Nuclear medicine is better described by its modern title: Molecular Imaging. It involves recording tiny amounts of radiation emitted from within the body, rather than by shining a beam of radiation through the body from an external source (like conventional X-rays).
A radioactive isotope (most often Technetium-99m, which is low-energy and safe) is bound to a special molecule (pharmaceutical) which is designed to be taken up by a specific organ. After injection the radiopharmaceutical (or “tracer”) accumulates in the target organ and we can image the function of that organ. We use a special scanner called a gamma camera to capture images from the gamma radiation emitted by the tracer in the organ.
There are several diagnostic imaging techniques used across nuclear medicine, which includes:
Whole body bone scan: Used to evaluate bony pathology, such as for bone pain, stress fractures, benign bone lesions, bone infections and metastases (spread of cancer to the bones).
Myocardial perfusion (MIBI) scan : Plays a pivotal role in the non-invasive evaluation of coronary artery disease. The study not only identifies patients with coronary artery disease, it also determines overall risk of future cardiac events for the patient.
Bone scan: Spect-CT slices of patient with back pain due to facet joint arthritis.
Whole body bone scan: metastases from prostate carcinoma.
Ventilation and perfusion (V/Q) scan: the patient had multiple pulmonary emboli (lung blood clots).
Gallium whole body scan: Patient had fever of unknown origin due to TB in chest lymph nodes. Accumulation in the large bowel is normal.
Thyroid scan: Overactive thyroid due to Graves’ disease.
Thyroid scan: Thyroiditis – the thyroid is not visualized due to low tracer uptake.
Renogram: Left kidney outflow system is obstructed and dilated due to a stone in the ureter.
Sentinel node scan: To locate the sentinel lymph node for biopsy, to determine lymphatic spread of breast cancer.