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Yukihiko Fujii

Publications and source records attributed to Yukihiko Fujii.

At least 19 recordsLinked to original sources
PubMed2006

Modified buddy wire technique for coil embolization of posterior circulation aneurysms.

INTRODUCTION: In coil embolization of a posterior circulation aneurysm, tortuosity or a small vessel caliber frequently prevents placement of a guiding catheter in the vertebral artery. Even in such difficult situations, however, coil embolization is the only treatment option when the patient's clinical condition is very poor, or the aneurysm is inaccessible by microsurgery. METHODS: Three patients with a posterior circulation aneurysm were treated by coil embolization with the use of a modified buddy wire technique to stabilize a guiding catheter that could not be placed into the vertebral artery. RESULTS: The guiding catheter was stabilized in the subclavian artery and the microcatheter was firmly supported. As a result, coil embolization was performed safely in all patients. There were no procedural complications. CONCLUSION: The modified buddy wire technique could provide patients with a chance to undergo endovascular surgery despite having a tortuous or narrow vertebral artery.

Aged↗
PubMed2006

A case of split cord malformation associated with myeloschisis.

INTRODUCTION: Split cord malformation (SCM) associated with myeloschisis is a very rare form of spinal dysraphism. We encountered a case of SCM associated with myeloschisis showing split neural placodes (hemicords) in the upper lumbar region. RESULTS: Radiological examinations, including prenatal MRI and postnatal CT scan, clearly demonstrated a bony spur between the two hemicords as well as myeloschisis, which facilitated a precise preoperative diagnosis of this complex anomaly. Resection of the spur, closure of the myeloschisis, and untethering of the thickened filum terminale were successfully accomplished in one stage. The presence of SCM associated with myeloschisis is consistent with the hypothesis of an ontogenic basis of neural development, and we emphasize the importance of early imaging including prenatal MRI for diagnosing this complex anomaly.

Adult↗
PubMed2006

Human primary motor cortex shows hemispheric specialization for speech.

Hemispheric specialization is a prominent characteristic of the human brain. Should the 'dominant' hemisphere possess differential neural organization for language production in the 'higher order' cortex, it would be rational to consider that the primary motor cortex may also show similar hemispheric specialization for speech production. In order to test this hypothesis, we investigated the spatial distribution of neural activities associated with phonation (M1p), silent tongue motion (M1t), and vocalization (M1v) within the primary motor cortex, utilizing independent component-cross correlation-sequential epoch analysis of high-field functional magnetic resonance imaging time series. While M1t showed no significant differences between the two hemispheres, M1p and M1v exhibited significant hemispheric differences. The study demonstrated direct evidence that human primary motor cortex possesses clear-cut hemispheric specialization similar to that observed for the higher order cortices.

Adult↗
PubMed2006

Assessment of axonal degeneration along the human visual pathway using diffusion trace analysis.

PURPOSE: The effectiveness of diffusion trace value analysis for non-invasive assessment of retinal ganglion cell (RGC) axonal degeneration at multiple anatomic levels along the human visual pathway under clinical setting was evaluated. DESIGN: Imaging study. METHODS: Ten patients with unilateral chronic optic neuropathy of varying cause and 16 age-matched normal subjects were studied. Trace, a tensor invariant that is considered to be a sensitive index for pathologic changes in axons, was analyzed at nine anatomic sites in each subject, namely, bilaterally at the level of the optic nerves, uncrossed chiasmal fibers, optic tracts and optic radiations, and crossed chiasmal fibers, using a 3.0 Tesla magnetic resonance imaging system. RESULTS: Trace values of the optic nerve and uncrossed chiasmal fibers ipsilateral to the affected eye, the crossed chiasmal fibers, and optic tracts bilaterally were significantly higher than those of the corresponding anatomic sites in normal subjects. The optic nerve and uncrossed chiasmal fibers ipsilateral to the unaffected side and optic radiations, bilaterally, had trace values which were not significantly different from the values of the corresponding anatomic levels in normal subjects. The increase in trace value in the optic nerve and uncrossed chiasmal fibers ipsilateral to the affected side was greater than those of the crossed chiasmal fibers and optic tracts. CONCLUSIONS: Findings are highly consistent with a degenerative process of RGC axons and trace values are quantitatively well correlated to predicted pathology at the given anatomical sites. Trace value measurement at multiple sites along fiber pathways appears to be a powerful addition to clinical assessment of the functionality of components of the visual pathways during various stages of a pathologic process.

Adult↗
PubMed2006

Three-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction (3DAC PROPELLER) on a 3.0T system: a new modality for routine clinical neuroimaging.

