Nobuyuki Hayashi

Nagasaki University, Nagasaki, Nagasaki, Japan

Are you Nobuyuki Hayashi?

Claim your profile

Publications (9)14.46 Total impact

  • Source
    [Show abstract] [Hide abstract] ABSTRACT: We examined the characteristic changes in vestibular schwannoma (VS) volume after treatment with linear accelerator-based radiosurgery (LBRS) and the long-term therapeutic effects, by performing three-dimensional (3D) MRI evaluations of tumor volumes. We included 44 patients in whom tumor volume changes could be observed using 3D-spoiled gradient-echo MRI for at least 5years. Examinations were performed every 3-4months for the first 2years after treatment and every 6-12months thereafter. Enlargement or shrinkage was determined as a change of at least 20% from the volume at the time of treatment. The median observation period was 13.8years (range, 5.5-19.5years). The tumor control rates at 5 and 10years after treatment and at the final MRI were 90.9%, 90.0%, and 88.6%, respectively. Tumor volume changes were categorized into the following four patterns: enlargement, five patients (11.4%); stable, three patients (6.8%); transient enlargement, 24 patients (54.5%); and direct shrinkage, 12 patients (27.3%). Bimodal peaks were observed in three of the 24 patients with transient enlargement. Tumor volume changes from 5 and 10 years post-LBRS to the final observation point were observed in 27 (64.2%) and 10 patients (33.3%), respectively. The long-term tumor volume changes observed after LBRS suggest that radiation exerts long-term effects on tumors. Furthermore, while transient enlargements in tumor volume were characteristic, true tumor enlargements should be characterized by increased volumes of more than two-fold and continued growth for at least 2years. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Full-text · Article · Oct 2014 · Journal of Clinical Neuroscience
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: Purpose Although radiosurgery is an accepted treatment method for intracranial arteriovenous malformations (AVMs), its long-term therapeutic effects have not been sufficiently evaluated, and many reports of long-term observations are from gamma-knife facilities. Furthermore, there are few reported results of treatment using only linear accelerator (LINAC)-based radiosurgery (LBRS). Methods and Materials Over a period of more than 12 years, we followed the long-term results of LBRS treatment performed in 51 AVM patients. Results The actuarial obliteration rates, after a single radiosurgery session, at 3, 5, 10, and 15 years were 46.9%, 54.0%, 64.4%, and 68.0%, respectively; when subsequent radiosurgeries were included, the rates were 46.9%, 61.3%, 74.2%, and 90.3%, respectively. Obliteration rates were significantly related to target volumes ≥4 cm3, marginal doses ≥12 Gy, Spetzler-Martin grades (1 vs other), and AVM scores ≥1.5; multivariate analyses revealed a significant difference for target volumes ≥4 cm3. The postprocedural actuarial symptomatic radiation injury rates, after a single radiation surgery session, at 5, 10, and 15 years were 12.3%, 16.8%, and 19.1%, respectively. Volumes ≥4 cm3, location (lobular or other), AVM scores ≥1.5, and the number of radiosurgery were related to radiation injury incidence; multivariate analyses revealed significant differences associated with volumes ≥4 cm3 and location (lobular or other). Conclusions Positive results can be obtained with LBRS when performed with a target volume ≤4 cm3, an AVM score ≤1.5, and ≥12 Gy radiation. Bleeding and radiation injuries may appear even 10 years after treatment, necessitating long-term observation.
    Full-text · Article · Jul 2014 · International journal of radiation oncology, biology, physics
  • [Show abstract] [Hide abstract] ABSTRACT: Cyst formation is a well-known complication following radiosurgery for arteriovenous malformations (AVMs). In this retrospective study, the authors studied predictors for AVMs using magnetic resonance imaging (MRI) to assess the mechanism of cyst formation after linac-based radiosurgery (LBRS). From April 1993 to April 2008, LBRS was performed on 109 patients with cerebral AVMs at our institution. Six patients (5.5%) were diagnosed with cyst formation after LBRS, and 5 of them underwent regular MRI follow-up every 3-4 months for 2 years post-LBRS, and every 6-12 months thereafter. Time from initial LBRS until cyst formation ranged from 8 months to 10.5 years. MRI showed contrast changes at the