Feasibility studies for extracting an Input Function for Quantitative Positron Emission Tomography using a Wrist Scanner

Tracer kinetic modeling techniques for quantitative Positron emission tomography (PET) require an accurately measured radiotracer concentration in arterial blood as a function of time as an input to the model (arterial input function). Since the input function (IF) is derived from blood samples from the wrist arteries, a scanner is begin devised to detect radioactivity in the wrist as a function of time and extract an IF. 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.