Abstract: To suppress eddy current generation by a gradient magnetic field while an RF shield has a function of reducing magnetic coupling of an RF coil with a gradient magnetic coil, the RF shield must be formed of a conductive material of a tiled or slitted strip-shaped thin plate. On the other hand, cooling must be performed to suppress temperature rise due to heat generation by the eddy current. Furthermore, to enlarge an opening through which a patient is inserted, the gradient magnetic coil, the RF coil, and the RF shield, which are located in a static field magnet and have roughly concentrically cylindrical shapes, are required to be reduced in thickness.

Abstract: Provided is a coil device capable of improving operability or durability thereof, being attached to a subject in a close contact state regardless of the size of a head of the subject, and obtaining a high-quality MRI image. The coil device includes at least one coil unit which has a coil element and a coil support portion which has a mechanism for attaching the coil unit to a head of a subject. The coil support portion includes a base portion, a support body which is connected to the base portion and has an elastic member, and a holder which connects the support body to the at least one coil unit and the holder has at least three contact points which are formed directly or indirectly with respect to the base portion.

Abstract: The receiving coil device includes one or a plurality of receiving coils configured to cover a head of a subject, a base portion on which the head of the subject is to be placed, a holder portion supported by the base portion, one of the receiving coils being fixed to the holder portion, a mechanism portion configured to bring the receiving coil fixed to the holder portion into close contact with a part of the head, and further, a detection unit configured to detect a physical quantity related to a displacement of the holder portion on the holder portion or the base portion. The physical quantity detected by the detection unit is sent to an MRI apparatus including the receiving coil device.

Abstract: A radio frequency coil unit performs at least one of transmission of a radio frequency signal to a subject placed in a static magnetic field and reception of a nuclear magnetic resonance signal generated from the subject. The radio frequency coil unit includes a radio frequency coil including a first ring conductor, a second ring conductor, a plurality of rung conductors that electrically connect the first ring conductor and the second ring conductor to each other, and a plurality of capacitors, and a cylindrical shield conductor surrounding the radio frequency coil. A distance between the second ring conductor and the shield conductor is shorter than a distance between the first ring conductor and the shield conductor. A width of the second ring conductor is smaller than a width of the first ring conductor.

Abstract: The receiving coil device includes one or a plurality of receiving coils configured to cover a head of a subject, a base portion on which the head of the subject is to be placed, a holder portion supported by the base portion, one of the receiving coils being fixed to the holder portion, a mechanism portion configured to bring the receiving coil fixed to the holder portion into close contact with a part of the head, and further, a detection unit configured to detect a physical quantity related to a displacement of the holder portion on the holder portion or the base portion. The physical quantity detected by the detection unit is sent to an MRI apparatus including the receiving coil device.

Abstract: A radio frequency coil unit performs at least one of transmission of a radio frequency signal to a subject placed in a static magnetic field and reception of a nuclear magnetic resonance signal generated from the subject. The radio frequency coil unit includes a radio frequency coil including a first ring conductor, a second ring conductor, a plurality of rung conductors that electrically connect the first ring conductor and the second ring conductor to each other, and a plurality of capacitors, and a cylindrical shield conductor surrounding the radio frequency coil. A distance between the second ring conductor and the shield conductor is shorter than a distance between the first ring conductor and the shield conductor. A width of the second ring conductor is smaller than a width of the first ring conductor.

Abstract: Provided is a coil device capable of improving operability or durability thereof, being attached to a subject in a close contact state regardless of the size of a head of the subject, and obtaining a high-quality MRI image. The coil device includes at least one coil unit which has a coil element and a coil support portion which has a mechanism for attaching the coil unit to a head of a subject. The coil support portion includes a base portion, a support body which is connected to the base portion and has an elastic member, and a holder which connects the support body to the at least one coil unit and the holder has at least three contact points which are formed directly or indirectly with respect to the base portion.

Abstract: To avoid the complication of an MRI apparatus and avoid the overestimation of a calculated value of SAR without extending a processing time and to perform accurate SAR management. To this end, the MRI apparatus is equipped with a high frequency antenna which has a plurality of channels and resonates at a predetermined frequency, and a measuring instrument which measures the amplitudes of a forward traveling and reflected waves of each high frequency signal supplied to the high frequency antenna. In the MRI apparatus, a reflection matrix S is determined based on the measured amplitudes. Diagonal terms of the determined reflection matrix S are used to calculate Q values for each of the channels. Each non-diagonal term of the reflection matrix S is used to correct the calculated Q value.

Abstract: To avoid the complication of an MRI apparatus and avoid the overestimation of a calculated value of SAR without extending a processing time and to perform accurate SAR management. To this end, the MRI apparatus is equipped with a high frequency antenna which has a plurality of channels and resonates at a predetermined frequency, and a measuring instrument which measures the amplitudes of a forward traveling and reflected waves of each high frequency signal supplied to the high frequency antenna. In the MRI apparatus, a reflection matrix S is determined based on the measured amplitudes. Diagonal terms of the determined reflection matrix S are used to calculate Q values for each of the channels. Each non-diagonal term of the reflection matrix S is used to correct the calculated Q value.

Abstract: An object of the present invention is to provide a radio-frequency coil device that can be brought into close contact with a subject regardless of a size of the subject and can obtain a high-quality MRI image. The radio-frequency coil device includes at least one flexible coil unit, and a fixture is disposed to surround an outer periphery of the coil unit. The fixture includes, for example, a pair of panels disposed on both sides of the coil unit, and a fixing belt that is provided between the panels and fastens and fixes the panels. The coil unit is deformed by fastening the fixture, to be disposed in close contact with various head shapes.

Abstract: With an MRI apparatus using a transmission coil having multiple channels, a region desired to be diagnosed is efficiently imaged with high image quality. The MRI apparatus comprises a region setting means for setting a region in an imaging region, of which high quality image is desired to be obtained, as a first region, and an optimization means for determining at least one of amplitude and phase of a radio frequency wave transmitted to each of the multiple channels as a radio frequency magnetic field condition, and the optimization means determines the radio frequency magnetic field condition so that at least one of specific absorption ratio and signal value of a region that generates artifacts is not higher than a predetermined value defined for each, under a uniformity constraint condition that uniformity of radio frequency magnetic field distribution in the first region is not lower than a predetermined value.

Abstract: Provided is a technique that enables accurate SAR management using power consumption by an object (Pobject) that was calculated based on accurately acquired Q-factors. For this purpose, the present invention calculates Q-factors of each channel of a high-frequency antenna using measurement results of amplitudes of forward waves and reflected waves of each high-frequency signal between three or more different frequencies. An existing SAR monitor in an MRI apparatus is used for the amplitude measurement. Also, the Q-factors are calculated based on a circuit coefficient to be acquired by fitting the measurement results to a predetermined circuit model. Then, the power consumption by an object (Pobject) is calculated using the calculated Q-factors in order to manage the SAR.

Abstract: In order to provide a technique in which, in the TEM type antenna, the uniformity of sensitivity in the internal portion of the antenna can be maintained with simple configuration, without scarifying the internal space of the antenna, regardless of a size, a shape and a location of a load, and also regardless of locations of the constitutional members of the antenna, the TEM type antenna includes rung conductors which branch out into plural pieces in the middle portion and join into one piece in the two end portions. In other words, the rung conductor having a void space in the middle portion of the rung conductor in the longitudinal direction is provided. The adjacent rung conductors are disposed to be further closer to each other in the middle portion, and to maintain the same distance as that in the related art in the end portion.

