Nuclear Medicine studies

Principle

• Uses unsealed radioactive substances in diagnosis and therapy.
• Based on function of organs.

How it is done

• Most of the studies start with by injecting or inhaling or ingesting a radioisotope. 
• The type of isotope used varies with each study.
• The isotope concentrates in the organ that is being tested.
• Scanning of body or organ follows.
• When to start and end scanning, varies with each study.
• Majority of diagnostic tests involve formation of an image using a gamma camera.
• Most diagnostic radio nuclides emit gamma rays.

Useful for

• Primarily useful to evaluate the function of the organ studied.

Commonly Used Radionuclides:

• technetium-99m
• iodine-123 and 131
• thallium-201
• gallium-67
• PET scan

Positron Emission Tomography (PET)

Metabolocally active molecule (sugar)

• Oncology: (18F) flourodeoxyglucose (FDG, FDG-PET) retained by tissues with high metabolic activity.
• Neurology: radioactivity associated with brain activity
• Cardiology: "hibernating myocardium"

Example Indications

• Renal scan: To evaluate renal function.
• Bone scan: To evaluate bone metastasis.
• Perfusion lung scan: Suspected patients with pulmonary embolism.
• Myoview: Suspected patients with coronary artery disease.
• Testicular scan: To evaluate testicular torsion.
• PET scan: Tissue functions such as blood flow, oxygen use and sugar metabolism, i.e. to detect increased metabolic rate as is seen with cancer.
• MUGA scan: To document LVEF and track over time in patients receiving cardiotoxic chemo, such as like Adriamycin.

Advantages

• Radionuclide imaging is safe since it does not carry the risk of allergic reaction encountered with contrast.
• Radiation exposure is minimal.

Limitation

• No anatomical details provided.
• Isotope availability is sometimes limited or restricted.

Cost: $$