Non-invasive and selective measurement of the arterial input function using a PET Wrist Scanner

Kinetic modeling permits quantification of radiotracer dynamics in tissue by using the amount of radioactivity in blood as an input function to a kinetic model. This usually requires obtaining multiple blood samples during dynamic PET scans. As this procedure is considered a health risk for the patient and medical personnel, a wrist scanner has been devised that can be used to obtain an input function with minimum discomfort to the patient and without drawing arterial blood. A prototype using two detector pairs has been evaluated. The spatial resolution, sensitivity and the masking of the arterial signal by the surrounding wrist tissue radioactivity are determined. The results show that the detector was able to discriminate the arterial and venous flows from each other using planar coincidence images. MicroPET images of the wrist show that the radioactivity from the tissue does not interfere with the arterial signal. Minimization of venous and tissue interference, optimal number and placement of the detectors are being evaluated. The two detector pair prototype was used in a routine PET study.