Feasibility of myocardial PET imaging using a benzylguanidine analog: meta -(3-[ 18 F]fluoropropyl)benzylguanidine ([ 18 F] m FPBG)

Abstract Introduction Global and regional sympathetic activity in the heart can be evaluated using [ 123 I] meta -iodobenzylguanidine ([ 123 I] m IBG) imaging. However, [ 123 I] m IBG is associated with low image spatial resolution and sensitivity in cardiac imaging. We investigated the capability of an F-18-labeled m IBG derivative, meta -(3-[ 18 F]fluoropropyl)benzylguanidine ([ 18 F] m FPBG), for identifying ischemic and viable myocardium in a rat model of myocardial infarction. Materials and methods The ex vivo biodistribution and in vivo metabolic stability of [ 18 F] m FPBG were investigated in Sprague–Dawley rats. Selective cardiac adrenergic activation was confirmed via a blocking experiment involving pretreatment with desipramine (2 mg kg −1 ), followed by the administration of [ 18 F] m FPBG. Imaging properties of [ 18 F] m FPBG were compared with those of traditional cardiac imaging radiotracers ([ 123 I] m IBG and [ 99m Tc]MIBI) in a rat model of myocardial infarction. Non-invasive image-based measurements of infarct sizes were then compared with histological findings by using Bland–Altman analysis. Results The differences in infarct sizes determined using histological analysis and [ 18 F] m FPBG PET were −2.55 ± 4.99% (range: −12.33 to 7.22), −2.35 ± 3.32% (range: −8.87 to 4.16), and −3.15 ± 6.16% (range: −15.24 to 8.93) at 5, 20, and 40 min, respectively. Furthermore, [ 18 F] m FPBG PET was superior to traditional imaging methods in assessing the degree of ischemia in areas of myocardial infarction, as well as the actual infarct size. Conclusion Compared to [ 123 I] m IBG, [ 18 F] m FPBG showed improved spatial resolution and sensitivity in a rat model of myocardial infarction. This result suggested that [ 18 F] m FPBG is a promising cardiac PET imaging agent for potential diagnostic application in PET cardiology.