irradiated site and its periphery within a period of 4 months to 7 years after the initial LBRS. Moreover, the emergence of a high-intensity area (HIA) was observed on T2-weighted MRI (T2W-MRI) during the same period when changes were found on contrast-enhanced imaging. The emergence of a low-intensity area on T2W-MRI was observed prior to cyst formation or expansion, which was believed to be due to a subclinical hemorrhage near the irradiated region in all patients. Histological examination of the cyst nodule revealed hemosiderin deposits and microbleeding. Future cyst formation was suggested by the emergence of subclinical hemorrhage (microbleeding) in an irradiated field after gadolinium-enhanced MRI showed contrast changes and T2W-MRI showed a HIA around the irradiated field. MRI follow-up should be conducted on a regular basis in such patients, even after a complete occlusion has been diagnosed.
    No preview · Article · Jun 2014 · Clinical neurology and neurosurgery
  • [Show abstract] [Hide abstract] ABSTRACT: A 63-year-old woman presented with right hearing disturbance and vertigo. Magnetic resonance (MR) imaging revealed the presence of right vestibular schwannoma (VS). Stereotactic radiosurgery (SRS) was performed with a tumor marginal dose of 14 Gy using two isocenters. She was followed up clinically and neuroradiologically using three-dimensional spoiled gradient-echo MR imaging. She experienced temporal neurological deterioration due to peritumoral edema in her right cerebellar peduncle and pons for a few months beginning 1.5 years after SRS, when she experienced transient right facial dysesthesia and hearing deterioration. Ten years after SRS, the patient presented with sudden onset of vertigo, gait disturbance, diplopia, dysarthria, and nausea. MR imaging demonstrated a new lesion in the right cerebellar peduncle, which was diagnosed as radiation-induced stroke. The patient was followed up conservatively and her symptoms disappeared within a few months. Multiple delayed onset radiation injuries are possible sequelae of SRS for VS.
    No preview · Article · Dec 2012 · Neurologia medico-chirurgica
  • [Show abstract] [Hide abstract] ABSTRACT: To analyses the result of linac radiosurgery (LRS) for the treatment of intracranial benign lesions and to assess possible factors related to complications. The authors retrospectively reviewed 204 patients treated with LRS between May, 1993 and December, 2003. The study determined the correlation between radiosurgical complications including imaging changes after LRS and multiple factors such as radiosurgical parameters, location, volume and shape. We divided the patients into three groups by MRI imaging changes and clinical symptoms. Group 1 (Gr. 1): Imaging change only. Group 2 (Gr. 2): Imaging change with transient symptoms. Group 3 (Gr.3): Imaging change with permanent symptoms. Ninty-three patient with AVM: Gr. 1, 8 cases (8.6%), Gr. 2, 1 case (1.1%), Gr. 3, 2 cases (2.1%). A significantly higher incidence of imaging change was noted in patients with arteriovenous malformation (AVM) volumes greater than 10 cc, irregular shape of the nidus and deep location. Fifty-eight patients with vestibulan schwannoma (VS): Gr. 1, 6 cases (10.3%), Gr. 2, 1 case (1.8%), Gr. 3, 2 cases (3.4%). Imaging changes were seen mostly in cases with tumor volume greater than 5 cc. Fifty-three patients with meningioma: Gr. 1, 4 cases (7.5%), Gr.2, 2 cases (3.7%), Gr.3, 0 case. Imaging changes were seen mostly in convexity, parasaggital, and falx meningiomas that were deeply embedded in the cortex. The symptom continued the until last serial observation in four cases. We used various interventions in these patients including steroid, anticoagulant, surgical removal, and hyperbaric oxygen therapy; but these therapies were not effective. LRS for each disease seems to be a safe and effective treatment. However, once serious radiation injuries occur there is no effective therapy, so it is important to make appropriate selection of patients for radiosurgery.
    No preview · Article · Dec 2009 · No shinkei geka. Neurological surgery
