems: pentacene-doped [carboxyl-13C] benzoic acid and microdiamonds containing NV- centers. For both samples, the integrated solid effect (ISE) is used to polarize the 13C spin system in magnetic fields of 350–400 mT. In the benzoic acid sample, the 13C spin polarization is enhanced up to 0.12 % through direct electron-to-13C polarization transfer without performing dynamic 1H polarization followed by 1H-13C cross polarization. In addition, ISE has been successfully applied for the first time to polarize naturally abundant 13C spins in a microdiamond sample to 0.01 %. To characterize the buildup of the 13C polarization, we discuss the efficiencies of direct polarization transfer between the electron and 13C spins as well as that of 13C–13C spin diffusion, examining various parameters which are beneficial or detrimental for successful bulk dynamic 13C polarization.

We theoretically analyze the performance of the nuclear magnetic resonance (NMR) spectroscopy with a superconducting flux qubit (FQ). Such NMR with the FQ is attractive because of the possibility to detect the relatively small number of nuclear spins in a local region ($\ensuremath{\approx}\ensuremath{\mu}\mathrm{m}$) with low temperatures ($\ensuremath{\approx}\mathrm{mK}$) and low magnetic fields ($\ensuremath{\approx}\mathrm{mT}$), in which other types of quantum sensing schemes cannot easily be accessed. A sample containing nuclear spins is directly attached on the FQ, and the FQ is used as a magnetometer to detect magnetic fields from the nuclear spins. Especially, we consider two types of approaches to NMR with the FQ. One of them is to use spatially inhomogeneous excitations of the nuclear spins, which are induced by a spatially asymmetric driving with radio-frequency (rf) pulses. Such an inhomogeneity causes a change in the dc magnetic flux penetrating a loop of the FQ, which can be detected by a standard Ramsey measurement on the FQ. The other approach is to use a dynamical decoupling on the FQ to measure ac magnetic fields induced by Larmor precession of the nuclear spins. In this case, neither a spin excitation nor a spin polarization is required since the signal comes from fluctuating magnetic fields of the nuclear spins. We calculate the minimum detectable density (number) of the nuclear spins for the FQ with experimentally feasible parameters. We show that the minimum detectable density (number) of the nuclear spins with these approaches is around ${10}^{21}/{\mathrm{cm}}^{3}$ (${10}^{8}$) with an accumulation time of 1 s.

Using a home-built Ku band ESR spectrometer equipped with an arbitrary waveform generator and a stripline resonator, we implement two types of pulses that would benefit quantum computers: BB1 composite pulse and a microwave frequency comb. Broadband type 1 (BB1) composite pulse is commonly used to combat systematic errors but previous experiments were carried out only on extremely narrow linewidth samples. Using a sample with a linewidth of 9.35 MHz, we demonstrate that BB1 composite pulse is still effective against pulse length errors at a Rabi frequency of 38.46 MHz. The fast control is realized with low microwave power which is required for initialization of electron spin qubits at 0.6 T. We also digitally design and implement a microwave frequency comb to excite multiple spin packets of a different sample. Using this pulse, we demonstrate coherent and well resolved excitations spanning over the entire spectrum of the sample (ranging from -20 to 20 MHz). In anticipation of scaling up to a system with large number of qubits, this approach provides an efficient technique to selectively and simultaneously control multiple qubits defined in the frequency-domain.

Dissolution dynamic nuclear polarization (DNP) has recently gained attention as a method to enhance the sensitivity of liquid NMR spectroscopy and MRI. We demonstrate dissolution of the sample hyperpolarized by DNP using photoexcited triplet electrons in 0.38 T at room temperature. The achieved polarization of 0.8% is 6100 times as high as that at thermal equilibrium under the condition. The result is an important step for DNP using photoexcited triplet electrons to become widely used in chemical and biomedical research.

