A method of designing a refocusing pulse or pulse train for Magnetic Resonance Imaging comprises the steps of: a) determining a phase-free performance criterion representative of a proximity between a rotation of nuclear spins induced by the pulse and a target operator, summed or averaged over one or more voxels of an imaging region of interest; and b) adjusting a plurality of control parameters of the pulse to maximize the phase-free performance criterion; wherein each target operator is chosen so the phase-free performance criterion takes a maximum value when the nuclear spins within all voxels undergo a rotation of a same angle around a rotation axis lying in a plane perpendicular to a magnetization field B.sub.0, called a transverse plane, with an arbitrary orientation; wherein the angle is different from M radians, with integer M, preferably with < radians and even preferably with 0.9.Math. radians.

In imaging using 2-dimensional selective excitation pulses, regardless of applications thereof, a technique for obtaining a high quality image is provided. In the technique, a 2-dimensional selective excitation sequence is carried out while changing a coefficient for determining the cylinder diameter of a region excited by the 2-dimensional selective excitation sequence and a time difference for determining an offset position. The obtained excitation region and a desired region are compared with each other, and the coefficient and time difference with which the obtained excitation region and the desired region match each other are determined to be the optimum ones. The determination processing may be performed as an initial adjustment, may be performed according to need in each imaging, or may be performed on a per-application basis.

A method and a control sequence determination device for the determination of a magnetic resonance system activation sequence including at least one high-frequency pulse sequence to be transmitted by a magnetic resonance system are provided. A current B.sub.0 map and optionally a target magnetization are acquired. In addition, a k-space trajectory type is determined. An error density is calculated in a k-space based on the current B.sub.0 map and optionally based on the target magnetization using an analytic function. This analytic function defines an error density in the k-space as a function of the current B.sub.0 map and optionally the target magnetization. Taking account of the error density in the k-space, a k-space trajectory of the specified k-space trajectory type is determined. The high-frequency pulse sequence is determined for the k-space trajectory in an HF pulse optimization process.

A method for operating a magnetic resonance imaging scanner, comprising: providing 3D data from a patient; providing target parameters, wherein the target parameters include an excitation of nuclear spins to be achieved; ascertaining a spectrally selective excitation pulse for emission by a transmitter based on the 3D data from the patient, wherein the spectrally selective excitation pulse is configured to generate the target parameters; and outputting the spectrally selective excitation pulse via the transmitter.

Disclosed herein is a medical system (100, 300) comprising a memory (110) storing machine executable instructions (120) and a convolutional neural network (122). The convolutional neural network is configured to receive as input a complex array (128) encoding a selection of at least one excitation field of view (324, 900) and in response output a radio frequency wave form (130) and multiple spatially selective gradient pulse waveforms (132). The convolutional neural network is a multi-task convolutional neural network. The execution of the machine executable instructions causes a computational system (104) to: receive (200) a selection (124) of the at least one excitation field of view; receive (202) initial pulse sequence commands (126); encode (204) the complex array using the at least one excitation field of view; receive (206) the radio frequency wave form and the multiple spatially selective gradient pulse waveforms in response to inputting the complex array into the convolutional neural network; and construct (208) modified pulse sequence commands (134) by modifying the initial pulse sequence commands with the radio frequency wave form and the multiple spatially selective gradient pulse waveforms.

The present disclosure provides technologies that allow reduced field of view or fast imaging with reduced image distortion. The first technique capitalizes on the benefit of reduced field of view imaging for full field of view coverage. The second technique allows achieves high resolution 3D images in a focused region. These techniques are expected to have applications for cancer imaging, neuro imaging, and other biomedical imaging areas.