MR Technology Inc.
MR Technology Inc.
Ogawa K.,Keio University |
Haishi T.,MR Technology Inc. |
Aoki M.,Digital Signal |
Hasegawa H.,Digital Signal |
And 2 more authors.
Review of Scientific Instruments | Year: 2017
A small radio-frequency (rf) coil inserted into a polymer electrolyte fuel cell (PEFC) can be used to acquire nuclear magnetic resonance (NMR) signals from the water in a membrane electrode assembly (MEA) or in oxygen gas channels in the PEFC. Measuring the spatial distribution of the water in a large PEFC requires using many rf probes, so an NMR measurement system which acquires NMR signals from 128 rf probes at intervals of 0.5 s was manufactured. The system has eight rf transceiver units with a field-programmable gate array (FPGA) for modulation of the excitation pulse and quadrature phase detection of the NMR signal, and one control unit with two ring buffers for data control. The sequence data required for the NMR measurement were written into one ring buffer. The acquired NMR signal data were then written temporarily into the other ring buffer and then were transmitted to a personal computer (PC). A total of 98 rf probes were inserted into the PEFC that had an electrical generation area of 16 cm × 14 cm, and the water generated in the PEFC was measured when the PEFC operated at 100 A. As a result, time-dependent changes in the spatial distribution of the water content in the MEA and the water in the oxygen gas channels were obtained. © 2017 Author(s).
Haishi T.,MR Technology Inc. |
Koizumi H.,Waseda University |
Arai T.,Japan National Agriculture and Food Research Organization |
Koizumi M.,Waseda University |
Kano H.,Oak Hill Georgic Patch Work Laboratory
Applied Magnetic Resonance | Year: 2011
Infestation of harvested apple fruits by the peach fruit moth (Carposina sasakii Matsumura) was studied using a dedicated magnetic resonance imaging (MRI) apparatus equipped with a 0. 2-T permanent magnet. Infested holes on the three-dimensional (3-D) images tracked ecological movements of peach fruit moth larvae within the food fruits, and thus in their natural habitat. Sensitive short solenoid coil and surface coil detectors were devised to shorten measurement times. The short solenoid coil detected infestation holes at a rate of 6. 4 s per image by the single-slice 2-D measurement. The multi-slice 2-D measurement provided six slice images of a fruit within 2 min taken by the two detectors. These results indicate that the 0. 2-T MRI apparatus allows one to distinguish sound fruits from infested ones, and also as a means for plant protection and the preservation of natural ecological systems in foreign trade. © 2011 The Author(s).
Koizumi M.,Waseda University |
Ihara F.,Japan National Agriculture and Food Research Organization |
Yaginuma K.,Japan National Agriculture and Food Research Organization |
Kano H.,Oak Hill Georgie Patch Work Laboratory |
Haishi T.,MR Technology Inc.
Journal of Insect Science | Year: 2010
Infestation of young apple fruits by the larvae of the peach fruit moth, Carposina sasakii Matsumura (Lepidoptera: Carposinidae), was studied by a small dedicated micro-magnetic resonance imaging (MRI) apparatus using the three-dimensional (3D) gradient-echo method and the two-dimensional (2D) and 3D spin-echo methods. Changes from a young larva at 1.8 mm in length to a mature one ready to leave the fruit were observed in relation to the progression of infestation of the fruit tissues. The trace of larva intrusion was demonstrated by a series of sliced images in the 3D image data of an infested fruit, where it entered from outside the calyx, and migrated to near the vasculature around the carpel through the core. The small, dedicated MRI device was proven useful for ecological studies of the growth and movement of insect larvae in their food fruits. It can also be applied to detect the infestation of small fruits by insect larvae.
Fukuda K.,University of Tokyo |
Kawaguchi D.,University of Tokyo |
Aihara T.,Okayama University |
Ogasa M.Y.,University of Tokyo |
And 4 more authors.
