Yo Tsuda

Bio: Yo Tsuda is an academic researcher from Nagoya City University. The author has contributed to research in topics: Magnetic resonance imaging & Synaptic vesicle. The author has an hindex of 1, co-authored 3 publications receiving 2 citations.

Importance of Chronological Changes on High-Resolution Vessel Wall Imaging for Diagnosis of Isolated Anterior Cerebral Artery Dissection.

Abstract: Introduction The accurate diagnosis of isolated anterior cerebral artery dissection (iACA-D) is made difficult by the spatial resolution on conventional magnetic resonance imaging (MRI) techniques including time-of-flight magnetic resonance angiography that is too limited to detect minute arterial wall abnormalities. Recent advances in high-resolution vessel wall imaging (HRVWI), which can detect intramural hematomas (IMH), have improved the noninvasive diagnostic accuracy of iACA-D. However, despite the risk of overlooking minute IMH and aneurysmal dilations especially at the early disease stage, the utility of T1-weighted and T2-weighted HRVWI at each disease stage (i.e., acute, early subacute, late subacute and chronic) has not been evaluated thoroughly enough. This prompted us to undertake the present study to determine the diagnostic value of chronological changes of IMHs on T1-weighted HRVWI and arterial dilations on T2-weighted HRVWI to achieve the earliest possible and most accurate diagnosis of iACA-D. Methods In addition to six patients with iACA-D, five previously reported iACA-D patients from three institutions for whom reliable information on HRVWI and its examination date was available were enrolled in this study. IMHs on T1-weighted HRVWI and aneurysmal dilations on T2-weighted HRVWI and their chronological changes were visually evaluated. Results Either or both of IMHs on T1-weighted HRVWI and aneurysmal dilations on T2-weighted HRVWI were detected in all our six patients and the five previously reported ones. The disease stage showed a notable influence on the degree of their visualization. In contrast to IMHs which are regarded as the gold standard for the diagnosis of intracranial dissections, aneurysmal dilations were identified in 80% of cases even at the acute stage, reaching 100% at the early subacute stage. Despite the excellent detection rate of IMHs at the late subacute stage (100%), their detectability is poor at the acute and early subacute stages (0 and 40%, respectively). Conclusion The results of this study highlighted the importance of aneurysmal dilations on T2-weighted HRVWI as a diagnostic marker to raise suspicion of iACA-D at the acute and early subacute stages, and similarly IMHs on T1-weighted HRVWI to confirm the diagnosis of iACA-D at the late subacute stage. These stage-dependent detectability changes in IMHs and aneurysmal dilations make an understanding of the chronological changes of these abnormal imaging findings mandatory to achieve an early and accurate diagnosis of iACA-D.

Reduction of acetylcholine in the hippocampus of hippocampal cholinergic neurostimulating peptide precursor protein knockout mice

Abstract: The cholinergic efferent network from the medial septal nucleus to the hippocampus plays an important role in learning and memory processes. This cholinergic projection can generate theta oscillations in the hippocampus to encode novel information. Hippocampal cholinergic neurostimulating peptide (HCNP), which induces acetylcholine (Ach) synthesis in the medial septal nuclei of an explant culture system, was purified from the soluble fraction of postnatal rat hippocampus. HCNP is processed from the N-terminal region of a 186-amino acid, 21-kDa HCNP precursor protein, also known as Raf kinase inhibitory protein and phosphatidylethanolamine-binding protein 1. Here, we confirmed direct reduction of Ach release in the hippocampus of freely moving HCNP-pp knockout mice under an arousal state by the microdialysis method. The levels of vesicular acetylcholine transporter were also decreased in the hippocampus of these mice in comparison with those in control mice, suggesting there was decreased incorporation of Ach into the synaptic vesicle. These results potently indicate that HCNP may be a cholinergic regulator in the septo-hippocampal network.

Low signal intensity lesions on brain susceptibility-weighted MRI in a patient with intravascular large B-cell lymphoma.

Abstract: A 71-year-old man was admitted to our hospital because of abnormal behavior and generalized convulsion. Brain MRI revealed no abnormalities upon admission. Levels of serum lactate dehydrogenase and soluble interleukin-2 receptors were significantly elevated, whereas the initial bone marrow puncture and random skin biopsy findings were non-malignant. On the tenth day of admission, brain MRI revealed dot and strip-shaped low signal intensity lesions on susceptibility-weighted images (SWI) disseminated mainly within the cerebral cortex. Administration of high dose methyl-prednisolone improved neither his condition nor these MRI findings. Ground-glass opacities within the bilateral lungs later emerged on the chest CT. The results of a transbronchial lung biopsy and second bone marrow puncture were consistent with a diagnosis of intravascular large B-cell lymphoma (IVLBCL). Despite the lack of histopathological confirmation, the low signal intensities on brain SWI in this case were also considered IVLBCL lesions, reflective of micro-hemorrhagic changes.

