Method and control device for operating a magnetic resonance system

A method for producing magnetic resonance image data of an examination subject, comprising:

• operating an MR data acquisition unit, in which a subject is situated, according to a pulse sequence module in which a plurality of spatially selective radio-frequency (RF) slice excitation pulses are radiated that respectively excite nuclear spins in a plurality of respective slices in the examination subject, whereby the time between two consecutive of these RF slice excitation pulses defines in a first time interval;
• operating said MR data acquisition unit in said sequence module to execute a preparation block following a last of said plurality of RF slice excitation pulses and, in said preparation block, radiating at least one RF refocusing pulse that causes each of the excited slices to produce one respective echo signal, with a time interval between two consecutive ones of said echo signals equaling said first time interval;
• operating said MR data acquisition unit to radiate a second RF refocusing pulse at a time interval after a last of said echo signals produced by said preparation block, and configuring said second RF refocusing pulse to cause each of the excited layers to produce one further echo signal, with a time interval between two consecutive ones of said further echo signals equaling said first time interval;
• operating said MR data acquisition unit to radiate at least one further RF refocusing pulse at a third time interval after a respective preceding RF refocusing pulse, and configuring said at least one further RF refocusing pulse to cause the excited slices to produce a plurality of temporally separated echo signals for each further RF refocusing pulse, and setting a duration of said third time interval to cause the plurality of echo signals caused by each further RF refocusing pulse to be twice as high as said plurality of excited slices;
• operating said MR data acquisition unit to readout raw data during a scanning window around each of said echo signals and entering said raw data into an electronic memory organized as k-space, thereby producing an electronic memory filled with data in a form allowing reconstruction of images of said plurality of slices of the subject;
• from a processor, accessing said raw data in said electronic memory and operating on said raw data in said processor according to an image reconstruction algorithm to calculate a plurality of separate magnitude images from the raw data acquired during each of said scanning windows;
• and
• in said processor, combining the respective magnitude images from each slice to form a single MR image for that slice, and making said magnitude image for each slice available at an output of said processor in electronic form.

A method for producing magnetic resonance image data of an examination subject, comprising:

• operating an MR data acquisition unit, in which a subject is situated, according to a pulse sequence module in which a plurality of spatially selective radio-frequency (RF) slice excitation pulses are radiated that respectively excite nuclear spins in a plurality of respective slices in the examination subject, whereby the time between two consecutive of these RF slice excitation pulses defines a first time interval;
• operating said MR data acquisition unit in said sequence module to execute a preparation block following a last of said plurality of RF slice excitation pulses and, in said preparation block, radiating at least one RF refocusing pulse that causes each of the excited slices to produce one respective echo signal, with a time interval between two consecutive ones of said echo signals equaling said first time interval;
• operating said MR data acquisition unit to radiate a second RF refocusing pulse at a time interval after a last of said echo signals produced by said preparation block, and configuring said second RF refocusing pulse to cause each of the excited layers to produce one further echo signal, with a time interval between two consecutive ones of said further echo signals equaling said first time interval;
• operating said MR data acquisition unit to radiate at least one further RF refocusing pulse at a third time interval after a respective preceding RF refocusing pulse, and configuring said at least one further RF refocusing pulse to cause the excited slices to produce a plurality of temporally separated echo signals for each further RF refocusing pulse, and setting a duration of said third time interval to cause the plurality of echo signals caused by each further RF refocusing pulse to be twice as high as said plurality of excited slices;
• operating said MR data acquisition unit to readout raw data during a scanning window around each of said echo signals and entering said raw data into an electronic memory organized as k-space, thereby producing an electronic memory filled with data in a form allowing reconstruction of images of said plurality of slices of the subject;
• and
• from a processor, accessing said raw data from said electronic memory and generating an MR image therefrom by executing an algorithm in said processor in which image data for a respective slice are formed as a complex-valued combination of raw data acquired for that slice in different ones of said scanning windows.

A computerized control device for operating a magnetic resonance (MR) data acquisition unit in which an examination subject is situated, said control device being configured to:

