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Biomedical subjects

T Yoshimine

Publications and source records attributed to T Yoshimine.

At least 109 records · Page 6Linked to original sources
PubMed1998

Spatial perception in macroscopic and microscopic surgical manipulations: differences between experienced and inexperienced surgeons.

The spatial perceptions of the phantom surgical field with the naked eye and under the surgical microscope were analyzed in a group of experienced and a group of inexperienced neurosurgeons. The phantom surgical field contained a start point, a virtual gate, and a target point. The virtual gate was an invisible zone arbitrarily set in the phantom surgical field. The examinees were first instructed regarding the position of the invisible virtual gate. Then they were asked to point consecutively to the three points with a suction tube under three different circumstances: with the naked eye, under the microscope, and by watching a navigation monitor. A surgical navigator was used to record the three-dimensional position of the suction tip. The pointing deviation from the suction tip to the center of the virtual gate was evaluated. The pointing accuracy with the naked eye did not differ between the two groups, but that under the microscope was significantly better in the experienced group than in the inexperienced group. Fluctuations in pointing deviation were significantly greater in the inexperienced neurosurgeons, especially with the microscope. Further analysis demonstrated that these differences were attributable to poorer depth perception of the phantom surgical space among the inexperienced neurosurgeons.

Clinical Competence↗
PubMed1998

A peritoneal marker for optimal timing of ventriculo-peritoneal shunt revision in early childhood.

The ventriculo-peritoneal shunt placed in a neonate or infant needs revision to lengthen the peritoneal tube at certain times during childhood. The critical time for this revision is not exactly the same between individuals. Furthermore, the level of peritoneal insertion of the shunt tube is often unclear on x-ray films. To plan for and determine the optimal timing of revision, we applied a titanium clip on the peritoneal suture line in three infants as a marker of peritoneal insertion level. During the 31- to 37-month follow-up period, abdominal x-ray clearly demonstrated the peritoneal insertion level in all three patients, allowing accurate determination of the length of the intraperitoneal portion (i.p.) of the shunt tube. The rate of shortening of the length of i.p was 20 to 27% of the increase in body height (BH). This technique allows accurate determination of the length of i.p. and also optimal timing for revision.

Body Height↗
PubMed1998

Translucence stereoscopy of interictal magnetoencephalographic epileptiform discharge.

We have developed a translucence stereoscopy method for displaying the distribution of multiple interictal epileptiform discharges within the intracranial space. The epileptiform discharges, measured using a whole-head magnetoencephalography system, were modeled by a least-squares method to obtain the equivalent current dipoles. The dipoles were located in the stereo pair of intracranial images composed of translucent brain slices at several selected levels. The technique demonstrated clearly the distribution of interictal dipoles within the brain in three patients. Three dimensional understanding of the intracranial distribution of multiple dipoles in one image is valuable in analyzing the intracerebral neurophysiological events in epileptic patients.

Adult↗
PubMed1998

Chromosomal losses and gains in meningiomas: comparative genomic hybridization (CGH) study of the whole genome.

We investigated chromosomal aberrations in meningiomas using newly developed comparative genomic hybridization (CGH) technique and compared the results with the proliferating potential of the tumors. This technique permits the entire genome to be surveyed in one session of experiments. Our results revealed chromosomal aberrations in 5 out of 10 (50%) of the tumor samples studied. Losses of the distal parts of chromosome 1p (5 out of 10) and 22q (3 out of 10) were the two most frequent chromosomal aberrations. Losses and/or gains in other regions were only sporadic. The MIB-1 staining indices (MIB-SI, %) were 1.9 +/- 0.9% (mean +/- SD) in benign (n = 8), 4.5% in atypical (n = 1), and 11.7% in anaplastic (n = 1) meningiomas. The comparison of MIB-SI between the tumors with (2.3 +/- 0.6%) and without (1.6 +/- 0.3%) chromosomal aberrations demonstrated a trend towards an increased MIB-SI in meningiomas with chromosomal aberrations (p < 0.07) by unpaired Student's t-test. This study suggests that alterations in chromosomes 1p and 22q could be a primary focus of further detailed assessment of tumorigenesis and in understanding the biological behavior of meningiomas.

