Biomedical subjects

Shinji Naganawa

Publications and source records attributed to Shinji Naganawa.

At least 19 recordsLinked to original sources

PubMed2006

Risk factors for neovascular glaucoma after carbon ion radiotherapy of choroidal melanoma using dose-volume histogram analysis.

PURPOSE: To determine the risk factors for neovascular glaucoma (NVG) after carbon ion radiotherapy (C-ion RT) of choroidal melanoma. METHODS AND MATERIALS: A total of 55 patients with choroidal melanoma were treated between 2001 and 2005 with C-ion RT based on computed tomography treatment planning. All patients had a tumor of large size or one located close to the optic disk. Univariate and multivariate analyses were performed to identify the risk factors of NVG for the following parameters; gender, age, dose-volumes of the iris-ciliary body and the wall of eyeball, and irradiation of the optic disk (ODI). RESULTS: Neovascular glaucoma occurred in 23 patients and the 3-year cumulative NVG rate was 42.6 +/- 6.8% (standard error), but enucleation from NVG was performed in only three eyes. Multivariate analysis revealed that the significant risk factors for NVG were V50IC (volume irradiated > or =50 GyE to iris-ciliary body) (p = 0.002) and ODI (p = 0.036). The 3-year NVG rate for patients with V50IC > or =0.127 mL and those with V50IC <0.127 mL were 71.4 +/- 8.5% and 11.5 +/- 6.3%, respectively. The corresponding rate for the patients with and without ODI were 62.9 +/- 10.4% and 28.4 +/- 8.0%, respectively. CONCLUSION: Dose-volume histogram analysis with computed tomography indicated that V50IC and ODI were independent risk factors for NVG. An irradiation system that can reduce the dose to both the anterior segment and the optic disk might be worth adopting to investigate whether or not incidence of NVG can be decreased with it.

Adult↗

PubMed2006

3D-FLAIR magnetic resonance imaging in the evaluation of mumps deafness.

A 6-year-old boy suffered acute profound right side deafness after his classmates had mumps. Although his salivary glands were not swollen, he had high levels of anti-mumps IgM and IgG antibodies. The three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) procedure applied to magnetic resonance imaging (MRI) showed high signals in the right cochlea and vestibule. This indicated hemorrhage or a high concentration of protein in the right inner ear. This is the first case demonstrating a high 3D-FLAIR MRI signal of the inner ear in a patient with mumps deafness. Our findings suggest that 3D-FLAIR MRI may help to identify and define labyrinthitis in mumps deafness.

Child↗

PubMed2006

Relationship between CT densitometry with a slice thickness of 0.5 mm and audiometry in otosclerosis.

The appropriate cutoff Hounsfield unit (HU) value for the diagnosis of otosclerosis was determined and the correlation between the bone conduction threshold and the findings of computed tomography (CT) densitometry investigated. CT images, 0.5-mm thick, were evaluated in 24 ears with otosclerosis and 19 control ears. Eight regions of interest were set around the otic capsule. The mean HU values in the area anterior to the oval window (A-OW) and anterior to the internal auditory canal (A-IAC) were significantly lower in otosclerosis than in controls. Based on receiver operating characteristic (ROC) analysis, the cutoff HU value in A-OW was determined to be 2,187.3 HU. The mean HU value in retrofenestral otosclerosis was significantly lower in the area A-OW, A-IAC and around the cochlea than in controls. Based on ROC analysis, the cutoff HU value in the latter was determined to be 2,045 HU. A statistically significant correlation was found between the density of the area A-OW and the hearing level at 500 and 1,000 Hz, and between the density of the area around the cochlea and the hearing level at most frequencies. These results suggest the semi-automated diagnosis of otosclerosis may be possible.

Absorptiometry, Photon↗

PubMed2006

Lateral semicircular canal and vertigo in patients with large vestibular aqueduct syndrome.

