PET and PET/CT Imaging
When first developed Positron Emission Tomography (PET) imaging was utilized primarily as a research tool; this was because of the expense of the scanner and the difficultly in generating the needed radioisotope by an on-site cyclotron. In the last several years PET imaging has come into routine clinical use as radioisotope became commercially available and the price of PET scanners decreased.
Today, PET imaging has been combined with CT to provide anatomic and metabolic information from a single exam in a single system. PET and PET/CT are used primarily in the diagnosis and staging of cancer. The PET exam pinpoints metabolic activity in cells and the CT exam provides an anatomical reference. When these two scans are fused together, a physician can view metabolic changes in the proper anatomical context of a patient’s body.
The most common applications include the initial work-up of a solitary pulmonary nodule which may have been initially detected through CT imaging. Other PET/CT indications include the initial diagnosis, staging or restaging for Non-Small Cell Lung Cancer, Head/neck Cancer – (Excluding CNS), Breast Cancer, Cervical Cancer, Esophageal Cancer, Lymphoma, Melanoma, Solitary Pulmonary Nodule, Refractory Seizures, Dementia and Myocardial Viability.
PET imaging is also a valuable tool in neuroradiology, helping to define recurrent tumor from radiation necrosis in brain neoplasms. Outside of oncology, PET imaging is utilized in other neurological conditions such as epilepsy, neuro-degenerative disorders and psychiatric illness.
Single photon emission computed tomography (SPECT)
Single photon emission computed tomography (SPECT) is a nuclear medicine tomographic imaging technique using gamma rays to study local metabolic and physiological functions in tissues. SPECT imaging is very similar to conventional nuclear medicine planar imaging using a gamma camera, however, it is able to provide true 3D information. SPECT can be used to complement any gamma imaging study including tumor imaging, infection (leukocyte) imaging, thyroid imaging or bone imaging.
A bone scan is a technique for producing pictures of the internal structure of bones using a radioactive tracer.
Common indications for ordering a bone scan include:
- Detect or rule out bone cancer when X-rays reveal no abnormalities but a malignancy is suspected.
- Detect bone infection.
- Determine the location of an abnormality before bone biopsy or surgery is performed.
- Diagnose stress fractures that do not always appear on x-rays.