BACKGROUND: Clinical magnetic resonance imaging (MRI) has recently entered the "high-field" era, and systems equipped with 3.0-4.0T superconductive magnets are becoming the gold standard for diagnostic imaging. While higher signal-to-noise ratio (S/N) is a definite advantage of higher field systems, higher susceptibility effect remains to be a significant trade-off. To take advantage of a higher field system in performing routine clinical images of higher anatomical resolution, we implemented a vector contrast image technique to 3.0T imaging, three-dimensional anisotropy contrast (3DAC), with a PROPELLER (Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction) sequence, a method capable of effectively eliminating undesired artifacts on rapid diffusion imaging sequences. METHODS: One hundred subjects (20 normal volunteers and 80 volunteers with various central nervous system diseases) participated in the study. Anisotropic diffusion-weighted PROPELLER images were obtained on a General Electric (Waukesha, WI, USA) Signa 3.0T for each axis, with b-value of 1100 sec/mm(2). Subsequently, 3DAC images were constructed using in-house software written on MATLAB (MathWorks, Natick, MA, USA). RESULTS: The vector contrast allows for providing exquisite anatomical detail illustrated by clear identification of all major tracts through the entire brain. 3DAC images provide better anatomical resolution for brainstem glioma than higher-resolution T2 reversed images. Degenerative processes of disease-specific tracts were clearly identified as illustrated in cases of multiple system atrophy and Joseph-Machado disease. CONCLUSION: Anatomical images of significantly higher resolution than the best current standard, T2 reversed images, were successfully obtained. As a technique readily applicable under routine clinical setting, 3DAC PROPELLER on a 3.0T system will be a powerful addition to diagnostic imaging.

Anisotropy↗
PubMed2006

Kissing aneurysms at the junction of the internal carotid artery and the ipsilateral duplicate anterior choroidal arteries--case report.

A 45-year-old woman presented with kissing aneurysms located at the junctions of the internal carotid artery and the duplicate anterior choroidal arteries manifesting as acute subarachnoid hemorrhage. The aneurysms were clipped during temporary occlusion of the internal carotid artery. Surgery for kissing aneurysms requires special consideration including analysis of the anatomical relationship before clipping, control of premature rupture during clipping, and preservation of the patency of the two anterior choroidal arteries after clipping.

Aneurysm↗
PubMed2005

High-field, T2 reversed MRI of the hippocampus in transient global amnesia.

OBJECTIVE: To investigate the fine structural integrity of the hippocampus in patients with transient global amnesia (TGA) using high-resolution T2 reversed (T2R) MRI. METHODS: The authors performed detailed structural analysis of the hippocampus in 15 patients who had recovered from an episode of TGA and 150 randomly recruited normal volunteers across the adult age spectrum using high-resolution T2R MRI obtained on a 3.0-T system. An additional 100 subjects, with stroke or tumor, were similarly studied and served as disease controls. RESULTS: The overall incidence of hippocampal cavities detected in normal volunteers increased with age but never exceeded 40%, whereas the incidence in disease control group was 31%. They were always unilateral. In contrast, cavities were found in all 15 patients with TGA (100%), an incidence higher than in normal or disease controls (p < 0.05; Ryan's multiple comparison test), and were bilateral in eight patients (53%). The cavities in all but one of the normal volunteers (99%) and all disease controls (100%) were crescent shaped and < or =2 mm in width. The cavities in 14 of 15 patients with TGA (93%) were considerably larger (>3 mm in width), and five of the patients had giant cavities (>5 mm in width). Most of the cavities in patients with TGA had a rounded shape and resembled pathologic cavities described in specimens of hypoxia-related CA1 necrosis. CONCLUSION: The data indicate that transient global amnesia may not be a benign entity. Delayed neuronal loss within CA1 area of Lorente de No may represent its important sequel.

Adolescent↗
PubMed2005

Rapid administration of antifibrinolytics and strict blood pressure control for intracerebral hemorrhage.

