Method and apparatus to generate angiographic magnetic resonance images

A magnetic resonance system comprising:

• a magnetic resonance data acquisition unit adapted to interact with a subject to acquire magnetic resonance data from an examination region of the subject, as a predetermined first number of angiographic magnetic resonance images, in an image series, of the examination subject;
• a computerized control unit supplied with an operating protocol comprising a gradient echo sequence comprising radio-frequency pulses respectively having flip angles in a flip angle series comprising a predetermined second number of flip angles, wherein the first flip angle at the beginning of the flip angle series is smaller than the last flip angle at the end of the flip angle series, and wherein an arbitrary flip angle is greater than the preceding flip angle in the flip angle series;
• said control unit being configured to operate the data acquisition unit according to the protocol to acquire first magnetic resonance data, and to enter said first magnetic resonance data into a predetermined third number of first regions of k-space, reserved for the first magnetic resonance data, with each first region comprising first magnetic resonance data acquired during respective first time intervals and each first region comprising a plurality of components equal to said second number with each component in each first region being acquired according to said gradient echo sequence with a respective flip angle that exists at a position in the flip angle series that gives, at a beginning of each first time interval, a fluid flowing into the examination region a first predetermined spin marking;
• said control unit being configured to operate the data acquisition unit according to the protocol to acquire second magnetic resonance data, and to enter said second magnetic resonance data into a predetermined fourth number of second regions of k-space, reserved for the second magnetic resonance data, with each second regions comprising second magnetic resonance data acquired during respective second time intervals and each second region comprising a plurality of components equal to said second number, with each component in each second region being acquired according to said gradient echo sequence with a respective flip angle that exists at a position in the flip angle series that gives, at a beginning of each second time interval, said fluid flowing into the examination region a second predetermined spin marking that is different than the first spin marking;
• said control unit being configured to establish contiguous flip angle index ranges for each angiographic magnetic resonance image in said image series;
• a computerized processor supplied with the first magnetic resonance data and the second magnetic resonance data, said processor being configured to generate each angiographic magnetic resonance image of the examination region in said image series as a difference image formed between a portion of the first magnetic resonance data and a portion of the second magnetic resonance data, the portion of the first magnetic resonance data comprising components of the third number of first regions that were acquired with flip angles in the flip angle index range established for that respective angiographic magnetic resonance image, and the portion of the second magnetic resonance data comprising components of the fourth number of second regions that were acquired with flip angles in the flip angle index range established for that respective angiographic magnetic resonance image;
• and
• said processor being configured to make the angiographic magnetic resonance images in said image series available in electronic form at an output of said processor.

A non-transitory computer-readable storage medium encoded with programming instructions, said storage medium being loaded into a computerized control and processing system of a magnetic resonance system, said magnetic resonance system also comprising a magnetic resonance data acquisition unit adapted to interact with a subject to acquire magnetic resonance data from an examination region of the subject in order to generate an image series comprising a predetermined first number of temporally successive angiographic magnetic resonance images of the examination region of the subject, said programming instructions causing said control and processing system to:

• establish a flip angle series comprising a predetermined second number of flip angles, wherein the first flip angle at the beginning of the flip angle series is smaller than the last flip angle at the end of the flip angle series, and wherein an arbitrary flip angle is greater than the preceding flip angle in the flip angle series;
• operate the data acquisition unit according to a gradient echo sequence that includes excitation of nuclear spins in said examination region with radio-frequency pulses respectively having flip angles in said flip angle series, to acquire first magnetic resonance data and to enter said first magnetic resonance data into a predetermined third number of first regions of k-space, reserved for the first magnetic resonance data, with each first region comprising first magnetic resonance data acquired during respective first time intervals and each first region comprising a plurality of components equal to said second number, with each component in each first region being acquired according to said gradient echo sequence method with a respective flip angle that exists at a position in the flip angle series that gives, at a beginning of the first time intervals, a fluid flowing into the examination region a first predetermined spin marking;
• operate the data acquisition unit according to said gradient echo sequence to acquire second magnetic resonance data and to enter said second magnetic resonance data into a predetermined fourth number of second regions of k-space, reserved for the second magnetic resonance data, with each second region comprising second magnetic resonance data acquired during respective second time intervals and each second region comprising a plurality of components equal to said second number, with each component in each second region being acquired according to said gradient echo sequence with a respective flip angle that exists at a position in the flip angle series that gives, at a beginning of each second time interval, said fluid flowing into the examination region a second predetermined spin marking that is different than the first spin marking;
• establish contiguous flip angle index ranges for each angiographic magnetic resonance image in said image series;
• generate each angiographic magnetic resonance image of the examination region in said image series as a difference image formed between a portion of the first magnetic resonance data and a portion of the second magnetic resonance data, the portion of the first magnetic resonance data comprising components of the third number of first regions that were acquired with flip angles in the flip angle index range established for that respective angiographic magnetic resonance image, and the portion of the second magnetic resonance data comprising components of the fourth number of second regions that were acquired with flip angles in the flip angle index range established for that respective angiographic magnetic resonance image;
• and
• make the angiographic magnetic resonance images in said image series available in electronic form at an output of said processor.