Positron Emission Tomography

The photons are then tracked by a tomographic scintillation counter, and the information is processed by a computer to provide both image and data on blood flow and metabolic processes within bodily tissues. PET scans are particularly useful for diagnosing brain tumor and the effects of strokes on the brain, along with various mental illnesses. They are also used in brain research and in mapping of brain functions.

     The brain function being studied during a PET scan determines which positron-emitting radiopharmaceutical is used. Oxygen-15 can be used to label oxygen gas for the study of oxygen metabolism, carbon monoxide for the study of blood volume, or water for the study of blood flow in the brain. Similarly, fluorine-18 can be attached to a glucose molecule to produce 2-fluoro-2-deoxy-D-glucose (FDG) for use in the observation of the brain’s sugar metabolism.

In nuclear medicine diagnosing techniques, a very small amount of radioactive material is introduced into the body. Because medical isotopes are attracted to specific organs, bones or tissues, the emissions they produce can provide crucial information about a particular type of cancer or disease. Information gathered during a nuclear medicine technique is more comprehensive than other imaging procedures because it describes organ function, not just structure. The result is that many diseases and cancers can be diagnosed much earlier.

The PET scan also will show two and three-dimensional images of the brain; however, the PET scan measures brain activity. This is done by injecting radioactive isotopes into the blood stream. The isotopes attach to

FDG-Positron Emission Tomography (PET) is not routinely performed as part of the diagnostic work up for Alzheimer’s disease. Thus, it is not the standard of care to rule in or rule out a diagnosis of Alzheimer’s disease.

When it comes to medical imaging, there are several different options to choose from for different testing. There are similarities and differences; pros and cons to each. This paper will discuss MRI, CT, and ultrasound. They each have important things to know regarding radiation dose, cost, and reasons to use one over another.

As early as 1996, Moon et al evaluated the use of Whole-Body Fluorine-18-FDG PET in 57 patients suspected to have recurrent or metastatic breast cancer and proved that FDG PET was 93% sensitive and 79% specific

Positron emission tomography (PET) is a functional imaging modality that has shown promise in tumor depiction, but it is unable to provide detailed high spatial resolution images (5-7).

18F-FDG-PET can be used for detecting most types of lymphoma. However, even if the 18F-FDG-PET scan is positive in a pattern that is highly suggestive of lymphoma, diagnosis of lymphoma requires histological confirmation. The major utility of 18F-FDG-PET in diagnosis is often in directing a biopsy. PET can also be used to guide biopsies to the site of highest 18F-FDG uptake, representing the most aggressive site of lymphoma. 18F-FDG-PET may identify other involved regions, which can be biopsied at much lower morbidity (Delbeke et al, 2009).

The PET scanning is particularly useful in detecting cancer because most cancer cells use more glucose than normal tissues. In lung cancer, pet scans are sometimes used to observe for cancer in particular areas such as the lymph nodes, in the chest or to demonstrate the spreading activity of cancer cells to other areas the body. This would help the doctor to take a further decision about the treatment of a

A CT scan can be used to assess the tumor, by evaluating the change in tumor size pre and post treatment. However, there are some drawbacks when utilizing the tumor diameter as a response assessment. CT is not able to distinguish tumor cells from left over necrosis and fibrosis (Usmanij). Alternatively, imaging with FDG-PET can monitor the metabolic changes in the nodule, and more accurately predict the effect of administering the treatment. Figure 4 shows FDG-PET/CT imaging in a patient before and after treatment with chremoradiotherapy. The latter scan shows significant reduction in FDG uptake of the tumor after being treated, while no such change was visualized on CT

A reduction on the regional uptake of 18F labeled fluordeoxyglucose is another biomarker of AD that is measured by PET (Kazemifar et al., 2017). Amyloid PET scan is a new imaging technique that directly visualize the amyloid plaques in the brain with high affinity binding of Amyvid (Florbetapir F-18) (Page et al., 2017). A positive amyloid scan indicates moderate to frequent amyloid plaques (Page et al., 2017). Amyloid scan should be utilized in addition to clinical diagnostic evaluation since elderly patients without AD can have a degree of accumulation of amyloid plaque (Page et al., 2017). A negative amyloid imaging is significant in a patient who has a clinical diagnosis of AD, could indicate a misdiagnosis and oftentimes produce changes in therapeutic planning (Page et al., 2017). A positive PET scan highly indicates fibrillary amyloid beta which is a hallmark of AD (Grill et al., 2017). An increased amyloid

Keywords: Positron emission tomography, single photon emission computed tomography, magnetic resonance imaging, ultrasound, bioluminescent, fluorescence

• A PET (positron emission tomography) scan may help to show cancer activity in some other parts of the body. This can be helpful for “staging” the cancer (see

There are several technologies to allow researchers to create structural images of the brain. We can use computerised tomography and magnetic resonance imaging to produce a series of X-rays of the brain with the MRI this does produce much higher definition pictures more helpful because it goes beyond just the structural data. Newer techniques like the position emission tomography and functional magnetic resonance imagery. Where the pet requires the participant or patient to ingest a radioactive substance that many if not all participants in a research study may be, are very unwilling do.