Dissolution dynamic nuclear polarization (DNP) has wide variety of important applications such as real-time monitoring of chemical reactions and metabolic imaging. We construct DNP using photoexcited triplet electron spins (Triplet-DNP) apparatus combined with dissolution apparatus for solution NMR in a high magnetic field. Triplet-DNP enables us to obtain high nuclear polarization at room temperature. Solid-state samples polarized by Triplet-DNP are transferred to a superconducting magnet and dissolved by injecting aqueous solvents. The 13C polarization of 0.22% has been obtained for [caryboxy-13C]benzoic acid-d in the liquid state. Our results show that Triplet-DNP can be applied to real-time monitoring with solution NMR.

Quantum reservoir computing provides a framework for exploiting the natural dynamics of quantum systems as a computational resource. It can implement real-time signal processing and solve temporal machine learning problems in general, which requires memory and nonlinear mapping of the recent input stream using the quantum dynamics in computational supremacy region, where the classical simulation of the system is intractable. A nuclear magnetic resonance spin-ensemble system is one of the realistic candidates for such physical implementations, which is currently available in laboratories. In this paper, considering these realistic experimental constraints for implementing the framework, we introduce a scheme, which we call a spatial multiplexing technique, to effectively boost the computational power of the platform. This technique exploits disjoint dynamics, which originate from multiple different quantum systems driven by common input streams in parallel. Accordingly, unlike designing a single large quantum system to increase the number of qubits for computational nodes, it is possible to prepare a huge number of qubits from multiple but small quantum systems, which are operationally easy to handle in laboratory experiments. We numerically demonstrate the effectiveness of the technique using several benchmark tasks and quantitatively investigate its specifications, range of validity, and limitations in detail., Comment: 15 pages

Dynamic nuclear polarization using photoexcited triplet electrons (Triplet-DNP) is a method to significantly enhance nuclear spin polarization even in a low magnetic field and at room temperature. Pentacene has been practically used as an efficient polarizing agent for Triplet-DNP. In this study, we demonstrate room temperature 1H and 13C hyperpolarization of eutectic mixtures of deuterated benzoic acid doped with pentacene and a target molecule such as salicylic acid, nicotinic acid, or 2-naphthoic acid. These molecules are otherwise difficult to hyperpolarize by Triplet-DNP due to the low pentacene dopabilities of these molecules. The highest 1H polarization of 1.2% has been obtained for the eutectic mixture of salicylic acid in 0.39 T. The present sample preparation is a crucial method to widen the range of applications of Triplet-DNP to chemical and biomedical analyses.

A solution with hyperpolarized nuclear spins encoded into a long-lived state has been utilized for sensing chemical phenomena. In a conventional way, nuclear spins are hyperpolarized at very low temperatures. In this work, we demonstrate the encoding of a four-nuclear-spin system hyperpolarized at room temperature into a long-lived state in a solution. We apply the solution with the long-lived state as a sensor in ligand--receptor binding experiments.

We propose a classical-quantum hybrid algorithm for machine learning on near-term quantum processors, which we call quantum circuit learning. A quantum circuit driven by our framework learns a given task by tuning parameters implemented on it. The iterative optimization of the parameters allows us to circumvent the high-depth circuit. Theoretical investigation shows that a quantum circuit can approximate nonlinear functions, which is further confirmed by numerical simulations. Hybridizing a low-depth quantum circuit and a classical computer for machine learning, the proposed framework paves the way toward applications of near-term quantum devices for quantum machine learning.

Background: 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. Materials and Methods: 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. Results: 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. Conclusions: 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.

Computer-based simulations are essential for clarifying the hemodynamics of brain aneurysms. Since cerebrovascular disease is often fatal, it is strongly desirable to predict its progression. While previous studies have clarified the initiation mechanism of aneurysms, their growth mechanism remains unclear. Consequently, it is difficult to develop a diagnostic system for predicting aneurysm rupture. This study seeks to clarify the mechanism of aneurysm growth by identifying significant hydrodynamic factors. We focus on a single ruptured aneurysm that was followed up for five years. Computer simulations and fluid dynamic experiments with silicone vessel models were performed. To confirm the reliability of data in the computer simulations, we conducted particle image velocimetry measurements in steady flow. We then performed computer simulations for pulsatile conditions to determine an effective index for aneurysm growth. We obtained good agreement between the trends in the obtained computer simulation and experimental data. Numerical simulations for pulsatile flow in three models revealed that aneurysms grew in regions having a low wall shear stress, a low aneurysm formation indicator, and a high oscillatory shear index.

