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Positron emission tomography (PET) [1] is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption.
PET is a functional imaging technique that produces a three-dimensional image of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron -emitting radionuclide ( tracer ), which is introduced into the body on a biologically active molecule.
PET scanning is also used for diagnosis of brain disease, most notably because brain tumors, strokes, and neurondegenerative diseases (such as Alzheimer's disease and Parkinson's disease) all cause great changes in brain metabolism, which in turn causes detectable changes in PET scans. PET is probably most useful in early cases of certain ...
In addition, nuclear medicine scans differ from radiology, as the emphasis is not on imaging anatomy, but on the function. For such reason, it is called a physiological imaging modality. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) scans are the two most common imaging modalities in nuclear medicine. [3]
U.S. health officials on Friday lifted curbs on reimbursement of a non-invasive imaging test called amyloid PET used to diagnose Alzheimer's, ending a once-per-lifetime limitation that clears the ...
Thus, within 24 hours (13 half-lives after the injection), the radioactivity in the patient and in any initially voided urine which may have contaminated bedding or objects after the PET exam will have decayed to 2 −13 = 1 ⁄ 8192 of the initial radioactivity of the dose.
Positron emission tomography–computed tomography (better known as PET-CT or PET/CT) is a nuclear medicine technique which combines, in a single gantry, a positron emission tomography (PET) scanner and an x-ray computed tomography (CT) scanner, to acquire sequential images from both devices in the same session, which are combined into a single superposed (co-registered) image.
For a bone scan, the patient is injected with a small amount of radioactive material, such as 700–1,100 MBq (19–30 mCi) of 99m Tc-medronic acid and then scanned with a gamma camera. Medronic acid is a phosphate derivative which can exchange places with bone phosphate in regions of active bone growth, so anchoring the radioisotope to that ...