  • [Show abstract] [Hide abstract] ABSTRACT: The authors report on a series of 46 patients harboring vestibular schwannomas (VSs) treated using linear accelerator (LINAC) radiosurgery and an analysis of serial magnetic resonance (MR) imaging data, specifically the changes in tumor volume. Fifty-three consecutive patients underwent LINAC radiosurgery for VS between 1993 and 2002. Seven of these patients were lost to follow up. Three-dimensional (3D) spoiled gradient-echo (SPGR) MR imaging was performed at 3- to 4-month intervals after radiosurgery. Tumor volume was measured on Gd-enhanced MR images of each slice. The median duration of follow-up MR imaging studies was 56.5 months (range 12-120 months). Follow-up imaging studies were conducted for longer than 1 year in 42 of 53 patients. Tumor volume changes were categorized into four types: enlargement (eight lesions [19%]), no change (two lesions [4.8%]), transient enlargement followed by shrinkage (19 lesions [45.2%]), and direct shrinkage (13 lesions [31%]). Two cases (4.8%) with twice the initial tumor volume required repeated radiosurgery. All cases of transient enlargement had subsequent shrinkage within 2 years after radiosurgery. Nine (21.4%) of 42 patients demonstrated ventricular enlargement on MR images obtained after radiosurgery. Three patients (7.1%) required placement of a ventriculoperitoneal shunt because of symptomatic hydrocephalus, and another four cases (9.5%) spontaneously resolved. Volume measurement on 3D-SPGR MR imaging was a suitable method to assess tumor changes. Volume changes beyond twofold or continuous enlargement for longer than 2 years after radiosurgery are key criteria in rating the effects of radiation. Some cases of hydrocephalus after radiosurgery resolved spontaneously and their rates of occurrence were similar to the typical incidence of hydrocephalus associated with VS.
    No preview · Article · Aug 2005 · Journal of Neurosurgery
  • Nobuyuki Hayashi · Makoto Ochi · Kuniaki Hayashi
    [Show abstract] [Hide abstract] ABSTRACT: The prognosis of patients with brain metastases is poor. Consequently, the purposes of treatment for such patients are also limited. One goal is to prevent the metastatic tumors from causing death, and another is to improve the neurological symptoms that are causing deterioration of the patient's quality of life. There are several treatment options for brain metastases: whole brain irradiation, surgery, stereotactic radiosurgery, and combinations of these. We reviewed recent reports that were based on the evidence obtained from various treatment strategies for this condition. We concluded that the final decision should be made by the patients themselves. We refer to the concept of narrative-based medicine(NBM).
    No preview · Article · Apr 2002 · Nihon Igaku Hoshasen Gakkai zasshi. Nippon acta radiologica
  • [Show abstract] [Hide abstract] ABSTRACT: Although reports have been published describing clinical results in a large series of patients with metastatic brain tumors treated by stereotactic radiosurgery (SRS), clinical neuropathological correlation has rarely been available. The present paper describes three autopsy cases and one surgical case treated with linear accelerator based radiosurgery. The cases comprised a lung cancer, a rectal cancer, an osteosarcoma, and a malignant melanoma. Histological sections of each tumor were analyzed by light microscopy based on the Ohosi and Shimosato's histopathological classification of the effects of radiation therapy. In three cases (pulmonary squamous cell carcinoma, rectal adenocarcinoma and osteosarcoma), a large area of the tumors consisted of coagulation necrosis and non-viable tumor cells, while coagulation necrosis and non-viable tumor cells comprised a very small part of the malignant melanoma. Histopathological type of the metastatic brain tumor may be one of the factors influencing outcome after SRS.
    No preview · Article · Jan 2002 · Neuropathology
  • [Show abstract] [Hide abstract] ABSTRACT: The aim of this study was to investigate the role of the combined use of customized molds and recently available remote afterloading brachytherapy apparatus with more flexible catheters in the treatment of superficial oral carcinomas. Four patients with oral squamous cell carcinoma who were treated through use of this combined technique were analyzed retrospectively. The molds were made from transparent acrylic resin through use of a dental technique. The combined approach was applied as a boost therapy after external irradiation. The 4 patients had had no recurrence of tumor or radiation injury by the end of the follow-up period. The combined technique could be an excellent method of treating superficial carcinomas of the oral cavity.
    No preview · Article · May 1999 · Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology