摘要:
Methods, computer-readable storage devices, and systems are described for reducing movement of a patient undergoing a magnetic resonance imaging (MRI) scan. One method includes receiving a data frame from the MRI system performing the MRI scan of the patient, comparing the data frame to a reference image to assess motion of a body part of the patient during the MRI scan, generating stimulus to be communicated to the patient during the MRI scan based on a task of the MRI scan and the motion of the body part of the patient during the MRI scan, adjusting the stimulus during the MRI scan to adjust the task and as the motion of the body part of the patient changes, and communicating the stimulus to the patient during the MRI scan, wherein the sensory feedback includes at least one of a game, a movie, a cartoon, a shape, or an auditory signal.
摘要:
Various disclosed nuclear magnetic resonance (NMR) logging systems and methods employ a plurality of NMR sensors, including atomic magnetometers, mounted on pads. Certain method embodiments include: utilizing the Earth magnetic field to pre-polarize the protons in a formation; utilizing a plurality of atomic magnetometers to obtain NMR measurements; and determining at least one characteristic relaxation time of the formation. The NMR sensor may optionally include a permanent magnet assembly.
摘要:
Described here are systems and methods for obtaining measurements of both tissue perfusion and permeability with a magnetic resonance imaging (“MRI”) system after the administration of a single dose of contrast agent. To this end, the MRI system is directed to acquire T2*-weighted data, during which the acquired signal values are monitored for a trigger event. When the trigger event occurs, the MRI system is directed to switch from acquiring the T2*-weighted data to acquiring T1-weighted data. The systems and methods of the present invention can thus be used for a fully automated, single acquisition of perfusion and permeability measurements using only a single dose of contrast agent.
摘要:
In a method and magnetic resonance (MR) apparatus for acquiring an MR signal from an examination subject according to a pulse sequence, a first radio-frequency pulse is applied with a first phase and a gradient field is simultaneously applied in a first direction. Second and third radio-frequency pulses, with second and third phases, respectively, are applied simultaneously with a gradient field in a second direction. A fourth and a fifth radio-frequency pulse, with a fourth and a fifth phase, respectively, are applied and simultaneously with a gradient field in a third direction. A signal with a receiver phase is acquired =. The pulse sequence is repeated a number of times under phase rotation, wherein the third and fourth radio-frequency pulses in each repetition have the same phase, and the signals acquired in the repetition are added.
摘要:
A method of B1 field mapping relating to Magnetic resonance imaging (MRI) is given. In the method, RF and gradients are applied to excite and select a linear projection through a volume of interest; a radio frequency pulse sequence is transmitted to impart B1 dependent phase to the linear projection, following which a one dimensional spatial encoding signal is acquired along the linear projection; Subsequently a B1 field map based on the one dimensional spatial encoding signal is reconstructed.
摘要:
In a method and apparatus to create at least one magnetic resonance image data set in particular angiographic image data sets, first magnetic resonance image data are acquired using a first projection acquisition sequence, second magnetic resonance image data are acquired after administration of contrast agent, using a second projection acquisition sequence, and at least one magnetic resonance image data set is created using the first magnetic resonance image data and the second magnetic resonance image data.
摘要:
Accumulated spin magnetization phase within a RF MRI procedure can be used for providing an orderly k-space traversal. By operating a transmit array adapted to produce two B1 fields in alternation, where the B1 fields are substantially uniform in amplitude over a sample volume of the MRI setup, and the B1 fields have respective spatial phase distributions such that selection of a difference in spatial derivatives of the spatial phase distributions permits control over a size of a step in k-space applied by successive refocusing pulses for generating the B1 fields in alternation. Each alternating refocusing pulse issued within a T2 time causes a step through k-space in an encoding direction determined by the difference in spatial derivatives.
摘要:
A common method of RF encoding assumes that the Bi field generated by the RF coils is linear, which is likely not the case in many situations. It is therefore desirable to have a method of operating an MR system to reconstruct an image of a subject, wherein the method is capable of also handling arbitrary Bi fields used for RF encoding. Accordingly, such an MR system employing one or more RF coils is disclosed herein. The method comprises obtaining transmit sensitivities and weighting factors for individual RF coils. Each RF coil is activated based on its respective weighting factor to apply RF excitation to a subject under examination in the MR system. MR signals—such as free induction decays (FID) signals or echo signals—generated from the subject in response to the RF excitation are received and processed based on the transmit sensitivities to generate an MR image or spectrum representative of the subject.
摘要:
Methods, computer-readable storage devices, and systems are described for reducing movement of a patient undergoing a magnetic resonance imaging (MRI) scan by aligning MRI data, the method implemented on a Framewise Integrated Real-time MRI Monitoring (“FIRMM”) computing device including at least one processor in communication with at least one memory device. Aspects of the method comprise receiving a data frame from the MRI system, aligning the received data frame to a preceding data frame, calculating motion of a body part between the received data frame and the preceding data frame, calculating total frame displacement, and excluding data frames with a cutoff above a pre-identified threshold of the total frame displacement.
摘要:
A method and apparatus for characterizing a sample using a nuclear magnetic resonance spectrameter in which an effective field is generated. The field has an effective vector and results from a static magnetic field and a radiofrequency magnetic field. The effective vector rotates relative to a terrestrial reference frame.