PT - JOURNAL ARTICLE AU - Chris Suckow AU - David Stout TI - MicroCT liver contrast agent enhancement over time, dose, and mouse strain DP - 2007 May 01 TA - Journal of Nuclear Medicine PG - 346P--346P VI - 48 IP - supplement 2 4099 - http://jnm.snmjournals.org/content/48/supplement_2/346P.4.short 4100 - http://jnm.snmjournals.org/content/48/supplement_2/346P.4.full SO - J Nucl Med2007 May 01; 48 AB - 1499 Objectives: Fenestra LC™ (ART Inc. Quebec, Canada) is a contrast agent with sufficient duration to image mouse livers and liver tumors using microCT, which are otherwise indistinguishable from surrounding soft tissues. Fenstra LC imitates chylomicron remnants which allows it to localize into the liver’s parenchyma after intravenous injection. We examined dose effects on contrast, duration of enhancement and uptake in SCID, nude and C57 mice to determine optimal imaging conditions for single and repeat imaging studies. Methods: Fenestra LC was injected via tail vein at three different dosages (7.5ml/kg, 10ml/kg, and 15ml/kg) and in three different strains of mice, (Nude, SCID, C57BL/6J) and imaged until loss of visible contrast (Liver to background ratio <1.1). Mice were imaged once a day with a low resolution (400 um), low dose, CT protocol optimized for longitudinal oncology studies in a Siemens MicroCAT II system. Results: Regions of interest (ROI) drawn in the gastrointestinal (GI) tract and brain had consistent values and showed very little variation in all strains, doses, and days post-injection, making them good non-specific background ROI’s for measuring liver and spleen contrast ratios. Day 1 post injections produced an average liver/GI ratio in C57 mice for doses 15ml, 10ml, 7.5ml of 1.28 (±0.02), 1.20 (±0.03), 1.17 (±0.02), respectively, and spleen/GI ratios of 1.62 (±0.03), 1.31 (±0.08), 1.30 (±0.11), respectively. At 10ml/kg the average liver/GI ratios for day 1 post injection for NUDE, C57, and SCID were 1.26, 1.2, and 1.1 respectively, whereas spleen/GI ratios were 1.2, 1.31, and 1.45 respectively. For all strains and dosages, the spleen to GI ratio peaked on day 2 post-injection, the liver/GI ratio peaked on day 1. The spleen showed large amounts of contrast at the 15ml/kg level out to 9 days with an average spleen/GI ratio on day 9 in C57 mice of 1.59 (±0.06). Spleen uptake is significantly higher in C57 compared to liver uptake (n=3, ttest p value <0.01), which appears to be similar in the other strains as well. Conclusions: Liver uptake and washout are similar in all three mouse strains. Fenestra LC at 15ml/kg provides sufficient contrast for imaging a week or more, whereas 7.5ml is sufficient for 1-2 days.