摘要:
The invention relates to a device (1) for magnetic resonance imaging of a body (7), comprising a main magnet (2) for generation of a stationary and substantially homogeneous main magnetic field within the examination zone, a plurality of wireless receiving units (10a, 10b) placed in or near the examination zone, and sampling means (21a, 21b) operating at a variable sampling frequency for sampling the received MR signals and for converting them into digital signal samples. In order to provide an MR device (1), which is arranged to inductively energize the wireless receiving units (10a, 10b) without interference with the nuclear spin system of the examined object (7) and which does not necessarily require bulky energy storage means for the operation of the wireless receiving units (10a, 10b), the invention proposes to make provision for energizing means (17) generating an RF energizing field within the examination zone for inductively supplying electric power to the wireless receiving units (10a, 10b), wherein the frequency of the RF energizing field is an integer multiple of the sampling frequency.
摘要:
The invention relates to a device (1) for magnetic resonance imaging of a body (7), comprising a main magnet (2) for generation of a stationary and substantially homogeneous main magnetic field within the examination zone, a plurality of wireless receiving units (10a, 10b) placed in or near the examination zone, and sampling means (21a, 21b) operating at a variable sampling frequency for sampling the received MR signals and for converting them into digital signal samples. The invention proposes to make provision for energizing means (17) generating an RF energizing field within the examination zone for inductively supplying electric power to the wireless receiving units (10a, 10b), wherein the frequency of the RF energizing field is an integer multiple of the sampling frequency.
摘要:
The invention relates to an MR coil module for use in an MR imaging system for receiving and/or transmitting RF signals. In order to provide an MR coil module which allows a modular and user definable configuration of an RF coil system and which provides a high SENSE factor (>2), the MR coil module according to the invention comprises: at least two coil elements (21-26) positioned next to each other, a preamplifier (51-56) for each coil element (21-26), a signal bus (40) for transferring RF signals between said coil elements (21-26), an output means (10) and an input means (9), an output means (10) for outputting RF signals from the MR coil module (1), an input means (9) for inputting RF signals into the MR coil module (1), switching means (6) for switching the connections between said coil elements (21-26), said input means (9) and said output means (10), wherein said output means (10) and said input means (9) are adapted complementary so as to enable electrical and mechanical connection of the module (1) to other modules.
摘要:
The invention relates to a device (1) for magnetic resonance imaging of a body (7) placed in a stationary and substantially homogeneous main magnetic field comprising a main magnet (2) for generation of a stationary and substantially homogeneous main magnetic field within the examination zone. In order to provide an MR device (1) which is arranged to allow for massive parallel imaging without extensive cabling between the individual receiving coils and the back end electronics, the invention proposes to make provision for a plurality of receiving units (10a, 10b, 10c) placed in or near the examination zone, which receiving units (10a, 10b, 10c) each comprise a receiving antenna (12a, 12b, 12c) for receiving MR signals from the body, a digitizing means (21a, 21b, 21c) for sampling the received MR signals and for transforming the signal samples into digital signals, and a transmitter (22a, 22b, 22c) for transmitting the digital signals to a central processing unit (13). Further, the device (1) comprises synchronization means (17) for synchronizing the operation of the individual digitizing means (21a, 21b, 21c) of the receiving units (10a, 10b, 10c).
摘要:
The invention relates to a device (1) for magnetic resonance imaging of a body (7) placed in a stationary and substantially homogeneous main magnetic field comprising a main magnet (2) for generation of a stationary and substantially homogeneous main magnetic field within the examination zone. In order to provide an MR device (1) which is arranged to allow for massive parallel imaging without extensive cabling between the individual receiving coils and the back end electronics, the invention proposes to make provision for a plurality of receiving units (10a, 10b, 10c) placed in or near the examination zone, which receiving units (10a, 10b, 10c) each comprise a receiving antenna (12a, 12b, 12c) for receiving MR signals from the body, a digitizing means (21a, 21b, 21c) for sampling the received MR signals and for transforming the signal samples into digital signals, and a transmitter (22a, 22b, 22c) for transmitting the digital signals to a central processing unit (13). Further, the device (1) comprises synchronization means (17) for synchronizing the operation of the individual digitizing means (21a, 21b, 21c) of the receiving units (10a, 10b, 10c).
摘要:
A magnetic resonance imaging (MRI) system includes an examination volume (9), a main magnet system (17) for generating a main magnetic field (B0) in the examination volume, a gradient magnet system (25) for generating gradients of the main magnetic field, and a control system (37) for compensating disturbances of the magnetic field caused by mechanical vibrations of the MRI system. The control system is a feed-forward control system which determines a necessary compensation for said disturbances in dependence on an electric current in the gradient magnet system according to a predetermined response relation. Since in most MRI systems the mechanical vibrations are predominantly caused by the altering electric currents in the gradient magnet system and by eddy currents induced thereby, an accurate and reliable compensation for said disturbances is provided, so that artifacts and other distortions of the reconstructed image caused by said disturbances are considerably reduced.
摘要:
The invention provides a magnetic resonance imaging (MRI) device (21), comprising a diagnostic space (25), a main magnetic system (22) for generating a main magnetic field in said diagnostic space, a gradient magnetic coil system (23) comprising a gradient coil for generating at least one gradient of the main magnetic field, and noise reducing means (29, 32) for reducing noise that is generated as a result of vibrations of the gradient coil. The noise reducing means comprise a sound-absorbing panel (29) disposed between the gradient coil and the diagnostic space. The sound-absorbing panel (29) comprises channels having an open end and a closed end.
摘要:
The invention relates to a magnetic resonance imaging system (1) comprising: a main magnet (2) for generating a uniform, steady magnetic field within an examination volume, at least one RF antenna (9) for transmitting RF pulses to the examination volume for magnetic resonance spin excitation, a gradient coil unit comprising gradient coils (4, 5, 6) for generating gradient magnetic fields in the examination volume (100), an RF shield (104) disposed between said RF antenna (9) and said gradient coils (4, 5, 6), said RF shield (104) comprising a shielding material adapted for suppressing Eddy currents induced in the shield by said gradient magnetic fields and for screening RF fields towards the gradient coils (4, 5, 6), said RF fields being generated by the RF antenna (9), wherein the RF shield comprises a conductive coating (104, 110) as shielding material.
摘要:
The invention relates to a magnetic resonance imaging system which comprises means for generating a static magnetic field and a gradient coils system for generating a time varying magnetic gradient field by use of a first electrical current and a second electrical current. The gradient coils system is located in the magnetic field and the gradient coils system has a plurality of vibrational modes. Lorentz forces are generated due to the interaction of the first and/or second electrical currents with the superposition of the static magnetic field and the magnetic gradient field. The gradient coils system and/or the first electrical current are adapted so that the integral of the in-products of said Lorentz forces and a vibrational mode of said plurality of vibrational modes is at a value close to zero, wherein said in-products are determined for all points of the gradient coils system, and wherein the integral is determined by summing the in-products determined for all the points. As the above mentioned integral is close to zero or preferably zero, the Lorentz forces are not able to excite the vibrational mode (for example the lowest order bending mode) of the gradient coils system. Thus acoustical noise that is generated by a vibrating gradient coils system is reduced and the comfort for a patient that is examined by the magnetic resonance imaging system is therefore enhanced.
摘要:
The invention relates to a MRI system and to a method for producing an image with such an system. In order to provide a MR imaging technique with a high efficient MR signal acquisition, which provides a high level of comfort to a patient, a MRI system and method are suggested, where image data from an object are acquired while the object is moving with variable speed relative to the MRI system, and where the image data are combined and an image of the object is reconstructed.