%0 Journal Article %A John Floberg %A Sarah Mudd %A Charles Mistretta %A Jamey Weichert %T Improving SNR in dynamic PET imaging of copper-64 and iodine-124 using HYPR %D 2009 %J Journal of Nuclear Medicine %P 530-530 %V 50 %N supplement 2 %X 530 Objectives 64Cu and 124I have recently shown promise in PET imaging, but because only a fraction of these nuclides undergo positron decay, a greater activity is required to obtain adequate images.(1,2) This may raise dosimetry concerns.(3,4) The highly constrained backprojection local reconstruction algorithm, HYPR LR, has shown potential to improve the signal-to-noise ratio (SNR) in non-sparse dynamic PET images.(5) HYPR was used to study the initial kinetics of 124I and 64Cu tracers at reduced activities while maintaining SNR. Methods Four mice were scanned for 1 hour using a Siemens Inveon microPET/CT scanner immediately after injection of either 283 or 74 μCi of 64CuCl, or 289 or 105 μCi of 124I labeled NM404, a tumor imaging agent. PET data were divided into 15 frames of varying duration and underwent HYPR processing using MATLAB. Images were analyzed using the Inveon Research Workplace to measure SNR and tissue activity curves. Results For a 20 second time frame with a 117 second HYPR composite, the SNR from the mice injected with 64CuCl increased from 2.3 to 4.4 when injected with 283 μCi, and from 1.1 to 2.8 when injected with 74 μCi following HYPR processing. In the mice injected with 124I labeled NM404, SNR improved from 3.2 to 7.0 when injected with 289 μCi, and from 1.8 to 4.6 when injected with 105 μCi. In addition, HYPR processing preserved the accuracy of tissue activity curves, even in cases with fast kinetics. Conclusions For PET tracers using 64Cu or 124I where there may be dosimetry concerns, particularly when looking processes of short duration, HYPR provides a way to reduce injected activity, and thus dose, while preserving or improving SNR, and preserving the accuracy of activity measurements. %U