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Biomedical subjects

K Hashikawa

Publications and source records attributed to K Hashikawa.

At least 19 recordsLinked to original sources
PubMed2007

Association of vascular parkinsonism with impaired neuronal integrity in the striatum.

The purpose of this study is to identify the underlying differences between patients with white matter lesions (WMLs) who manifested gait disturbance suggestive of vascular parkinsonism (VaP) and those who did not, using the PET scan. Fourteen patients with extensive WMLs, as determined by MRI, were divided into two groups - 7 with gait disturbance and 7 without it. Neuronal integrity was evaluated with a PET scan using [(11)C]flumazenil (FMZ) by calculating the distribution volume of FMZ (FMZ-V(d)) in various regions of interest by non-linear curve fitting. Additionally, tracer kinetic analysis was applied for voxel-by-voxel quantification of FMZ-V(d) and data analysis was performed using statistical parametric mapping. The striatal FMZ-V(d) values were inversely correlated with the motor UPDRS scores (r = 0.70, p < 0.005), and their reductions were associated with the presence of gait disturbance. Therefore, differences in neuronal integrity in the striatum may determine whether patients with WMLs develop VaP or not.

Aged↗
PubMed2006

Prefrontal hypofunction in patients with intractable mesial temporal lobe epilepsy.

We compared the cognitive functions and interictal cerebral glucose metabolism of 11 patients with mesial temporal lobe epilepsy (MTLE) with frequent seizures to those of 10 patients with MTLE with rare seizures; the groups were matched for age, sex, education, IQ, and focus side. The frequent-seizure group had more set-shifting impairment that correlated with glucose hypometabolism in the prefrontal cortices. Our results suggest that frequent seizures in MTLE are associated with hypofunction of the prefrontal cortex.

Adult↗
PubMed2005

Regional cerebral blood flow in Parkinson disease with nonpsychotic visual hallucinations.

BACKGROUND: Patients with Parkinson disease (PD) often experience visual hallucinations (VH) with retained insight (nonpsychotic) but the precise mechanism remains unclear. OBJECTIVE: To clarify which neural substrates participate in nonpsychotic VH in PD, the authors evaluated regional cerebral blood flow (rCBF) changes in patients with PD and VH. METHODS: The authors compared 24 patients with PD who had nonpsychotic VH (hallucinators) and 41 patients with PD who had never experienced VH (non-hallucinators) using SPECT images with N-isopropyl-p-[(123)I]iodoamphetamine. There were no significant differences in age, sex, duration of disease, doses of PD medications, Hoehn and Yahr scale, or Mini-Mental State Examination (MMSE) scores between the two groups. The rCBF data were analyzed using statistical parametric mapping (SPM). RESULTS: The rCBF in the right fusiform gyrus was lower in the hallucinators than in the non-hallucinators (corrected p < 0.05 at cluster levels). The hallucinators revealed higher rCBF in the right superior and middle temporal gyri than the non-hallucinators (uncorrected p < 0.001). These significant differences were demonstrated after MMSE scores and duration of disease, which are the relevant factors associated with VH, were covariated out. CONCLUSIONS: Nonpsychotic visual hallucinations in Parkinson disease (PD) may be associated with hypoperfusion in the right fusiform gyrus and hyperperfusion in the right superior and middle temporal gyri. These temporal regions are important for visual object recognition and these regional cerebral blood flow changes are associated with inappropriate visual processing and are responsible for nonpsychotic visual hallucinations in PD.

Aged↗
PubMed2004

Paroxysmal dysarthria and ataxia after midbrain infarction.

The authors describe a patient who showed paroxysmal dysarthria and right-limb ataxia after midbrain infarction. SPECT imaging showed marked hypoperfusion in the left parietal lobe while the patient was having frequent paroxysmal attacks. After treatment with phenytoin, the symptoms and hypoperfusion in SPECT imaging improved. The authors conclude that dysfunction of the cerebellothalamocortical pathway after midbrain infarction may cause paroxysmal dysarthria and ataxia.

Aged↗
PubMed2004

Decrease in cortical benzodiazepine receptors in symptomatic patients with leukoaraiosis: a positron emission tomography study.

