Publications by authors named "Hiroshi Oba"

We herein report a case of neurosyphilis that presented with isolated bilateral abducens nerve palsy. A 39-year-old man was referred to our department with diplopia. He had a history of homosexual relationships and showed only bilateral abducens nerve palsy upon a neurological examination.

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Left-sided portal hypertension (LSPH), an uncommon manifestation of portal hypertension, is characterized by conditions such as isolated gastric varices and splenomegaly, which result from impeded splenic venous drainage in the presence of pancreatic disease. We employed a percutaneous transhepatic technique to achieve regression of isolated gastric varices by implanting a covered stent within a blocked splenic vein and by embolizing the posterior gastric vein and varices using N-butyl-2-cyanoacrylate. We report the successful treatment of stenting for LSPH by the covered stent placement.

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This study assessed the influence of deep learning reconstruction (DLR) on the quality of diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) using an ice-water phantom. An ice-water phantom with known diffusion properties (true ADC = 1.1 × 10 mm/s at 0 °C) was imaged at various b-values (0, 1000, 2000, and 4000 s/mm) using a 3 T magnetic resonance imaging scanner with slice thicknesses of 1.

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Percutaneous treatments, including thoracic duct embolization (TDE) and thoracic duct disruption (TDD), are reportedly effective and safe alternatives to surgical thoracic duct ligation for refractory chylothorax. When catheterization of the thoracic duct is impossible, TDD can be performed as long as the thoracic duct can be opacified by lymphangiography. However, no report has described percutaneous treatment when the thoracic duct cannot be visualized.

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It is more than 50 years since the concept of transjugular intrahepatic portosystemic shunt (TIPS) was first introduced as a percutaneous procedure for patients with refractory variceal bleeding and ascites. TIPS has become widely accepted in the management of complications of portal hypertension because it is less invasive than surgery. In the early days of TIPS, complications included the poor long-term patency of the stent and a high incidence of hepatic encephalopathy.

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Arm positions employed during magnetic resonance imaging (MRI) can affect magnetic field distribution, which may result in variability in proton density fat fraction (PDFF) measurements. This study evaluated the effect of arm position on lumbar PDFF measured using chemical-shift-encoded MRI (CSE-MRI). Fifteen healthy volunteers from a single-center underwent lumbar CSE-MRI at two different arm positions (side and elevated) using a single 3T scanner.

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Background: Brain imaging studies have reported that the effect of repetitive transcranial magnetic stimulation (rTMS) is associated with the activities of the dorsolateral prefrontal cortex (DLPFC) and ventral medial prefrontal cortex (VMPFC). However, few studies have been conducted in Japanese patients.

Aim: We aimed to identify brain regions associated with depressive symptom changes by measuring regional cerebral blood flow (rCBF) in the DLPFC and VMPFC before and after the high-frequency rTMS to the left DLPFC in Japanese patients with treatment-resistant depression.

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Purpose: Intranodal embolization using n-butyl cyanoacrylate glue is an emerging treatment option for persistent lymphatic leakage. This report describes the procedure details of intranodal embolization for groin lymphocele and evaluates the efficacy of intranodal embolization at our institution via retrospective chart review.

Material And Methods: Nine consecutive patients (six men and three women; median age, 77.

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For interventional radiology, dose management has persisted as a crucially important issue to reduce radiation exposure to patients and medical staff. This study designed a real-time dose visualization system for interventional radiology designed with mixed reality technology and Monte Carlo simulation. An earlier report described a Monte-Carlo-based estimation system, which simulates a patient's skin dose and air dose distributions, adopted for our system.

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Out-of-field organs are not commonly designated as dose calculation targets during radiation therapy treatment planning, but they might entail risks of second cancer. Risk components include specific internal body scatter, which is a dominant source of out-of-field doses, and head leakage, which can be reduced by external shielding. Our simulation study quantifies out-of-field organ doses and estimates second cancer risks attributable to internal body scatter in whole-breast radiotherapy (WBRT) with or without additional regional nodal radiotherapy (RNRT), respectively, for right and left breast cancer using Monte Carlo code PHITS.

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Background: Previous studies have reported a significant increase in age-related magnetic resonance imaging (MRI) changes in relatively younger people living with HIV (PLWH). However, there is little data available for brain changes in Asian PLWH. The data to differentiate HIV specific brain change from usual aging change was also sparse.

