Nuclear Medicine in the Age of Personalized Medicine
In the last decade, nuclear medicine has gained significant importance in patient management. Imaging techniques such as Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) enable the visualization of molecular processes for therapy selection, monitoring, and risk stratification of patients.
In particular, the clinical success of [18F]FDG PET in imaging tumor metabolism has greatly increased the acceptance of nuclear medicine procedures and contributed to a shift in understanding tumor biology. However, glucose is metabolized not only by tumor cells but also by the body's immune cells, which complicates tumor characterization during therapy monitoring. Recently, numerous radiopharmaceuticals have been developed that bind more specifically to molecular targets in various tumors, offering greater potential to predict responses to modern drug therapies.
A number of recent publications have highlighted the limitations of current personalized diagnostic and therapeutic approaches in relation to tumor heterogeneity. Significant molecular genetic variability has been observed not only within primary tumors but also among individual metastatic lesions, making it challenging to validate single biomarkers for therapy selection. When genetic analyses are based solely on individual tumor biopsies, it often leads to an underestimation of mutation burden and, with corresponding therapy, the selection of therapy-resistant clones, which can indirectly promote tumor recurrence. Additionally, this impacts the success of clinical Phase I and II trials when the overall tumor burden regarding molecular targets is not sufficiently characterized or potentially toxic therapy effects are not adequately considered.
Functional imaging techniques like SPECT or PET could significantly influence treatment decisions and the selection of potentially effective drugs in the future through the use of highly specific biomarkers for in-vivo characterization of tumor lesions and their microenvironment.
These techniques allow for non-invasive serial imaging of the entire body, enabling characterization of all tumor manifestations within a single examination and advancing our systemic biological understanding of tumor behavior.
Another advantage of nuclear medicine techniques is the ability to use the same basic substance for both diagnostic imaging and therapies, such as radiopeptide or radioimmunotherapy. This concept, familiar from the diagnostic and therapeutic use of radioactive iodine isotopes for thyroid tumors, can serve as a model for modern so-called "theranostic" approaches.
Nuclear medicine imaging techniques have also rapidly improved with the development of hybrid scanners like PET/CT, PET/MR, and SPECT/CT, revolutionizing the processing of multiple imaging data in multiparametric concepts and advancing toward virtual tumor histology. This requires close integration with medical physics, bioinformatics, and various radiological disciplines.
All these trends pave a way for nuclear medicine imaging to become a central component of modern personalized medicine.