There is a need to develop quantitative evaluation for simulator based training in medicine. Photoelastic stress analysis can be used in human tissue modeling materials; this enables the development of simulators that measure respect for tissue. For applying this to endovascular surgery, first we present a model of saccular aneurism where stress variation during micro-coils deployment is measured, and then relying on a bi-planar vision system we measure a catheter trajectory and compare it to a reference trajectory considering respect for tissue. New photoelastic tissue modeling materials will expand the applications of this technology to other medical training domains.

We describe a patient with subcutaneous hematoma associated with manual cervical massage during carotid artery stenting. A 73-year-old man with left cervical carotid artery stenosis presented with left amaurosis fugax. We performed carotid artery stenting using distal embolic protection with balloon occlusion. Dual antiplatelet therapy was maintained in the periprocedural period and an anticoagulant agent was administered during the procedure. Because the aspiration catheter became entrapped by the stent, it did not reach the distal side of the stenotic lesion, and manual compression of the cervical region was therefore performed. Immediately afterwards, a subcutaneous hemorrhage occurred in the cervical region. There was no postoperative dyspnea due to enlargement of the hematoma, which was absorbed spontaneously. Cervical subcutaneous hematoma can occur in the cervical region due to cervical massage in patients who are receiving adjuvant antiplatelet therapy and anticoagulation therapy.

Numerical criteria for evaluating stress on vasculature models have applications in evaluating medical tools and surgical skills enabling better endovascular surgery training and the development of better medical techniques and tools. We propose using the stress produced by blood pressure simulation in the vasculature model wall for this criterion and use photoelastic effect for measuring the principal stress magnitude component. We simulated human blood pressure with 5.6% average error and developed shielded urethane model of vasculature enabling water circulation and avoiding plastic deformation at pressures below 182 mmHg. We developed software to calculate model wall stress. We quantitatively compared in four ranges stress produced on the model wall by blood pressure simulation and a guide wire.

●Abstract● Purpose: We report two cases of acute ischemic stroke patients treated by additional thrombectomy using a basket-shaped microsnare (Soutenir) after infusion of intravenous recombinant tissue plasminogen activator (rtPA). Successful recanalization and good prognosis were achieved in both cases. Case 1: A 67-year-old man presented with left hemiplegia and agnosia. After completion of the intravenous rtPA infusion, he continued to show severe neurological deficit. Angiography revealed occlusion of the posterior trunk and a branch of the anterior trunk of the right middle cerebral artery (MCA). The two occluded arteries were successfully recanalized by removing the clot with Soutenir, resulting in neurological improvement. Case 2: A 49-year-old man presented with right hemiplegia and aphasia. After completion of the intravenous rtPA infusion, he continued to show severe neurological deficit. Angiography revealed occlusion of the left MCA at the proximal M1 segment. The occluded artery was successfully recanalized by removing the clot in the manner described above, resulting in neurological improvement. Conclusion: To our knowledge, this is the first report describing patients treated by additional thrombectomy using a Soutenir after failed intravenous infusion of rtPA. This procedure is a therapeutic option for selected acute ischemic stroke patients who are unresponsive to intravenous rtPA.

