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F Mihara

Publications and source records attributed to F Mihara.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Clinical experience of image-guided neurosurgery with a frameless navigation system (StealthStation)].

We have applied the frameless navigation system (StealthStation) to various neurosurgical procedures to examine its usefulness. The system consists of a UNIX based workstation that creates triplanar and 3-dimensional images; an infrared optical digitizer with camera array; a reference-light-emitting diode (LED) array (e.g., reference array); and pointer probe modified by the addition of LEDs. This system was used to assist in placing a minimal skin incision and craniotomy in 4 cases, to determine the tumor/brain interface in 2 cases, to target the subcortical lesion in one case, and to correlate bony structure with a skull base tumor in 3 cases. The combined use with magnetic source imaging of the somatosensory cortex allowed a fast orientation of eloquent areas in 2 cases with peri-Rolandic tumor. This system, thus, was proved to be a useful adjunct to open-tumor biopsy or resection.

Adult↗
PubMed1999

[Usefulness of T2* weighted magnetic resonance image in the diagnosis of head injury on chronic stage].

T2* weighted gradient echo image has heightened diagnostic sensitivity to hemorrhage, which is attributed to magnetic susceptibility-induced static field inhomogeneities arising from paramagnetic blood breakdown products such as hemosiderin, which shorten T2*. We examined 4 cases of head injury in chronic stage by T2* weighted images and assessed the clinical application of this sequence for diagnosis of the intracranial lesion. All patients underwent CT scan on acute stage and long-term follow up was performed. In all cases, abnormally low signals in the brain and subarachnoid space were more conspicuous with the T2* weighted image than with any of the conventional sequences. In 2 cases with diffuse axonal injury, of which lesions were not detected on acute stage CT scan, hypointensity area was clearly demonstrated in the cerebral peduncle and corpus callosum on T2* weighted images. Selection of T2* weighted image into the routine MR examination of patients with chronic stage of the head injury is recommended.

Adult↗
PubMed1999

[Schizencephaly: clinical and MRI features].

We report the clinical and neuroimaging features of 4 cases with schizencephaly. Case 1 had bilateral schizencephaly with open-lip on the right and closed-lip on the left. Case 2 had unilateral schizencephaly with closed-lip on the left and subcortical heterotopia on the right. Case 3 had unilateral schizencephaly with closed-lip on the left. Case 4 had bilateral closed-lip schizencephaly. Although all cases except for Case 3 had bilateral lesions, neurodevelopmental outcome was generally good; Case 1 and 3 had mild hemiparesis. All patient have epilepsy which are well-controlled with antiepileptic drugs. Thus, the clinical presentation of schizencephaly, even if bilateral lesions, are quite variable.

Adolescent↗
PubMed1998

Heterogeneity of glucose metabolism in corticobasal degeneration.

A positron emission tomography (PET) study on the regional cerebral glucose metabolism (rCMRglc) was performed in six patients with corticobasal degeneration (CBD). The clinical features included asymmetrical parkinsonism with apraxia, were related to the cerebral cortical and basal ganglionic dysfunction. An MRI study showed all cases to have asymmetrical atrophy in the front-parietal cortex contralateral to the dominantly affected limb; however, no case was pathologically verified. A PET study revealed three cases to have asymmetrical glucose hypometabolism in the parietal lobe and thalamus, which was compatible with the results of previous reports. However, two patients demonstrated symmetrical glucose hypometabolism in the frontal lobe, striatum and parietal lobe while one case had a diffuse hypometabolism, in spite of a marked asymmetry of the neurological findings. These results therefore suggest the heterogeneity of the glucose hypometabolism in CBD based on the PET findings.

Aged↗
PubMed1998

A comparative study of thallium-201 SPET, carbon-11 methionine PET and fluorine-18 fluorodeoxyglucose PET for the differentiation of astrocytic tumours.

