Comparison between Monte Carlo simulation and measurement with a 3D polymer gel dosimeter for dose distributions in biological samples.

In this research, we used a 135 MeV/nucleon carbon-ion beam to irradiate a biological sample composed of fresh chicken meat and bones, which was placed in front of a PAGAT gel dosimeter, and compared the measured and simulated transverse-relaxation-rate (R2) distributions in the gel dosimeter. We experimentally measured the three-dimensional R2 distribution, which records the dose induced by particles penetrating the sample, by using magnetic resonance imaging. The obtained R2 distribution reflected the heterogeneity of the biological sample. We also conducted Monte Carlo simulations using the PHITS code by reconstructing the elemental composition of the biological sample from its computed tomography images while taking into account the dependence of the gel response on the linear energy transfer. The simulation reproduced the experimental distal edge structure of the R2 distribution with an accuracy under about 2 mm, which is approximately the same as the voxel size currently used in treatment planning.

Flow in a tube with an aneurysmal sac: effect of aneurysm and stent.

SUMMARY: Ruptured saccular aneurysms were severe condition for intracerebral Condition. And the cause for their rupture is not yet clear. In this study (I), since the configurations of aneurysms are considered to be a factor for the rupture of aneurysms, several shapes has been modeled using Aspect ratio AR and inclination angle of saccular aneurysms. In vitro the parametric study has been conducted on the range of Reynolds Number in human blood flow for aneurismal models of AR=2.1 and 1.3 and q=90 degrees and 70 degrees , As results, it was con firme d that there are characteristic flow patterns with Reynolds Number, And that the aneurismal configuration has effects on the shear stress and pressure losses. II) The object of this paper is to study the effects of STENTS.We made the model of aneurysm and performed in vitro study in range of Reynolds number of human blood flows using three kinds of STENTS. As results, it was confirmed that flow pattern and pressure loss changes with the kinds of STENTS. This study aims the accumulation of data to predict the hazard of aneurysmal rupture by their shapes and STENTS.

Computational fluid dynamics for brain circulation and aneurysm with therapeutic devices.

SUMMARY: We analysed fluid dynamics at brain arteries having multiple inflow and out flow like Willis ring based on clinical imaging modalities. In addition, we analysed fluid dynamics with therapeutic devices like coils and stents to simulate their influences to blood flow. 3D CTA and MRA obtained three-dimensional structures of the brain vessels. The centreline was obtained from the three dimensional structure. Diameter of the blood vessels was measured by 3D CTA/MRA then smooth surfaced blood vessel models were created. For the fluid analysis, we developed a home brew software which can display parameters such as streamline, etc. In addition, our CFD (computational fluid dynamics) software can work in collaboration with a CAD (computer aided design) software which we also developed (VCAD: Volume CAD). So, therapeutic devices such as coils, balloons and stents could be placed in the models and CFD analysis could be performed placing devices in the models. The flow pattern in the complicated vascular structure could be calculated such as Willis ring which has multiple inputs like ICA, VA and multiple outlets like MCA and PCA with communicating arteries. CFD with therapeutic devices could also analysed with our system. CFD including communicating arteries will assist the simulation of parent artery occlusion. CFD with therapeutic devices is helpful not only for simulation for embolization, but will help us to design therapeutic devices under computer simulation.

Fine Structure of Detached Coils Observed by Micro-CT.

SUMMARY: Detached GDC was observed by high resolutional industrial microCT, whose resolution was higher than 0.1 mm. Unexpected destruction of the coils (kinking) was detected and unraveling also clearly visualized. Much higher resolution can improve safe and effectivity of GDC procedure.

Remote Manipulation of Guidewire using a Virtual Reality Device.

SUMMARY: A trial of remote manipulation for micro guidewire is reported. The system had masterslave style. When an operator manipulated the virtual torque device at the master side, a machine at the distant slave side reproduced the manipulation. At the same time, the operator could feel the force feedback from the manipulation at the slave. We could experimentally realize this remote manipulating system using a virtual reality device.

An intelligent catheter system robotic controlled catheter system.

SUMMARY: We have developed a novel catheter system, an intelligent catheter system, which is able to control a catheter by an externally-placed controller. This system has made from master-slave mechanism and has following three components; 1) a joy stick as a master (for operators) 2) a catheter controller as a slave (for a patient), 3) a micro force sensor as a sensing device. This catheter tele-guiding system has abilities to perform intravascular procedures from the distant places. It may help to reduce the radiation exposures to the operators and also to help train young doctors.

