Biomedical subjects

Hiroshi Fukatsu

Publications and source records attributed to Hiroshi Fukatsu.

At least 19 recordsLinked to original sources

PubMed2006

Prostate cancer detection with 3-T MRI: comparison of diffusion-weighted and T2-weighted imaging.

OBJECTIVE: To compare the clinical value of diffusion-weighted (DW) and T2-weighted (T2W) imaging in detecting prostate cancer using a 3-Tesla (3T) magnetic resonance (MR) system. MATERIALS AND METHODS: Thirty-seven patients with suspected prostate cancer underwent T2W and DW imaging at 3T using an 8-channel phased-array coil. These images and apparent diffusion coefficient (ADC) maps were read retrospectively and blindly. The results were compared with histopathologic findings, and receiver operating characteristic (ROC) analysis was used to compare the cancer detection performance of T2W and DW imaging. RESULTS: The areas under the ROC curves for DW imaging and T2W imaging were 0.89 and 0.82, respectively. The performance of DW imaging in prostate cancer detection was significantly better than that of T2W imaging (P=0.0371). CONCLUSION: With a 3T MR system, the performance of DW imaging in detecting prostate cancer was better than that of T2W imaging. DW imaging appears to be a robust and reliable method to examine the whole prostate within an acceptable scan time in clinical settings.

Adenocarcinoma↗

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

High-level expression of a novel amine-synthesizing enzyme, N-substituted formamide deformylase, in Streptomyces with a strong protein expression system.

N-substituted formamide deformylase (NfdA) from Arthrobacter pascens F164 is a novel deformylase involved in the metabolism of isonitriles. The enzyme catalyzes the deformylation of an N-substituted formamide, which is produced from the corresponding isonitrile, to yield the corresponding amine and formate. The nfdA gene from A. pascens F164 was cloned into different types of expression vectors for Escherichia coli and Streptomyces strains. Expression in E. coli resulted in the accumulation of an insoluble protein. However, Streptomyces strains transformed with a P(nitA)-NitR system, which we very recently developed as a regulatory gene expression system for streptomycetes, allowed the heterologous overproduction of NfdA in an active form. When Streptomyces lividans TK24 transformed with pSH19-nfdA was cultured under the optimum conditions, the NfdA activity of the cell-free extract amounted to 8.5 U/mg, which was 29-fold higher than that of A. pascens F164. The enzyme also comprised approximately 20% of the total extractable cellular protein. The recombinant enzyme was purified to homogeneity and characterized. The expression system established here will allow structural analysis and mutagenesis studies of NfdA.

Amidohydrolases↗

PubMed2005

Optimum culture conditions for the production of N-substituted formamide deformylase by Arthrobacter pascens F164.

We investigated the optimum culture conditions for the production of a novel enzyme, N-substituted formamide deformylase, which acts mainly on N-benzylformamide, in Arthrobacter pascens F164. The highest enzyme activity was obtained when this strain F164 was cultivated in a synthetic medium with N-benzylformamide as sole nitrogen source. This deformylase was found to be an inducible enzyme depending on N-benzylformamide.

Amidohydrolases↗

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

Amine-synthesizing enzyme N-substituted formamide deformylase: screening, purification, characterization, and gene cloning.

N-substituted formamide was produced through the hydration of an isonitrile by isonitrile hydratase in the isonitrile metabolism. The former compound was further degraded by a microorganism, strain F164, which was isolated from soil through an acclimatization culture. The N-substituted formamide-degrading microorganism was identified as Arthrobacter pascens. The microbial degradation was found to proceed through an enzymatic reaction, the N-substituted formamide being hydrolyzed to yield the corresponding amine and formate. The enzyme, designated as N-substituted formamide deformylase (NfdA), was purified and characterized. The native enzyme had a molecular mass of approximately 61 kDa and consisted of two identical subunits. It stoichiometrically catalyzed the hydrolysis of N-benzylformamide (an N-substituted formamide) to benzylamine and formate. Of all of the N-substituted formamides tested, N-benzylformamide was the most suitable substrate for the enzyme. However, no amides were accepted as substrates. The gene (nfdA) encoding this enzyme was also cloned. The deduced amino acid sequence of nfdA exhibited the highest overall sequence identity (28%) with those of regulatory proteins among known proteins. Only the N-terminal region (residues 58-72) of NfdA also showed significant sequence identity (27-73%) to that of each member of the amidohydrolase superfamily, although there was no similarity in the overall sequence except in the above limited region.

Amidohydrolases↗

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↗

PubMed2004

Whole-brain vascular reactivity measured by fMRI using hyperventilation and breath-holding tasks: efficacy of 3D prospective acquisition correction (3D-PACE) for head motion.

