Reliable imaging services are now considered necessities in confirming or negating certain medical conditions. It provides critical inputs when doctors and physicians are in the process of determining and identifying a patient’s medical problem. Imaging or diagnostic radiation is generally a non-invasive method of detecting an illness since it does not require opening up a patient. It is basically creating pictures and images of internal organs through X-Ray. The succeeding steps to take in treatment would usually depend on the results.
Preliminary “Initial” Read of CT, MRI, US
Preliminary reading of various CT/MRI images
Sub-specialty expertise as required (neurology, cardiology, oncology, etc.
Final Read of CT, MRI, US
Initial read of images covering most major specialties and modalities
Final report – performed either at customer location or remote location
A Positron Emission Tomography - Computed Tomography (PET-CT scan) combines a CT scan and a PET scan into one to give detailed information about the cancer in question.
A CT scan takes pictures from all around the body and uses a computer to put them together. There is detailed information about CT scans in our section about cancer tests. A PET scan uses a very small amount of an injected radioactive drug to show where cells are active in the body.
PET-CT has revolutionised medical diagnosis in many fields, by adding precision of anatomic localisation to functional imaging, which was previously lacking from pure PET imaging. For example, in oncology, surgical planning, radiation therapy and cancer staging have been changing rapidly under the influence of PET-CT availability, to the extent that many diagnostic imaging procedures and centres have been gradually abandoning conventional PET devices and substituting them with PET-CTs. Although the combined/hybrid device is considerably more expensive, it has the advantage of providing both functions as stand-alone examinations, being, in fact, two devices in one.
Before carrying out a PET scan, a radioactive medicine is produced in a cyclotron. The radioactive medicine is then tagged to a natural chemical. This natural chemical could be glucose, water, or ammonia. The tagged natural chemical is known as a radiotracer. The radiotracer is then inserted into the human body.
When it is inside, the radiotracer will go to areas inside the body that use the natural chemical. For example, FDG (fluorodeoxyglucose - a radioactive drug) is tagged to glucose to make a radiotracer. The glucose goes into those parts of the body that use glucose for energy. Cancers, for example, use glucose differently from normal tissue - so, FDG can show up cancers.
A PET scan detects the energy emitted by positively-charged particles (positrons). As the radiotracer is broken down inside the patient's body, positrons are made. This energy appears as a three-dimensional image on a computer monitor.
The image reveals how parts of the patient's body function by the way they break down the radiotracer. A PET image will display different levels of positrons according to brightness and colour.
When the image is complete, it is examined by a radiologist who reports his/her findings to a doctor.
The following are considered to be the biggest advantages of a PET CT Scan:
A powerful source of data to help make the right decisions
Reduces number of invasive procedures
Can help avoid unnecessary surgery
Can tell whether a tumour is benign or cancerous
Can show all the organ systems of the body in a single exam, showing, for example, whether cancer has spread
Detects disease often before it shows up on other tests
Is an early predictor of patients' response to their therapy
Assists in planning for radiation therapy
PET CT Scan
The effective radiation dose from CT ranges from 2 to 10 mSv, which is about the same as what the average person receives from background radiation in 3 to 5 years. Usually, CT is not recommended for pregnant women or children unless absolutely necessary.
Moderate to high radiation
Effects on the body
Despite being small, CT can pose the risk of irradiation. Painless, non-invasive.
Radiation risk from the injection of a radioactive tracer is about the same as an X-ray
Principle used for imaging
Uses X-rays for imaging
Radioactive tracers that emit positrons are used. The positrons are tracked by the system to generate a 3D image over time
Scope of application
CT scan outline bone inside the body very accurately.
PET scans can image biological processes within the body.
In general, PET scans may be used to evaluate organs and/or tissues for the presence of disease or other conditions. PET may also be used to evaluate the function of organs such as the heart or brain. Another use of PET scans is in the evaluation of the treatment of cancer. PET CT scans are used to
Diagnose dementias such as Alzheimer's disease, as well as other neurological conditions such as Parkinson's disease, Huntington's disease, epilepsy and cerebrovascular accidents
Locate the specific surgical site prior to surgical procedures of the brain
Evaluate the brain after trauma to detect haematoma, bleeding, and/or perfusion of the brain tissue
Detect the spread of cancer to other parts of the body from the original cancer site
Evaluate the effectiveness of cancer treatment
Evaluate perfusion to the myocardium (heart muscle) as an aid in determining the usefulness of a therapeutic procedure to improve blood flow in that area
Identify lung lesions or masses detected on chest x-ray and/or chest CT
To assist in the management and treatment of lung cancer by staging lesions and following the progress of lesions after treatment
To detect recurrence of tumours earlier than with other diagnostic modalities