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Biomedical subjects

Yoshihiro Muragaki

Publications and source records attributed to Yoshihiro Muragaki.

17 recordsLinked to original sources
PubMed2026

Leptomeningeal Dissemination in TERT Promoter-mutant Anaplastic Pleomorphic Xanthoastrocytoma Responding to BRAF-MEK Inhibition: A Case Report.

Pleomorphic xanthoastrocytoma is a rare brain tumor that frequently harbors the oncogenic BRAF V600E mutation. Approximately 28.6%-47% of high-grade pleomorphic xanthoastrocytomas are associated with TERT promoter mutation and leptomeningeal dissemination, for which no established treatment exists and the prognosis remains poor. Combination therapy with BRAF and MEK inhibitors has demonstrated efficacy in BRAF V600E-mutant brain tumors. We report a case of a 22-year-old man with a right temporal lobe tumor initially diagnosed as World Health Organization grade 2 pleomorphic xanthoastrocytoma after gross total resection. Two years later, the tumor recurred and underwent malignant transformation to World Health Organization grade 3 pleomorphic xanthoastrocytoma. At the third resection, pathological and genomic analyses confirmed BRAF V600E mutation together with TERT promoter mutation. Following chemoradiotherapy, spinal leptomeningeal dissemination developed. After spinal irradiation, dabrafenib plus trametinib was initiated, resulting in partial radiological response and symptomatic improvement. Although regrowth occurred 10 months after initiation of targeted therapy, the patient remains alive at the time of writing. Here, we report a case of recurrent anaplastic BRAF V600E-mutant pleomorphic xanthoastrocytoma with leptomeningeal dissemination that showed a transient but clinically meaningful response to combined BRAF-MEK inhibition and spinal radiation therapy. In addition, this case raises the possibility of an association between TERT promoter mutation and leptomeningeal dissemination, although further studies are required to clarify this relationship.

BRAF V600E↗
PubMed2007

[Information guided technology and procedure in neurosurgical field].

Translational Research is the research to apply and mediate a fundamental research result to the clinical field effectively. The integration of the diagnosis and the treatment is an important item in the life science field from the viewpoint of quality of therapy and minimally invasive therapy. The standardization of mechanical interface of the medicine related machine, system and a medical information system are important from the viewpoint such as prevention of medical malpractice. A high function operating robot (manipulator) as an endoscopic robot and image-guided minimally invasive device are important in the point of view of the development of a medical device shown with a medical device industry vision. We describe an outline of our ongoing development of endoscope system, intraoperative MRI (intelligent operating theater) and robot surgery system in neurosurgical field.

Humans↗
PubMed2006

New radiofrequency coil integrated with a stereotactic frame for intraoperative MRI-controlled stereotactically guided brain surgery.

Mislocalization errors caused by MR image distortions or brain shift are one of the main causes of complications after stereotactically guided neurosurgical procedures. A special device, which could ameliorate such effects and provide intraoperative acquisition of MR images of sufficient diagnostic accuracy, was developed. It is composed of a radiofrequency receiver coil integrated with a modified Komai stereotactic frame and a Sugita four-pin head holder. Clinical testing revealed that the use of the device during stereotactically guided procedures under the control of low magnetic field strength (0.3 T) intraoperative MRI ameliorates the effects of brain shift, and permits to obtain informative tissue samples and to perform aggressive removal of the lesion without any damage of the eloquent cerebral structures. The possibility of an easy shift from a stereotactically guided to a routine microneurosurgical procedure represents an additional benefit of the developed device.

Adolescent↗
PubMed2006

Three-way bipolar forceps: a novel bipolar coagulator system for nerve stimulation and detection of nerve potentials.

Preoperative characterization of brain anatomy by magnetic resonance imaging and intraoperative functional characterization of the nervous system is essential in patients undergoing radical resection of brain tumors. A novel integrated system was developed combining conventional bipolar forceps with an electric stimulator and an oscilloscope. The system consists of a mechanical switching circuit allowing a wide range of electric characteristics and was designed to perform intraoperative electrophysiological studies, including functional mapping and measurements of motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs). This system achieved a significant reduction in exchange time (from 3.63+/-1.00 sec to 1.12+/-0.42 sec) between coagulation and stimulation, and reproducible measurement of MEPs from porcine limbs by cortical stimulation using the bipolar forceps. Functional mapping under awake craniotomy was carried out by cortical stimulation in patients with glioblastoma, and median nerve SEPs with high signal-to-noise ratio were elicited from the bipolar forceps on the sensory cortex of patients under general anesthesia. This integrated system is technically easy to operate and allows functional monitoring of an area that would otherwise be difficult to access using conventional methods. This three-way bipolar forceps system may reduce postoperative complications in patients undergoing neurosurgical procedures.

