Various methods and systems are provided for correcting transmit attenuation of an amplifier of a transmit radio frequency (RF) coil for use in a magnetic resonance imaging (MRI) system. In one example, a method includes setting a reference value of transmit attenuation for an amplifier of a transmit radio frequency (RF) coil, acquiring a three-dimensional B.sub.1 field map with the transmit attenuation set at the reference value, determining a plurality of mean flip angles for a plurality of slice locations in a pre-scan imaging volume from the B.sub.1 field map, determining a transmit attenuation correction value for each of the slice locations based on a prescribed flip angle and the mean flip angle determined for the respective slice location, correcting the reference value of transmit attenuation with the transmit attenuation correction value at each of the slice locations to obtain a final value of transmit attenuation for each of the slice locations, and performing an MRI scan with the transmit attenuation set at the value.

In a Method and a device for magnetic resonance imaging of a subject using a spoiled gradient echo sequence, a B.sub.0 magnetic field strength of at most 1.5 T is used during the sequence. As part of the sequence a slice select gradient acting as a spoil gradient is played out. Substantially simultaneously with the slice select gradient a predetermined RF pulse is played out in the sequence, wherein a time-bandwidth product of the RF pulse is set so that a majority of the energy of the RF pulse is transmitted in its central main lobe.

In a method and magnetic resonance apparatus for determining a B1 field map in a scanner of the apparatus, the B1 field map describing a local field distribution of a B1 field resulting from excitation pulses radiated in a measurement sequence, first and second measured values are acquired from a region in which nuclear spins are excited by an excitation pulse having an assigned flip angle, and a provisional flip angle is determined from the first and second measured values. A correction factor, dependent on the pulse shape of a selected excitation pulse, is then determined, and the provisional flip angle is multiplied thereby to obtain a corrected value for entry into said B1 field map.

Various methods and systems are provided for correcting transmit attenuation of an amplifier of a transmit radio frequency (RF) coil for use in a magnetic resonance imaging (MRI) system. In one example, a method includes setting a reference value of transmit attenuation for an amplifier of a transmit radio frequency (RF) coil, acquiring a three-dimensional B.sub.1 field map with the transmit attenuation set at the reference value, determining a plurality of mean flip angles for a plurality of slice locations in a pre-scan imaging volume from the B.sub.1 field map, determining a transmit attenuation correction value for each of the slice locations based on a prescribed flip angle and the mean flip angle determined for the respective slice location, correcting the reference value of transmit attenuation with the transmit attenuation correction value at each of the slice locations to obtain a final value of transmit attenuation for each of the slice locations, and performing an MRI scan with the transmit attenuation set at the value.

Various methods and systems are provided for correcting transmit attenuation of an amplifier of a transmit radio frequency (RF) coil for use in a magnetic resonance imaging (MRI) system. In one example, a method includes setting a reference value of transmit attenuation for an amplifier of a transmit radio frequency (RF) coil, acquiring a two-dimensional B.sub.1 field map with the transmit attenuation set at the reference value, determining a mean flip angle from the B.sub.1 field map, determining a transmit attenuation correction value based on a prescribed flip angle and the mean flip angle, correcting the reference value of transmit attenuation with the transmit attenuation correction value to obtain a final value of transmit attenuation, and performing an MRI scan with the transmit attenuation set at the value.

A method can include obtaining a scaling factor for a location proximate a metallic object by optimizing a function of an acquired dataset and a simulated dataset. The simulated dataset can include a first signal from a first pulse having a first excitation flip angle and a first refocusing flip angle. The simulated dataset can include a second signal from a second pulse having a second excitation flip angle and a second refocusing flip angle.

A method for correcting a magnetic resonance imaging error using a heart rate interval may include: measuring T1 of a stand-alone phantom for correcting the error; obtaining a T1 map generated by mapping a recovery time according to a reference recovery rate of protons in heart tissues of a subject inverted by a radio frequency (RF) pulse in pixel units into a two-dimensional space; calculating a correction function based on the measured T1 of the phantom; and correcting an error of the T1 map based on the calculated correction function.

High-quality magnetic resonance (MR) recordings are triggered with movements of an object, for example the heartbeat. In a method and apparatus for obtaining raw data reconstruction for an MR image, a spin-echo-based sequence is executed that includes applying a static magnetic field and applying a magnetization pulse train. A movement of the object to be imaged is detected and a target contrast for two tissue types of the object is prespecified. The repetition time of the pulse train is set in dependence on the movement of the object to be imaged, and the flip angle is set such that prespecified target contrast for the two tissue types is obtained at the set repetition time.

A method for correcting a magnetic resonance imaging error using a heart rate interval may include: measuring T1 of a stand-alone phantom for correcting the error; obtaining a T1 map generated by mapping a recovery time according to a reference recovery rate of protons in heart tissues of a subject inverted by a radio frequency (RF) pulse in pixel units into a two-dimensional space; calculating a correction function based on the measured T1 of the phantom; and correcting an error of the T1 map based on the calculated correction function.

The invention relates to a method for the hyperpolarization of a material sample (4), which hits a number of first spin moments (10) of a first spin moment type, wherein the number of first spin moments (10) is brought into interaction with a second spin moment (16) of a second spin moment type, wherein the first spin moments (10) are nuclear spin moments and the second spin moment (16) is an election spin moment, wherein the first and second spin moments (10, 16) are exposed to a homogeneous magnetic field (B), wherein the second spin moment (16) is polarized along the magnetic field (B), wherein the second spin moment (16) is coherently manipulated by means of a, preferably repeated, sequence (S) having a number of successive high-frequency pulses (P.sub.ki, P.sub.k′i) temporally offset to each by durations (T.sub.ki, T.sub.k′i, T), in such a way that a polarization transfer from the second spin moment (16) to the first spin moments (10) occurs, and wherein durations (T.sub.ki, T.sub.k′i, T) inversely proportional to a Lamor frequency (ω.sub.Larmor) of the first spin moments (10) in the magnetic field (B) are inserted between high-frequency pulses (P.sub.ki, P.sub.k′i).