BACKGROUND AND PURPOSE: [11C]flumazenil (FMZ), a ligand that selectively binds to the central benzodiazepine receptor in the neuronal membrane, is useful for evaluating neuronal viability in a positron emission tomography (PET) scan. Using this ligand, we investigated whether there was a correlation between neuronal integrity in various brain structures and dementia in patients with leukoaraiosis. METHODS: Twelve patients with extensive leukoaraiosis on magnetic resonance imaging were divided into groups of patients with or without dementia. Based on a 2-compartment, 2-parameter model that included metabolite-corrected arterial input and PET-measured cerebral radioactivity, the distribution volume of FMZ (FMZ-V(d)) was calculated in various regions of interest by nonlinear curve fitting. Additionally, tracer kinetic analysis was applied for voxel-by-voxel quantification of FMZ-V(d), and data analysis was performed by statistical parametric mapping. RESULTS: The presence of dementia was associated with a reduced FMZ-V(d) in widespread areas of the cerebral cortex, including the bilateral frontopolar and frontal/insular areas, the left temporo-occipital border areas, and the left marginal cortical areas. CONCLUSIONS: Differences in neuronal integrity in the cerebral cortex might determine whether patients with leukoaraiosis become symptomatic or not.

Aged↗
PubMed2003

Mechanical compression of the extracranial vertebral artery during neck rotation.

Using duplex ultrasonography (US), the authors showed compression of the extracranial vertebral artery (ECVA) during neck rotation in 5.0% of 1,108 patients. Age (per 10-year increase, OR 0.80, 95% CI 0.67 to 0.96), vessel diameters (per 0.5-mm diameter increase, OR 0.63, 95% CI 0.51 to 0.79), and symptoms upon neck rotation (OR 4.01, 95% CI 1.35 to 11.9) were associated with vessel compression. In one case, SPECT revealed decreased cerebral perfusion of the hindbrain during rotation. ECVA US is useful in identifying vessel compression, especially in patients with symptoms on neck rotation.

Aged↗
PubMed2002

Effects of iterative reconstruction on image contrast and lesion detection in gamma camera coincidence imaging in lung and breast cancers.

To investigate the effects of iterative reconstruction in 18F-fluorodeoxyglucose (FDG) gamma camera coincidence imaging (GCI), image contrast and visual detection obtained by using the iterative ordered-subsets expectation maximization (OSEM) reconstruction, in a phantom and in patients with lung cancer and breast cancer, were compared with those obtained by using the conventional filtered backprojection (FBP) reconstruction. Images of a cylindrical phantom containing hot spheres of various sizes (10-38 mm) were acquired by positron emission tomography (PET) and GCI at various sphere-to-background activity ratios. Forty-one consecutive patients with biopsy-proven cancer of lung (n = 20) and breast (n = 21) underwent PET and GCI on the same day after intravenous injection of 370 MBq of FDG. GCI images reconstructed by the OSEM and the FBP were compared. FDG PET was considered as the standard of reference. In GCI phantom images, OSEM yielded better contrast and signal-to-noise ratio (SNR) than FBP over the range of sphere sizes. Attenuation correction improved both the image measures and sphere detection obtained by the OSEM in GCI. In the study involving patients, FDG PET depicted 41 primary tumours and 25 metastatic lymph nodes. All of the tumours >2 cm in diameter (n = 25), six of the nine tumours 1.5-2.0 cm in diameter (67%), two of seven tumours <1.5 cm in diameter (29%), and 20 metastatic lymph nodes (80%) were detected in attenuation uncorrected GCI reconstructed by the OSEM as well as the FBP. The undetected lesions in GCI were identical between the OSEM and the FBP reconstructions. OSEM yielded significantly greater tumour-to-background (T/B) ratios and lower noise than FBP in GCI (T/B ratios, 4.1+/-3.2 vs 3.7+/-2.7, P = 0.02; noise, 0.09+/-0.04 vs 0.14+/-0.05, P<0.0001). In conclusion, OSEM yielded better image contrast and less noise than the FBP in GCI, but the lesion detection obtained by the OSEM and the FBP in attenuation uncorrected GCI in patients with lung cancer and breast cancer were similar. Phantom data suggest the potential of OSEM for improving lesion detection in GCI after attenuation correction.

Breast Neoplasms↗
PubMed2001

Feasibility of a short acquisition protocol for whole-body positron emission tomography with fluorine-18 fluorodeoxyglucose.

