**2. Molecular imaging and Nuclear Medicine**

Molecular imaging is defined as the visualization, characterization, and measurement of physiological mechanisms at the molecular and cellular levels, in living systems. Apart from Nuclear Medicine, it includes several other techniques, such as magnetic resonance imaging and spectroscopy, certain ultrasound technologies, and others [1, 2].

One of the biggest advantages of molecular imaging is the ability to characterize specific dis‐ ease processes in different individuals, using noninvasive assessment and quantification; i.e., providing information that is inaccessible with any other imaging techniques or that other‐ wise would require more invasive procedures such as biopsy or surgery. Also, it identifies disease in its earliest phases and determines the precise location of a tumor, frequently be‐ fore symptoms occur or changes can be detected at the anatomical level. Identifying small differences between patients allows the tailoring of specific treatments for each individual [1–3].

Nuclear Medicine is a molecular‐imaging modality that diagnoses and treats diseases using radioactive materials, known as radiopharmaceuticals. Radiopharmaceuticals, at diagnostic levels, have the ability to portray human physiology, biochemistry, or pathology without causing any physiological effect [1, 3].

For example, it can be used to identify the presence or absence of specific receptors or molecular changes, which are crucial for the selection of patients for certain targeted therapies [1].

This step for "personalized medicine" also allows a more precise identification of research subjects, leading to more exact and cost‐effective clinical trials [3].
