Evaluation of99mTc labeled diadenosine tetraphosphate as an atherosclerotic plaque imaging agent in experimental models

The potential of99mTc labeled P1, P4-di (adenosine-5’)-tetraphosphate (Ap4A) for imaging experimental atherosclerotic plaques was evaluated in New Zealand white (NZW) rabbits. To label the99mTc to Ap4A, stannous tartrate solution was used.99mTc-Ap4A was purified on a Sephadex G-25 column. The radiochemistry purities of99mTc-Ap4A were 85% to 91%. Biodistribution study revealed99mTc-Ap4A cleared from blood rapidly. Thirty min after99mTc-Ap4A administrated on NZW atherosclerotic rabbits, lesion to blood (target/blood, T/B) ratio was 3.17±1.27, and lesions to normal (target/non-target, T/NT) ratio was 5.23±1.87. Shadows of atherosclerotic plaques were clearly visible on radioautographic film. Aortas with atherosclerotic plaques also could be seen on ex vivo gamma camera images. Atherosclerotic abdominal aortas were clearly visible on in vivo images 15 min to 3 h after99mTc-Ap4A administration.99mTc-labeled Ap4A can be used for rapid noninvasive detection of experimental atherosclerotic plaque.