Recent advances in devices and materials, and therapeutic technical improvements in interventional neuroradiology practice make it possible to use this therapeutic method for the treatment of neurovascular disease. In view of the spread of this treatment and increasing numbers of the procedures, there is a social demand to maintain a certain therapeutic quality. One of the methods used to present the therapeutic quality of doctors to the public is technical and knowledge authorization by an official organization or society. According to the ideas of the Japanese Society of Neuro-Endovascular Therapy (JSNET) “The basic therapeutic standard should be secured by the Society to avoid unnecessary complications which are caused by improper techniques and immature experiences.” JSNET start to develop a Specialist Qualification System in 1997, and the first examination was held in 2002. Details of the development of the system and the requirement of specialists have previously been reported1. It has been ten years since development of this system and we have had eight examinations since 2002. Following six years of experience and two years of examinations using an animal model, we would like to introduce the JSNET Specialist Qualification System.

Endovascular intervention using interventional radiology (IVR) is most commonly used in cerebralvascular treatment. Medical imaging such as digital subtraction angiography (DSA) and vascular mapping make vasculature and catheters easier to read from fluoroscopy during endovascular intervention. We propose simulating IVR using augmented reality, reproducing fluoroscopic images and a patient-specific blood vessel model without X-ray imaging. The advantages of the patient-specific vascular model reproducing the human vasculature lumen with 13 μm resolution include 1) a realistic “feel,” 2) excellent tool behavior simulation during intervention, and 3) surgical training alternative to physician training in-vitro. Simulated fluoroscopic images are created in two steps: First, the blood vessel model refraction index is matched to surrounding glycerin solution to conceal the vascular model, making the silicone vasculature appear human as seen in endovascular intervention. Second, an augmented reality (AR) environment is created using image subtraction and overlap, making model-based endovascular simulation more understandable for catheter use and fluoroscopy use and reading.

Magnetic motion capture sensors (MMCS) are not commonly used for robot control due to the need for complex, resource-consuming calibration to correct error introduced by the magnetic sensor. We propose avoiding such calibration using a rule-based controller that only uses spatial coordinates from the magnetic sensor. This controller uses a sparse look-up table of spatial coordinates and actions conducted by the robot and reacts to the presence of the sensor near reference points. The control method was applied to manipulate a robotic camera to track a catheter-shaped sensor inside vessels silicone models. A second evaluation was done guiding a mechanism to reconstruct catheter insertion in major silicone vasculature models. The robotic camera tracked the catheter by reacting to the sensor within 10 mm of each reference point. The catheter insertion mechanism reconstructed the catheter trajectory by reacting to the sensor within 6 mm of each reference point. We found that the proposed method allowed robot control in a bounded space without having to correct for the magnetic tracker output distortion.

Biodegradable scaffolds are of great value in tissue engineering. We have developed a method for fabricating patient-specific vascular scaffolds from a biocompatible and biodegradable polymer, poly( l -lactide-co-ɛ-caprolactone). This method's usefulness is due to flexibility in the choice of materials and vascular configurations. Here, we present a way to fabricate scaffolds of human carotid artery by combining processes of rapid prototyping, lost wax, dip coating, selective dissolution, and salt leaching. The result was the successful development of porous biodegradable scaffolds, with mechanical strength covering the range of human blood vessels (1–3 MPa). Human umbilical vein endothelial cells were also cultured on the scaffolds and their biocompatibility was confirmed by cell growth. The Young's modulus of scaffolds could be controlled by changing polymer concentration and porosity. The wall thickness of the tubular scaffold was also controllable by adjusting polymer concentration and pull-up velocity during dip coating. We believe that this fabrication technique can be applied to patient-specific regeneration of blood vessels.

In this paper, we propose a novel method to product biological models using polyurethane elastomer, which has high photoelastic coefficient and a method to analyze stress states on the model by photoelastic method. With this method, stress condition on vascular wall represented by two principal stresses is clearly visualized on vascular fringe as rainbow-colored photoelastic stress pattern, and the quantitative stress is analyzed from that pattern. For analysis of stress states by photoelastic method, retardation and path length of penetration light through the model must be observed. Proposed method is possible to observe these two parameters simultaneously. Retardation is decided from RGB value of rainbow-colored photoelastic stress pattern and path length is decided from permeability of light. The accuracy of stress analysis is evaluated by tensile test using artery-like cylindrical model. Lastly using the model produced by new method, we analyze stress states quantitatively on the model of cerebral artery. Consequently, it should be valuable for various applications not only surgical simulations but also hemodynamic studies and pathological studies.

