Method and apparatus for multislice magnetic resonance fingerprinting

A method for magnetic resonance (MR) fingerprinting, comprising:

• with a computer, operating an MR data acquisition scanner to execute a repetition sequence in a plurality of repetitions and, in each repetition, radiating a first radio-frequency (RF) excitation pulse into an examination subject, situated in the scanner, that excites a magnetization of nuclear spins in a first slice of the subject, and acquiring first MR data resulting from said first RF excitation pulse;
• with said computer, operating said scanner, in each repetition, to also radiate a second RF excitation pulse that excites a magnetization of nuclear spins in a second slice of the examination subject, that is different from said first slice, and acquiring second MR data resulting from said second RF excitation pulse;
• with said computer, operating said scanner to radiate said first RF excitation pulse and said second RF excitation pulse in the respective repetitions so as to be radiated at least partly in parallel in time and, in at least some of said repetitions, radiating said first RF excitation pulse with flip angle that differs from a flip angle of said second RF excitation pulse;
• in said computer, implementing a first optimization of the flip angles of the first RF excitation pulses dependent on at least one optimization criterion for said first RF excitation pulses, and implementing a second optimization of the flip angles of the second RF excitation pulses dependent on an optimization criterion for said second RF excitation pulses;
• in said computer, determining a first MR image of the first slice based on a fingerprinting directory and said first MR data, and determining a second MR image of the second slice based on said fingerprinting directory and said second MR data;
• and
• making the first MR image and the second MR image available in electronic form from said computer as respective data files.

A magnetic resonance (MR) apparatus comprising:

• an MR data acquisition scanner;
• a computer configured to operate said MR data acquisition scanner to execute a repetition sequence in a plurality of repetitions and, in each repetition, to radiate a first radio-frequency (RF) excitation pulse into an examination subject, situated in the scanner, that excites a magnetization of nuclear spins in a first slice of the subject, and to acquire first MR data resulting from said first RF excitation pulse;
• said computer being configured to operate said scanner, in each repetition, to also radiate a second RF excitation pulse that excites a magnetization of nuclear spins in a second slice of the examination subject, that is different from said first slice, and to acquire second MR data resulting from said second RF excitation pulse;
• said computer being configured to operate said scanner to radiate said first RF excitation pulse and said second RF excitation pulse in the respective repetitions so as to be radiated at least partly in parallel in time and, in at least some of said repetitions, to radiate said first RF excitation pulse with flip angle that differs from a flip angle of said second RF excitation pulse;
• said computer being configured to operate said scanner to execute said repetitions of said repetition sequence with a scattering of local maxima of a sum of RF energy of said first RF excitation pulse and said second RF excitation pulse in each repetition, to be less than 80% of an average value of said sum over all of said repetitions of said repetition sequence;
• said computer being configured to determine a first MR image of the first slice based on a fingerprinting directory and said first MR data, and to determine a second MR image of the second slice based on said fingerprinting directory and said second MR data;
• and
• said computer being configured to make the first MR image and the second MR image available in electronic form from said computer as respective data files.

A magnetic resonance (MR) apparatus comprising:

• an MR data acquisition scanner;
• a computer being configured to operate said MR data acquisition scanner to execute a repetition sequence in a plurality of repetitions and, in each repetition, to radiate a first radio-frequency (RF) excitation pulse into an examination subject, situated in the scanner, that excites a magnetization of nuclear spins in a first slice of the subject, and to acquire first MR data resulting from said first RF excitation pulse;
• said computer being configured to operate said scanner, in each repetition, to also radiate a second RF excitation pulse that excites a magnetization of nuclear spins in a second slice of the examination subject, that is different from said first slice, and to acquire second MR data resulting from said second RF excitation pulse;
• said computer being configured to operate said scanner to radiate said first RF excitation pulse and said second RF excitation pulse in the respective repetitions so as to be radiated at least partly in parallel in time and, in at least some of said repetitions, to radiate said first RF excitation pulse with flip angle that differs from a flip angle of said second RF excitation pulse;
• said computer being configured to implement a first optimization of the flip angles of the first RF excitation pulses dependent on at least one optimization criterion for said first RF excitation pulses, and to implement a second optimization of the flip angles of the second RF excitation pulses dependent on an optimization criterion for said second RF excitation pulses;
• said computer being configured to determine a first MR image of the first slice based on a fingerprinting directory and said first MR data, and determining a second MR image of the second slice based on said fingerprinting directory and said second MR data;
• and
• said computer being configured to make the first MR image and the second MR image available in electronic form from said computer as respective data files.