OBJECTIVE: Hematoma growth is a major cause of poor outcome in patients with intracerebral hemorrhage. We evaluated the efficacy of a combination of rapid antifibrinolytic therapy and strict blood pressure control for prevention of hematoma growth in this retrospective study. METHODS: Systolic blood pressure was strictly controlled below 150 mm Hg by use of intravenously administered nicardipine (BPC). Prolonged infusion of antifibrinolytic therapy was given by intravenous administration of 1 g tranexamic acid over a period of 6 hours (PAF). Rapid administration of antifibrinolytic therapy was given by intravenous administration of 2 g tranexamic acid over a period of 10 minutes (RAF). Immediately after diagnosis of intracerebral hemorrhage on computed tomographic scan, 156 patients who were admitted within 24 hours of onset were treated with either a combination of PAF and BPC (PAF group) or a combination of RAF and BPC (RAF group). The incidence of hematoma growth determined by a second computed tomographic scan the day after admission was compared between the PAF and the RAF groups. RESULTS: Hematoma growth was observed in 11 (17.5%) of 63 patients in the PAF group and 4 (4.3%) of 93 patients in the RAF group using a 20% cutoff value for hematoma enlargement. The RAF group showed a significantly low incidence of hematoma growth compared with the PAF group (P < 0.05). Between the two groups, there was no significant difference in any of the other factors reported to affect hematoma growth. CONCLUSION: The combination of rapid administration of antifibrinolytics and strict blood pressure control may prevent hematoma growth in patients with intracerebral hemorrhage.

Aged↗
PubMed2005

MT+/V5 activation without conscious motion perception: a high-field fMRI study.

While activity of MT+/V5 neurons is believed to be necessary for the conscious perception of visual motion, whether neural activity in MT+/V5 is a sufficient condition for the conscious perception of motion in vision still remains unanswered. A high-field (3.0 Tesla) functional magnetic resonance imaging (fMRI) study was designed and performed to answer this specific question. Eleven healthy subjects viewed a checkerboard pattern stimulus reversed in contrast at 0.2, 12, 30, and 60 Hz while being probed for activation in MT+/V5. At 0.2 Hz, all viewers perceived pattern-reversal which was stationary in position. However, at 12, 30, and 60 Hz, many subjects perceived apparent motion (e.g., vertical and horizontal flows) in the square pattern. At 12 and 30 Hz reversals, MT+/V5 was activated in all subjects (11/11). Nevertheless, three out of eleven (3/11) subjects denied motion perception in these conditions. At 60 Hz reversal, as many as seven out of eleven (7/11) subjects failed to see motion but activation in MT+/V5 was found in the majority (5/7) of the subjects. The results demonstrated that significant MT+/V5 activation occurs without accompanying subjective awareness of seeing motion in an apparent-motion stimulus, indicating that neural activity in MT+/V5 does not represent a sufficient condition for conscious perception of motion in vision.

Adult↗
PubMed2005

Diffusion tensor analysis of peritumoral edema using lambda chart analysis indicative of the heterogeneity of the microstructure within edema.

OBJECT: Histopathological studies indicate that cerebral edema associated with tumors (peritumoral edema) does not represent a single pathophysiological or clinical entity. In this study the authors investigated peritumoral edema by performing lambda chart analysis (LCA), a noninvasive technique that can be used to make visible and analyze apparent water diffusivity in tissues in vivo, and assessed the utility of LCA in differentiating high-grade gliomas from nonglial tumors. METHODS: The water diffusivity characteristics of peritumoral edema associated with four tumor groups-12 high-grade gliomas, five low-grade gliomas, 11 metastatic tumors, and 15 meningiomas-were assessed in 43 patients by performing magnetic resonance imaging with the aid of a 3-tesla magnetic resonance imaging system. In all tumor groups, peritumoral edema exhibited greater trace values and reduced anisotropy compared with normal white matter. Edema associated with high-grade gliomas had significantly higher trace values than edema associated with the other three tumor groups, although the anisotropic angles of those groups were comparable. CONCLUSIONS: Lambda chart analysis identified two distinct types of peritumoral edema: edema associated with high-grade gliomas and edema associated with low-grade gliomas or nonglial tumors. The apparent water diffusivity was significantly greater in high-grade gliomas, whereas the anisotropy in these lesions was comparable to that of edema in other tumors. These findings indicated that water movement in areas of edema, predominantly in the extracellular spaces, was less restricted in high-grade gliomas, a phenomenon that likely reflected the destruction of the extracellular matrix ultrastructure by malignant cell infiltration and consequently greater water diffusion. Although preliminary, this study indicates that LCA could be used as a clinical tool for differentiating high-grade gliomas and for evaluating the extent of cellular infiltration.

Adolescent↗
PubMed2005

Blood pressure in the artery distal to an intraarterial embolus during thrombolytic therapy for occlusion of a major artery: a predictor of cerebral infarction following good recanalization.