Adult↗
PubMed2005

Large facial nerve schwannomas without facial palsy: case reports and review of the literature.

Although approximately 30% of facial nerve schwannoma cases present with no facial palsy, a large facial nerve schwannoma extending to the middle and posterior cranial fossa quite rarely presents without facial palsy. The authors encountered two patients with large facial nerve schwannoma who presented with only hearing impairment and no facial palsy. The first patient was a 64-year-old woman who presented with right auditory impairment without facial palsy. MR images demonstrated a dumbbell-shaped tumor in the cerebellopontine angle. Another patient, a 40-year-old woman, also presented with vertigo and right tinnitus without facial palsy. MR images demonstrated a huge tumor expanding into both the posterior cranial fossa and middle cranial fossa. In both cases, intraoperative findings confirmed that the tumors had grown from the facial nerve. Facial nerve schwannoma can be easily diagnosed if detailed neurological evaluations and appropriate neuroimagings are conducted. However, in spite of such huge tumoral size and expanding pattern, the facial nerve function was relatively preserved. Anatomical features of the facial schwannoma are discussed. A tumor extending to the middle and posterior cranial fossa should remind neurosurgeons to consider facial nerve schwannomas even in the absence of facial palsy.

Aged↗
PubMed2005

Intraoperative tumor segmentation and volume measurement in MRI-guided glioma surgery for tumor resection rate control.

RATIONALE AND OBJECTIVES: Gross-total surgery under intraoperative magnetic resonance imaging (MRI) is a promising method of glioma removal. The purpose of this article is intraoperative measurement of resected tumor volume in MRI-guided glioma surgery using semiautomatic image segmentation to unbiased resection rate control. MATERIALS AND METHODS: A newly developed software program based on a fuzzy connectedness (FC) segmentation algorithm was used to achieve fast and semiautomatic tumor segmentation and tumor volume measurement. The program was validated by retrospective study of eight glioma cases and then applied to seven glioma cases. All clinical cases underwent actual MRI-guided surgery using 0.3-T open magnets. RESULTS: The volume of the tumor before resection ranged from 10.1 to 206.7 mL. A comparison of the results of manual segmentation with those of the semiautomatic FC-based segmentation gave an average dice similarity coefficient of 0.80 and an average match of 76%. Volume measurement combined with a developed software program enabled quantitative monitoring of tumor removal, which was critical in the near-total resection of glioma in MRI-guided surgery. CONCLUSION: The FC-based tumor segmentation method can be used for intraoperative tumor segmentation and volume measurement in MRI-guided glioma surgery using 0.3-T open magnets. This method is useful for objective resection rate monitoring, which may ultimately minimize the amount of residual tumor in glioma surgery.

Adolescent↗
PubMed2005

Intelligent operating theater using intraoperative open-MRI.

Malignant brain tumors vary among patients and are characterized by their irregular shapes and infiltration. Localization of functional areas in the brain also differs among patients, and excess removal of tumor near eloquent areas may increase the risk of damage of function, such as motor paresis and speech disturbance. Recent progress in magnetic resonance (MR) imaging technology has enabled acquisition of intraoperative images and totally changed the neurosurgery of malignant brain tumors. Before, surgeons could merely speculate about the results of surgical manipulation and have no certainty about procedure outcomes until postoperative examination. Because intraoperative MR images allow visualization of the size of residual tumor(s) and the positional relationship between the tumor(s) and eloquent areas, surgeons are now able to achieve safe and reliable surgery. As an example, positional error on preoperative MR images caused by shifting of the brain (brain shift), a long-standing annoyance for surgeons, has been resolved using intraoperative MR images for surgical navigation, allowing precise resection. Two types of open-MR imaging scanner, a 0.2- or 0.3-tesla hamburger-type scanner with a horizontal gap and a 0.12- or 0.5-tesla double doughnut-type scanner with a vertical gap, are now available in the operating theater, and 1.5-tesla bore-type scanners are available. A 3.0-tesla bore-type scanner is planned. Intraoperative MR imaging includes diffusion-tensor and diffusion-weighted imaging, which allows visualization of nerve fibers in the white matter, especially the pyramidal tract. Such images are valuable aids in the precise resection of residual lesions of malignant brain tumors near eloquent areas without injuring motor function.

Brain Neoplasms↗
PubMed2004

Preoperative mapping for patients with supplementary motor area epilepsy: multimodality brain mapping.

