Experimental study of ¹¹C-N-CH₃-Dopamine neuroimaging on myocardial "ischemic memory"

Objectives: To establish myocardial ischemia models in Bama mini-pigs with different degrees of ischemia, and to use cardiac nerve imaging agent 11C-N-CH3-Dopamine to detect different levels of ischemia in mini-pigs Like, and with 18F-BMSmyocardial perfusion imaging and 18F-FDG myocardial metabolism imaging were compared to explore the changes of cardiac nerves over time after myocardial ischemia reperfusion and establish cardiac neuroimaging as a more sensitive method for non-invasive detection of "ischemic memory".

Methods: Eight Bama miniature pigs were used to seal the distal end of the LAD after the first diagonal branch using balloon occlusion to make myocardial ischemia models with different degrees of ischemia. Balloon closure time was divided into 8min group and 15min group. Each piglet was monitored by cardiac enzymes, troponin T and electrocardiogram before and after modeling. Each pig underwent 11C-N-CH3-Dopamine, 18F-FDG and 18F-BMS PET/CT myocardial imaging before modeling, 24h, 48h, 72h and 1w after modeling. After the imaging is completed, the radioactivity counts in the ischemic area and the normal area are measured and the ratio of the two is calculated and analyzed.

Results: (1) The 18F-BMS, 18F-FDG and 11C-N-CH3-Dopamine PET/CT myocardial imaging results before and after modeling in the 8min group are as follows: The radioactive count ratio of the ischemic/non-ischemic area of ​​the imaging agent was not statistically different; the radioactive count ratio of the ischemic/non-ischemic area imaged at each time after modeling was analyzed by variance , The results show that there is a significant difference between the ratios of the three imaging agents in the same time period of imaging. Further pairwise comparison results show that 24h after modeling, the three imaging agents (18F-BMS and 18F-FDG, 18F-BMS and 11C-N-CH3-Dopamine, 18F-FDG and 11C-N- There was a statistically significant difference in the radioactive count ratio in the ischemic/non-ischemic area between CH3-Dopamine; at 48h, 72h and 1w after modeling, there was no significant difference between the ratios of 18F-BMS and 18F-FDG, but Compared with the ratio of 11C-N-CH3-Dopamine, there are significant differences. (2) The 18F-BMS, 18F-FDG and 11C-N-CH3-Dopamine PET/CT myocardial imaging results before and after the 15-minute model modeling are as follows: There was no statistically significant difference in the radioactive count ratio in the ischemic/non-ischemic area of ​​the imaging agent ; the variance analysis of the radioactive count ratio in the ischemic/non-ischemic area at each time after modeling, The results show that there are significant differences between the ratios of the three imaging agents in the imaging at the same time period. Further pairwise comparison results show that at 24h and 48h after modeling, three imaging agents (18F-BMS and 18F-FDG, 18F-BMS and 11C-N-CH3-Dopamine, 18F-FDG and 11C- There was a statistically significant difference in the radioactive count ratio between N-CH3-Dopamine in the ischemic/non-ischemic area; there was no significant difference between the ratios of 18F-BMS and 18F-FDG at 72h and 1w after modeling, but Compared with the ratio of 11C-N-CH3-Dopamine, there are significant differences.

Conclusions: 18F-BMS, 18F-FDG and 11C-N-CH3-Dopamine can detect myocardial ischemia after transient myocardial ischemia and reperfusion, but the recovery time of ischemic tissue is different, that is, "ischemic memory". Time window is different. 11C-N-CH3-Dopamine has the longest time window, 18F-FDG is the second, and 18F-BMS has the shortest time window. Therefore, the damage of the cardiac nerves in the ischemic state is more severe than the metabolic and perfusion damage. Therefore, 11C-N-CH3-Dopamine cardiac nerve imaging is more sensitive in diagnosing myocardial "ischemic memory".