PT - JOURNAL ARTICLE AU - Josh Knowland AU - Steven Perrin AU - Ronald Lattanze AU - Jesse Kingg TI - Initial development and assessment of a practical intravascular probe for in-vivo blood input function measurement. DP - 2018 May 01 TA - Journal of Nuclear Medicine PG - 1718--1718 VI - 59 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/59/supplement_1/1718.short 4100 - http://jnm.snmjournals.org/content/59/supplement_1/1718.full SO - J Nucl Med2018 May 01; 59 AB - 1718Objectives: Quantification is becoming more important in PET, yet the methods for measuring blood input function are not ideal for routine clinical use. Our objective was to develop and assess a prototype device intended to quantify blood concentration of ß-emitting radiotracers, immediately following administration and during the ensuing uptake period. Methods: We compared two prototypes that were similarly constructed. Each prototype used a sample of 50mm plastic scintillating fiber (BCF-12, Saint-Gobain, 0.25mm and 0.5mm diameter) polished and mounted to a 3mm diameter x 3mm divergent acrylic light guide. This light guide was polished and mounted to a 3mm x 3mm silicon photomultiplier (SensL Technologies, Ltd.) and custom detector circuitry. We constructed artificial veins with thin-walled plastic tubing (0.25mm to 0.35mm wall thickness) of internal diameters (2.3mm, 4.75mm, and 6.3mm) to represent arm veins that are routinely used in PET radiotracer administration. We sealed each artificial vein on one end with epoxy. Additionally, we used a plastic cylinder of 27mm internal diameter to simulate tissue surrounding these artificial veins. Detector linearity and sensitivity were assessed by taking measurements with the 0.5mm diameter fiber in a solution of 18F-FDG as it decayed from 250 µCi/mL to 1 µCi/mL. We assessed the impact of vein diameter by measuring the 2.3 and 6.3 artificial veins and 27mm cylinder filled with 18F-FDG of concentration 10 µCi/mL. We also inserted each fiber into the artificial veins filled with water and then inserted these veins into the 27mm diameter plastic cylinder filled with 10 µCi/mL 18F-FDG solution to test the impact of background activity. The 10 µCi/mL solution was ~10x higher than the anticipated steady-state concentration of 1 µCi/mL in arm tissue to simulate extreme background noise. We defined the signal-to-noise ratio (SNR) as the ratio of measured activity from inside the vein to that from outside the vein. Results: Linearity measurements demonstrated repeatable results (R2=0.999) in two separate experiments on different days. Sensitivity was 15 cps/µCi/mL. Detector output correlated with vein diameter, as expected, based on detector sensitivity and solution concentration. Signal to noise ratios in simulated extreme-case clinical scenarios were: 12:1 for 2.3mm diameter vein and 0.25mm diameter fiber, 19:1 for 2.3mm diameter vein and 0.5mm diameter fiber, 26:1 for 6.3mm diameter vein and 0.25mm diameter fiber, 32:1 for 6.3mm diameter vein and 0.5mm diameter fiber. Conclusions: While further refinements are needed, our initial testing indicates that an intravascular probe shows promise to routinely provide blood input function data in the lab and clinic. Providing a patient-friendly, low-cost, practical tool to capture the blood input function may augment recent efforts to further develop PET quantification.