PET CT SCAN
PET/CT Scan at Saint James Hospital
PET/CT stands for Positron Emission Tomography/Computed Tomography. It is a special and unique technique in that it combines two different imaging modalities into one scan, a concept called ‘hybrid imaging’. This is the first PET/CT scanner on the islands and will allow for a better management, treatment and follow-up of numerous patients who up till now had to travel abroad.
PET/CT imaging represents an innovative procedure in that it combines metabolic and biochemical data from a PET scan and structural or anatomic data from CT scan into one powerful imaging investigation. PET/CT scanning has revolutionised many fields of medical diagnosis. This methodology is quickly expanding worldwide since it enables detection of functional molecular biology detail even before structural changes appear in the body using conventional imaging techniques. The largest application in many countries where this technology is available is cancer.
PET/CT now plays a pivotal role in imaging of tumours and spread of disease (metastases), in particular staging of cancer before treatment, restaging of cancer during and after therapy, in surgery and radiotherapy planning, and in follow-up of numerous neoplastic pathologies. Besides oncology, PET/CT also finds application in:
- characterising indeterminate pulmonary lesions
- tracing active inflammatory disease such as sarcoidosis and large vessel vasculitis and assessing response to treatment of these pathologies
- neurology; by associating tracer uptake patterns with brain activity in various pathologies such as Alzheimer’s disease and Parkinson’s disease
- cardiology; by giving unique information regarding viable, reversible heart tissue and also the possibility of evaluating cardiac tissue perfusion
Advantages of PET/CT
The greatest advantage is that the biochemical and metabolic information cannot be obtained by any other imaging modality. These changes usually occur before structural modifications, if any anatomic alterations take place at all. Nevertheless, the CT images are also evaluated, summing up synergistically information collected from both methodologies.
Another significant advantage of PET/CT scan in oncology is that it is usually performed from eyebrows to thighs. In this way, all the organs within this field of view are evaluated with just one scan. In some cases (depending on pathology) the whole body must by included in the field-of-view.
Yet another benefit of this examination is that no contrast medium is used in PET/CT scanning, therefore it can still be carried out by patients who are allergic to contrast medium or in patients with renal failure.
The PET/CT scanner and the procedure
A PET/CT scanner is a machine with a round hole in the middle, similar to a CT scanner.
Patients are required to fast for at least 6 hours before the scan. The patient’s blood glucose levels will be checked on arrival. The specialist uses a very small amount of mildly radioactive tracer (for example radioactive sugar) injected intravenously to show structures of the body where cells are more active than normal and in some cases to show reduction or lack of expected cell activity. PET/CT permits specialists to evaluate any changes in the activity of cells and see exactly where these changes are happening. It will take approximately 45 to 60 minutes for the tracer to circulate through the patient’s body and to be absorbed by the organs or tissues being studied. The patient will be asked to sit down and rest quietly in the waiting room within the PET/CT department. The patient will also be instructed to drink water.
The patient will then be positioned on an examination table that slides into and out of the PET/CT gantry. An oncology PET/CT scan is usually performed from the eyebrows to the thighs. The same scanner will automatically perform a CT and a PET scan. The actual CT scan takes approximately one minute. The PET scan usually takes 10 to 15 minutes. The patient should plan on being at the facility for a total of 1½ to 2 hours.
The patient may resume normal activities after the imaging session. The small amount of radiotracer in the patient’s body will lose its radioactivity over time through the natural process of radioactive decay. It is also advisable for patients to drink a lot of water after the scan to help flush the radioactive material out of the body.
PET/CT scans are very safe. The procedure in non-invasive, painless and is very rarely associated with significant discomfort or side-effects. The examination poses no significant health risks and patients may resume normal activities after the PET/CT scan. The only contra-indication for a PET/CT scan is pregnancy. PET/CT is mostly performed on an outpatient basis. Some undergo PET/CT examination as inpatients.
The tracer is produced in a cyclotron in a specialised centre and shipped in from abroad on the same day of the scan.
The specialist responsible for the Saint James Hospital PET/CT department is Dr. Mark Anthony Aquilina, a nuclear medicine physician with 5½ years experience at San Raffaele Hospital in Milan.