Stability of Myocardial ¹⁸F-flurpiridaz Distribution after Transient Coronary Occlusion in Pigs

Background: Flurpiridaz F18 is a promising ¹⁸F-labeled myocardial perfusion radiotracer utilising all intrinsic advantages of PET technology. We aimed to elucidate the stability of myocardial Flurpiridaz F18 distribution in a pig model of transient coronary occlusion.

Methods: Myocardial Flurpiridaz F18 distribution was analyzed by 120 min dynamic cardiac PET imaging in controls (n = 4 healthy pigs), pigs with 2 min transient mid left descending artery occlusion at the time of tracer injection followed by reperfusion (n = 4) and a pig model of myocardial infarction with permanent mid left descending artery occlusion one month prior to the imaging study (n = 3).

Results: Normal control hearts demonstrated rapid, intense and almost homogenous radiotracer uptake throughout the left ventricle over the imaging session of 2 hours, while both coronary occlusion models demonstrated a clear tracer uptake defect in the distal anteroseptal wall. Using a 50% threshold, the investigated tracer uptake defect remained almost similar in a model of myocardial infarction (% defect areas normalized at 8 min: 13 min, 104 ± 4%; 23 min, 107 ± 1%; 45 min, 110 ± 1%; 75 min, 114 ± 3%; 105 min, 116 ± 3% LV, averaged slope 0.12 ± 0.10%/min). On the other hand, in a transient coronary occlusion model at the time of tracer injection, the defect size showed continuous and significant decrease throughout the 2 hour imaging session (% defect areas normalized at 8 min: 13 min, 96 ± 8%; 23 min, 82 ± 11%; 45 min, 68 ± 16%; 75 min, 56 ± 21%; 105 min, 37 ± 32% LV, averaged slope -0.62± 0.19%/min[asterisk], [asterisk]p<0.05 vs infarction model). Conclusions: Clear myocardial distribution defect in both coronary occlusion models indicates promising properties of this new class of ¹⁸F perfusion PET tracer. The observed change of perfusion defect size after coronary reperfusion emphasizes the relevance of early imaging protocols after tracer injection for accurate assessment of perfusion abnormalities. Moreover, assessment of viability with an additional delayed imaging session using a single tracer injection protocol is feasible. This work was supported by the Competence Network of Heart Failure funded by the Integrated Research and Treatment Center (IFB) of the Federal Ministry of Education and Research (BMBF) and German Research Council (DFG grant HI 1789/3-3). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 701983.

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