Dynamic Infrared Thermography (DIRT) involves taking sequential IR images following a provocation test. In Medical Thermography thermal provocations are often used (this can be either a heating or a cooling challenge). The rate and thermal pattern of the spontaneous recovery following such a challenge provides the examiner with much more information on the dynamics of skin blood perfusion that can be obtained from static IR images.
In this example both hands were subjected to a mild convective cooling for a period of 2 minutes using an ordinary desk top fan. Note how the rewarming pattern starts at the fingertips and that the hand rewarms in a proximal direction (towards the arm). The video is slightly speeded up.