What are the units for the BOLD signal?


What are units for the BOLD signal? I know that it measures the presence of oxygen in the brain, but I’m not sure what the correct units are.

Thanks in advance.

The units are arbitrary.

See also this answer from mriquestions. Some studies manage a quantitative/calibrated value, but that’s rare. It’s tricky because the BOLD signal is affected by many more factors than just the presence of oxygen (e.g., the same amount of oxygen will lead to a different signal in a 3T and 7T magnet).

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