PET-CT FAQ

A: PET-CT examinations involve injection of radioactive isotope. The radiation dose is small and will not affect your body function or cause discomfort during the procedure. Besides, the residual radiation inside your body will diminish through natural half-life decay. You will be encouraged to drink plenty of water after the examination to facilitate the excretion of radioactivity. You can get rid of radiation usually within a few hours. You can then resume all daily activities. Avoidance of unnecessary contact with pregnant women and infants on the day of examination is suggested.

A: Depending on the examination requested by your doctor and the clinical indications, you may be required to have contrast medium injection for more information. Our staff will discuss with you before a contrast enhanced study.

A: Iodinated contrast media are commonly used in radiological investigations. They are generally safe although adverse reactions are occasionally encountered.

A) Acute Adverse Reaction

Acute adverse events can be categorised as either allergic-like or physiologic. Allergic-like reactions often occur immediately or within 20 minutes after contrast injection. The severity of acute adverse reaction can be defined as mild, moderate and severe.

1. Mild reactions
   Mild reactions are self-limited and usually no medical management is required, such as limited urticaria, itchiness, erythema, nausea, mild vomiting, sneezing, coughing, warmth, chills, rhinorrhea, etc.

2. Moderate reactions*
   Reactions namely marked urticaria, mild bronchospasm, facial edema, laryngeal edema, shortness of breath, wheezing.

3. Severe reactions*
   They are often life-threatening, such as hypotensive shock, respiratory arrest, cardiac arrest, arrhythmia, convulsion, death.

* Acute moderate or severe adverse reactions usually require medical treatment. A mild reaction may develop into a more serious reaction and can even cause serious harm. Nevertheless, our staff are professionally trained and well equipped to recognise and manage the contrast adverse reactions properly. Patient will be asked to rest in a medical environment for at least 20 minutes after contrast agent injection.

Please inform referring doctor and our staff before examination if the patient has previous history of allergy to iodinated contrast medium. Steroid premedication may be advised before the scan.

B) Delayed Adverse Reaction

Delayed adverse reactions to intravascular iodinated contrast media are defined as reactions which occur between 1 hour and 1 week following iodinated contrast media injection.  Most of the late reactions are skin reactions which include maculopapular rash, angioedema, urticaria and erythema. (Skin reactions are often mild to moderate and self-limited.)

A: Pregnancy is relatively contraindicated. Please consult our staff if you are pregnant or may be pregnant.

A: Breast-feeding mother may be requested to stop breast-feeding within 48 hours after the examination. Please consult our staff for the precautions of different studies.

A: Yes, a requisition form signed by your doctor will provide us with your necessary clinical information; and we will tailor the examination accordingly.

A: The more information that our radiologist has when he reviews your study, the more specific the interpretation will be. Correlations with other studies are often helpful.

A: After the PET-CT scan, radiologist will interpret the PET-CT scan and issue an imaging report to the referring doctor who will then explain the findings and diagnosis.