Thallium-201, carbon-11 methionine (MET) and fluorine-18 fluorodeoxyglucose (FDG) have all been used to assess brain tumours. The aim of this study was to determine which of these tracers are of use for evaluating the histological grade and the extent of astrocytoma. 201Tl single-photon emission tomography (SPET), MET positron emission tomography (PET) and FDG PET were all performed in 23 patients (13 men, 10 women) with newly diagnosed astrocytic tumours [seven with astrocytoma (grade II), ten with anaplastic astrocytoma (grade III) and six with glioblastoma (grade IV)]. The 201Tl uptake of the tumours was evaluated by a lesion-to-normal region count ratio. Both MET and FDG uptake of the tumours was evaluated by a semiquantitative analysis using the standardized uptake value. 201Tl uptake was found to increase in rank order with histological grade and was significantly different among the three groups (grade II: 1.51+/-0.36; grade III: 2.58+/-1.50; grade IV: 7. 65+/-3.84). MET uptake in grade II (1.49+/-0.44) was also significantly lower than that in both grade III (3.29+/-1.44) and grade IV (3.20+/-0.92). FDG uptake was not significantly different among the three groups (grade II: 2.90+/-0.45; grade III: 3.86+/-1. 56; grade IV: 3.57+/-0.83). No significant correlation was observed between 201Tl uptake and either MET uptake or FDG uptake. In most patients, the extent of the increased MET uptake was the largest while that of the increased FDG uptake was the smallest. In patients with positive 201Tl uptake, the extent of the 201Tl uptake was equal to or smaller than that of gadolinium enhancement. For evaluation of histological grade of astrocytic tumours. 201Tl is therefore considered to be useful though the 201Tl uptake in some grade III astrocytomas was not different from that in grade II astrocytomas. MET was found to be highly useful for detecting astrocytomas, for differentiating between benign and malignant astrocytomas, and for evaluating the extent of astrocytomas; however, it was not sufficiently useful permit evaluation of the histological grade. FDG was not found to be useful either for evaluating the histological grade or for differentiating between benign and malignant astrocytomas.

Astrocytoma↗
PubMed1998

[Efficacy of the fluid attenuated inversion recovery (FLAIR) sequence of MRI as a preoperative diagnosis of hippocampal sclerosis].

A newly advanced MRI pulse sequence, the FLAIR (fluid attenuated inversion recovery) imaging, in which a long TE spin echo sequence is used with suppression of the CSF with an inversion pulse, displays the CSF space as a no-signal intensity area. There have been only a few reports on the FLAIR pulse sequence of temporal lobe epilepsy (TLE) as yet. We examined 9 cases of intractable TLE by FLAIR images and analyzed the advantages and disadvantages of the FLAIR pulse sequence for decision making on temporal lobectomy. All patients underwent anterior temporal lobectomy with hippocampectomy, and the diagnoses were confirmed histologically after surgery. Abnormally high T2 signals (HT2S) were more conspicuous with the FLAIR sequence than with any of the conventional sequences. Tilted axial plane, orientated along to the long axis of the hippocampal body, clearly demonstrated hippocampal atrophy (HA). Selection of a FLAIR sequence into the routine MR examination of patients with TLE is recommended.

Adolescent↗
PubMed1997

Neural networks analysis of astrocytic gliomas from MRI appearances.

A three-layered backpropagation neural network was developed to differentiate malignant from benign brain tumors in a group of patients with astrocytic gliomas. The MRI findings of 43 patients were reviewed before biopsy by three neuroradiologists independently. This provided a database made up of 129 patients' records each of which comprised 13 parameters derived from pre- and post-contrast MR images. The network's generalizing ability was then tested to predict the outcome of biopsy in 36 new cases and its performance compared to that of radiologist using ROC analysis. The output of the network with and without radiologists' impression yielded a better diagnostic performance with relative ROC areas of 0.94 and 0.91, respectively; compared to 0.84 obtained by radiologist. These results demonstrate that the neural network can effectively differentiate malignant from benign brain tumors.

Algorithms↗
PubMed1997

Increased activity of the ipsilateral motor cortex during a hand motor task in patients with brain tumor and paresis.

PURPOSE: To look for changes in the motor cortex in patients with brain tumors. METHODS: Both cerebral hemispheres in seven patients with brain tumors were examined with functional MR imaging during a motor task performed by the hand opposite the site of tumor. The ratio of the activated area in the motor cortex ipsilateral/contralateral to the tested hand was calculated for each subject. Twenty healthy subjects were also examined in the same manner for comparison. RESULTS: The ratio of the ipsilateral/contralateral activated area was abnormally high in three patients with tumor-related paresis of the tested hand. The ratio was significantly greater in patients with paresis than in healthy subjects. CONCLUSION: This study demonstrated increased activity in the ipsilateral (unaffected) motor area during a hand motor task in patients with brain tumor and paresis, which was thought to reflect compensatory reorganization induced by the functional damage.

