A method is provided for determining a movement-corrected B1 field map on contrast medium injection, wherein before the injection, a B1 field map is determined. Following the contrast medium administration, a position change is determined at the position at which the B1 field map was determined. With the position change and the B1 field map, the movement-corrected B1 field map is determined.

An asymmetric 3D shells k-space trajectory design with partial Fourier acceleration is described. A non-iterative homodyne reconstruction framework is also described.

In some embodiments, an apparatus and a system, as well as methods, may include operating a transmitting antenna and a receiving antenna as equivalent tilted dipoles, wherein the tilted dipoles provide a selection of equivalent tilt angles for at least one of the transmitting antenna or the receiving antenna. Further activity may comprise receiving signals by the receiving antenna disposed in a geological formation, the signals to be inverted to obtain at least one of resistivity or dielectric constant properties of the geological formation at a selected depth of investigation, the depth determined by the selection of the equivalent tilt angles and weighting with pre-computed integrated radial sensitivity signal data. Additional methods, apparatus, and systems are disclosed.

An apparatus and a method for spatial encoding in magnetic resonance tomography using a radio frequency signal are provided. A first set of parameters from a first frequency and from a first amplitude, and from a second frequency and a second amplitude is determined by the magnetic resonance tomograph, and corresponding signals are generated by a radio frequency device and transmitted by an antenna apparatus. A first gradient above the Larmor frequency of the nuclear spins is generated by the Bloch-Siegert effect. The same thing ensues with a second set of parameters that differs from the first set of parameters at least in one frequency or amplitude and therefore generates a second, different gradient.

A method for correcting a B0 inhomogeneity in a magnetic resonance scan with a magnetic resonance tomograph is provided. The magnetic resonance tomograph includes a controller, a radio frequency unit, and a transmitting antenna. In the method, the controller determines a transmission signal that is suitable for correcting an effect of an inhomogeneity of a static B0 magnetic field in an examination volume by the Bloch-Siegert effect. The transmission signal is emitted into the examination volume.

In a case where a subject parameter distribution is obtained using MRI, a magnetization transfer effect is suppressed such that the calculation accuracy of T1 and T2 of brain parenchyma can be improved and a variation in the T1 value of blood caused by the effect of blood flow can be reduced. In imaging for parameter estimation, a magnetization transfer effect is suppressed by using a high frequency magnetic field pulse having a narrow frequency band as an excitation pulse. In a case where the frequency band is narrow, the high frequency magnetic field pulse has a shape in which the excitation profile is similar to a Gaussian function. A rising portion of the shape is arranged in a field of view where the head is an imaging target.

Radio frequency (RF) gradient based magnetic resonance imaging (MRI) is provided by establishing a gradient in the RF transmit (B1) field using frequency-modulated RF pulses. A difference between the time-bandwidth product of the frequency-modulated RF pulses can be varied to provide impart different phases to magnetic resonance signals, where these different phases provide phase encoding of the acquired data. The time-bandwidth product difference can be created and varied by changing the pulse duration of one frequency-modulated RF pulse relative to the other while keeping the bandwidth of the pulses constant.

Described here are systems and methods for performing magnetic resonance imaging (MRI) using radio frequency (RF) phase gradients to provide spatial encoding of magnetic resonance signals rather than the conventional magnetic field gradients. Particularly, the systems and methods described here implement swept RF pulses (e.g., wideband, uniform rate, and smooth transition (WURST) RF pulses) and a quadratic phase correction to enable RF phase gradient encoding in inhomogeneous background (B.sub.0) magnetic fields.

A method and an apparatus for measuring oil content of a tight reservoir based on nuclear magnetic resonance includes applying a pulse sequence to a tight reservoir rock, and after applying a first pulse and a last pulse in the pulse sequence, applying a gradient magnetic field to the tight reservoir rock, respectively, directions of the two applied gradient magnetic fields being opposite to each other, wherein the pulse sequence is composed of three 90 pulses; acquiring a nuclear magnetic resonance signal of the tight reservoir rock; and determining oil content of the tight reservoir rock according to an intensity of the nuclear magnetic resonance signal. The method can accurately distinguish an oil phase nuclear magnetic resonance signal and a water phase nuclear magnetic resonance signal in nanopores of tight reservoir rock, thereby effectively improving the accuracy of the detection result of the oil content of the tight reservoir rock.

A magnetic resonance imaging system (1) includes at least one processor (28) configured to receive (48) diffusion weighted imaging data based on a diffusion weighted imaging sequence with magnetic gradient fields applied in different directions and with different b-values. The at least one processor (28) is further configured to detect (50) motion corrupted data present in the received imaging data based on a comparison of data redundant in the received data, and substitute (52) alternative data for detected motion corrupted data.