OBJECTIVE: To evaluate the hypothesis that there are differences in the morphology of the lateral semicircular canal (LSCC) between patients with large vestibular aqueduct syndrome (LVAS) and control subjects and to investigate the clinical implications of these differences. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Nine patients (two male patients and seven female patients; age range, 8-54 yr) with LVAS (one patient had unilateral LVAS, and eight patients had bilateral LVAS). Five patients had vertigo, and four patients, including the one with unilateral LVAS, did not have vertigo. MAIN OUTCOME MEASURES: The area of the LSCC was traced on the magnetic resonance imaging console and compared between LVAS patients and 12 control subjects who did not have sensorineural hearing loss. The LSCC fluid-containing area was divided by the sum of the LSCC inner area and the LSCC fluid-containing area for evaluation of the degree of the LSCC dysplasia. RESULTS: The LSCC fluid-containing ratio was significantly larger in LVAS patients than in control subjects. Moreover, the LSCC fluid-containing ratio was significantly larger in the eight ears with vertigo than in the nine ears without vertigo. There was no relationship between hearing level and the LSCC fluid-containing ratio. CONCLUSION: Patients with LVAS may have disturbed morphogenesis of both membranous and bony labyrinths. Our results reveal that the morphology of semicircular canals is clinically associated with vertigo.

Adolescent↗

PubMed2006

Inner ear hemorrhage in systemic lupus erythematosus.

A 33-year-old man had systemic lupus erythematosus (SLE) with anticardiolipin antibody. At the age of 40 years, he experienced bilateral hearing deterioration. The three-dimensional fluid-attenuated inversion recovery of magnetic resonance imaging showed high signals bilaterally in the cochlea and vestibule. He was diagnosed with bilateral inner ear hemorrhage on the basis of the presence of anticardiolipin antibody. This is the first published case of inner ear hemorrhage in a patient with SLE. Our findings suggest that inner ear hemorrhage is associated with hearing deterioration in some patients with SLE.

Adult↗

PubMed2006

Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging findings in patients with sudden sensorineural hearing loss.

OBJECTIVE: To evaluate the inner ear in sudden sensorineural hearing loss (SNHL) using three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) at 3 Tesla (T). BACKGROUND: 3D-FLAIR MRI has recently been developed to detect high concentrations of protein or hemorrhage. Application of this method to sudden SNHL has not been described. METHODS: We used 3D-FLAIR at 3 T with and without gadolinium enhancement to evaluate eight patients with sudden SNHL. RESULTS: In four of eight ears with idiopathic sudden SNHL, high precontrast signals were observed within the inner ear on 3D-FLAIR. The high-signal areas observed on 3D-FLAIR were not detected by T1- or T2-weighted MRI in any of these patients. In one of these four ears, significant gadolinium enhancement was observed on 3D-FLAIR. CONCLUSION: Half the patients with sudden SNHL examined had high signals in the SNHL-affected ear on 3D-FLAIR at 3 T. High precontrast signals in the inner-ear fluid space may reflect minor hemorrhage, or an increased concentration of protein that had passed through blood vessels with increased permeability, or had originated from disrupted cells in the inner ear. Gadolinium enhancement in one ear suggested the breakdown of the blood-labyrinth barrier. 3D-FLAIR MRI should contribute markedly to the elucidation of pathologic conditions in the inner ears of patients with idiopathic sudden SNHL.

Aged↗

PubMed2006

Prompt contrast enhancement of cerebrospinal fluid space in the fundus of the internal auditory canal: observations in patients with meningeal diseases on 3D-FLAIR images at 3 Tesla.

We speculated that meningeal pathologies might facilitate the permeability of cranial nerves at the fundus of the internal auditory canal (IAC), causing prompt enhancement after administration of Gd-DTPA. Using a 3D- fluid-attenuated inversion recovery (FLAIR) sequence, we evaluated the enhancement of the cerebrospinal fluid (CSF) space in the IAC fundus 10 min after Gd-DTPA administration in patients with meningeal diseases. Twenty patients (aged 22 to 79 years) were divided into 2 groups, a group with meningeal disease comprising 9 patients with meningeal abnormalities (6, tumor dissemination; 3, infection) and a control group of 11 patients with unilateral IAC pathology whose healthy sides were included as controls. Six of the 9 patients in the group with meningeal disease showed bilateral enhancement; one showed unilateral enhancement. None of the control group showed enhancement in the healthy side. One patient with Ramsay-Hunt syndrome showed only ipsilateral enhancement. Enhancement in the IAC fundus was frequently observed in patients with meningeal disease, even just 10 min after administration of contrast agent. This enhancement in the IAC fundus was never visible on T1-weighted 3D-FLASH images.

Adult↗

PubMed2005

Diffusion-weighted imaging of the liver: technical challenges and prospects for the future.