Abstract: Provided is an antenna such as a TEM-type antenna and a microstrip-type antenna that has rung conductors and a shield conductor to electrically connect and use them. A holding member that maintains a shape of the shield conductor is composed by assembling ribs and thin walls. An inner holding member is a structural material. Holes are provided on at least either one of the shield conductor and the holding member adhered thereto or the inner holding member, which can adjoin conductors from the outside of the cylindrical antenna through the said holes during the antenna production.

Abstract: A radiofrequency antenna has a plurality of channels. A Q-value calculating unit computes reflected signals of the plurality of channels of the radiofrequency antenna, respectively, in a case where transmission signals as electrical signals are simultaneously supplied to the plurality of channels of the radiofrequency antenna, also including a signal obtained when the transmission signal supplied to one channel of the plurality of channels is reflected from another channel, and computes a Q value of the radiofrequency antenna using the reflected signal. An SAR calculating unit calculates a specific absorption rate (SAR) using the Q value.

Abstract: Systems and methods for magnetic resonance imaging, including adjusting spatial distribution of a rotating magnetic field. By minimizing imaging time, the B1 nonuniformity reducing effect of RF shimming is maximized for an imaging section of an arbitrary axis direction and an arbitrary position. B1 distributions are measured for only several sections of one predetermined direction, and a radio frequency magnetic field condition that maximizes the B1 non-uniformity reducing effect for an imaging section of an arbitrary direction and an arbitrary position is calculated from the B1 distribution data.

Abstract: In order to provide a technique which can suppress coupling to homogenize the spatial distribution of an RF magnetic field and can improve penetration of the RF magnetic field into the subject, pad-like electric field conductors having a predetermined area are provided outside both ends of a rung conductor as a part of a configuration which forms a loop-like circuit and is driven as an antenna. An antenna device includes a sheet-like conductor, a rung conductor which is arranged at a predetermined distance from the sheet-like conductor, two electric field conductors which are arranged in both end portions of the rung conductor at a predetermined distance from the sheet-like conductor, and connection terminals which are transmission and reception terminals provided in the rung conductor and the sheet-like conductor. The rung conductor and the sheet-like conductor configure a loop circuit which resonates at a preset frequency.

Abstract: Provided is a technique that enables accurate SAR management using power consumption by an object (Pobject) that was calculated based on accurately acquired Q-factors. For this purpose, the present invention calculates Q-factors of each channel of a high-frequency antenna using measurement results of amplitudes of forward waves and reflected waves of each high-frequency signal between three or more different frequencies. An existing SAR monitor in an MRI apparatus is used for the amplitude measurement. Also, the Q-factors are calculated based on a circuit coefficient to be acquired by fitting the measurement results to a predetermined circuit model. Then, the power consumption by an object (Pobject) is calculated using the calculated Q-factors in order to manage the SAR.

Abstract: A technique is provided to reserve large examination space in the tunnel type MRI apparatus, without increasing production cost nor reducing significantly irradiation efficiency and homogeneity in an irradiation distribution within an imaging region. The present invention provides an RF coil unit in which four partial cylindrical coils are placed with a gap therebetween in the circumferential direction inside a cylindrical RF shield, in such a manner that two pairs of the partial cylindrical coils are opposed to each other, and magnetic fields produced by the individual partial cylindrical coils are combined, thereby producing a circularly polarized wave field or an elliptically polarized wave field.

Abstract: There is provided a technique for suppressing increase of SAR without sacrificing sensitivity in RF coils used in MRI apparatuses. The present invention provides an antenna device comprising a sheet-shaped conductor and a ribbon-shaped conductor disposed on the subject side with respect to the sheet-shaped conductor with a predetermined distance from the sheet-shaped conductor. The ribbon-shaped conductor has a meandering shape, and is adjusted so as to resonate at transmission and reception frequencies, and it is constituted so that distance to the sheet-shaped conductor becomes smaller at both end part thereof along the static magnetic field direction compared with the distance to the sheet-shaped conductor at the center thereof. Moreover, the ribbon-shaped conductor is constituted so as to have a smaller width, as the distance to the sheet-shaped conductor becomes smaller.