Whole-body PET scanners are not optimized for imaging small structures in the human brain. Several PET devices specifically designed for this task have been proposed either for stand-alone operation or as MR-compatible inserts. The main distinctive features of some of the most recent concepts and their performance characteristics, with a focus on spatial resolution and sensitivity, are reviewed. The trade-offs between the various performance characteristics, desired capabilities, and cost that need to be considered when designing a dedicated brain scanner are presented. Finally, the aspirational goals for future-generation scanners, some of the factors that have contributed to the current status, and how recent advances may affect future developments in dedicated brain PET instrumentation are briefly discussed. PET provides unique information about the human brain that has proved useful in a variety of studies ranging from basic neuroscience to clinical applications. In parallel with the development of dozens of radiotracers and the implementation of methods for extracting ever-more-accurate estimates of parameters related to many biologic processes (1), PET instrumentation has ...