Dynamic susceptibility contrast using a pre-determined arterial input function

A system for determining a perfusion metric in a subject comprising:

• a processor for pre-determining an arterial input function comprising a square input function, the square input function corresponding to a first end tidal partial pressure of oxygen (PETO2), and a second PETO2;
• a sequential gas delivery device configured to induce an increase in arterial partial pressure of oxygen in a subject by:
• targeting the first PETO2;
• targeting the second PETO2, wherein the first PETO2 is less than the second PETO2;
• and
• controlling an end tidal partial pressure of carbon dioxide (PETCO2);
• an imaging device configured to measure a magnetic signal in a selected voxel in the subject responsive to the increase in arterial partial pressure of oxygen;
• and
• a display configured to output a perfusion metric calculated for the selected voxel, the perfusion metric calculated based on the pre-determined arterial input function and the magnetic signal,
• wherein the square wave input function is substituted for the arterial input function in the perfusion calculation.

A non-transitory computer-readable medium comprising instructions for determining a perfusion metric in a subject, the instructions comprising:

• pre-determining an arterial input function comprising a square input function, the square input function corresponding to a first end tidal partial pressure of oxygen (PETO2), and a second PETO2;
• controlling a sequential gas delivery device to induce an increase in arterial partial pressure of oxygen in a subject by:
• targeting the first PETO2;
• targeting the second PETO2, wherein the first PETO2 is less than the second PETO2;
• and
• controlling an end tidal partial pressure of carbon dioxide (PETCO2);
• measuring a magnetic signal in a selected voxel in the subject responsive to the increase in arterial partial pressure of oxygen;
• and
• outputting a perfusion metric for the selected voxel at a display, the perfusion metric calculated based on the pre-determined arterial input function and the magnetic signal,
• wherein the square wave input function is substituted for the arterial input function in the perfusion calculation.