Neck protective basket.

SUMMARY: 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.

The selection and result of AVM treatment.

The treatment selection for cerebral arteriovenous malformation (AVM) still is in controversy. In order to find out the best way to treat AVM, we summarized the treatment result of AVM patients in our hospital. Sixty-three AVM patients who had been treated at Nagoya University Hospital since 1988 to 1997 were studied. The patient characteristics were nearly the same as other reported series. The treatment modalities include surgery, embolization and radiosurgery. Rate of nidus disappearance was assessed in each treatment. Highest rate was observed in surgery or surgery with embolization. But new neurological deficits were seen in 37% of the patients of same group. Nidus occlusion rate was not high in radiosurgery with embolization, but low in complication rate. The result showed the importance of embolization procedure in the treatment selection of AVM. The value of functional MRI as pre-therapeutic study is high in those patients whose AVM adjacent to eloquent area.

Intravascular treatment for cerebral aneurysms.

SUMMARY: We have treated 142 aneurysms with intrasaccular or parent artery occlusions. Selective intrasaccular occlusions were attempted on 109 cases. Total or subtotal saccular occlusion was achieved in 93 of 96 cases. lntrasaccular occlusion could not be achieved in 13 cases because of various reasons such as wide neck, branching from aneurysmal dome, difficult to catheterize, and aneurysm too small. Parent artery occlusion was attempted on 33 cases. Twenty-five patients had giant aneurysms of the internal carotid artery (ICA) at the cavernous portion. The rest of this group had dissecting or fusiform aneurysms of the vertebral artery. Parent artery occlusion was achieved in 30 cases with six ischemic symptoms. High percentage of occlusion rate and low morbidity and mortality for metallic coil embolization prove the efficacy of this endovascular treatment.

Factors affecting the radiologic appearance of peripheral bronchogenic carcinomas.

The use of high-resolution computed tomography and magnetic resonance imaging have allowed the detailed description of morphologic findings associated with lung cancer. In particular, the desmoplastic response of lung tissue to tumor growth has not been adequately described. This article reviews roentgenologic and pathologic correlations of primary lung carcinomas. An irregular or indistinct tumor margin may be caused by tumor infiltration, an irregular desmoplastic response to the tumor growth, or irregular contraction in the central portion of the tumor. Solid tumor growth, on the other hand, may be associated with a well-defined tumor margin, with or without displacement of adjacent anatomical structures.

Determining the Optimal Fluoroscopic View during Aneurysmal Embolization with Rotation DSA.

SUMMARY: To prevent coil protrusion into the parent artery, the fluoroscopic view during coil packing is quite important. However it is not always easy to find out the optimal fluoroscopic view. We applied a rotation DSA to predict the optimal fluoroscopic view for the endovascular treatment of 4 cases with a cerebral aneurysm. Since the trajectory of the C-arm is restricted within 60 degrees only around the patient's head and the number of DSA shots are limited rather than conventional DSA, we employed three dimensional CT angiography (3D-CT angiography) to focus the range of C-arm rotation. Rotation DSA proved quite useful to determine the optimal fluoroscopic view, when combined with preestimation by 3D-CT angiography.

Results of 55 AVM Cases Treated by Embolization and/or Surgery.

SUMMARY: In order to build a data base for future comparison, we summarized the treatment results of cerebral arteriovenous malformation (AVM) patients in our hospital. Fifty five AVM patients who had been treated at Nagoya University Hospital from 1988 to 1995 were enrolled in the study. The patient characteristics were nearly the same as other reported series. Trend of treatment modality was changing in this period and embolization was increasing in its role. Karnofsky score was used to follow the patients' clinical status. It was useful to assess pretreatment clinical status and post treatment status. The results showed the improvement of the embolization procedure.

3D CT Angiography as a Pre-embolization Study for Embolization of Cerebral Aneurysms.

SUMMARY: An image guide for aneurysm embolization based on three dimensional CT angiography is reported. Multiplanner reformation (MPR) can measure the neck and dome of the aneurysm accurately enough to select the first coils for aneurysms. For neck evaluation, cut model and virtual endoscope are helpful because we can observe the neck from inside of dome or parent artery. Proximal arteries are visualized by 3D images and MPR if needed. Using laser lithography, we can get a real model of aneurysm and parent artery through which we can insert microcatheters and coils. 3D CTA is a dependable modality for embolization of cerebral aneurysms.

