About Nuclear Medicine & Molecular Imaging

Nuclear Medicine is branch of medicine that uses the radioactivity for diagnosis and therapy. It started in the mid-1920s when German scientists experimented with radionuclides on rats. The first clinical use was in the late 1930s with the use of P-32 to treat leukemia but the field really began to take shape after 1946 with the use of I-131 to treat thyroid cancer. Although it began as a therapeutic branch, the diagnostic aspect of radionuclides soon became the dominant portion of Nuclear Medicine. Development of PET (Positron Emission Tomography) and its widespread implementation for cancer in the first part of this century has led to exponential growth of Nuclear Medicine.

Diagnostic Nuclear Medicine (Radionuclide Imaging, Nuclear Scintigraphy):

Tracers (pharmaceuticals labeled with radiation emitting isotopes or radionuclides) are administered to patients (either intravenous, orally, inhalation, subcutaneously/subdermally) and the radiation emitted is detected by scintillation cameras (gamma cameras or PET cameras) and images are produced from this, depicting the distribution of the tracer within the body.
Examples include bone scans, thyroid scans, renal scans, and many others as well as SPECT scans (including Cardiac Stress SPECT Perfusion scans) and PET scans.

Therapeutic Nuclear Medicine:

Radiopharmaceuticals are administered (usually intravenously) to treat disease with curative or palliative intent. They act by killing abnormal cells within the body by high but localized radiation exposure (akin to targeted internal radiation).
Examples include I-131 therapies for thyroid disorders (hyperthyroidism and thyroid cancer), Strontium and Samarium bone palliation for bone metastases, Zevalin/Bexxar for non-Hodgkin’s lymphoma, Xofigo for Castration Resistant Metastatic Prostate Cancer with bone metastases and Lutathera for metastatic neuro-endocrine tumors (with additional therapies in the pipeline).

Molecular Imaging:

PET/CT, a hybrid imaging technique, combines functional/physiologic imaging with the more traditional anatomic/structural imaging. By providing the best of both worlds, it has played a pivotal role in ushering in the new era of Molecular Imaging, to go hand in hand with Molecular Medicine in the 21st century.
Molecular Imaging is different than regular imaging and pertains to visualizing processes at the cellular and tissue level, providing better insights about the biological characteristics of disease. Techniques used include radiotracer imaging/nuclear medicine, MR imaging (including spectroscopy), optical imaging (bioluminescence and fluorescence), and others.
In contrast to conventional diagnostic imaging, Molecular Imaging interrogates biologic processes in the cells of a living subject in order to report on and reveal their molecular abnormalities that form the basis of disease. This allows biologic processes including disease pathology to be studied in their own physiologically authentic environment instead of in a culture dish or another animal. It encompasses a new imaging paradigm with hybrid imaging techniques. especially PET/CT with novel probes at its forefront. Technological advances leading to advent of SPECT/CT and PET/MRI as well as novel targeted and more specific tracers/probes have made Nuclear Medicine the key component of Molecular Imaging.
More Information at:
Nuclear Medicine – Wikipedia (https://en.wikipedia.org/wiki/Nuclear_medicine)
Nuclear Medicine – RadiologyInfo.org (https://www.radiologyinfo.org/en/info.cfm?pg=gennuclear)

Professional Organizations:

Society of Nuclear Medicine and Molecular Imaging (SNMMI) http://www.snmmi.org/
Society of Nuclear Medicine – India (SNM-I) http://www.snmindia.com
American College of Nuclear Medicine (ACNM) http://www.acnmonline.org/
American Board of Nuclear Medicine (ABNM) https://www.abnm.org/
European Association of Nuclear Medicine (EANM) https://www.eanm.org/
Radiological Society of North America (RSNA) http://www.rsna.org/
American College of Radiology (ACR) https://www.acr.org/
American Board of Radiology (ABR) https://www.theabr.org/