Method and magnetic resonance system to acquire MR data in a predetermined volume segment
In a method and magnetic resonance (MR) system to acquire MR data in a predetermined volume segment of an examination subject, the data are acquired with at least one echo train that includes at least two signal echoes. The same number of echoes is acquired for each echo train of the at least one echo train, with this number of echoes corresponding to an echo train length. The total number of echoes that are required to acquire the MR data and the echo train length is adapted so that the total number corresponds to a whole number multiple of the echo train length.
1. A method for acquisition of magnetic resonance (MR) data, comprising:
operating an MR data acquisition unit to execute a magnetic resonance data acquisition sequence to excite nuclear spins in a predetermined volume segment of an examination subject, the excited spins producing multiple echo trains each comprising at least two signal echoes and, in said sequence, acquiring MR data from a same number of signal echoes in each of said echo trains, said same number defining an echo train length; and
operating said MR data acquisition unit to acquire MR data from a total number of signal echoes collectively from all of said echo trains, and adapting the echo train length and said total number to each other to cause said total number to be a whole number multiple of the echo train length.
2. A method as claimed in claim 1 comprising:
operating said MR data acquisition unit with a spin echo sequence as said MR data acquisition sequence;
in said spin echo sequence, executing an RF excitation of nuclear spins in said volume segment of said examination subject before acquiring MR data from the respective echo trains; and
activating a refocusing pulse in said spin echo sequence before acquisition of each signal echo in a respective echo train.
3. A method as claimed in claim 1 comprising operating said MR data acquisition unit with a gradient echo sequence as said MR data acquisition sequence.
4. A method as claimed in claim 1 comprising adapting said total number of echoes and said echo train length to each other by reducing or increasing said echo train length.
5. A method as claimed in claim 1 comprising adapting said total number of echoes and said echo train length by reducing or increasing said total number of echoes.
6. A method as claimed in claim 5 comprising:
entering the acquired MR data into k-space at respective k-space points;
adapting said total number and said echo train length to one another by reducing said total number, thereby causing MR data not to be acquired from at least one signal echo; and
selecting said predetermined set of k-space points that would be filled with MR data from said at least one signal echo to be as far as possible from a center of k-space.
7. A method as claimed in claim 6 comprising entering said MR data into said k-space points along radial trajectories.
8. A method as claimed in claim 6 comprising selecting said predetermined volume segment as a two-dimensional volume segment or a three-dimensional volume segment.
9. A method as claimed in claim 6 comprising:
in said MR data acquisition sequence, activating a first phase coding gradient in a first spatial direction and activating a second phase coding gradient in a second spatial direction;
in said MR data acquisition sequence, activating an additional magnetic field gradient for spatial coding in a third spatial direction that is orthogonal to said first spatial direction and to said second spatial direction; and
entering said MR data into said predetermined set of k-space points while said additional magnetic field gradient is activated.
10. A magnetic resonance (MR) apparatus comprising:
an MR data acquisition unit;
a control unit configured to operate said MR data acquisition unit to execute a magnetic resonance data acquisition sequence to excite nuclear spins in a predetermined volume segment of an examination subject, the excited spins producing multiple echo trains each comprising at least two signal echoes and, in said sequence, acquiring MR data from a same number of signal echoes in each of said echo trains, said same number defining an echo train length; and
said control unit being configured to operate said MR data acquisition unit to acquire MR data from a total number of signal echoes collectively from all of said echo trains, and to adapt the echo train length and said total number to each other to cause said total number to be a whole number multiple of the echo train length.
11. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a computerized control unit of a magnetic (MR) apparatus that comprises an MR data acquisition unit, said programming instructions causing said control unit to:
operate said MR data acquisition unit to execute a magnetic resonance data acquisition sequence to excite nuclear spins in a predetermined volume segment of an examination subject, the excited spins producing multiple echo trains each comprising at least two signal echoes and, in said sequence, acquiring MR data from a same number of signal echoes in each of said echo trains, said same number defining an echo train length; and
operate said MR data acquisition unit to acquire MR data from a total number of signal echoes collectively from all of said echo trains, and adapt the echo train length and said total number to each other to cause said total number to be a whole number multiple of the echo train length.