Plant, Cell and Environment | Year: 2015
Development of xylem embolism during water stress in two diffuse-porous hardwoods, Katsura (Cercidiphyllum japonicum) and Japanese white birch (Betula platyphylla var. japonica), was observed non-destructively under a compact magnetic resonance imaging (MRI) system in addition to conventional quantitation of hydraulic vulnerability to cavitation from excised stem segments. Distribution of white and dark areas in MR images corresponded well to the distribution of water-filled/embolized vessels observed by cryo-scanning electron microscopy in both species. Water-filled vessels were observed in MR images as white areas in Katsura and as white dots in Japanese white birch, respectively, and embolisms could be detected as a change to dark areas. The increase in the relative embolized area (REA: %) in the cross-sectional area of total xylem during water stress, which was estimated from the binarized MR images, was consistent with the hydraulic vulnerability curves of these species. From the non-destructive MRI observations, cavitation induced by water stress was shown to develop earlier in 1- or 2-year-old xylem than in the current-year xylem in both species; that is, the vulnerability to cavitation differs between vessels in the current-year xylem and those in older annual rings. Development of xylem embolism during water stress in two diffuse-porous hardwoods, Katsura (Cercidiphyllum japonicum) and Japanese white birch (Betula platyphylla var. japonica), was observed nondestructively under a compact magnetic resonance imaging (MRI) system in addition to conventional quantitation of hydraulic vulnerability to cavitation from excised stem segments. The increase in the relative embolized area estimated from the binarized MR images was consistent with the hydraulic vulnerability curves of these species. From the MRI observations, cavitation induced by water stress was shown to develop earlier in 1- or 2-year-old xylem than in the current-year xylem in the both species; i.e., the vulnerability to cavitation differs between vessels in the current-year xylem and those in older annual rings. © 2015 John Wiley & Sons Ltd.
Hashimoto S.,University of Tsukuba |
Kose K.,University of Tsukuba |
Haishi T.,MR Technology Inc
Magnetic Resonance in Medical Sciences | Year: 2014
We critically evaluated analog and digital transceivers for magnetic resonance (MR) imaging systems under identical experimental conditions to identify and compare their advantages and disadvantages. MR imaging experiments were performed using a 4.74-tesla vertical-bore superconducting magnet and a high sensitivity gradient coil probe. We acquired 3-dimensional spin echo images of a kumquat with and without using a gain-stepping scan technique to extend the dynamic range of the receiver systems. The acquired MR images clearly demonstrated nearly identical image quality for both transceiver systems, but DC and ghosting artifacts were obtained for the analog transceiver system. We therefore concluded that digital transceivers have several advantages over the analog transceivers. © 2014 Japanese Society for Magnetic Resonance in Medicine.
Inoue Y.,Advanced Clinical Research Center |
Inoue Y.,University of Tokyo |
Inoue Y.,MR Technology Inc. |
Inoue Y.,Tokyo Medical University |
And 18 more authors.
Molecular Imaging | Year: 2010
We developed an integrated imaging method using bioluminescence imaging (BLI) and magnetic resonance imaging (MRI) and applied it to mouse tumor monitoring. BLIs and MRIs were successively acquired from mice fixed on a transparent flat plate and were registered using three small markers. After spatial coregistration, the two-dimensional BLI was fused with all MRI slices. The accuracy of image registration was evaluated using fluorescence imaging and MRI of many markers attached to the mice. Mice were inoculated with luciferase-expressing tumor cells subcutaneously or directly into the liver, and disease progression was evaluated repeatedly by integrated BLI-MRI. Image registration was achieved with acceptable accuracy, although the registration error increased with increasing distance from the center of the imaging field and was larger in imaging the convex dorsal side of the mouse than in imaging the flat ventral side. Integrated BLI-MRI allowed longitudinal assessment of disease progression and appeared to facilitate detailed interpretation of the imaging findings. It aided the anatomic localization of lesions demonstrated by BLI and recognition of MRI abnormalities corresponding to BLI foci. Integrated BLI-MRI is feasible and appears to be a practical method for comprehensive, longitudinal assessment of disease model mice. © 2010 BC Decker Inc.