The present invention generally relates to novel synthetic methods, systems, kits, salts, and precursors useful in medical imaging. In some embodiments, the present invention provides compositions comprising an imaging agent precursor, which may be formed using the synthetic methods described herein. An imaging agent may be converted to an imaging agent using the methods described herein. In some cases, the imaging agent is enriched in 18F. In some cases, an imaging agent including salt forms (e.g., ascorbate salt) may be used to image an area of interest in a subject, including, but not limited to, the heart, cardiovascular system, cardiac vessels, brain, and other organs.本發明大體係關於適用於醫學造影之新穎合成方法、系統、套組、鹽及前驅體。在一些實施例中,本發明提供組合物,其包含可使用本文所述之合成方法形成的造影劑前驅體。可使用本文所述之方法將造影劑前驅體轉化為造影劑。在一些情況下,造影劑係以18F增濃。在一些情況下,包括鹽形式(例如抗壞血酸鹽)之造影劑可用以對個體之相關區域造影,該相關區域包括(但不限於)心臟、心血管系統、心臟血管、腦及其他器官。