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Anomalous retro-psoas artery is an extremely rare congenital anomaly of the iliac arteries reported in the English-language literature. Using contrast-enhanced computed tomography, we incidentally diagnosed an anomalous retro-psoas artery in a 60-year-old male patient with right renal cancer. Although anomalous retro-psoas artery is extremely rare and mostly asymptomatic, knowledge of it is needed to avoid severe vascular complications in the event of vascular intervention and surgery.

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For interventional radiology (IR), understanding the precise dose distribution is crucial to reduce the risks of radiation dermatitis to patients and staff. Visualization of dose distribution is expected to support radiation safety efforts immensely. This report presents techniques for perceiving the dose distribution using virtual reality (VR) technology and for estimating the air dose distribution accurately using Monte Carlo simulation for VR dose visualization.

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Purpose: To share the experience of an iridium-192 (Ir) source stuck event during high-dose-rate (HDR) brachytherapy for cervical cancer.

Material And Methods: In 2014, we experienced the first source stuck event in Japan when treating cervical cancer with HDR brachytherapy. The cause of the event was a loose screw in the treatment device that interfered with the gear reeling the source.

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Adipose tissue plays multiple and complex roles not only in mechanical cushioning and energy storage but also as an important secretory organ that regulates energy balance and homeostasis multilaterally. Fat tissue is categorized into subcutaneous fat tissue (SCAT) or visceral fat tissue (VSA) depending on its distribution, with the two having different metabolic functions. Near-total lack of fat in congenital/acquired generalized lipodystrophy, cachexia, or any other severe malnutrition condition induces severe multi-organ dysfunction due to lack of production of leptin and other adipokines.

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Neurocognitive disorder has been noted as a long-term complication in individuals with HIV. In people living with HIV, regardless of treatment, age-related changes like arteriosclerosis are well-known to be accelerated. Such accelerated aging changes may decrease cerebral blood flow in younger generations with HIV, increasing the rate of occurrence of neurocognitive disorders.

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Background: The differential diagnosis of dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) is particularly important because DLB patients respond better to cholinesterase inhibitors but sometimes exhibit sensitivity to neuroleptics, which may cause worsening of clinical status. Antemortem voxel-based morphometry (VBM) using structural MRI has previously revealed that patients with DLB have normal hippocampal volume, but atrophy in the dorsal mesopontine area.

Objectives: The aim of this multicenter study was to determine whether VBM of the brain stem in addition to that of medial temporal lobe structures improves the differential diagnosis of AD and DLB.

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This short report clarifies the heterogeneity of structural magnetic resonance imaging (MRI) findings in seven demented patients due to pathologically accumulated TAR DNA-binding protein-43 (TDP-43) protein using visual analyses including visual rating scales (i.e., global cortical atrophy and medial temporal atrophy scales).

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Purpose: The purpose of this study is to clarify the characteristic structural magnetic resonance imaging (MRI) findings in demented patients with pathologically confirmed argyrophilic grain disease (AGD).

Methods: Nine pathologically confirmed AGD patients with cerebral three-dimensional T1-weighted MRI were evaluated in this study. In addition to visual rating scales of atrophic and asymmetric changes in the limbic and temporal lobes, voxel-based morphometry (VBM) was performed to assess group difference between pathologically confirmed AGD and Alzheimer's disease (AD) patients.

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Symptomatic calcification is an entity in which hydroxyapatite calcific deposits cause inflammation, then burst and dissolve into the surrounding structures. Although a well-known pathologic condition in the rotator cuff tendons, it can also occur in other structures of the locomotor system. Radiographs are usually taken at the initial examination but can also be useful for follow-up evaluation of the course of the calcified matter.

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Cerebral tuberculosis (TB) presents most frequently as meningitis in the basilar cistern; however, it can also manifest in various other ways, such as localized encephalitis, abscess, and tuberculoma. Here, focusing on imaging findings, we report an immunocompetent case who demonstrated multiple parenchymal lesions and was diagnosed with cerebral TB after testing positive on QuantiFERON (QTF); her clinical signs/symptoms and laboratory findings responded well to anti-TB medication therapy. The patient was a 60-year-old woman with the chief complaints of headache and consciousness disturbance.

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