Publications by authors named "Yoshio Imahori"

For the patients who underwent fluorinated para-boronophenylalanine (FBPA) positron emission tomography (PET) and fluorodeoxyglucose (FDG) PET within a period of 2 weeks, maximum standardized uptake value (SUVmax), tumor-to-normal tissue ratio (TNR), and tumor-to-blood ratio (TBR) for FBPA were compared with SUVmax for FDG. A total of 30 patients were selected for comparison. SUVmax for FBPA was correlated the best with SUVmax for FDG.

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To understand the mechanism of cell death induced by boron neutron capture reaction (BNCR), we performed proteome analyses of human squamous tumor SAS cells after BNCR. Cells were irradiated with thermal neutron beam at KUR after incubation under boronophenylalanine (BPA)(+) and BPA(-) conditions. BNCR mainly induced typical apoptosis in SAS cells 24h post-irradiation.

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To understand the mechanism of tumor cell death induced by boron neutron capture therapy (BNCT) and to optimize BNCT condition, we used rat tumor graft models and histological and biochemical analyses were carried out focusing on DNA damage response. Rat lymphosarcoma cells were grafted subcutaneously into male Wister rats. The rats with developed tumors were then treated with neutron beam irradiation 45min after injection of 330mg/kg bodyweight boronophenylalanine ((10)BPA) (+BPA) or saline control (-BPA).

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It is necessary to explore new treatments for recurrent head and neck malignancies (HNM) to avoid severe impairment of oro-facial structures and functions. Boron neutron capture therapy (BNCT) is tumor-cell targeted radiotherapy that has significant superiority over conventional radiotherapies in principle. We have treated with BNCT 42 times for 26 patients (19 squamous cell carcinomas (SCC), 4 salivary gland carcinomas and 3 sarcomas) with a recurrent and far advanced HNM since 2001.

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Objective: Since 2002-2007, we applied boron neutron capture therapy (BNCT) to >50 cases of malignant gliomas (MGs) with epithermal neutron irradiations. Recently, we showed the early radiographical improvement of malignant glioma patients by our modified BNCT, with simultaneous use of BPA (borono-phenylalanine) and BSH (sodium borocaptate). In this time, we focused on the survival benefit from BNCT for the newly diagnosed glioblastoma patients.

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We evaluate the clinical results of a form of tumor selective particle radiation known as boron neutron capture therapy (BNCT) for newly-diagnosed glioblastoma (NDGB) patients, especially in combination with X-ray treatment (XRT). Between 2002 and 2006, we treated 21 patients of NDGB with BNCT utilizing sodium borocaptate and boronophenylalanine simultaneously. The first 10 were treated with only BNCT (protocol 1), and the last 11 were treated with BNCT followed by XRT of 20 to 30 Gy (protocol 2) to reduce the possibility of local tumor recurrence.

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Here we demonstrate that differentiation between glioblastoma (GB) tumor progression (TP) and radiation necrosis (RN) can be achieved with fluoride-labeled boronoalanine positron emission tomography (F-BPA-PET). F-BPA-PET images were obtained from histologically verified 38 GB, 8 complete RN, and 5 RN cases with partial residual tumors. The lesion/normal (L/N) ratios for these groups were 4.

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In symptomatic stenosis of the internal carotid artery (ICA), the predominant mechanism of ischemic event is considered thromboembolic. Carotid endarterectomy (CEA) removes the embolic source and is accepted as the major benefit from the surgery. Even in high-degree stenosis, hemodynamic compromise as a causal factor for cerebral ischemia remains controversial, however.

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Objective: To distinguish idiopathic-normal pressure hydrocephalus (i-NPH) from the elder with brain atrophy is difficult. This investigation was undertaken to determine the cerebral oxygen metabolism and the cerebral blood flow using positron emission tomography (PET) in patients with i-NPH. Comparison of the variables between i-NPH patients and the age-comparable control with asymptomatic ventricular dilatation were performed.

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Purpose: To analyze the dose-volume histogram (DVH) of head-and-neck tumors treated with boron neutron capture therapy (BNCT) and to determine the advantage of the intra-arterial (IA) route over the intravenous (IV) route as a drug delivery system for BNCT.

Methods And Materials: Fifteen BNCTs for 12 patients with recurrent head-and-neck tumors were included in the present study. Eight irradiations were done after IV administration of boronophenylalanine and seven after IA administration.

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Object: To improve the effectiveness of boron neutron capture therapy (BNCT) for malignant gliomas, the authors used epithermal rather than thermal neutrons for deep penetration and two boron compounds-sodium borocaptate (BSH) and boronophenylalanine (BPA)-with different accumulation mechanisms to increase the boron level in tumors while compensating for each other's faults.

Methods: Thirteen patients, 10 of whom harbored a glioblastoma multiforme (GBM), one a gliosarcoma, one an anaplastic astrocytoma, and one an anaplastic oligoastrocytoma, were treated using this modified BNCT between January 2002 and December 2003. Postoperatively, neuroimaging revealed that only one patient with a GBM had no lesion enhancement postoperatively.

