摘要:
The degree of sub-sampling in magnetic resonance imaging is such that the ensuing acquisition time for receiving (echo) series of magnetic resonance signals due to an individual RF excitation is shorter than the decay time of such magnetic resonance signals. Preferably, a segmented scan of the k space is performed, the number of segments and the number of lines scanned in each segment being adjustable and a predetermined total number of lines being scanned. Preferably, a small number of segments is used such that the acquisition time for receiving the magnetic resonance signals for the complete magnetic resonance image is shorter than the process time of the dynamic process involved.
摘要:
The degree of sub-sampling in magnetic resonance imaging is such that the ensuing acquisition time for receiving (echo) series of magnetic resonance signals due to an individual RF excitation is shorter than the decay time of such magnetic resonance signals. Preferably, a segmented scan of the k space is performed, the number of segments and the number of lines scanned in each segment being adjustable and a predetermined total number of lines being scanned. Preferably, a small number of segments is used such that the acquisition time for receiving the magnetic resonance signals for the complete magnetic resonance image is shorter than the process time of the dynamic process involved.
摘要:
The invention relates to a method of characterizing the RF transmit chain of a magnetic resonance imaging scanner (1) using a local transmit/receive coil system (204; 210), comprising a first local NMR probe and a first local magnetic resonance coil, the first NMR probe being spatially located in immediate neighborhood to the first coil, a local receive coil system (206; 208), comprising a second local NMR probe and a second local magnetic resonance coil, the second NMR probe being spatially located in immediate neighborhood to the second coil, wherein the transmit chain comprises an external MR coil (9; 11; 12; 13), the method comprising: determining with the first magnetic resonance coil, a first MR signal phase evolution of the local RF transmit field generated by MR excitation of the first probe using the first magnetic resonance coil by measuring the RF response of the first probe upon said excitation, determining with the second magnetic resonance coil a second MR signal phase evolution of the local RF transmit field generated by MR excitation of the second probe using the external MR coil (9; 11; 12; 13) by measuring the RF response of the second probe upon said excitation, calculating a phase offset between the first and second MR signal phase evolution.
摘要:
A diagnostic imaging system (1), in particular a magnetic resonance imaging system. The diagnostic imaging system comprises control system (2) to control the execution of operational items by the diagnostic imaging system. A user interface (3) is coupled to the control system, the user interface including a scheduler module which forms an ordered selection of operational items. The operational items are executed on the basis of the ordered selection. The ordered selection concerns the order, timing and conditions to be fulfilled to execute the operational items. Notably, in an magnetic resonance imaging system the actual acquisition concerns the execution of acquisition pulse sequences to receive magnetic resonance signals which is carried out for the planned geometry, the preferred embodiment comprises a patient support that can be moved among various positions which is used in a multi-station examination.
摘要:
The invention relates to a method for magnetic resonance imaging of at least a portion of a body placed in a stationary and substantially homogeneous main magnetic field. The body is subjected to a sequence of RF and magnetic field gradient pulses during an interval TSE, thereby generating a plurality of spin echo signals, which are measured and processed for reconstruction of an image. Thereafter, during an interval TDRV, an additional spin echo is generated by subjecting the body to at least one further refocusing RF pulse and/or magnetic field gradient pulse, and a RF drive pulse (βX) is irradiated at the time of this additional spin echo. In order to provide a fast and reliable method for T1-weighted imaging, which gives a high T1 contrast and also a sufficient signal-to-noise ratio, the phase of the RF drive pulse (βX) is selected such that nuclear magnetization at the time of the additional spin echo is transformed into negative longitudinal magnetization. The sequence is repeated beginning with another sequence of RF and magnetic field gradient pulses after a recovery period TREC.
摘要:
A method of deriving a directional structure from an object dataset is proposed. The object dataset assigns local directions to positions in a multidimensional geometrical space. For example the local directions concern local flow directions in a diffusion tensor magnetic resonance image at least one ‘region of interest’ is selected on the basis of spatial functional information, such as an fMRI image, time correlation of an fMRI image series with a functional paradigm or an anatomical image. These ‘region of interest’ are employed to initialize a fibre tracking to derive the directional structure that represents the nervous fibre system.