Diffusion-weighted imaging (DWI) has recently been attempted in the abdominal region. We review diffusion-weighted images of the liver, especially from the technical point of view. We discuss selection of pulse sequence parameters, effects of anti-breathing motion technique, tips for measuring apparent diffusion coefficient (ADC), and utility of superparamagnetic iron oxide (SPIO), showing clinical cases, including those at 3T. Our current trial of new pulse sequencing, such as SPIO-mediated breath-holding black-blood fluid-attenuated inversion recovery (BH-BB-FLAIR), imaging is shown. Some prospects for the future in DWI of the liver are also stated.

Adult↗

PubMed2005

Observation of contrast enhancement in the cochlear fluid space of healthy subjects using a 3D-FLAIR sequence at 3 Tesla.

In animals, the enhancement of perilymph in the cochlea has been reported using 1.25 mmol/kg of Gd-DTPA, allowing the separate visualisation of perilymph and endolymph for the diagnosis of Meniere's disease. The purpose of this study was three-fold: (1) to determine the optimal timing for detecting cochlear fluid enhancement using 3D-FLAIR (fluid-attenuated inversion recovery) after intravenous administration of 0.1 mmol/kg of Gd-DTPA in healthy human subjects; (2) to examine the reliability of enhancement in multiple healthy subjects; and (3) to investigate whether endolymph and perilymph space can be visually discriminated. In two healthy subjects, 3D-FLAIR images were obtained before, immediately after and 2 h, 4 h and 6 h after the injection. Three more healthy subjects were scanned before and 4 h after the injection. In all four ears of the initial two subjects, cochlear fluid was found to be most intensely enhanced 4 h after the injection. In all of the additional three subjects, the cochlear fluid signal had increased after 4 h from injection. However, visual differentiation of endolymph and perilymph fluid could not be achieved. Using 3D-FLAIR and Gd-DTPA, cochlear fluid enhancement can be observed in healthy human ears, even with a single dose of contrast-medium injection.

Cochlea↗

PubMed2005

Long-term follow-up in patients with Pendred syndrome: vestibular, auditory and other phenotypes.

Fourteen patients with a Pendred syndrome gene (Pds) mutation and three patients without the mutation were studied to evaluate long-term vestibular and auditory manifestations among patients with bilateral enlarged vestibular aqueducts (EVA). Charts were reviewed retrospectively for age, gender, otological history, presence or absence of vertigo, results of magnetic resonance imaging, relevant gene mutations and perchlorate discharge test. A missense mutation, His 723 Arg (H723R), was identified in the homozygous state in six patients and in the heterozygous state in seven patients. Another missense mutation, Tyr 410 Met (T410 M), was identified in the heterozygous state in one patient. Patients with vertigo tended to have hearing fluctuation, compared with the patients without vertigo. Patients homozygous for H723R tended to have more episodes of vertigo than the heterozygous individuals. Only one patient who was homozygous for H723R had goiter. The long-term outcome of hearing level in patients with the H723R mutation was significantly better compared with published results for patients with a Pds mutation, but not for those with the H723R mutation. Whether environmental factors or a subtype of the Pds mutation H723R are related to the long-term outcome for these patients must be clarified.

Adolescent↗

PubMed2005

Differentiation of noncancerous tissue and cancer lesions by apparent diffusion coefficient values in transition and peripheral zones of the prostate.

PURPOSE: To compare the apparent diffusion coefficient (ADC) values of prostate cancer in both the peripheral zone (PZ) and the transition zone (TZ) with those of benign tissue in the same zone using echo-planar diffusion weighted imaging with a parallel imaging technique. MATERIALS AND METHODS: A total of 29 consecutive male patients (mean age 61.3 years, age range 53-88 years) with suspected prostate cancer were referred for MR imaging. All patients underwent transrectal ultrasound (TRUS)-guided biopsy of the prostate after MR imaging at 1.5 T, including ADC. For each patient, seven to 10 specimens were obtained from the prostate, and regions of interest (ROIs) were drawn on the ADC map by referring to the urologist's illustration of TRUS-guided biopsy sites. ADC values of cancerous tissue in both the PZ and TZ were compared to those of noncancerous tissue in the same zone. RESULTS: Out of 29 patients, 23 had cancer tissue. In the 23 patients with cancer, the mean ADC value of all cancer ROIs and that of all noncancer ROIs, respectively, were 1.11 +/- 0.41 x 10(-3) and 1.68 +/- 0.40 x 10(-3) mm(2)/second (values are mean +/- SD) (P < 0.01). The mean ADC value of TZ cancer ROIs and that of TZ noncancer ROIs, respectively, were 1.13 +/- 0.42 x 10(-3) and 1.58 +/- 0.37 x 10(-3) mm(2)/second (P < 0.01). CONCLUSIONS: ADC measurement with a parallel imaging technique showed that ADC values of prostate cancer in both the PZ and TZ were significantly lower than those of benign tissue in the PZ and TZ, respectively.

