PT - JOURNAL ARTICLE AU - Lawrence MacDonald AU - Marna Eissa AU - David Haseley AU - Mary Kelly AU - Franklin Liu AU - Jay Parikh AU - Eric Rosen AU - Carolyn Wang AU - J. David Beatty AU - James Rogers TI - Reduced dose PEM scanning DP - 2011 May 01 TA - Journal of Nuclear Medicine PG - 1981--1981 VI - 52 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/52/supplement_1/1981.short 4100 - http://jnm.snmjournals.org/content/52/supplement_1/1981.full SO - J Nucl Med2011 May 01; 52 AB - 1981 Objectives Optimal injected dose for positron emission mammography (PEM) has not yet been evaluated. In this study, we investigated PEM performance vs dose. Methods Patients and phantoms were scanned on a PEM Flex Solo II (Naviscan, Inc.). Phantoms (N=91) consisted of 0, 1, or 2 hot spheres in a warm background (BG). Spheres were 4-to-20mm in diam., and 3-to-20X hotter than BG. BG activity was 0.4-to-4.1 kBq/mL. Eight radiologists scored the presence of spheres on a 5-point confidence scale. Patients were imaged at 1-hr post injection of 185 MBq FDG for 14min. Fractions of list-mode data were reconstructed to simulate lower dose scans. Results Count rate and image BG-recovery deviated from linearity above ~3 kBq/mL. Image BG %StdDev varied little for BG>2kBq/mL, but increased from 9.3-18.6% as BG decreased from 2-0.4kBq/mL. Reader studies showed overall sensitivity decrease from 95% to 82% as BG decreased from 4.1-to-0.4 kBq/mL. Sensitivity was 100% for spheres > 1cm at all BG and all sphere:BG ratios. For spheres < 1cm, sensitivity dropped from 88-54% as BG decreased from 4-0.4 kBq/ml. Specificity was 96%. Reducing counts by 75% in patient images had little effect on interpretation, except at the chest wall. Conclusions Stable image noise properties above ~2kBq/mL suggest there is little benefit using higher dose (2kBq/mL~5mCi/70L after 60min). Image noise can degrade detection of spheres < 1cm, but did not affect detection for spheres > 1cm. Effects of reduced dose are most notable at the chest wall portion of the image