Functional MR imaging (fMRI) study using hyperventilation and breath-holding task has been reported to be one of the non-invasive methods to examine whole-brain vascular reactivity. The purpose of this study was to evaluate the efficacy of a method for 3D prospective detection and correction of head motion (3D-PACE) in a study of whole-brain vascular reactivity using hyperventilation and breath-holding tasks. Eight healthy volunteers were scanned using an fMRI protocol of hyperventilation and breath-holding task blocks at 3 T in separate runs with and without 3D-PACE. In two subjects, two more runs with and without 3D-PACE were repeated. The mean total number of activated voxels +/- standard deviation was 26,405.3+/-1,822.2 in the run with 3D-PACE and 17,329.9+/-2,766.3 in the run without 3D-PACE ( P<0.05), although there is some intersubject variation regarding the effect of 3D-PACE. In the two subjects whose performed two more runs, the number of activated voxels were smaller in the run without 3D-PACE than even in the run with 3D-PACE performed later. We conclude that 3D-PACE is beneficial for fMRI studies of whole-brain vascular reactivity induced by hyperventilation and breath-holding.

Adult↗

PubMed2004

Enlarged endolymphatic duct and sac syndrome: relationship between MR findings and genotype of mutation in Pendred syndrome gene.

Pendred syndrome (PDS) is characterized by profound deafness in childhood, positive perchlorate challenge, and goiter. PDS is often associated with enlarged endolymphatic duct and sac (EEDS), and recently, PDS gene mutations have been reported even in those patients with EEDS without classic Pendred syndrome. In a previous report, the number of mutant alleles was correlated with the degree of subclinical thyroid abnormality, but not with hearing loss, in patients with missense mutation H723R. It also has been reported that the hearing loss in EEDS was not correlated with the EEDS volume, cochlear modiolar area, or signal intensity of the endolymphatic sac. We evaluated the correlations between the number of mutant alleles and these parameters in patients with EEDS to investigate the mechanisms underlying this condition. The study group was comprised of 16 Japanese patients with EEDS diagnosed by MR imaging. The H723R mutation was homozygous in six patients and heterozygous in six patients, with no mutation found in four patients. The modiolar area, EEDS volume, and signal intensity ratio (sac signal/cerebrospinal fluid signal) were not significantly correlated with the number of mutant alleles. PDS gene mutations may not be the only cause of EEDS, and the mechanisms underlying EEDS remain unclear.

Adolescent↗

PubMed2004

Diffusion tensor imaging in frontal lobe epilepsy.

We report a 13-year-old female with refractory frontal lobe epilepsy in whom diffusion tensor imaging was useful for exploring subtle cortical malformation. She had frequent simple partial seizures characterized by clonic movement of the right upper extremity. Conventional magnetic resonance imaging was not conclusive. A diffusion tensor imaging revealed an increased apparent diffusion coefficient and reduced anisotropy in the left frontal lobe. Positron emission tomography disclosed hypermetabolism in the adjacent area. We could identify the relatively thick cortex with an indistinct gray-white matter junction in a thin-slice T(1)-weighted image.

Adolescent↗

PubMed2004

High-speed imaging at 3 Tesla: a technical and clinical review with an emphasis on whole-brain 3D imaging.

Improvements to the inherently high specific-absorption rate (SAR) of high-speed imaging at 3T are necessary in order to render this method clinically feasible. Various efforts have been undertaken to improve the associated hardware and software. In this review, we focus on whole-brain isotropic 3D imaging with a turbo spin-echo sequence with variable flip-angle echo trains (3D-TSE-VFL) and present its technical and clinical features. This sequence can be used to acquire images of various contrasts including T2-weighted, fat-suppressed T2-weighted, fluid-attenuated inversion recovery (FLAIR), fat-suppressed FLAIR, and STIR (short tau inversion recovery). Various aspects of 3D-TSE-VFL are discussed, including CSF (cerebrospinal fluid) and metal artifacts, STIR contrast, small-part visualization other than brain, and the possibility of serial subtraction. Some images from clinical cases are presented.

Adult↗

PubMed2003

Optimization of diffusion-tensor MR imaging data acquisition parameters for brain fiber tracking using parallel imaging at 3 T.

The purpose of this study was to optimize the parameters of diffusion-tensor magnetic resonance imaging (DT MRI) for brain fiber tracking using a slice thickness of 2 mm, a resolution advantage allowed by the high signal-to-noise ratio at 3 T, combined with an 8-channel phased-array head coil. The b-factor, number of motion probing gradient (MPG) directions, and number of averages were varied, and the results of brain fiber tracking for the pyramidal tract and trigeminal nerve were compared qualitatively and quantitatively. The DT MRI data sufficient for brain fiber tracking in healthy subjects can be obtained in <2 min with a 2-mm slice thickness, 700-s/mm2 b-factor, 6 MPG directions, and no averaging (number of averages=1).

Adult↗

PubMed2003

Flow ghost artifact in slice-encoding direction mimicking vestibular schwannoma in contrast-enhanced 3D spoiled gradient-echo sequence.