Adult↗
PubMed1996

Contrast-enhanced MRI in spinal arteriovenous malformations and fistulae before and after embolisation therapy.

MRI was performed in six cases of spinal arteriovenous malformation (AVM) and arteriovenous fistula (AVF) before and after embolisation. Intramedullary and perimedullary AVMs showed marked vascular enhancement after embolisation. This was thought to reflect feeding vessel occlusion and correlated well with a favourable clinical outcome. In dural AVFs, contrast-enhanced studies were essential for the diagnosis, unenhanced images being nonspecific. After embolisation, enhancement of the spinal cord was reduced, although one case with a poor outcome showed persistent enhancement.

Adult↗
PubMed1996

Type D dural carotid-cavernous fistula. Results of combined treatment with irradiation and particulate embolization.

PURPOSE: To assess the efficacy of irradiation combined with particulate embolization for treating type D dural carotid-cavernous fistulas, supplied by the meningeal branches of both external (ECA) and internal carotid arteries. MATERIAL AND METHODS: Nine patients were treated by particulate embolization via the ECA branches, followed by radiation therapy with doses of 30 Gy. One of these patients with recurrent symptoms received an additional 30 Gy one year after initial treatment, making a total dose of 60 Gy. RESULTS: In all cases, symptoms were improved immediately after the particulate embolizations. In 8 cases, complete resolution of symptoms were obtained in 4-19 months and an average of 8 months after treatment. In one case, chemosis was markedly improved and persisted minimally 41 months later. CONCLUSION: Particulate embolization is effective for immediate symptomatic improvement, and complete resolution of symptoms can usually be achieved by subsequent radiation therapy.

Aged↗
PubMed1996

[Diagnostic value of high N-isopropyl-p-[123I] iodoamphetamine (IMP) uptake in brain tumors].

The diagnostic value of high N-isopropyl-p-[123I] iodoamphetamine (123I-IMP) uptake in histologically proven intracranial tumors was evaluated in 54 patients with both early (15-35 min after injection) and delayed (4 hours) SPECT before treatment. Higher uptake in the tumor compared with normal cerebral cortex was observed in early scans in all of the five patients with primary intracranial malignant lymphoma, in two of 16 meningiomas, two of seven astrocytomas, one of three pituitary adenomas, and one central neurocytoma. Among these 11 cases all the malignant lymphomas showed persistent high uptake in delayed scans, whereas other tumors showed decreased uptake in delayed scans. This persistent high 123I-IMP uptake was characteristic of primary intracranial malignant lymphomas and was useful in the diagnosis of intracranial malignant lymphoma.

Adult↗
PubMed1995

MRI of silicone vitreous ocular implants with phantom correlation.

We imaged two patients who had silicone oil injected their vitreous cavities. The images demonstrated an increased chemical shift artifact. We developed and tested an in vitro silicone oil model in an attempt to explain this. To our knowledge, this artifact has not been previously described. We constructed a phantom using medication cups containing water, lard and two types of silicone. Background control baths of water and lard were used to simulate different local environments. The phantoms were imaged with T1-and T2-weighted and T1-weighted fat suppression sequences. The artifacts were due to the pronounced chemical shift of silicone in relation to intraconal fat. Our model accurately reproduced our clinical images. Spectral analysis of the silicone model revealed different resonating frequencies for fat/silicone, thereby explaining the pronounced chemical shift artifact.

Artifacts↗
PubMed1995

Assessment of MRI criteria for MS in Japanese MS and HAM/TSP.

We evaluated the usefulness of the MRI criteria for multiple sclerosis (MS) proposed by Paty et al and Fazekas et al in 36 Japanese MS patients, using HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP) as the control. Although 30 of 36 HAM/TSP patients had multiple white matter lesions on T2-weighted cranial MRI, only two fulfilled the MRI criteria for MS. At the same time, 31 of the 36 MS patients fulfilled the primary MRI criterion, yielding 93% specificity and 86% sensitivity for the criterion. MS has disease-specific MRI abnormalities.

