99 results about "Saturation pulse" patented technology

A system and method of free-breathing MR imaging saturates an entire navigator profile at the end of an imaging segment of physiological motion cycle, e.g., heart cycle, thereby providing a uniform recovery of longitudinal magnetization for the next imaging cycle. Through use of at least one dephaser gradient following the image acquisition segment and a navigator RF saturation pulse, residual transverse magnetization is dephased and spins within a navigator tracker are saturated to ensure a uniform recovery of longitudinal magnetization for the next imaging period.

The invention discloses a ferromagnetic pipeline quantitative lossless evaluating method based on nonlinear magnetic saturation pulsed eddy current. An electromagnet coil is conducted with high direct current to form a strong static magnetic field so that a detected object can be magnetically saturated, pulse excitation and pulse signal detection are finished on a TR type pulsed eddy current probe when the detected object is in the magnetic saturation state, and quantitative lossless evaluating on the local thinning defect in a ferromagnetic pipeline is achieved based on a magnetic saturation pulsed eddy current nonlinear efficient direct problem signal simulation method and a defect reconstruction inverse problem algorithm. The method has the advantages of being free of contact, easy to achieve and operate, high in detecting efficiency and the like and can be widely applied to the quantitative lossless evaluating on the local thinning defect of a large number of ferromagnetic material pipeline containers used in a power station, chemical engineering and other structures.

A method for generating a magnetic resonance image includes a series of inversion and saturation pulses, in which the pulses null the MRI signal from both fat and a second tissue for a single MRI acquisition. An inversion pulse is used to provide a null point for the second tissue. A pair of fat-selective saturation and inversion pulses are used to null the MRI signal from fat at approximately the same time as the second tissue reaches its null point. The saturation pulse is used to create a known state for the fat magnetization, allowing the flip angle of the fat-selective inversion pulse to be determined such that the null point of fat approximately coincides with the null point of the second tissue.

The invention relates to a method of CEST or APT MR imaging of at least a portion of a body (10) placed in a main magnetic field B₀ within the examination volume of a MR device. The method of the invention comprises the following steps: •a) subjecting the portion of the body (10) to a saturation RF pulse at a saturation frequency offset; •b) subjecting the portion of the body (10) to an imaging sequence comprising at least one excitation/refocusing RF pulse and switched magnetic field gradients, whereby MR signals are acquired from the portion of the body (10) as spin echo signals; •c) repeating steps a) and b) two or more times, wherein the saturation frequency offset and/or a echo time shift in the imaging sequence are varied, such that a different combination of saturation frequency offset and echo time shift is applied in two or more of the repetitions; •d) reconstructing a MR image and/or B₀ field homogeneity corrected APT/CEST images from the acquired MR signals. Moreover, the invention relates to a MR device (1) for carrying out the method of the invention and to a computer program to be run on a MR device.

The invention discloses a magnetic resonance imaging method and system, wherein the method comprises: before imaging scanning, determining a preset deflection angle of a radio frequency pulse to excite specific tissues; analyzing a corresponding dual-saturated pulse deflection angle according to the preset deflection angle; combining a dual-saturated pulse and a gradient pulse to form a dual-saturated pulse saturation module, wherein the gradient pulse includes a layer-selecting gradient pulse that is used for exciting a corresponding layer of the specific tissues; executing an imaging scanning process, to be specific, applying the dual-saturated pulse saturation module and an imaging pulse sequence sequentially to a scanning area to perform magnetic resonance imaging. By carrying out magnetic resonance imaging through the dual-saturated pulse saturation module and the imaging pulse sequence, saturated band signal inhibition non-uniformity due to non-uniformity of B1 field can be overcome, and motion artifacts due to organ motion, tissue motion and other motions can be inhibited.

