U-SPECT-I: a novel system for submillimeter-resolution tomography with radiolabeled molecules in mice.

U-SPECT-I allows discrimination between molecular concentrations in adjacent volumes of as small as about 0.1 muL, which is significantly smaller than can be imaged by any existing SPECT or PET system. Our initial in vivo images of the mouse heart and spine show that U-SPECT-I can be used for novel applications in the study of dynamic biologic systems with a clear projection to clinical applications. The combination of high resolution and detection efficiency of U-SPECT-I opens up new possibilities for the suborgan-level study of radiotracers in mouse models.