摘要:
A novel magnetic resonance imaging method is described, for forming an image of an object from a plurality of signals sampled in a restricted homogeneity region of a main magnet field of a magnetic resonance imaging apparatus. A patient disposed on a table is moved continuously through the bore of the main magnet and spins in a predetermined area of the patient are excited by an excitation pulse from a transmitter antenna, such that an image is formed over a region exceeding largely the restricted region. Data is undersampled in the restricted region by means off at least one receiver antenna in a plurality of receive situations being defined as a block of measurements contiguous in time having preserved magnetisation and presaturation conditions within the excited area of the patient. Fold-over artefacts due to said undersampling are unfolded by means of the known sensitivity pattern of the receiver antenna and/or the properties of selected factors determining said receive situations.
摘要:
The present invention relates to a magnetic resonance imaging apparatus comprising an RF coil system comprising M RF coils (11-18) for detecting RF signals from a region of interest, M being an integer larger than 2, and N receiver channels (C1-C4) for receiving and processing the detected RF signals, N being an integer larger than 1 and smaller than M. According to the invention at least two RF coils (12, 16; 14, 18) are combined for reception of RF signals of said RF coils with a single receiver channel, wherein said at least two RF coils are selected so as to provide maximum spatially varying coil sensitivities along the principal axis for coil sensitivity encoding. The proposed MRI apparatus provides an optimal solution enabling it to be used with the SENSE method. The general idea is to have as much individuality as possible along the preferred or actual sense reduction direction and to feature as much spatial distinctness as possible along the axes of primary clinical interest.
摘要翻译:本发明涉及一种包括RF线圈系统的磁共振成像设备,该RF线圈系统包括用于检测来自感兴趣区域的RF信号的M个RF线圈(M-M为大于2的整数),以及N个接收器通道(C1- C 4),用于接收和处理所检测的RF信号,N是大于1且小于M的整数。根据本发明,至少两个RF线圈(12,16; 14,18)被组合用于接收RF信号 所述RF线圈具有单个接收器通道,其中所述至少两个RF线圈被选择为沿着所述主轴提供最大空间变化的线圈灵敏度以用于线圈灵敏度编码。 所提出的MRI装置提供了使其能够与SENSE方法一起使用的最佳解决方案。 一般想法是沿着优选或实际的感官减少方向具有尽可能多的个性,并且沿着主要的临床兴趣的轴线具有尽可能多的空间独特性。
摘要:
A magnetic resonance imaging method for forming an image of an object from a plurality of signals acquired by an array of multiple receiver antennae, wherein spins are excitated in a part of the object. MR signals are measured along a predetermined trajectory containing a plurality of lines in k-space by application of a read gradient and other gradients. Further, a navigator gradient is applied for the measurement of navigator MR signals and an additional gradient is applied in order to achieve diffusion sensitivity of the MR signal, wherein phase corrections are determined from phases and moduli of the navigator MR signals so as to correct the measured MR signals. An image of the part of the object is determined from the corrected MR signals. The corrected phase is determined from the weighted phase difference between a reference navigator signal for each antenna and the actual navigator MR signal of said antenna.
摘要:
The invention relates to a method of characterizing the RF transmit chain of a magnetic resonance imaging scanner (1) using a local transmit/receive coil system (204; 210), comprising a first local NMR probe and a first local magnetic resonance coil, the first NMR probe being spatially located in immediate neighborhood to the first coil, a local receive coil system (206; 208), comprising a second local NMR probe and a second local magnetic resonance coil, the second NMR probe being spatially located in immediate neighborhood to the second coil, wherein the transmit chain comprises an external MR coil (9; 11; 12; 13), the method comprising: determining with the first magnetic resonance coil, a first MR signal phase evolution of the local RF transmit field generated by MR excitation of the first probe using the first magnetic resonance coil by measuring the RF response of the first probe upon said excitation, determining with the second magnetic resonance coil a second MR signal phase evolution of the local RF transmit field generated by MR excitation of the second probe using the external MR coil (9; 11; 12; 13) by measuring the RF response of the second probe upon said excitation, calculating a phase offset between the first and second MR signal phase evolution.