Time-activity curve

It shows the concentration of a radiotracer within a region of interest in an image, measured over time from a dynamic scan.

Each data-point in the time-activity curve represents a measurement of tracer-concentration from the region segmented on each of these image time-frame acquired over time.

The region-of-interest analysis restricts the image data to a specific region on which measurements can be made, for example, lumbar vertebrae or the femoral neck.

In this image, let's assume, each voxel shows the concentration of tracer in the units Bq per ml.

The majority of the semi-automatic methods can also be automated but they do need to be validated against the manual gold-standard drawn by experts.

Time-activity curve showing concentration of tracer within a tissue regions of interest (region of interest) over time.
Time-Activity curve for the example explained in the text