Adenocarcinoma↗

PubMed2005

Diffusion-weighted images of the liver: comparison of tumor detection before and after contrast enhancement with superparamagnetic iron oxide.

PURPOSE: To study the recognition of malignant lesions of the liver on diffusion-weighted images (DWI) can be improved by the administration of superparamagnetic iron oxide (SPIO). MATERIALS AND METHODS: Pre- and post-SPIO mediated DWI of the liver was compared in six patients with suspected malignant liver lesions at 1.5 Tesla using a parallel imaging technique. RESULTS: Post-SPIO DWI showed improved contrast-to-noise ratio between malignant lesions and liver. Furthermore, the spleen signal was decreased on post-SPIO DWI, thus avoiding the overlap of the spleen and left lobe of the liver on maximum intensity projections (MIP). CONCLUSION: Recognition of malignant lesions of the liver was improved by SPIO on DWI. On MIP images of DWI, SPIO helped to decrease the overlap of spleen signal on the liver in some projection angles.

Adult↗

PubMed2005

Hearing loss in patients with enlarged vestibular aqueduct: air-bone gap and audiological Bing test.

The Bing test is based on the principle that occlusion of the external auditory meatus improves the perception of bone-conducted sounds unless there is a conductive hearing impairment. An air-bone gap has been reported in patients with large vestibular aqueduct (LVA) syndrome without apparent middle ear dysfunction. We therefore performed the Bing test on nine patients with this syndrome to evaluate whether it is associated with an air-bone gap or middle ear dysfunction. Bone conduction thresholds did not change significantly during the Bing test in any patient. Because an air-bone gap is observed in patients with abnormal communication between the inner ear and cerebrospinal fluid through the LVA, dehiscent superior canal, or dilated inner ear meatus; we propose that a 'three windows' model (in which the abnormal communication provided by the enlarged endolymphatic duct and sac in LVA acts as the 'third window' for sound conductance) might explain the air-bone gap in such patients.

Adolescent↗

PubMed2005

Sudden sensorineural hearing loss associated with inner ear anomaly.

OBJECTIVE: This study was conducted to evaluate the frequency of inner ear anomaly in patients with sudden sensorineural hearing loss and in control subjects. STUDY DESIGN: Retrospective case review. SETTING: A tertiary referral center. PATIENTS AND INTERVENTION: We evaluated 366 patients (165 men and 201 women; age range, 3-91 yr) with sudden sensorineural hearing loss and 228 control subjects without sensorineural hearing loss using magnetic resonance imaging. Three hundred fifty-six patients had unilateral and 10 patients had bilateral sudden sensorineural hearing loss. RESULTS: Eleven (2.9%) of 376 ears with sudden sensorineural hearing loss had inner ear anomaly. Nine patients (2.5%) had inner ear anomaly associated with sudden sensorineural hearing loss, but none of the 228 control subjects had the anomaly. The current study demonstrated that the frequency of inner ear anomaly in patients with sudden sensorineural hearing loss was significantly higher than in control subjects. CONCLUSION: Our study reveals that inner ear anomaly may be associated with sudden sensorineural hearing loss in 2.5% of patients.

Acoustic Impedance Tests↗

PubMed2004

Contralateral and ipsilateral responses in primary somatosensory cortex following electrical median nerve stimulation--an fMRI study.

OBJECTIVE: Ten healthy adult subjects were examined using functional magnetic resonance imaging (fMRI) to investigate responses in the contralateral and ipsilateral primary somatosensory cortex (SI) following electrical stimulation of the median nerve. METHODS: The right and left median nerves were stimulated alternately at the wrist in the different sessions. First, the location of the response in contralateral SI was identified following median nerve stimulation, and then, a spherical search volume with a 10mm radius centered on the region of the contralateral response was determined. Whether or not fMRI activation occurred within this sphere following ipsilateral stimulation was examined using a 3T MR imager. RESULTS: A response in contralateral SI was observed in 8 of the 10 subjects in right and left hemisphere. Responses in ipsilateral SI were observed in 6 of 8 subjects in right hemisphere, and the region of the response tended to be posterior to the contralateral region. On the other hand, in left hemisphere, the ipsilateral responses were found in three. CONCLUSIONS: In the present study, not only contralateral SI but also ipsilateral SI was activated following median nerve. The location of the ipsilateral activation was significantly more posterior than the contralateral one in right hemisphere. SIGNIFICANCE: The region of activation in ipsilateral SI was located in the posterior portion of post central gyrus, corresponding to around BA2 and 5 in human.

