Pharmaceutical preparations, agents and substances for diagnostic imaging; radiopharmaceutical imaging agents for detection, diagnosis and monitoring of Alzheimer's disease, neurological and neurodegenerative diseases and disorders, and brain conditions; diagnostic pharmaceutical preparations, agents and substances for detecting and monitoring of Tau neurofibrillary tangles to aid the evaluation/assessment of Alzheimer's disease and treatments, neurological and neurodegenerative diseases and disorders, and brain conditions.