In a method and apparatus for measuring activity of a tracer in a subject in a medical imaging protocol, comparable features in each of a time series of image data sets of the subject are detected. Piperidino pyridinium cations and compositions containing these cations are also described. The plurality of lateral supports are configured to allow the center section of the table frame to be expanded and collapsed in unison in substantially the same horizontal plane, to allow the table frame to be easily manipulated. The first magnetic force generator is provided inside the magnetic roller such that a magnetic pole face thereof faces the developing roller. Multiple CCVs can point to the same method object so that only a single copy of a method object needs to be provided.