There is provided a diagnostic imaging agent for early bone metastasis from cancer, containing trans-1-amino-[18F]fluorocyclobutanecarboxylic acid or a pharmaceutically acceptable salt thereof as an active ingredient.提供一個用於癌症早期骨轉移的診斷性造影劑,包含反式-1-氨基-氟18標示氟環丁烷羧酸(trans-1-amino-[18F]fluoro cyclobutane carboxylic acid)或其一個藥劑學上可接受的鹽類作為活性成分。