The conventional protocol for whole-body positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) requires a total acquisition time of 40-60 min, which is inconvenient for many oncological patients owing to fatigue and discomfort. This study examined the feasibility of a short protocol for whole-body PET. A phantom containing six "hot" spheres of gradually increasing diameter (10-38 mm) was imaged using a dedicated PET scanner for 20, 40, 60, 80, 120 and 600 s at various count rates. Thirty-four patients with various neoplasms underwent whole-body emission scans for 1 min per bed position 1 h after intravenous injection of 370 MBq of FDG (short protocol). A standard simultaneous transmission-emission acquisition for 10 min per bed position was performed thereafter. The images were reconstructed using an iterative algorithm. At a count rate of 40 kcps, which is close to the average count rate obtained in a whole-body FDG PET study, the 60-s image visualised five spheres, of which the smallest was 13 mm in size. Despite the better image quality, lesion detection was not improved in images acquired for more than 60 s (80-600 s). Only three of the six spheres could be detected in images acquired for less than 60 s. In the patient study, the standard protocol visualised 120 tumour lesions, of which 93 (78%) could be detected using the short protocol. Among the non-visualised lesions, 22 (82%) were < or =1.5 cm in size and 17 (63%) were lymph nodes. It is concluded that the proposed short protocol for whole-body FDG PET has a reasonably high detection rate and may be suitable for patients who are unable to undergo scanning for a prolonged period. It may also be useful as a pre-scan guide before a standard whole-body acquisition.

Adult↗
PubMed2001

Functional reconstruction of mobile tongue and suprahyoid muscles after resection of cancer of the tongue.

The mobile tongue and the suprahyoid muscles were reconstructed in a man who had had a total resection of the mobile tongue with the oral floor and bilateral radical neck dissection (extensive resection of the bilateral suprahyoid muscles) for cancer of the tongue. A rectus abdominis musculocutaneous flap with the tenth intercostal nerve anastomosed to the remaining hypoglossal nerve was used for the reconstruction. The rectus abdominis muscle was inserted between the mandible and the hyoid bone, taking account of the anatomical positions of the tongue and suprahyoid muscles; the rectus sheath was then firmly sutured to the mandible and hyoid bone. This procedure created firm tendinous insertions between the mandible and hyoid bone. After the operation, the reconstructed tongue showed no sign of atrophy, and the reconstructed supra-hyoid muscles (rectus abdominis muscle) could be moved, and the hyoid bone could be raised.

Carcinoma, Squamous Cell↗
PubMed2001

Functional and aesthetic reconstruction of full-thickness cheek, oral commissure and vermilion.

PURPOSE: This paper presents surgical techniques for reconstruction of the cheek, oral commissure and vermillion in the repair of full-thickness cheek defects after resection of buccal-mucosal squamous cell carcinoma. PATIENTS AND METHODS: Four reconstructions in one-stage surgery with either a free radial forearm flap or a rectus abdominis musculocutaneous flap for cheek and oral commissure were carried out. There were combined with a new approach for vermillion advancement flaps. Most challenging was the need not only for morphological reconstruction of the orifice, but also for physiological reestablishment of sphincteric and sensory functions in the vermillion. RESULTS: Morphological and physiological reconstruction of the lip with sphincteric and sensory functions was attained. CONCLUSION: This valuable reconstruction technique was demonstrated in large, full thickness defects involving the cheek, oral commissure and vermilion.

Aged↗
PubMed2001

Transient crossed cerebellar diaschisis following thalamic hemorrhage.

This report concerns a 65-year-old right-handed woman with cerebral hemorrhage who presented with mild right-sided hemiparesis. Computed tomography (CT) revealed hematoma in the left thalamus and compression of the posterior limb of the internal capsule by a brain edema surrounding the lesion. 99mTc-hexamethylpropyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) images obtained 4 days after onset showed hypoperfusion in the left thalamus containing a hematoma as well as contralateral cerebellar hypoperfusion to the supratentorial lesion, which is well recognized as crossed cerebellar diaschisis (CCD) after stroke. CT 14 days after the onset revealed reduction of the brain edema of the posterior limb of the internal capsule accompanied by gradual neurological improvement. SPECT obtained 14 and 28 days later showed that CCD had disappeared. In this case report, the authors discuss the disappearance of CCD due to transient edematous compression of the internal capsule following thalamic hemorrhage on serial 99mTc-HMPAO SPECT scans. CCD was possibly caused by the lesion confined to the posterior limb of the internal capsule, which anatomically constitutes the cerebropontocerebellar pathway.

Aged↗
PubMed2000

Functional anatomical study of psychogenic amnesia.

Psychogenic amnesia is characterized by an inability to recall information already stored in the patient's memory. It is usually related to a stressful or traumatic event that cannot be explained by manifest brain damage. To examine the underlying functional disturbance of brain areas in this condition, we performed a positron emission tomography (PET) activation study on a psychogenic amnesic patient and on 12 normal control subjects. A task requiring explicit retrograde memory of faces was compared with a control task. To assess functional modifications associated with the processes of recovery, a second PET study was performed on the patient 12 months after onset. During the task, activation of the right anterior medial temporal region including the amygdala was increased in the psychogenic amnesic patient. Activation of the bilateral hippocampal regions increased only in the control subjects. During recovery, the right anterior medial temporal region became less active while the right hippocampal region became more active. Activation levels also differed in the anterior cingulate cortex, prefrontal cortex and some other cortical regions between control subjects and the patient. These findings suggest that the changes in these limbic and limbic-cortical functions are related to symptoms of the psychogenic amnesia.