Adolescent↗
PubMed1998

Mobile fluoroscopic open stereotaxy for MRI-negative angiographic microlesions.

The approach to the deep-seated angiographic microlesion is often difficult, particularly when it is not demonstrated by computed tomography (CT) or magnetic resonance imaging (MRI). We have developed a method to localize these lesions for open stereotactic surgery employing mobile fluoroscopy. Prior to craniotomy, the patient's head is fixed in a stereotactic frame in a position optimal for the routine microscopic surgery. Following the injection of contrast media, the location of the lesion is marked on the fluoroscope monitor. Under fluoroscopic control, the scalp is marked using radiopaque pointer on each side of the patient's head so that the scalp marks and the target lesion overlap each other on the fluoroscope monitor. Thus the imaginary line connecting these scalp marks passes through the lesion. An additional pair of scalp marks is obtained by changing the projection angle of the fluoroscope. By simple calculation, the coordinates of the lesion are obtained as the nearest point to these two imaginary lines, each of which connects a pair of scalp marks. After craniotomy, the lesion is approached using an open stereotactic technique. The first patient had an aneurysm 1.5 mm in diameter that arose from the feeder of the arteriovenous malformation. The second patient had a small residual nidus of arteriovenous malformation 1.5 cm in diameter in the deep frontal lobe, not recognizable by CT or MRI because of artifacts from a previous surgery. Both patients were successfully operated by employing the present method. This method requires only a conventional stereotactic frame and a mobile fluoroscope, and provides simple and reliable localization of the small lesions recognizable only by cerebral angiography.

Arteriovenous Malformations↗
PubMed1998

Direct ethanol injection for skull metastasis from hepatocellular carcinoma. The techniques and consequences of a therapeutic trial.

The frequency of skull metastasis from hepatocellular carcinoma (HCC) is increasing together with the recent progress in the management of the primary lesion. Cases are often complicated with poor general conditions or metastasis to the other organs, and not readily indicated for surgery. A direct injection of ethanol to the lesion could be one of the therapeutic options to cope with this complicated situation. To evaluate the feasibility of this technique, we planned a therapeutic trial in a patient with HCC associated with lumbar and skull metastasis, the latter metastasis repeated twice during the past one year. A total of 10 ml of ethanol was injected into the skull metastasis percutaneously under ultrasound (US) guidance. US guidance was very useful in determining the sites of injections and the distribution of ethanol as well as monitoring the blood flow within the tumor vessels. The patient transiently complained of local pain at the injection sites, but there were no other adverse effects. Four days after the injection, the lesion was resected by surgery, which confirmed the pathologic diagnosis as well as the nearly-total necrosis of the tumor. This technique is simple, safe and repeatable with low cost. The technical details and the histologic effects are described.

Aged↗
PubMed1998

Computerized tomography angiography of ruptured cerebral aneurysms: factors affecting time to maximum contrast concentration.

OBJECT: This study was conducted to assess the diagnostic value of three-dimensional computerized tomography (3-D CT) angiography in demonstrating cerebral aneurysms in 42 consecutive patients presenting with acute subarachnoid hemorrhage (SAH). METHODS: To obtain the volume data for selective visualization of the cerebral arteries without enhancement of the venous system, the time delay was established between the injection of contrast medium and the start of scanning by using two different methods. The circulation time was calculated with Schad's formula in the first 13 cases, but the results were not satisfactory. In the 29 subsequent cases the time delay was established using a single-level dynamic CT prescan. The dynamic prescan demonstrated the statistical differences in peak time with regard to patient age, SAH grade, and the postresuscitation state after cardiopulmonary arrest. The 3-D CT angiograms were generated from the volume data by using a voxel transmission method. Computerized tomography angiography obtained after optimally adjusted time delay demonstrated the contour of the cerebral arteries in 97% of cases, and aneurysms were detected in 93%. Enhancement of the cavernous sinus and major cortical veins was avoided. Even in patients who suffered cardiopulmonary arrest, images of the major arteries were clearly demonstrated after resuscitation. CONCLUSIONS: In an emergency situation, CT angiography with a dynamic prescan may be an alternative to magnetic resonance angiography or digital subtraction angiography in the diagnosis of ruptured aneurysms. This modality would also be useful for the precise assessment of small aneurysms, blebs, and aneurysms adjacent to the cavernous sinus.