Surgical management and strategies for the supplementary motor area (SMA) epilepsy are described. The following is our preoperative evaluations. The steps include functional magnetic resonance imaging (fMRI), interictal dipole tracing (DT), subdural electrodes mapping, measurements of movement-related cortical potential (MRCP), and the use of the intraoperative open MRI under conscious craniotomy. Six patients with SMA epilepsy underwent surgery after the mapping procedures and are now seizure-free. Combinations of preoperative (fMRI, subdural electrodes mapping) and intraoperative mapping allow exact localization and identification of the critical functional areas. Early postoperative deficits in motor and speech function were profound but patients recovered rapidly. It is concluded that the step of mapping procedures plays an important role in the management of SMA epilepsy surgery.

Adolescent↗
PubMed2004

[Preface: intuitive visualization of medical information].

Information technology(IT), visualization, and manipulation will be the key words for next generation surgery. In other words, it is awaited to make good use of intuitive visualization of medical information management by extensive use of IT in which medical science and engineering are merged and incorporated and of the process management or the visualization of treatment course using three-dimensional intraoperative images and simulation data base. In order to put it into practice, it is inevitable to establish a treatment strategy system that certainly enables surgeons to provide constantly high quality medicine. This means that to achieve the goal while optimizing the strategy toward the goal(a road map) by monitoring real-timely the pre- and intraoperative surgical planning and the operating condition of surgical devices under the control of the surgical strategy system.

Decision Making, Computer-Assisted↗
PubMed2004

[Intraoperative MRI and updated navigation].

Although advanced preoperative imaging has been developed recent years, intraoperative imaging and monitoring are limited. We have developed an operating system to obtain objective and visible information for advanced neurosurgery. Intraoperative MRI and updated navigation are powerful tools to navigate surgeons to the residual lesions. This system has contributed to the improvement of the resection rate and the safety in the cases of gliomas and pituitary tumors.

Adult↗
PubMed2004

[Robotic surgery in neurosurgical field].

Computer-aided surgery commenced in the late 1980s when computer was clinically used for diagnosis and surgical planning. Since then the computer has been used in a surgical navigation system. In the early 1990s a robotic surgery using intelligent manipulator as surgeon's new hands took place. Nowadays intraoperative diagnostic imaging as surgeon's new eyes has become ubiquitous Diagnosis, surgical planning, and navigation are required to be real-timely performed intraoperatively. The time has really come to concurrently diagnose and treat, in which technology visualizing intraoperative medical information and minimally invasive surgery are fused. For that it is necessary to develop a system that real-timely updates information for decision making, and at the same time to present the timely, optimum treatment to be done according to the results of instant evaluation of ongoing treatment. To realize and support above system it is essential to combine a sensor which can precisely distinguishes a focal area from a normal tissue intraoperatively, and a manipulator which participates the treatment. In addition, the manipulator should be accurately controlled using a computer (computer-aided manipulation) according to the surgical plan made by a method aided by a computer (computer-aided design) based on intraoperatively acquired information. It is about to change quality of life to quality of treatment.

Humans↗
PubMed2002

Optic nerve arteriovenous malformation causing optic apoplexy: case report.

OBJECTIVE AND IMPORTANCE: Vascular malformations in the optic pathway are rare. Only one case of pathologically confirmed arteriovenous malformation (AVM) of the optic nerve has been reported previously. We document the case of a patient with an optic nerve AVM who presented with optic apoplexy that was diagnosed with the use of magnetic resonance imaging. CLINICAL PRESENTATION: A 15-year-old girl developed left visual disturbance of sudden onset while playing badminton. A magnetic resonance imaging scan disclosed left optic nerve swelling and intraoptical hemorrhage, although an angiogram did not reveal abnormal vessels. INTERVENTION: The patient underwent total removal of the hematoma and tangles of the abnormal vessels in the left optic nerve, which was diagnosed pathologically as an AVM. The patient recovered visual acuity, but the left visual field defect remained unchanged. CONCLUSION: Along with cavernous malformations and optic gliomas, AVMs can be a rare cause of optic nerve apoplexy. T2-weighted magnetic resonance imaging is useful in rendering the diagnosis of an optic nerve AVM, observed as a mass lesion consisting of serpiginous, tangled, low-intensity bands. Early surgical treatment is recommended to obtain a rapid recovery.

Adolescent↗
PubMed2002

[Recent advances in surgical technology--open MRI and "real-time" navigation].

Many advances of neurosurgery had been achieved about diagnostic and operative tools such as CT scan, MRI, stereotaxy, and microscope, in 20th century. However, intraoperative diagnostic tools are not sufficient for providing solid data. So we developed new operating system for 21st century (Intelligent Operating Theater: IOT). The IOT has an open MRI machine for intraoperative MR imaging that provides objective anatomical data and the "real-time" navigation updated with iMRI that navigates surgeons to the target area. The IOT has contributed to the improvement of the resection rate in brain tumor cases.

Brain↗