• operate said MR data acquisition unit, in which a subject is situated, according to a pulse sequence module in which a plurality of spatially selective radio-frequency (RF) slice excitation pulses are radiated that respectively excite nuclear spins in a plurality of respective slices in the examination subject, whereby the time between two consecutive of these RF slice excitation pulses defines in a first time interval;
• operate said MR data acquisition unit in said sequence module to execute a preparation block following a last of said plurality of RF slice excitation pulses and, in said preparation block, radiating at least one RF refocusing pulse that causes each of the excited slices to produce one respective echo signal, with a time interval of two consecutive ones of said echo signals equaling said first time interval;
• operate said MR data acquisition unit to radiate a second RF refocusing pulse at a time interval after a last of said echo signals produced by said preparation block, and configure said second RF refocusing pulse to cause each of the excited layers to produce one further echo signal, with a time interval between two consecutive ones of said further echo signals equaling said first time interval;
• operate said MR data acquisition unit to radiate at least one further RF refocusing pulse at a third time interval after a respective preceding RF refocusing pulse, and configure said at least one further RF refocusing pulse to cause the excited slices to produce a plurality of temporally separated echo signals for each further RF refocusing pulse, and setting a duration of said third time interval to cause the plurality of echo signals caused by each further RF refocusing pulse to be twice as high as said plurality of excited slices;
• and
• operate said MR data acquisition unit to readout raw data during a scanning window around each of said echo signals and to enter said raw data into an electronic memory organized as k-space, thereby producing an electronic memory filled with data in a form allowing reconstruction of images of said plurality of slices of the subject.

A magnetic resonance (MR) imaging apparatus comprising:

• an MR data acquisition unit comprising a basic field magnet that generates a basic field in which an examination subject in the MR data acquisition unit i situated, a radio-frequency (RF) transmission system, a gradient system, an RF reception system, and a control unit;
• said control unit being configured to operate said MR data acquisition unit, in which a subject is situated, according to a pulse sequence module in which a plurality of spatially selective RF slice excitation pulses are radiated by said RF transmission system that respectively excite nuclear spins in a plurality of respective slices in the examination subject, whereby the time between two consecutive of these RF slice excitation pulses defines a first time interval;
• said control unit being configured to operate said MR data acquisition unit in said sequence module to execute a preparation block following a last of said plurality of RF slice excitation pulses and, in said preparation block, radiating at least one RF refocusing pulse by said RF transmission system that causes each of the excited slices to produce one respective echo signal, with a time interval of two consecutive ones of said echo signals equaling said first time interval;
• said control unit being configured to operate said MR data acquisition unit to radiate a second RF refocusing pulse by said RF transmission system at a time interval after a last of said echo signals produced by said preparation block, with said second RF refocusing pulse being configured to cause each of the excited slices to produce one further echo signal, with a time interval between two consecutive ones of said further echo signals equaling said first time interval;
• said control unit being configured to operate said MR data acquisition unit to radiate at least one further RF refocusing pulse by said RF transmission system at a third time interval after a respective preceding RF refocusing pulse, and with said at least one further RF refocusing pulse being configured to cause the excited slices to produce a plurality of temporally separated echo signals for each further RF refocusing pulse, and to set a duration of said third time interval to cause the plurality of echo signals caused by each further RF refocusing pulse to be twice as high as said plurality of excited slices;
• and
• said control unit being configured to operate said gradient system of said MR data acquisition unit to execute a readout gradient during the readout of raw data to spatially encode said raw data, and to enter said raw data into an electronic memory organized as k-space, thereby producing an electronic memory filled with data in a form allowing reconstruction of images of said plurality of slices of the subject.

A non-transitory, computer-readable data storage medium encoded with programming instructions, said data storage medium being loaded into a control and evaluation system of a magnetic resonance (MR) apparatus that also comprises an MR data acquisition unit, said programming instructions causing said control and evaluation system to:

• operate said MR data acquisition unit, in which a subject is situated, according to a pulse sequence module in which a plurality of spatially selective radio-frequency (RF) slice excitation pulses are radiated that respectively excite nuclear spins in a plurality of respective slices in the examination subject, whereby the time between two consecutive of these RF slice excitation pulses defines a first time interval;
• operate said MR data acquisition unit in said sequence module to execute a preparation block following a last of said plurality of RF slice excitation pulses and, in said preparation block, radiating at least one RF refocusing pulse that causes each of the excited slices to produce one respective echo signal, with a time interval of two consecutive ones of said echo signals equaling said first time interval;
• operate said MR data acquisition unit to radiate a second RF refocusing pulse at a time interval after a last of said echo signals produced by said preparation block, with said second RF refocusing pulse being configured to cause each of the excited slices to produce one further echo signal, with a time interval between two consecutive ones of said further echo signals equaling said first time interval;
• operate said MR data acquisition unit to radiate at least one further RF refocusing pulse at a third time interval after a respective preceding RF refocusing pulse, with said at least one further RF refocusing pulse being configured to cause the excited slices to produce a plurality of temporally separated echo signals for each further RF refocusing pulse, and set a duration of said third time interval to cause the plurality of echo signals caused by each further RF refocusing pulse to be twice as high as said plurality of excited slices;
• and
• operate said MR data acquisition unit to readout raw data during a scanning window around each of said echo signals, and enter said raw data into an electronic memory organized as k-space, thereby producing an electronic memory filled with data in a form allowing reconstruction of images of said plurality of slices of the subject.