OBJECT: The aim in this study was the investigation of back pressure in arteries distal to the occlusion site during intraarterial thrombolysis as well as the usefulness of back pressure measurement in combination with diffusion-weighted (DW) magnetic resonance (MR) imaging to predict the occurrence of ischemic lesions following good recanalization. METHODS: . Twenty-five consecutive patients with severe hemiparesis caused by embolism of the internal carotid artery (10 patients) and the proximal middle cerebral artery (15 patients) were treated using intraarterial thrombolysis. Systolic back pressure, measured through a microcatheter in the artery just distal to the emboli, ranged from 22 to 78 mm Hg. According to an angiographic inclusion criterion for good recanalization--that is, recanalization of the M2 or more distal arteries at the end of thrombolysis--21 of 25 patients underwent evaluation in this study. In 14 patients volumes of low-density areas on computerized tomography (CT) scans obtained 2 months postthrombolysis were smaller in comparison with volumes of hyperintense areas on DW MR images acquired before treatment, whereas these low-density areas were larger in seven patients. Compared with those on initial DW MR images, the volume of abnormalities on CT scans obtained 2 months posttreatment were significantly reduced in patients with a systolic back pressure greater than 30 mm Hg (16 patients) than in those with a back pressure of 30 mm Hg or less (five patients) (p < 0.05). Systolic back pressures greater than 30 mm Hg were associated with significantly better modified Rankin Scale scores than those 30 mm Hg or less (p < 0.05). CONCLUSIONS: Back pressure measurement in combination with DW MR imaging can be used to predict the occurrence of infarction as demonstrated on CT scans following thrombolysis.

Aged↗
PubMed2004

The primary motor area for voluntary diaphragmatic motion identified by high field fMRI.

In order to identify the precise location of the primary motor area for the diaphragm with respect to the classical motor homunculus, functional magnetic resonance imaging (fMRI) experiments were performed utilizing independent component-cross correlation- sequential epoch (ICS) analysis on a high-field (3.0 Tesla) system. Activations which correlated with voluntary diaphragmatic motion mapped onto the area anterolateral to that for voluntary hand motion (internal control in ICS analysis). Multiple subject analysis yielded the primary motor cortex for the diaphragm to be (+/-48, -4, 47) in the Talairach and Tournoux coordinates. The results were highly consistent with the previously reported cortical area for the diaphragm determined by transcranial electrical/magnetic stimulation.

Adult↗
PubMed2004

Serial evaluation of axonal function in patients with brain death by using anisotropic diffusion-weighted magnetic resonance imaging.

OBJECT: The purposes of this study were to evaluate the serial changes in diffusion anisotropy of the brain, probably reflecting axonal function in brain-dead patients, and thus to explore the possibility of quantitatively estimating the risk of brain death. METHODS: Ten patients suffering from stroke with or without impending brain death and 10 healthy volunteers were studied using three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) axonography with the aid of a 1.5-tesla MR imaging system. To detect changes in the diffusion anisotropy of neural bundles, the corticospinal tract was evaluated. Diffusion anisotropy of short axonal fibers decreased immediately after apparent brain death. Whereas the trichromatic coefficients of the corticospinal tract greatly diminished between 6 and 12 hours after apparent brain death, the coefficients of the corpus callosum and the optic radiation decreased in less time, that is, between 1 and 6 hours. The coefficients of these three bundles turned isotropic between 24 and 44 hours after apparent brain death. CONCLUSIONS: Results of 3DAC MR axonography revealed that diffusion anisotropy of neural bundles diminished between 1 and 12 hours after the onset of apparent brain death, probably depending on the length of the bundles, and disappeared between 24 and 44 hours after the onset of brain death, which might reflect dynamic changes of axonal structure and indirectly herald axonal dysfunction. These findings seem to be greatly helpful in establishing an appropriate method to estimate the risk of brain death quantitatively and in forming the basis of future definitions of brain death.

Aged↗
PubMed2004

Coerced training of the nondominant hand resulting in cortical reorganization: a high-field functional magnetic resonance imaging study.

OBJECT: The authors investigated brain strategies associated with hand use in an attempt to clarify genetic and nongenetic factors influencing handedness by using high-field functional magnetic resonance imaging. METHODS: Three groups of patients were studied. The first two groups comprised individuals in whom handedness developed spontaneously (right-handed and left-handed groups). The third group comprised individuals who were coercively trained to use the right hand and developed mixed handedness, referred to here as trained ambidexterity. All trained ambidextrous volunteers were certain that they were innately left-handed, but due to social pressure had modified their preferred hand use for certain tasks common to the right hand. Although right-handed and left-handed volunteers displayed virtually identical cortical activation, involving homologous cortex primarily located contralateral to the hand motion, trained ambidextrous volunteers exhibited a clearly unique activation pattern. During right-handed motion, motor areas in both hemispheres were activated in these volunteers. During left-handed motion, the right supplemental motor area and the right intermediate zone of the anterior cerebellar lobe were activated significantly more frequently than observed in naturally right-handed or left-handed volunteers. CONCLUSIONS: The results provide strong evidence that cortical organization of spontaneously developed right- and left-handedness involves homologous cortex primarily located contralateral to the hand motion, and this organization is likely to be prenatally determined. By contrast, coerced training of the nondominant hand during the early stages of an individual's development results in mixed handedness (trained ambidexterity), indicating cortical reorganization.