Technologies to develop scaffolds with controlled pore layout and porosity have great significance in tissue engineering. As one method of scaffold fabrication, porogen leaching has been commonly used to control pore size, pore structure and porosity in the scaffold. In this paper, we describe a novel approach to fabricate 2D and 3D porous biodegradable scaffolds made of poly(L-lactide-co-epsiv-caprolactone) by using magnetic sugar particles as porogens. First, ferrite micro/nano particles were encapsulated in sugar microspheres to make them magnetized. After sieving magnetic sugar particles, those diameter-controlled particles were attracted by a magnetic force to form an assembled template for polymer casting. A magnetic field with polka-dot pattern was also utilized to align particles on desired positions. After polymer casting and removal of the sugar template, spherical pores were generated inside scaffold. For future application in vascular tissue engineering, we extended the scaffold fabrication to straight tubular scaffolds by winding 2D porous sheets on sacrificial molds. The biocompatibility of the developed scaffold was confirmed by viable cells after 4-day culture.

We have been developing scaffolds of three-dimensional (3D) synthetic vascular prosthesis in tailor-made. Human umbilical vein endothelial cells (HUVECs) attached on the inner surface of the scaffold have anticoagulant effects. Asperity structures of the inner surface are important to cell adhesion. It is important to quantify the inner surface asperity condition of the scaffold by observing HUVECs behavior and morphology. For this purpose, we recreated the inner surface profile of the scaffold on a poly(dimethilsiloxane) (PDMS) substrate by microfabrication. We made semiround convex patterns of resist that had 8 µm in diameter and 5 µm high using photolithography, and the concave pattern on the PDMS substrate by printing. We observed HUVECs adhering to the PDMS substrate having concave pattern on it surface. The distribution density of the concaves of the tested pattern is 1600 /mm2or 40,000 in a 25 mm2area. In addition, we fabricated an arteriole model by photolithography, creating an arteriole tube model that had 1.1 cm long and 300-400 µm in diameter. We confirmed that the arteriole model had no leakage using a methylene blue solution flow in the channel.

Several advanced multiple catheter techniques have been invented for endovascular treatment. Stent-supported coil embolization is one of the most useful methods for wide neck aneurysms. We report 13 vertebral artery aneurysms treated with this method and discuss its efficacy. Between April 1999 and March 2006, we treated 13 patients with wide neck vertebral aneurysms, comprising 9 males and 4 females aged 38 to 79 (mean 60.0 years old) and treated with stent-supported coil embolization. Stent for coronary intervention was used in all cases. Using our original method, the microcatheter was inserted into the aneurysmal sac in advance, followed by deployment of the stent at the orifice. In this method, the microcatheter is placed out of the stent, which is useful to stabilize the microcatheter and to prevent the kick-back of microcatheter into the parent artery. Further, we repeated the inflation of balloon catheter at the orifice to prevent the coil herniation whenever placing coils. Complete obliteration of the aneurysm was achieved in 9 patients and subtotal occlusion in 4 patients. Two stents were needed in 1 patient because of stent migration into the aneurysm. A stent slipped down during withdrawal of the balloon catheter in 1 case without coil herniation or vessel injury. In follow-ups of 3 months to 7 years, there was no recurrence except for 1 case whose aneurysm regrew resulting in trapping of VA. The only procedure-related symptomatic complication was 1 case with transient abducens nerve palsy. Stent supported coil embolization for wide-based vertebral aneurysms is a very useful and valuable technique. It permanenty prevents coil herniation and the rectification of parent artery flow. Although sufficient results were initially obtained, long term follow-up should be carried out.

