How frequently can I repeat NIS imaging in the same subject?
One of the advantages of NIS is that it is not immunogenic and can be used for long term studies; in principle, a single animal can be imaged numerous times. However, because animals have to be anesthetized for each imaging session, there may be limits on the number of images that can be obtained as a result of IACUC rules governing exposure to anesthetic agents. In human subjects, anesthesia is not required, so the number of imaging studies is limited by international radiation exposure standards. The time needed between repeated imaging in the same subject depends on the physical and biological half-lives of the radiotracer you are using. Basically, you need to be sure that your imaging study is not contaminated by residual radiotracer signals from the preceding study. For example, pertechnetate has a half life of 6 hours so imaging can be repeated daily, while tetrafluoroborate has a half life of only 110 minutes so imaging can be repeated the same day. For more information about the half lives of different radiotracers click here.