Vessel Wall Magnetic Resonance Imaging in Cerebrovascular Diseases

Abstract: Cerebrovascular diseases are a leading cause of disability and death worldwide. The definition of stroke etiology is mandatory to predict outcome and guide therapeutic decisions. The diagnosis of pathological processes involving intracranial arteries is especially challenging, and the visualization of intracranial arteries’ vessel walls is not possible with routine imaging techniques. Vessel wall magnetic resonance imaging (VW-MRI) uses high-resolution, multiparametric MRI sequences to directly visualize intracranial arteries walls and their pathological alterations, allowing a better characterization of their pathology. VW-MRI demonstrated a wide range of clinical applications in acute cerebrovascular disease. Above all, it can be of great utility in the differential diagnosis of atherosclerotic and non-atherosclerotic intracranial vasculopathies. Additionally, it can be useful in the risk stratification of intracranial atherosclerotic lesions and to assess the risk of rupture of intracranial aneurysms. Recent advances in MRI technology made it more available, but larger studies are still needed to maximize its use in daily clinical practice.

Intracranial Fusiform and Circumferential Aneurysms of the Main Trunk: Therapeutic Dilemmas and Prospects.

Abstract: Intracranial fusiform and circumferential aneurysms (IFCAs), especially those located on the main trunk, are uncommon and difficult to manage. Currently, literature focused on IFCAs on the main trunk of cerebral arteries is lacking. The treatment of IFCAs is still under debate. Therefore, in this review, we further explore the treatment of this complicated entity. In addition, we also present some interesting cases. Based on the literature review and our experience, we found that IFCAs are often located in the vertebrobasilar system and that ruptured or large symptomatic IFCAs are associated with increased mortality and higher rebleeding rates. The treatment strategies for IFCAs can be classified as deconstructive and reconstructive methods via open surgery and/or endovascular treatment (EVT). Currently, EVT is a popular method and the main therapeutic choice. In particular, flow diversion has revolutionized the treatment of IFCAs. Parent artery occlusion (PAO) with or without revascularization may still be considered a suitable choice. Complex IFCAs that cannot be resolved by EVT can also be treated via open surgery with or without extracranial-intracranial bypass. Targeted embolization for the weak points of IFCAs is a temporary or palliative choice that is rarely used. In summary, despite complications, both surgical treatment and EVT are effective options for appropriately selected cases. Due to the development of endovascular implants, EVT will have better prospects in the future.

Susceptibility-Weighted Imaging of Intravascular Lymphoma of the Central Nervous System

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Intravascular Large B-Cell Lymphoma Diagnosed by Open Brain Biopsy and Achievement of Remission After Early Initiation of Chemotherapy: Case Report

Abstract: A 60-year-old man presented with progressive disturbance of consciousness. His father had died of malignant lymphoma, while his mother and sister died of acute leukemia. Magnetic resonance imaging (MRI) revealed multiple high-intensity lesions in the bilateral cerebral hemispheres on diffusion-weighted images. Serum soluble interleukin 2 receptor was 5,640 U/mL. Screenings of blood antibodies known to rise in autoimmune diseases were all normal. Cerebrospinal fluid examinations demonstrated slight elevation of protein and glucose, while the oligoclonal band and myelin basic protein were not elevated. Biopsies of bone marrow and random skin did not show any malignant features. His consciousness gradually deteriorated over a week, with lesions in his right frontal, left temporal, and bilateral parietal lobes shown to be growing. Therefore, open brain biopsy was performed, and one block of the right frontal lesion was harvested. Histological examination revealed atypical large cells only in the capillaries. Although immunohistochemical examinations showed positive staining for CD20, they were negative for CD3. Histopathological diagnosis was intravascular large B-cell lymphoma. After undergoing six cycles of intravenous chemotherapy with rituximab, cyclophosphamide, doxorubicin, and prednisone, his consciousness and neurological symptoms improved, and he appeared to achieve remission. Two years later, there have been no apparent recurrences, and the brain lesions have disappeared.