We treated ruptured intracranial aneurysms with endosaccular embolization using Guglielmi Detachable Coils (GDC) in 192 patients treated in Nagoya University and affiliated hospitals over the past 7 years. Hunt & Kosnik grading was I in 18 patients, II in 78, III in 51, IV in 38, and V in 7, respectively. One hundred and seven aneurysms were located in the anterior circulation and 85 in the posterior circulation. Complete obliteration was obtained in 105 (55%), subtotal in 76 (40%), and partial in 11 (5%) aneurysms. We experienced 27 intraprocedural complications, including 11 intraoperative ruptures and 16 thromboembolisms. Permanent morbidity and mortality related to the procedure were 4.7% and 2.1%, respectively. An analysis of complication cases based on the aneurysmal configuration and location showed that tiny aneurysms and vertebral aneurysms (VA-PICA) should be carefully treated to avoid possible perioperative hemorrhagic complications. Due attention should also be paid to thromboembolic complications on the treatment of aneurysms located in middle cerebral, basilar-tip and posterior inferior cerebellar artery because of its branching in close relationship to the aneurismal neck.

We propose an in vitro patient-specific anatomical model of the human cerebral artery and its simulation of endovascular intervention, a potent treatment modality for cerebrovascular diseases. Our proposed model reproduces the 3-dimensional vasculature lumen, using computed tomography (CT) and magnetic resonance (MR) fluoroscopic information, within a thin artery-like membranous configuration having material properties close to arterial tissue. This cerebral arterial model reproduces an exceedingly realistic surgical feel, dynamic vascular deformation and, other important aspects involving endovascular intervention, realizing a highly realistic surgical simulation. We also propose another vasculature model that reproduces the subarachnoid space around the cerebral arteries. This version simulates endovascular intervention realistically. The model is compatible with current major imaging modalities such as CT, MR, and transcranial Doppler (TDC), and should provide effective platforms for applications, such as diagnosis, surgical planning, medical training, hemodynamic analysis and medical system development and evaluation, especially surgical robots.

We reviewed 84 AVMs embolized over 7 years and studied the significance of the embolization for associated aneurysms. Out of 84 AVMs, 14 were preoperatively embolized and 66 were followed by radiosurgery. Ten intranidal aneurysms were found in 9 cases, all of which ruptured. Although 8 aneurysms were completely embolized, using glue, 2 incompletely treated aneurysms rebled. Out of 6 proximal feeder aneurysms, 3 ruptured ones were treated with detachable coils and have shown no rebleeding. The other 3 aneurysms that increased in size during the follow-up after the embolization of AVM were embolized without complications. Two flow-related aneurysms remained, and an AVM nidus was primarily treated. Both aneurysms disappeared after the embolization of AVM. The ruptured proximal feeder aneurysms located far from the nidus, which require another approach for the removal of AVM, should be embolized with coils to reduce surgical invasiveness. Embolization of intranidal aneurysms is very useful for the prevention of rebleeding, particularly in cases followed by radiosurgery. Among the flow-related aneurysm treatments, AVM may be the treatment of choice. As for the treatment strategy of AVM, it is important to detect and identify the associated aneurysms and treat them appropriately.

We investigated the indications for endovascular treatment of unruptured cerebral aneurysms based on the natural history reported in ISUIA and our treatment results. At Nagoya University hospital and affiliated hospitals over 7 years we treated or attempted embolization for 383 unruptured aneurysms, including 301 asymptomatic and 82 symptomatic ones. Among them, 326 were treated with embolization and 57 were left untreated due to the high risks involved. Ruptures during the follow-up occurred in 2 symptomatic cases without treatment. We experienced 28 technical complications including 9 hemorrhagic, 14 ischemic and 4 others at the intra- and perioperative stage, in addition to 14 recanalizations at the delayed stage. The rate of morbidity associated with procedure was 4.0%. There was a high risk of hemorrhagic complications from a tiny anterior communicating artery aneurysm and ischemic complications in the middle cerebral, basilar-tip, and vertebral dissecting aneurysms with a hypoplastic posterior inferior cerebellar artery. As for the symptomatic aneurysms, although 72 patients had a good outcome, symptoms due to mass effects did not improve in 19 cases and worsened in 7. Particularly large paraclinoid aneurysms with visual symptoms showed a reduced possibility of symptom improvement. Although embolization has proved highly effective for the treatment of unruptured aneurysms, the treatment decision should take into account the relevant guidelines, including those for surgical option and observation. Abbreviations: ISUIA: International Study of Unruptured Intracranial Aneurysms