Adult↗
PubMed1998

[Discrepancy between surgeon's binocular parallax perception and manipulation in the neurosurgical operation].

The application of virtual reality (VR) to the neurosurgical field has been increasing recently, however, the relation between the surgeon and the VR environment is rarely studied. We examined the trajectory of a surgical instrument during manipulation of a virtual object using a video-see-through microscope and a neurosurgical navigator (CANS Navigator) to find better surgeon-microscope interface. A resin cylindrical phantom was produced representing the surgical field, which included two 3 dimensionally arranged small spheres and a virtual 'gate'. The phantom was fixed and set under the microscope with a skull clamp mimicking conditions in an ordinary craniotomy. Firstly, the binocular parallax perception under microscope was examined. Experienced and inexperienced neurosurgeons were asked to learn the position of the virtual 'gate' for 3 minutes. Then, after 5 minutes to point with the navigator probe (suction tube), under various conditions; under the naked eyes, under the microscope, under the navigator without observing the phantom, and under the microscope with picture in picture (PIP) display of the navigational image. The positions of the suction tube were recorded at real time into the navigator for later analysis. Secondly, the task performance in this VR environment was studied by analyzing the trajectory of the suction tube from one sphere to the other sphere passing the virtual 'gate' under various conditions. A significant difference in pointing precision between experienced and inexperienced neurosurgeons was able to be observed only under microscope. This difference was mainly derived from overestimation of the depth of the virtual 'gate' by the inexperienced neurosurgeons. Among the above conditions, pointing under the microscope with PIP was able to be performed the most precisely and the most promptly. This study disclosed the presence of stereoscopic distortion in the microscope. The PIP display of the navigational image in the microscopic view remarkably improved the task performance, which could be accounted for by the correction of the somewhat distorted binocular parallax perception under the neurosurgical microscope by the provision of another visual key.

Brain↗
PubMed1998

Scalp localization using a simple algorithm.

We have developed a simple algorithm for scalp localization for craniotomy. Using a series of CT/MRI data, the point on the scalp closest to the center of the lesion (T) is determined by our program. A plane (plane R) is defined by three points: bilateral auditory meati and T. Point S is the intersection of three planes: the plane R, the scalp surface and the midsagittal plane. The distance from either S or the ipsilateral external auditory meatus to T is measured along the scalp surface on the plane R. The distance from the nasion to S along the scalp surface on the midsagittal plane is also measured. To determine the craniotomy site, these distances are measured directly on a patient's scalp in the operating room. This simple and accurate method for scalp localization could be used by installing our program in conventional CT/MR scanners.

Aged↗
PubMed1997

A case of giant cell reparative granuloma of the petrous bone: demonstration of the proliferative component.

BACKGROUND: Giant cell reparative granuloma (GCRG) is an uncommon benign lesion of the bone. It typically arises in the mandible and rarely involves the skull. The cytologic nature and genesis of the involved cells are poorly understood. METHODS AND RESULTS: We report a case of GCRG in the petrous bone of a 3-year-old girl. One year following gross total removal, the granuloma recurred locally and was resected en bloc at the second surgery. Histologically, the lesion was composed of oval or spindle-shaped stroma cells admixed with a number of multinucleated giant cells. Immunohistochemical study demonstrated that 5.6% of the stroma cells, but none of the multinucleated giant cells, were positive for MIB-1 antibody. CONCLUSION: These results suggest that this lesion expands by proliferation of the stromal component, with a growth rate roughly between those of the typical benign and malignant brain tumors. The cytologic nature of the cells comprising this uncommon disease remains to be elucidated.

