Small-animal PET refers to imaging of animals such as rats and mice using dedicated PET scanners. Small-animal PET has been used extensively in modern biomedical research. It provides a quantitative measure of the 3-dimensional distribution of a radiopharmaceutical administered to a live subject noninvasively. In this article, we will discuss the operational and technical aspects of small-animal PET; make some comparisons between small-animal PET and human PET systems; identify the challenges of, opportunities for, and ultimate limitations in applying small-animal PET; and discuss some representative small-animal PET applications. Education objectives: After reading this article, the technologist will be able to explain the requirements and benefits of small-animal PET in biomedical research, describe the design and general characteristics of a small-animal PET system, list and describe some of the challenges of imaging small animals, and discuss several small-animal PET applications.

The Society of Nuclear Medicine (SNM) published procedure guidelines for thyroid imaging in 1999. We wished to determine how many clinics performing thyroid imaging follow the guidelines and to what extent. Of particular interest to us was the choice of collimator. Methods: We developed a 10-question survey to obtain information on how hospitals perform thyroid imaging. The questions were designed to cover the procedure recommendations of the SNM guidelines. The survey was sent to 350 hospitals randomly selected from 11 states in the northeastern United States. Results: One hundred sixty-five surveys (47%) were returned. Most of the clinics that responded obtain a history, hyperextend the neck, and obtain anterior and anterior oblique views. Twenty-five percent of the respondents obtain all their images with a parallel-hole collimator. Seventy-five percent use a pinhole collimator or a combination of parallel-hole and pinhole collimators. The number of counts and time used for acquiring the images vary greatly. Less than half the respondents palpate the neck for correlation with the scan. Conclusion:The survey results indicated that many clinics do not follow the recommendations of the SNM guidelines. The major deviations from the guidelines were in the choice of collimator, the number of counts or amount of time used to acquire images, and the lack of neck palpation for correlation with the scan.