POSITRON EMISSION TOMOGRAPHY
Dr. Tanya Singh, Dr. Rakesh Dangi, Dr Supnesh Jain and Dr. Rahul Patidar
Positron emission tomography also called as PET imaging or a PET scan. PET is a nuclear medicine functional imaging technique that is used to observe metabolic processes in the body as an aid to diagnosis of disease. Nuclear medicine imaging uses small amounts of radioactive material to diagnose, evaluate, or treat a variety of disease. The system detects pair of gamma rays emitted indirectly by a positron emitting radioligand. This radioligand is introduced into the body on a biologically active molecule called as radioactive tracer. Different ligands are used for different imaging process purpose depending on what the radiograph wants to detect. Three dimensional images of tracer concentration within the body are then constructed by computer analysis. Nuclear medicine imaging procedures are non-invasive except for the intravenous injection that is given to the patient. PET provides functional information of body that means it identifies the changes at cellular level. In modern PET computed tomography scanners three-dimensional imaging is often accomplished with aid of a computed tomography. Common tracer which are use are oxygen15, fluorine-18, carbon-11 or nitrogen-13.
USES
- Used in clinical oncology with tracer fluorine18, this tracer is a glucose analogue that is taken up by glucose using cells and phosphorylated by hexokinase (whose mitochondrial form is greatly elevated in rapidly growing malignant tumours.
- Helps in detecting the margin of oral neoplasia particularly highly vascularized tissue such as lingual and laryngeal areas.
- Helps in lymph node metastasis
- Another commonly used tracer is 18F-NaF is an excellent marker of bone remodelling
- Used for detection of inflammation relates to neurologic disease
- Also used for evaluation of lameness in dogs and equines
- Helps to asses tissue metabolism and viability
- Determines the function of heart or areas of heart muscles
- Evaluates brain abnormalities such as tumours, seizers, and other central nervous system disorders
BENEFITS
- It includes details on the function and anatomy of body structures
- Provides the most useful diagnostic and treatment information for various disease
- By identifying changes in the body at the cellular level, PET imaging may detect the early onset of disease before it is evident.
- It yields more precise information than exploratory surgery.
RISKS
- It may cause small amount of radiation exposure
- Allergic reaction to radiotracers can occur
- Operating cost is slight high
- Injection to radiotracers may cause slight pain and redness
ADVANTAGE OF PET OVER CT AND MRI
| PET | CT AND MRI |
| Shows the extent of disease and can help in monitoring treatment and shows its effectiveness | Detects changes in body structure and simply detects a mass |
| Reveals disease earlier and faster | Not as earlier as PET |
| Can detect abnormalities before there is any anatomical abnormalities | Can detect anatomical abnormalities |
PET identifies osseous remodelling at ligament attachment