Usefulness of intravascular Doppler flow measurements in cerebral endovascular treatment. A comparison with trans cranial Doppler.

SUMMARY: Measurement of cerebral blood flow in cerebral endovascular procedures is useful for the assessment of treatment effects. We used transcranial Doppler sonography (TCD) and Doppler guide wires (SmartWire((R)), Cardiometries Co.) in intravascular treatment. The cases were 6 brain arteriovenous malformations (AVM), 2 carotid cavernous fistulas (CCF), 2 facial angiomas, and 2 carotid stenoses. Intravascular cerebral blood flow measurements with the SmartWire were performed during the endovascular procedure. TCD was used pre- and post-endovascular treatment, and velocity, pulsatility index (PI) and resistance index (RI) were compared with the SmartWire. For both TCD and Smart Wire, blood velocity of the main artery decreased, and PI and RI were improved after embolisation of AVM. In angioplasty cases, post stenotic flow velocity, as measured by SmartWire, was improved, and the flow of MCA measured with TCD was also improved after treatment. The SmartWire is useful to assess cerebral blood flow changes during the neuroendovascular procedure. Combined with repeated follow up with TCD, Doppler flow measurements are useful to assess the effect of endovascular treatment.

[Cerebral digital tomosynthetic angiography for planning stereotactic biopsy of brain tumor].

We used cerebral digital tomosynthetic angiography for planning the probe trajectory of stereotactic biopsy of brain tumors in four patients. The probe trajectory was basically planned by MRI examinations. However, cerebral digital tomosynthetic angiography demonstrated detailed three-dimensional vascular anatomy around the brain tumors, and therefore was very helpful in revising the planned trajectory when there was a fairly large vessel likely to cross with it.

Fusarium poae and Fusarium crookwellense, Fungi Responsible for the Natural Occurrence of Nivalenol in Hokkaido.

To determine the reasons for the natural occurrence of nivalenol in the northernmost area of Japan, scabby wheat was harvested from 19 crop fields in Hokkaido. Mycological surveys and analysis for mycotoxin contamination were performed. Among 13 wheat grain samples harvested in seven locations, 9, 2, and 6 samples were positive for deoxynivalenol, nivalenol, and zearalenone, respectively, at levels ranging from 0.03 to 1.28 mug/g, 0.04 to 1.22 mug/g, and 2 to 25 ng/g, respectively. The predominant Fusarium species of the scabby wheat examined were F. sporotrichioides, F. avenaceum, F. poae, and F. crookwellense. Fifteen of 48 F. poae isolates and all four F. crookwellense isolates were screened for the production of seven derivatives of trichothecenes and zearalenone respectively, on rice culture. One isolate of F. poae produced diacetoxyscirpenol alone (4.3 mug/g); seven produced nivalenol (1.3 to 23.8 mug/g), 4-acetylnivalenol (0.1 to 4.6 mug/g), and diacetoxyscirpenol (0.9 to 99.5 mug/g); and five produced nivalenol alone (0.4 to 3.5 mug/g). The remaining two isolates produced no trichothecenes. Zearalenone production was not found in any isolate of F. poae tested. All isolates of F. crookwellense produced nivalenol (0.9 to 22.5 mug/g), 4-acetylnivalenol (0.5 to 25.0 mug/g), and zearalenone (1.4 to 162.5 mug/g). From these results, it is apparent that deoxynivalenol and zearalenone, and occasionally nivalenol, occur naturally throughout Hokkaido, and it is suggested that nivalenol-producing F. poae and F. crookwellense strains are responsible for the natural contamination with nivalenol found in the northernmost area of Japan. Furthermore, it was found for the first time that several isolates of F. poae distributed in Hokkaido possessed the ability to produce both type A and type B trichothecenes.

Histological examination of the gadolinium-enhanced dura mater around meningiomas on magnetic resonance imaging.

Magnetic resonance imaging often demonstrates gadolinium (Gd) enhancement of the dura mater around meningiomas. The Gd-enhanced dura mater was histologically investigated to detect meningioma cells. Gd enhancement of the dura mater occurred in 11 (79%) of the 14 meningiomas studied, and extended as far as 35 mm from the tumor. Histological examination revealed generation of vascular-rich loose connective tissue at the surface of the dura in all five tumors examined. Some clusters of meningothelial cells were distributed in the loose connective tissue in three of the five specimens, and one cluster was obviously neoplastic. These observations suggest that clusters of meningioma cells occur in the Gd-enhanced dura mater around meningiomas.