Adult↗
PubMed2000

Neural plasticity detected in short- and long-term cochlear implant users using PET.

The interaction of listening to words and watching sign language in short-term and long-term cochlear implant (CI) users who have learned sign language after becoming deaf was measured using PET. In short-term CI users the auditory cortex was inactive while in long-term CI users it was fully activated with the simultaneous presentation of auditory and visual input. The result suggests the possibility that the interference of rival modalities may be diminished with experience and the preference switchover from the visual input to the auditory input could be accomplished by means of the neural plasticity persisting in the mature human auditory cortex.

Adolescent↗
PubMed2000

Functional brain areas used for the lifting of objects using a precision grip: a PET study.

Positron emission tomography (PET) was performed in 10 normal volunteers to investigate regional cortical and subcortical activation induced by the lifting of an object repetitively using a precision grip between the index finger and thumb. Data were obtained for three object weights (4, 200 and 600 g) and a resting condition. Grip and lift forces on a similar object and the activity of selected muscles in the hand, arm and shoulder were also recorded in separate lifting trials. A comparison between all movement conditions and the resting condition revealed significant activation of the primary motor (M1), primary sensory (S1), dorso-caudal premotor (PM), caudal supplementary motor (SMA) and cingulate motor (CMA) cortices contralateral to the hand used. On the ipsilateral side, activation of the M1, caudal SMA and inferior parietal cortex (BA 40) was also found. In the subcortical areas, the bilateral hemispheres and right vermis of the cerebellum, left basal ganglia and thalamus were activated. Behavioral adaptation to a heavier object weight was revealed in a nearly proportional increase of both grip and lift forces, prolonged force application period and a higher level of hand and arm muscle activities. An increase in the rCBF associated with these changes was noted in several cortical and subcortical areas. However, consistent object weight-dependent activation was observed only in the M1/S1 contralateral to the hand used.

Adult↗
PubMed2000

The neural basis of perceptual and conceptual word priming--a PET study.

Positron emission tomography scans were obtained in 13 normal subjects during perceptual and conceptual word priming tasks with the aim to investigate the neural system specific to the two priming conditions. In the prescan phase, subjects were primed perceptually or conceptually with two separate procedures, while in the scan phase, they performed the same stem completion task. Therefore we could compare the results of the two priming tasks in a direct manner. A fixation control task and a baseline task (completion of stems that did not correspond to previously seen words) were also given. A specific blood flow decrease was found in the left inferior temporal cortex in the perceptual word priming condition and in the left superior temporal / inferior parietal cortex in the conceptual word priming condition. Each blood flow change may reflect transient changes in the cortical areas subserving the processing of the perceptual and conceptual components of word priming.

Adult↗
PubMed2000

Effect of E5510, a novel antiplatelet agent, on platelet deposition in atherothrombotic lesions: evaluation by 111In platelet scintigraphy.

We evaluated the short-term effects of a novel antiplatelet agent, 4-cyano-5,5-bis(methoxyphenyl)-4-pentenoic acid (E5510), using 111In platelet scintigraphy (PSG) and B-mode ultrasonography (US). Fifteen patients with platelet deposition at either the carotid bifurcation or abdominal aorta on PSG were randomized into two groups: seven were followed without anti-thrombotic medication (Group A) and eight received E5510 (4 mg x day(-1)) (Group B). After 8 weeks, PSG and US were repeated in all patients. Platelet deposition was assessed visually and semi-quantitatively using a platelet accumulation index. Visual analysis showed that seven out of eight patients became negative for platelet deposition after treatment in Group B, while none changed in Group A. The platelet accumulation index of vessels with platelet deposition was significantly reduced after treatment in Group B (12.4+/-3.9% vs 6.0+/-7.1%, p <0.01), while there was no significant change in the vessels without platelet deposition (2.9+/-3.0% vs 2.9+/-4.1%). In Group A, none of the vessels showed any change (8.1+/-6.4% vs 8.9+/-7.3%). However, there was no significant reduction of carotid plaque size in either group. Short-term E5510 therapy inhibited platelet deposition in active atherothrombotic lesions, and the combination of PSG and US was useful for evaluating the effectiveness of anti-thrombotic drugs in vivo.

Aged↗