Brain↗
PubMed1995

[A case of multiple cranial neuropathy due to varicella-zoster virus infection: detection of involvement of cranial ganglia with MRI].

We describe here a 50-year-old patient who had multiple cranial nerve palsies (lt.VIII,IX,X,XI and rt.VII, IX,X) with varicella-zoster virus (VZV). He developed hoarseness, dysphagia on 30th, November, 1994. On the 8th day after the onset, he suffered from left tinnitus and left facial nerve palsy. Neurological examination on the 10th day revealed left peripheral facial nerve palsy, lt. vocal cord palsy, mild dysphagia and loss of bilateral taste. He did not show signs of meningeal irritation. On the 11th day, he felt vertigo and had horizontal nystagmus on the right lateral gaze. The cerebrospinal fluid findings revealed increased protein content but not pleocytosis. The antibody titer for varicella zoster virus elevated both in cerebrospinal fluid and in serum. Cranial magnetic resonance imaging (MRI) revealed gadlinium enhancement on the left geniculate ganglion and left superior or inferior ganglion of IX and X nerves, indicating that multiple cranial nerve palsies associated with VZV infection originate in the cranial ganglia. Focal brainstem encephalitis does not seem to be the main cause of multiple cranial neuropathy in this case.

Cranial Nerve Diseases↗
PubMed1994

Ultrasonographic abdominal screening of atomic bomb-exposed subjects.

Abdominal ultrasonographic screening for cancer was performed in 6,001 Hiroshima and Nagasaki A-bomb exposed and comparison subjects, all members of the Adult Health Study of the Radiation Effects Research Foundation, formerly the Atomic Bomb Casualty Commission. This study yielded 20 cancers, including 7 hepatocellular, 3 gastric, 3 renal and 2 urinary bladder cancers; one cancer each of the ovary, pancreas, colon and ureter; and one cancer metastatic to the liver, whose primary was unknown. Seventeen of these 20 subjects manifested no symptoms or signs of their disease. A variety of additional tumors, unproven and probably benign, including uterine myomata, and other abnormalities were also detected. Abdominal ultrasonographic screening greatly assisted in the detection of cancers, most of which neither the patients nor their physicians were aware. In this screened fixed population sample the cancer detection rate was 0.33%, exceeding any such rates previously reported in the medical literature.

Abdominal Neoplasms↗
PubMed1993

Spinal epidural abscess: evaluation with gadolinium-enhanced MR imaging.

Magnetic resonance (MR) imaging with gadopentetate dimeglumine was performed in 25 patients with spinal epidural abscess (SEA). Seventeen of 25 patients underwent follow-up MR imaging. The studies were retrospectively reviewed. In 20 patients, diskitis was the primary infectious foci; however, five patients developed diffuse SEA without diskitis. The two most common MR appearances were (a) homogeneous or heterogeneous enhancement of the solid portion of the SEA and (b) thin or thick enhancement around the liquefied collections of pus. Dural enhancement was frequently seen in patients with lengthy vertebral involvement of SEA. Engorgement of the epidural venous plexus or basivertebral veins was occasionally observed. The changes in abscess size noted on follow-up studies correlated well with clinical improvement or deterioration in most patients. Persistent contrast enhancement, however, was frequently noted at the site of diskitis, osteomyelitis, or surgical drainage sites despite clinical improvement. Careful correlation of MR imaging findings with clinical findings and laboratory data is important in predicting prognosis for these patients.

Abscess↗
PubMed1993

Normal age-related alterations on chest radiography. A longitudinal investigation.

To ascertain serial changes on chest radiography attributable to aging, 16 parameters and 4 pulmonary parenchymal manifestations were assessed at 2 intervals; namely, 18.5 and 10 years after initial radiography in healthy men (n = 51) and women (n = 149) (age range 41-82 years). The transverse cardiac diameter, cardiothoracic ratio, and aortic arch transverse diameter increased significantly in both sexes from the initial to the final examinations. Although several other factors changed significantly, these changes were relatively small and the individual variations large. Initially, 13% and finally, 27% of the subjects exhibited at least one of the selected pulmonary manifestations.

Adult↗