Diagnostic agents, preparations and substances for medical purposes; diagnostic agents for medical purposes, namely, diagnostic scanning agents for in vivo use for detection and monitoring of systemic amyloid diseases, such as transthyretin amyloidosis, Light Chain Amyloidosis and LECT2 Amyloidosis; diagnostic radiopharmaceutical preparations for clinical, medical and research use in the field of systemic amyloid disease; radioactive pharmaceutical preparations and non-radioactive reagents for producing radiopharmaceuticals for in vivo diagnostic or therapeutic use; pharmaceutical preparations for use in diagnosis and treatment of systemic amyloid disease; all of the aforesaid for human use