The value of MR imaging by post-contrast T1-weighted 3D spoiled gradient-echo (3D SPGR) is well established for the detection of small vestibular schwannomas in the cerebellopontine angle region. We describe a case in which a flow ghost artifact in the slice-encoding direction mimicked a vestibular schwannoma and heavily T2-weighted MR cisternography and multiplanar reconstruction images helped us to reach the correct diagnosis. In addition, we conducted a volunteer study to demonstrate that changing the k-space trajectory can reduce this artifact in post-contrast 3D SPGR images.

Adult↗

PubMed2003

Pre-surgical mapping of primary motor cortex by functional MRI at 3 T: effects of intravenous administration of Gd-DTPA.

The functional magnetic resonance imaging (fMRI) is often performed at the end of a routine MRI examination during which, dependent on the clinical indication, contrast agent has been administered; however, the effects of Gd-DTPA injection on the results of blood oxygenation level dependent (BOLD)-fMRI remain unknown. The present study was conducted to investigate the effects of the intravenous administration of Gd-DTPA on the results of pre-surgical localization of the primary motor cortex by BOLD-fMRI at 3 T. Eight normal subjects were included in this study. After the anatomical scans, pre- and post-contrast fMRI scanning was performed. The number of significantly activated voxels and the mean percentage signal change were compared. The mean number of significantly activated voxels was 115.0+/-27.0 in pre-contrast runs and 90.8+/-27.1 in post-contrast runs (mean value of all 8 volunteers+/-standard deviation; p<0.05). The mean mean percentage signal change was 4.07+/-0.39 in pre-contrast runs and 3.86+/-1.91 in post-contrast runs ( p=0.16). Pre-surgical localization of the motor area by BOLD-fMRI should be performed before the administration of Gd contrast material.

Adult↗

PubMed2003

High-resolution T1-weighted 3D real IR imaging of the temporal bone using triple-dose contrast material.

The small structures in the temporal bone are surrounded by bone and air. The objectives of this study were (a) to compare contrast-enhanced T1-weighted images acquired by fast spin-echo-based three-dimensional real inversion recovery (3D rIR) against those acquired by gradient echo-based 3D SPGR in the visualization of the enhancement of small structures in the temporal bone, and (b) to determine whether either 3D rIR or 3D SPGR is useful for visualizing enhancement of the cochlear lymph fluid. Seven healthy men (age range 27-46 years) volunteered to participate in this study. All MR imaging was performed using a dedicated bilateral quadrature surface phased-array coil for temporal bone imaging at 1.5 T (Visart EX, Toshiba, Tokyo, Japan). The 3D rIR images (TR/TE/TI: 1800 ms/10 ms/500 ms) and flow-compensated 3D SPGR images (TR/TE/FA: 23 ms/10 ms/25 degrees) were obtained with a reconstructed voxel size of 0.6 x 0.7 x 0.8 mm3. Images were acquired before and 1, 90, 180, and 270 min after the administration of triple-dose Gd-DTPA-BMA (0.3 mmol/kg). In post-contrast MR images, the degree of enhancement of the cochlear aqueduct, endolymphatic sac, subarcuate artery, geniculate ganglion of the facial nerve, and cochlear lymph fluid space was assessed by two radiologists. The degree of enhancement was scored as follows: 0 (no enhancement); 1 (slight enhancement); 2 (intermediate between 1 and 3); and 3 (enhancement similar to that of vessels). Enhancement scores for the endolymphatic sac, subarcuate artery, and geniculate ganglion were higher in 3D rIR than in 3D SPGR. Washout of enhancement in the endolymphatic sac appeared to be delayed compared with that in the subarcuate artery, suggesting that the enhancement in the endolymphatic sac may have been due in part to non-vascular tissue enhancement. Enhancement of the cochlear lymph space was not observed in any of the subjects in 3D rIR and 3D SPGR. The 3D rIR sequence may be more sensitive than the 3D SPGR sequence in visualizing the enhancement of small structures in the temporal bone; however, enhancement of the cochlear fluid space could not be visualized even with 3D rIR, triple-dose contrast, and dedicated coils at 1.5 T.

Adult↗

PubMed2003

3T MR for clinical use: update.

Clinical experience with 3-tesla MRI for body applications has only a short history; to date, it has no proven practical advantage over 1.5-tesla or less powerful systems. However, the theoretical advantage of higher field strength-which includes a higher signal-to-noise ratio with identical scan parameters, higher special resolution available within clinically acceptable scan time, and better spectral resolution-can contribute to the clinical outcome. This paper seeks to demonstrate some of the clinical advantages of the 3-tesla system through preliminary experiences as well as the potential advantages of a 3-tesla system when combined with much of the hardware and software that is clinically accepted in the 1.5-tesla world.

Abdomen↗