In this paper, we propose an in vitro patient-tailored anatomical model of human cerebral artery, a hardware platform for simulating intravascular neurosurgery for making diagnosis and surgical trainings. Proposed vessel model hollowly reproduces 3-dimensional configuration of vessel lumens within an elastic transparent silicone cube, using fluoroscopic information which is obtained with CT (Computed Tomography), MRI (Magnetic Resonance Imaging) and other imaging modalities. It also reproduces the physical characteristics of artery tissue, such as elastic modulus, Poisson's ratio and friction coefficient, within respectively 10% of errors. Consequently, it allows simulating neurovascular procedures, which is accompanied by the realistic feel of operating catheters, and the realistic behavior of surgical instruments (e. g. slip/stick motion and unwinding motion). Presented vasculature model should provide an innovative platform for interventionalists to make preliminary surgical simulation, for young trainees to practice intervention procedures and for developers to evaluate surgical robots, device and other various medical instruments.

Despite recent technical advances in embolization of cerebral aneurysms with platinum coils, some aneurysms eventually resulted in incomplete packing with remnant neck or dome filling. Such a situation with a remaining inflow zone may pose a risk of rupture and subsequent regrowth. Metals characteristically generate heat under high-frequency alternating magnetic fields (AMF). We used this property to induce local hyperthermia and promote thrombogenesis in incompletely packed aneurysms. Glass model aneurysms packed with coils were subjected to AMF to investigate the correlation between weight of platinum and temperature elevation and the correlation between flow rates of water through the model and temperature elevation. Next, activated coagulation time (ACT) of blood obtained from dogs was studied at various temperatures. Finally, side-wall aneurysms created in the canine carotid artery using a venous patch were packed with platinum coils. Change in temperature and angiographic changes were investigated after AMF application. In the glass model, the weight of platinum was correlated with elevation of temperature, and a negative logarithmic correlation was evident between flow rate and elevation of temperature. Elevation of blood sample temperature tended to shorten ACT. In canine carotid aneurysms, elevation of intra-aneurysmal temperature was confirmed and sufficient elevation of temperature was found to promote angiographically evident thrombogenesis of the remnant space after AMF application. Local hyperthermia may be useful in completing luminal obliteration of aneurysms after coil embolization. It may particularly useful for ruptured aneurysms to prevent the early rerupture.

The authors carried out a retrospective review of the records of 12 patients with aneurysms of the posterior cerebral artery (PCA). Four were asymptomatic, 1 presented with a mass effect, and 7 with a subarachnoid haemorrhage (SAH). Of the 7 ruptured aneurysms, 3 were embolized and 2 were clipped. However, 2 patients died from rebleeding before any treatment. Of the 5 unruptured aneurysms, 1 was embolized with coils but the remaining 4 have been conservatively observed. No aneurysms have ruptured during the follow-up period, and 3 have thrombosed spontaneously. According to our results, the PCA aneurysms should be treated aggressively in the early phase. Although the preservation of the anatomical integrity of the PCA should naturally be one of the prime objectives, PCA occlusion may sometimes be inevitable when treating large or fusiform aneurysms. On the other hand, conservative therapy is one of the options for the treatment of incidentally encountered unruptured ones, because these have the possibility of spontaneous thrombosis.