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Objective: Non-traumatic osteonecrosis of the femoral head (ONF) is considered to be a disease that occurs primarily due to ischemia of the femoral head, while its etiology and pathology are not fully understood. It is therefore necessary to identify the characteristics of the hemodynamics of the femoral head. In this study, the hemodynamics in the ilium and proximal regions of the femur, including the femoral head, was investigated using positron emission tomography (PET).

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To test the in vivo transport system and tumor proliferation of meningiomas, in comparison with gliomas, 25 patients with meningiomas and 8 gliomas underwent quantitative kinetic analysis of ([18F])fluoro-2-deoxy-D-glucose (FDG) - positron emission tomography (PET) imaging and immunohistochemical study. Kinetic analysis was obtained by calculation of the rate constants: K1 (ml/g/min), which represents the transport of FDG from plasma to tissue; k2 (min(-1)), which demonstrates the transport back from tissue to plasma; and k3 (min(-1)), an indicator of glucose metabolism, using Gjedde's plot methods in a three-compartment model. Surgical specimens were evaluated by means of three different methods: i) immunoreactivity to vascular endothelial growth factor (VEGF) and glucose transporter-1 (Glut-1), representing the permeability of tumor vessels; ii) immunostaining for von Willebrand Factor (vWF), reflecting vascular surface areas of arterioles; and iii) the MIB-1 labeling index (MIB-1 LI), representing the proliferative potential.

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Objective: Conventional methods of quantitative Na18F positron emission tomography require multiple arterial blood sampling in order to obtain the input function, and the procedures are invasive and complicated. This study aims to establish a simplified and reliable technique for obtaining the input function.

Methods: Multiple arterial blood sampling was performed on 12 persons.

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Unlabelled: Left ventricular (LV) remodeling after myocardial infarction (MI) is a maladaptive process that increases the risk of heart failure and death. The myocardial phosphoinositide cycle, which is located downstream from several neurohumoral factors, plays a crucial role in LV remodeling. Our animal studies demonstrated that 1-[1-11C]butyryl-2-palmitoyl-rac-glycerol (11C-DAG) can be used to visualize regions with an activated phosphoinositide cycle.

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Recurrent head and neck malignancies (HNM) are often radio-/chemo-resistant and show extensive growth, necessitating a wide resection including surrounding tissues. To avoid severe impairment of oro-facial structures and functions, it is necessary to explore new treatments for HNM. Boron neutron capture therapy (BNCT) is tumor-cell targeted radiotherapy that has significant superiority over conventional radiotherapies in principle.

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We very effectively treated two patients with recurrent glioblastoma with modified boron neutron capture therapy (BNCT). In this paper, we describe the effectiveness of this treatment, and discuss the ways in which we modified the treatment. A 61-year-old man had a first operation for a right temporal glioblastoma, followed by full-dose chemo-radiotherapy.

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Purpose: Boron neutron capture therapy (BNCT) for the treatment of brain tumors has attracted attention recently, and its clinical application has been progressing. We have focused on the use of BNCT with 10B-boronophenylalanine, which preferentially delivers boron-10 atoms to malignant cells through the amino acid transport system. In the present study, we evaluated the long-term outcomes of treatments using 18F-10B-fluoroboronophenylalanine (FBPA), which is an analogue of 10B-boronophenylalanine, by investigating the prognostic significance of the metabolic values and ratios of FBPA as determined by positron emission tomography (PET) in patients with gliomas.

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Positron emission tomography (PET) radiotracers have very short physical half-lives. It is hard to complete a bacterial endotoxins test prior to release from medical institutes. For endotoxin quantitative determination, limulus amebocyte lysate (LAL) reagent and kinetic-turbidimetry system were previously developed.

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We recently reported that myocardial phosphoinositide (PI) metabolism can be visualised by 1-[1-11C]-butyryl-2-palmitoyl-rac-glycerol (11C-DAG) in rats with myocardial infarction (MI). Angiotensin II, the receptors for which are expressed predominantly in infarcted areas with active fibrogenesis rather than in non-infarcted regions, is involved in the upstream signalling systems of PI metabolism and plays an important role in the process of left ventricular (LV) remodelling after MI. We therefore hypothesised that the distribution of 11C-DAG after MI may be affected by the inhibition of angiotensin converting enzyme, which is one of the most important factors in the development of LV remodelling after MI.

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Phosphoinositide turnover is closely connected to modulation of synaptic function and is part of an important second messenger-producing system. New radioligands for imaging second messenger systems by positron emission tomography have been developed: carbon-11-labeled 1,2-diacylglycerols. The theoretical background of second messenger imaging is described in detail and the relation between the biologically active compounds and potential tracers for imaging second messenger systems is discussed.

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