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A new - and very powerful - tool
In June 2008 the first Positron Emission Tomography (PET) Centre opened in Nova Scotia at the Queen Elizabeth II (QEII) Health Sciences Centre in Halifax. Since then, more than 2,400 patients have had the status of  their cancer assessed with this revolutionary tool.  

PET is a new procedure that, when combined with Computed Tomography (CT), helps physiciansPETscanner more accurately diagnose and manage disease, especially cancer. The PET scanner at the QEII has a built in CT, allowing both types of scans to be performed at the same time. Combining these two scanners has created a new very powerful diagnostic cancer imaging tool.

PET detects changes in activity in the cells of the body which can indicate the presence of a disease like cancer, whereas the CT scan detects changes in physical size and/or shape of a lesion as well its location. This type of information can help physicians improve treatment planning for individual patients.

How does PET work?

In PET, a sugar is combined with a safe radioactive component to produce a radioactive tracer called FDG (Fluorodeoxyglucose). This tracer, when injected into a vein, will be absorbed by cancer cells but will not be absorbed by benign cells and scar tissue. On the PET scan, the absorption of this tracer will indicate whether or not a lesion could be cancerous.

PET, particularly when combined with CT, is superior to other imaging techniques in many cancer situations. For example, in some cases PET may more accurately diagnose the presence of cancer. In those with a known cancer, PET may better establish how far the cancer has spread, whether it is responding to therapy or whether it has come back after treatement.

What to expect when getting a PET Scan

Several days before the scan, patients are contacted by PET department staff to remind them of their appointment, make sure they are aware of the preparation, and to answer any questions the patient may have. Patient preparation consists of skipping breakfast or having a light breakfast, depending on the time of the appointment. Special instructions are given to diabetics regarding their medications. Patients are asked to avoid physical exertion for 24 hours prior to the scan.

The PET scanner at the QEII is located on the second floor of the VG site. Patients check in at the CT reception area, complete a brief questionnaire, and review the procedure consent form. Patients are then taken to a private ‘uptake room’ where they are injected with the tracer. They are asked to sit quietly to allow the tracer to circulate through the body. When the uptake period is complete, patients go next door to the scan room to begin imaging. A typical PET scan takes approximately 30 minutes. Going through the scanner is a relatively peaceful experience; the machine is quiet and there are no needles or injections other than the injection of the tracer in the uptake room 45 minutes earlier. The entire procedure, from the time  a patient arrives at the PET centre, lasts approximately 2.5 hours.

Is PET always the best tool?

While PET is used to evaluate the status of many cancers at several points during the course of the disease, it is not always the best diagnostic tool. The patient’s oncologist makes the decision as to whether PET is beneficial for a specific patient.