Figure 7.

Image-derived estimates of ¹²⁴I activity concentration in the blood, compared with direct venous samples. Data were corrected for ¹²⁴I decay and averaged for 2 mice; each direct-assay data point is an average of samples taken just prior to, and just after, imaging. Phantom/positron emission tomography (PET) and Tissue/PET are microPET time-activity curves for heart calibrated, respectively, by imaging a known mouse phantom (24-cc vial) or normalizing to blood samples at the final time point. (Note that, by definition, direct-assay and Tissue/PET data agree at the final time point.) Mean errors (± standard error of the mean; n = 2) for Tissue/PET calibration are indicated. Clearly, Tissue/PET calibration was superior to Phantom/PET calibration.