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-99 m is preferable to 1–123 for imaging, we have studied 3 Tc-99 m-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 2 hr (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 30 min NL and CF did not differ, but at 2 hrs %ID/gm values were as follows: Aorta Time P352 P302 P380 SP-4 Upper NL 2 hr 0.00573 0.00208 0.00332 0.00088 CF 2 hr 0.00534 0.00238 0.00748 0.00296 * Middle NL 2 hr 0.00359 0.00194 0.00273 0.00078 CF 2 hr 000459 000212 0.00722 * 0.00203 * ‡ Lower NL 2 hr 0.00367 000162 000188 0.00061 CF 2 hr 0.00300 000195 0.00806 * 0.00209 * † * p l 0.05 vs NL. † p l 0.02 vs P380. ‡ p l 0.008 vs P380 Tc-99 m 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 99 mTc vs 123l, P380 holds particular promise for clinical imaging.