The invention provides a magnetic resonance chemical exchange saturation transfer imaging method and a magnetic resonance chemical exchange saturation transfer imaging system. The magnetic resonance chemical exchange saturation transfer imaging method comprises a main RF pulse generating step, applying a short-time main RF saturation pulse which lasts for a first preset time for aiming at a specific RF point, thereby generating the contrast of a magnetic resonance imaging signal; an image acquisition step, segmentally acquiring image data in a reading-out direction or/and a phase encoding direction based on the applied main RF saturation pulse by means of a segmental planar echo acquisition method; and a sub-RF pulse generating step, after one-time image data acquisition by means of the segmental planar echo acquisition method, applying a sub-RF saturation pulse which lasts for a second preset time, thereby keeping the contrast of the magnetic resonance imaging signal. The magnetic resonance chemical exchange saturation transfer imaging method and the magnetic resonance chemical exchange saturation transfer imaging system settle problems of low signal sensitivity and low imaging efficiency in existing magnetic resonance chemical exchange saturation transfer imaging technology.

The invention discloses a plant chlorophyll fluorescence detecting device for equalizing irradiation. The plant chlorophyll fluorescence detecting device for equalizing irradiation comprises a light source, a camera, a light filler and a light reflection mirror, wherein the light source is used for transmitting detection light for a to-be-detected sample; the camera is used for collecting light rays from the to-be-detected sample; the light filler is arranged between the camera and the to-be-detected sample; and the light reflection mirror is used for reflecting detecting light from the light source to the to-be-detected sample. The plant chlorophyll fluorescence detecting device for equalizing irradiation provided by the invention can provide three kinds of irradiation including measurement light, saturation pulse light and actinic light; the light emitted by the light source is reflected by the light reflection mirror; and a space with equal irradiation is formed in the device, so that irradiation imaging can be carried out on laminas of plants with different heights.

A pulse sequence for time-of-flight (TOF) magnetic resonance angiography (MRA) includes a fatsat segment, a magnetization transfer segment, and a spatial saturation segment that are applied by an MR apparatus to acquire MR data for image reconstruction with improved image quality. The pulse sequence is constructed such that at the beginning of each iteration of the inner loop of a 3D acquisition, a fatsat pulse is applied. After the fatsat pulse, MR data is acquired in a series of imaging segments with well-suppressed fat signal. Effective fat suppression is achieved by sampling central k-space data first, before signal from fat relaxes back to a pre-saturation level. Each imaging segment is immediately preceded by one of a MT pulse or a spatial saturation pulse and immediately followed by the other one of the MT pulse or the spatial saturation pulse.

In multi-echo imaging, in imaging in which pulses other than a 180° pulse are included in refocus RF pulses, a high-quality image in which the intended contrast is emphasized is obtained by reducing unnecessary contrast. Therefore, imaging parameters are adjusted so as to reduce the unnecessary contrast. The adjustment is performed so that, for echo signals from tissues having the same relaxation time to cause intended contrast among echo signals from a plurality of tissues having different relaxation times, the difference between the signal strengths of echo signals to determine the contrast, such as echo signals at the k-space center, is reduced. Imaging parameters to be adjusted include a repetition time, the FA of a DE pulse, the FA of a saturation pulse, the application timing of the saturation pulse, the application strength of a gradient magnetic field in a recovery period, application timing, and the like.

The present invention provides a novel approach for CEST MR imaging, called Multi-echo Parametric VARiation Saturation (Me-PaVARS) CEST. This method places multiple image readouts in between a series of saturation pulses. The saturation pulse parameters are varied in a designated systematic pattern, which allows the generation of CEST contrast maps by encoding the patterns of signal loss into the images for better discrimination between various CEST imaging agents. The saturation parameter changes include, but are not limited to, saturation amplitude (B₁), saturation length (t_sat), number of pulses, shape of saturation pulses, amplitude of saturation pulses, saturation offset frequency, or a combination of these variations.