Adult↗

PubMed2004

Apparent diffusion coefficient in cervical cancer of the uterus: comparison with the normal uterine cervix.

A relation between apparent diffusion coefficient (ADC) values and tumor cellular density has been reported. The purpose of this study was to measure the ADC values of cervical cancers in the uterus and compare them with those of normal cervical tissues, and to test whether ADC could differentiate between normal and malignant cervical tissues in the uterus. Twelve consecutive female patients with cervical cancer of the uterus and ten female patients with other pelvic abnormalities were included in this study. ADC was measured at 1.5 T with b-factors of 0, 300 and 600 s/mm2 using single-shot echo-planar diffusion-weighted imaging and a parallel imaging technique. The mean ADC value of cervical cancer lesions was 1.09+/-0.20 x 10(-3) mm2/s, and that of normal cervix tissue was 1.79+/-0.24 x 10(-3) mm2/s (P<0.0001). In nine patients treated by chemotherapy and/or radiation therapy, the mean ADC value of the cervical cancer lesion increased significantly after therapy (P<0.001). The present study showed, with a small number of patients, that ADC measurement has a potential ability to differentiate between normal and cancerous tissue in the uterine cervix. Further study is necessary to determine the accuracy of ADC measurement in monitoring the treatment response.

Adult↗

PubMed2004

MR imaging of gastric cancer in vitro: accuracy of invasion depth diagnosis.

The purpose of this study was to evaluate the accuracy of grading cancerous invasion of the gastric wall in vitro using magnetic resonance (MR) imaging. Twelve specimens of gastric carcinoma were examined at 1.5-T using a small, loop surface coil. They were imaged within 2 days of fixation in formalin. The field of view was 30 mm; the matrix size was 256x256, and the section thickness was 2 mm. T1-weighted, T2-weighted and short inversion time inversion recovery (STIR) images were obtained. Two radiologists evaluated the MR images independently, and in discrepant cases, consensus was obtained through discussion. Findings on MR images were compared with histopathologic findings. All T1-weighted, T2-weighted and STIR images depicted the normal gastric wall as consisting of six layers. STIR images depicted normal six layers most clearly. Histologically, the cancerous invasion was found to extend into the mucosa in 4 of the 12 specimens, the submucosa in 3, the muscularis propria in 2, the subserosa in 2 and the serosa in 1. The grading by MR imaging matched the histopathologic findings for all 12 tumors. The overall accuracy was 100%. Thus, MR imaging in vitro was sufficiently accurate for grading cancerous invasion of the gastric wall.

Adenocarcinoma↗

PubMed2004

Comparison of flow artifacts between 2D-FLAIR and 3D-FLAIR sequences at 3 T.

It has been reported that 3D-FLAIR can reduce the flow artifact resulting from cerebrospinal fluid (CSF) at 1.5 T compared to 2D-FLAIR. Flow-related artifacts tend to be worse at 3 T than at 1.5 T. The purpose of this study was to compare the CSF flow artifacts of 2D-FLAIR and 3D-FLAIR sequences at 3 T in eight healthy volunteers. The grade of CSF-related artifacts were scored through observing the perimedullary cistern, cerebellopontine angle cisterns, fourth ventricule, prepontine cistern, suprasellar cistern, ambient cisterns, sylvian fissures, third ventricle and lateral ventricles. Grading was performed on either axial or sagittal images. The CSF in-flow artifact scores were significantly higher on axial 2D-FLAIR than on axial 3D-FLAIR MPR images in all areas except the bilateral sylvian fissures, and higher on sagittal 2D-FLAIR than on sagittal 3D-FLAIR MPR images in perimedullary, bilateral CP angle and suprasellar cisterns. The CSF-related flow artifacts were significantly reduced by 3D-FLAIR, while structures in the cistern were depicted more clearly, even at 3 T. Further study is necessary to compare the clinical efficacy between 2D-FLAIR and 3D-FLAIR in depicting subtle abnormalities.

Adult↗