901-102 Atherosclerotic Plaques Imaged by Tc-99m-Labeled Synthetic Peptide

1–123 SP-4. a synthetic oligopeptide fragment of apolipoprotein B, identifies aortic atherosclerosis in a hyperlipidemic rabbit model by external gamma camera imaging. Because Tc-99m is preferable to 1–123 for imaging, we have studied 3 Tc-99m-labeled SP-4-derived peptides, each coinjected with 1–125 SP-4 into normal (NL) or cholesterol-fed (CF) New Zealand White Rabbits, sacrificed at 15–30 min (6 NL; 6 CF) or 2hr (11 NL;12 CF) later. Aortas in CF rabbits invariably revealed high atherosclerotic lesion density, while atherosclerotic lesions were absent from NL rabbit aortas. After sacrifice, the aorta was excised and divided into upper, middle and lower segments and percent injected dose per gram (%ID/gm) was determined. At 30min NL and CF did not differ, but at 2hrs %ID/gm values were as follows:AortaTimeP352P302P380SP-4UpperNL 2hr0.005730.002080.003320.00088CF 2hr0.005340.002380.007480.00296*MiddleNL 2hr0.003590.001940.002730.00078CF 2hr0004590002120.00722*0.00203*‡LowerNL 2hr0.003670001620001880.00061CF 2hr0.003000001950.00806*0.00209*†*p<0.05 vs NL.†p<0.02 vs P380.‡p<0.008 vs P380Tc-99m P380 showed greater absolute uptake in plaque than SP-4, and relatively similar CF-to-NL ratios. We conclude that P380 shows particular affinity for the atherosclerotic aorta. comparable to that apparent with 1-123 SP-4. Given the favorable imaging characteristics of 99mTc vs 123l, P380 holds particular promise for clinical imaging