Dynamic nuclear polarization (DNP), a means of transferring spin polarization from electrons to nuclei, can enhance the nuclear spin polarization (hence the NMR sensitivity) in bulk materials at most 660 times for 1H spins, using electron spins in thermal equilibrium as polarizing agents. By using electron spins in photo-excited triplet states instead, DNP can overcome the above limit. We demonstrate a 1H spin polarization of 34%, which gives an enhancement factor of 250,000 in 0.40 T, while maintaining a bulk sample (∼0.6 mg, ∼0.7 × 0.7 × 1 mm3) containing >1019 1H spins at room temperature. Room temperature hyperpolarization achieved with DNP using photo-excited triplet electrons has potentials to be applied to a wide range of fields, including NMR spectroscopy and MRI as well as fundamental physics.

As the embolization of AVMs is often an adjuvant therapy combined with surgical extirpation or radiosurgery, the goal is to optimize the outcome of the following procedure. As the natural history of AVMs predicts a relatively low rate of neurological injury, the combined therapeutic modalities should have a low complication rate. We report the perisurgical complications of 66 AVMs and discuss techniques to avoid complications. Of the 66 patients treated with endovascular embolization, 14 subsequently underwent surgical resection and 43 had radiosurgery. Four patients obtained total occlusion of their AVM by embolization alone and required no further treatment. In 48 patients, more than 70% of the nidus was occluded with embolization. We observed 3 permanent and 9 temporary complications. Four complications occurred immediately after embolization, due to overembolization or thromboembolism. Seven delayed complications occurred, possibly due to retrograde thrombosis or a chemical reaction to the glue. In 4 of the 14 cases without AVM obliteration following embolization and radiosurgery, meningeal feeders developed or recanalized after the treatment with absorbable particles. We recommend embolization prior to radiosurgery to treat all fistulous and meningeal feeders and packing of the nidus with non-absorbable embolic materials. In 10 cases, repeat embolization achieved further nidus reduction prior ro repeat radiosurgery. Intranidal aneurysms that pose a high risk of bleeding were also embolized. To avoid complications with embolization, the AVM angioarchitecture, hemodynamics and functional location should be well recognized. Complications can be reduced with preoperative functional imaging, superselective angiograms, appropriate selection of embolic materials, and appropriate selection of embolization targets. The priority of vessels to be embolized is dictated by the subsequent treatment. Agressive embolization of high-risk vessels or those that will cause abrupt hemodynamic changes should be avoided.

We investigated the methods for treating arteriovenous malformations (AVMs) based on the clinical data and questionnaires sent to affiliated hospitals over 9 years. In 27 institutes, there were twice as many embolizations in the second half (5 years) than in the first half, and the overall clinical results improved especially in the latter half. Responses to a questionnaire on treatment strategy for 62 patterns of virtual AVMs simulating various types and situations were obtained from 17 institutes. There were three general strategies showing more than 70% consensus: 1) radiosurgery for small AVMs without bleeding; 2) embolization plus radiosurgery for large AVMs with ischemic events, and for large, eloquent ones and deep-seated ones with minor hemorrhage; 3) surgical removal for small, middle-sized AVMs with large hematoma except for middle-sized eloquent and deep-seated ones. The strategy used for high-grade AVMs with large hematoma was very different among the institutes. Generally, there is less aggressive surgical extirpation for difficult AVMs, and the dependence on radiosurgery with or without embolization seem to have become greater. The significance of embolization is that it makes the following treatments easier and more effective. Although the indication of radiosurgery is expanding based on its excellent results, embolization still plays a role to reduce the size and hemorrhagic risks and to eliminate factors unfavorable for radiosurgery.

For neck protection technique to prevent migration or protrusion of GDCs, non detachable balloons or microcatheters/wires are used. Non detachable balloon has good protective effect with great effect to the flow in the parent artery which is risky for safe procedure. Microcatheter has little effect to the parent flow and poor protective effect. We have developed retrievable microbasket for neck protective technique which can be delivered and retrieved through standard 18 catheters. These baskets have good protective effect in aneurysm model.