Child, Preschool↗
PubMed1997

Topical application of fibrin adhesive in the rat brain: effects on different cellular elements of the wound.

Although fibrin adhesives are popular in the field of neurosurgery, the medical literature is devoid of study elucidating their effects on the brain tissue. To study the safety of applying fibrin glue to the brain and to explore new surgical potentialities, we implanted soft pellets made of fibrin glue into the brains of Wistar rat. Following 6 h and 3, 7 and 14 days post-implantation survival, the brains were removed and paraffin sections were processed for hematoxylin-eosin staining, as well as immunohistochemistry for microtubule-associated protein (MAP-1A) and glial fibrillary acidic protein. The changes in the neuronal and glial elements and also the numbers of inflammatory and endothelial cells in the vicinity of implanted fibrin glue pellets were compared with those of gelfilm pellets. The results demonstrated that topical application of fibrin glue to the brain causes significantly enhanced local accumulation of mononuclear cells and promoted angiogenesis close to the wound while not affecting the neuronal and glial elements. These findings suggest that fibrin glue can be considered as a safe supportive material for intradural procedures directly involving the brain tissue.

Adhesives↗
PubMed1997

Computer-assisted surgical planning for cerebrovascular neurosurgery.

OBJECTIVE: We used three-dimensional reconstructed magnetic resonance images for planning the operations of 16 patients with various cerebrovascular diseases. We studied the cases of these patients to determine the advantages and current limitations of our computer-assisted surgical planning system as it applies to the treatment of vascular lesions. METHODS: Magnetic resonance angiograms or thin slice gradient echo magnetic resonance images were processed for three-dimensional reconstruction. The segmentation, based on the signal intensities and voxel connectivity, separated each anatomic structure of interest, such as the brain, vessels, and skin. A three-dimensional model was then reconstructed by surface rendering. This three-dimensional model could be colored, made translucent, and interactively rotated by a mouse-controlled cursor on a workstation display. In addition, a three-dimensional blood flow analysis was performed, if necessary. The three-dimensional model was used to assist in three stages of surgical planning, as follows: 1) to choose the best method of intervention, 2) to evaluate surgical risk, 3) to select a surgical approach, and 4) to localize lesions. RESULTS: The generation of three-dimensional models allows visualization of pathological anatomy and its relationship to adjacent normal structures, accurate lesion volume determination, and preoperative computer-assisted visualization of alternative surgical approaches. CONCLUSION: Computer-assisted surgical planning is useful for patients with cerebrovascular disease at various stages of treatment. Lesion identification, therapeutic and surgical option planning, and intraoperative localization are all enhanced with these techniques.

Adolescent↗
PubMed1997

Chromosome 22q allelic losses at microsatellite loci in human astrocytic tumors.

Common regions of deletion(s) on chromosome 22q and the correlations between loss of heterozygosity and patient survival were analysed in 18 deoxyribonucleic acid samples from astrocytic tumors (3 astrocytomas, 5 anaplastic astrocytomas, and 11 glioblastomas) and matched normal brain tissues. The polymerase chain reaction products using five microsatellite markers were electrophoresed on polyacrylamide gels and the ethidium bromide stained bands were photographed. Loss of heterozygosity was observed in 14 (74%) of 19 samples, with similar incidences in astrocytomas, anaplastic astrocytomas, and glioblastomas (67%, 80%, and 82%, respectively). The locus D22S300 (q12.1-q13.1) was most frequently involved, with loss of heterozygosity in eight (80%) of 10 informative glioblastomas at this locus. Increased loss of heterozygosity during tumor progression or recurrence was seen in two patients at the D22S300 (q12.1-q13.1) and TOP1P2 (q11.2-q13.1) loci. No correlation between loss of heterozygosity on chromosome 22 and the postoperative survival was found. These findings suggest that loss of heterozygosity on chromosome 22q probably occurs quite frequently in astrocytic tumors. The chromosome segment 22q12.1-q13.1, around the D22S300 locus, may be the common region of deletion in glioblastomas.