Cerebral Cortex↗
PubMed2004

Striatal hyperintensity on T1-weighted magnetic resonance images and high-density signal on CT scans obtained in patients with hyperglycemia and no involuntary movement. Report of two cases.

The authors report on two patients in whom an increased signal on T1-weighted magnetic resonance images and a high-density signal on computerized tomography scans of the striatum were demonstrated, both of which were associated with nonketotic hyperglycemia. Involuntary movements, which have been present in all previously reported cases, were not observed in either patient at any time during the entire course of illness. One patient displayed hemiparesis, whereas the other had dementia, gait disturbance, and urinary incontinence. Clinical and radiological abnormalities improved on control of blood glucose levels. Invasive studies, including biopsy procedures, should be avoided on encountering this disease given the good prognosis that results from simple medical treatment.

Adult↗
PubMed2004

Recanalization by mechanical embolus disruption during intra-arterial thrombolysis in the carotid territory.

BACKGROUND AND PURPOSE: Mechanical disruption of a clot with a microcatheter and a guidewire has not been detailed in conjunction with intra-arterial thrombolysis in patients with acute ischemic stroke. The purpose of this study was to evaluate the efficacy of mechanical disruption of an embolus in the carotid artery distribution. METHODS: We analyzed clinical and radiologic findings and functional outcomes 3 months after thrombolysis with mechanical disruption. Outcomes were classified as good for modified Rankin scale (mRS) scores of 0-2, moderate for mRS scores of 3, and poor for death and mRS scores of 4 or 5. RESULTS: Twenty-three consecutive patients with severe hemispheric symptoms were treated with several methods of mechanical embolus disruption during the intra-arterial administration of urokinase. Twelve patients had occlusions of the proximal middle cerebral artery (MCA), and 11 had occlusions of the distal internal carotid artery (ICA). Recanalization was observed in all patients with MCA occlusions and in 10 (91%) with ICA occlusions. Outcomes were good in nine patients (75%) with MCA occlusions and in four (36.4%) with ICA occlusions. Early management of vessel perforation, caused by a microguidewire tip in two patients, resulted in early hemostasis. Neither patient had a major deficit attributable to the complication. CONCLUSION: A high incidence of recanalization and clinical improvement can be observed in patients with occlusions of not only the proximal MCA but also the distal ICA. This method might be an effective additional option to intra-arterial thrombolysis for acute distal ICA and proximal MCA occlusions.

Aged↗
PubMed2003

Cortical reorganization in patients with subcortical hemiparesis: neural mechanisms of functional recovery and prognostic implication.

OBJECT: A systematic investigation on cortical reorganization in patients with hemiparesis of a subcortical origin, with special emphasis on functional correlates, was conducted using functional magnetic resonance (fMR) imaging performed on a 3-tesla system specifically optimized for fMR imaging investigation. METHODS: The study group included 46 patients with hemiparesis (25 with right and 21 with left hemiparesis) and 30 age-matched healthy volunteers as controls. All study participants were originally right handed. The characteristics of the lesion were putaminal hemorrhage in 19 patients, thalamic hemorrhage in 10 patients, and striatocapsular bland infarction in 17 patients. Functional recovery in subcortical hemiparesis showed two distinct phases of the recovery process involving entirely different neural mechanisms. Phase I is characterized by the process of recovery and/or reorganization of the primary system. Successful recovery of this system is typically reached within 1 month after stroke onset. Its clinical correlate is a rapid recovery course and significant recovery of function within 1 month of stroke onset. Failure of recovery of the primary system shifts the recovery process to Phase II, during which reorganization involving the ipsilateral pathway takes place. The clinical correlate of Phase II is a slow recovery course with variable functional outcome. CONCLUSIONS: Effective functional organization of the ipsilateral pathway, as identified by linked activation of the ipsilateral primary sensorimotor cortex and contralateral anterior lobe of the cerebellum, is correlated with a good prognostic outcome for patients in the slow recovery group. A high degree of connectivity between supplementary motor areas, bilaterally, appears to influence functional recovery adversely.

Aged↗