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

Introduction Global and regional sympathetic activity in the heart can be evaluated using [123I]meta-iodobenzylguanidine ([123I]mIBG) imaging. However, [123I]mIBG is associated with low image spatial resolution and sensitivity in cardiac imaging. We investigated the capability of an F-18-labeled mIBG derivative, meta-(3-[18F]fluoropropyl)benzylguanidine ([18F]mFPBG), 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 [18F]mFPBG 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 [18F]mFPBG. Imaging properties of [18F]mFPBG were compared with those of traditional cardiac imaging radiotracers ([123I]mIBG and [99mTc]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 [18F]mFPBG 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, [18F]mFPBG 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 [123I]mIBG, [18F]mFPBG showed improved spatial resolution and sensitivity in a rat model of myocardial infarction. This result suggested that [18F]mFPBG is a promising cardiac PET imaging agent for potential diagnostic application in PET cardiology.