Adult↗
PubMed1997

Single solitary metastasis of the slowly progressive type of renal cell carcinoma to the choroid plexus--case report.

A 68-year-old male developed a solitary metastasis in the choroid plexus of the right lateral ventricle 7 years after left nephrectomy for renal cell carcinoma. The lesion was totally removed and the patient has been free from recurrence for 30 months postoperatively. Pure solitary metastasis to the choroid plexus is very rare, but five of the 15 cases originated from renal cell carcinoma. There may be a link between this type of metastasis and the slowly progressive type of renal cell carcinoma.

Aged↗
PubMed1997

[Localization of epileptogenic foci and visualization of propagating process in the seizure discharges using crosscorrelation analysis].

Electrocorticogram (ECoG) of intractable focal epilepsy was analyzed using AR model, wavelet analysis and crosscorrelation analysis. The sequential 3-dimensional visualization technique of phase shift maps was developed to localize the epileptic foci and to study their propagation process. The crosscorrelation of the epileptic discharges was calculated between the electrodes in every unit of time, to get the phase shift. More than two epileptogenic foci were localized and two kinds of propagating process were shown. These findings suggest that two kinds of mechanism might work in development of epileptic discharges, and our newly developed visualization technique is useful to investigate the epileptogenesis etiology.

Brain Mapping↗
PubMed1996

Hypothermia suppresses nitric oxide elevation during reperfusion after focal cerebral ischemia in rats.

We aimed to investigate effect of temperature on the jugular levels of nitric oxide (NO) at reperfusion after focal cerebral ischemia. Both nitrosyl hemoglobin (HbNO) (2.5 +/- 0.4 microM) and plasma nitrite plus nitrate levels (61 +/- 5 microM) in rats under normothermia (approximately 37 degrees C) after 30 min of reperfusion following 2 h of left middle cerebral artery occlusion were significantly high, compared with sham operated rats (1.3 +/- 0.1 microM, 40 +/- 4 microM, respectively). Both HbNO (1.5 +/- 0.3 microM) and nitrite plus nitrate levels (43 +/- 7 microM) under moderate hypothermia (approximately 32 degrees C) were significantly low, compared with normothermic rats. HbNO (2.8 +/- 0.8 microM) and nitrite plus nitrate levels (65 +/- 8 microM) under mild hyperthermia (approximately 39 degrees C) were not significantly high. These results firstly demonstrated that hypothermia suppresses the elevation in intrajugular NO after cerebral ischemia-reperfusion.

Animals↗
PubMed1996

Loss of heterozygosity of microsatellite loci on chromosome 9p in astrocytic tumors and its prognostic implications.

We analyzed 19 samples of various astrocytic tumors (3 astrocytomas, 5 anaplastic astrocytomas, and 11 glioblastomas) for loss of heterozygosity (LOH) on chromosome 9p at 6 microsatellite loci (D9S54, IFNA, D9S171, D9S104, D9S165, and D9S166). Polymerase chain reaction was performed and the products were electrophoresed on polyacrylamide gel. As many as 16 of the 19 samples (84%) exhibited LOH. Three of the 7 informative loci (43%) showed LOH at D9S54, 7 of 17 (41%) at IFNA, 8 of 14 (57%) at D9S171, 7 of 14 (50%) at D9S104, 4 of 8 (50%) at D9S165, and 2 of 7 (29%) at D9S166. LOH was recognized in 57% of the informative loci in anaplastic astrocytomas and 54% in glioblastomas, while it was seen in only 8% of the astrocytomas. Accumulation of LOH with progression or recurrence of tumor was seen in 2 patients. Although, the survival period of the patients correlated well to the histological types of astrocytic tumors, we could not find any obvious correlations between the presence/absence of LOH and the survival period in these patients. In conclusion, we speculate that LOH on chromosome 9p is involved in malignant progression of astrocytomas, but has no significance in predicting survival period in these patients.

Adult↗