A pH-weighted chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) method and system are provided that works by indirectly measuring the NMR signal from amine protons found on the backbones of amino acids and other metabolites, which resonate at a frequency of +2.8-3.2 ppm with respect to bulk water protons. The technique uses a modified magnetization transfer radiofrequency saturation pulse for the generation of image contrast. A train of three 100 ms Gaussian pulses at high amplitude (6 uT) or Sinc3 pulses are played at a particular frequency off-resonance from bulk water prior to a fast echo planar imaging (EPI) readout, with one full image acquired at each offset frequency. This non-invasive pH-weighted MRI technique does not require exogenous contrast agents and can be used in preclinical investigations and clinical monitoring in patients with malignant glioma, stroke, and other ailments.

In a magnetic (MR) method and apparatus to generate an MR angiography image of a vascular structure of an examination region, spins in the examination region are saturated by an RF saturation pulse to cause these spins to produce a lower signal intensity in the angiography image than spins that flow from a major artery via a feed artery into the examination region, which are not saturated by the RF saturation pulse. A saturation volume is established that is saturated by the RF saturation pulse in order to be able to depict substantially all the vascular structure, such that the major artery and the tissue surrounding the major artery are not situated at the level of the branching of the feed artery in the saturation volume. The MR angiography image is generated using the established saturation volume.

An MRI apparatus includes: a data processor configured to acquire a first set of T₂-weighted imaging data and a second set of T₂-weighted imaging data; a pulse sequence controller configured to generate a pulse sequence and apply the generated pulse sequence to a gradient coil assembly and RF coil assembly, the generated pulse sequence including: T₂-preparation modules and associated imaging modules to acquire the first set of T₂-weighted imaging data, and a saturation pulse sequence and an associated saturation imaging module to acquire the second set of T₂-weighted imaging data; a curve fitter configured to apply the first and second sets of T₂-weighted imaging data to a three-parameter model for T₂ decay, to determine a T₂ value at a plurality of locations; and an image processor configured to generate a T₂ map of the object based on the T₂ value determined at the plurality of locations.

A method is provided that includes applying at least one radiofrequency saturation pulse at a frequency or a range of frequencies to substantially saturate magnetization corresponding to an exchangeable proton in the ROI to generate magnetic resonance (MR) data. The MR data is then acquired using an echo-planar imaging readout, which is configured to sample a series of gradient echo pulse trains at a series of gradient echo times and a series of spin echo pulse trains at a series of spin echo times. One or more relaxometry measurement is then computed using the MR data sampled at the gradient echo times and the spin echo times. An oxygen-weighted image is then generated using the one or more relaxometry measurement, and a pH-weighted image is generated using MR data sampled at one or more of the spin echo times or gradient echo times.

In a method and apparatus for magnetic resonance imaging of an examination subject using an acquisition sequence that includes at least one acquisition cycle, wherein the acquisition cycle includes a readout block set with at least two readout blocks, and a saturation pulse set with at least two saturation pulses, the saturation pulses of the saturation pulse set are respectively associated with respective readout blocks of the readout block set, and the saturation pulses of the saturation pulse set have respectively varying flip angles.

The invention discloses a permanent magnet-based magnetic saturation pulsed eddy current infrared nondestructive evaluation method. Firstly, a computer controls a program controller to synchronously trigger an induction heater and a thermal infrared imager, the induction heater applies pulse current excitation to a heating coil connected with a heating head while receiving a trigger signal, and acooling device cools the induction heater, the heating head and the heating coil at the same time; a strong static magnetic field is generated around the permanent magnet, a ferromagnetic material reaches magnetic saturation under the action of a permanent magnet, then joule heat is generated under the action of the heating coil, and the surface temperature of the material is changed through heatconduction; and finally, temperature changes are collected through a thermal infrared imager, and defect nondestructive evaluation is conducted on the ferromagnetic material by analyzing the collectedimage sequence. Compared with a traditional pulsed eddy current infrared nondestructive detection method, the method has the advantages that the detection depth of the ferromagnetic material is larger, and the application prospect is wide.