PET/CT scan


Positron emission tomography (PET) combined with computed tomography (CT) is a powerful diagnostic tool for several medical conditions. Currently, we perform PET/CT scans primarily to diagnose, stage, and monitor treatment of most malignant tumors. PET/CT is also used for diagnosis of some infections and inflammatory conditions.

PET/CT provides information about both the structure and function of the scanned area. Under normal circumstances, standard examinations can be carried out on the neck, chest, and abdomen. The CT portion can either be carried out as a low-dose examination without contrast, or as a complete CT scan using intravenous contrast agents. The latter case is equivalent to an “ordinary” CT scan, which therefore does not need to be ordered separately.

Radiopharmaceuticals

We currently use FDG, a radioactive tracer resembling sugar, which is temporarily absorbed by the various organs of the body.

Method

On arrival a blood sugar sample is taken from the patient, after which venous access is established in the arm. After about 30 minutes, the radioactive tracer is injected intravenously. The patient is then allowed to rest for about one hour while the radioactive tracer is distributed in the body. Imaging then takes about 30 minutes. During imaging, the patient is asked to lie still on an examination table. If x-ray contrast is used, it is administered immediately during imaging, and may produce a mild sensation of heat in the body.

Risks

The radioactive tracer does not cause any hypersensitivity reactions. If x-ray contrast is used, the same precautionary principles governing renal function and hypersensitivity reactions apply as in other CT studies. The radiation dose from a PET/CT scan is about double that of a CT scan.


PET scan image of the abdomen showing uptake of radioactive substance in three areas. (Possible interpretation: three tumors?) 


 

CT image showing malignant change toward the back of the liver, in the dark area seen at left in the lower part of the image. (Possible interpretation: tumor?)


PET/CT image showing that two of the three uptake areas are in the liver and the third is in the left kidney, where it is normal. (Conclusion: two liver tumors.) 

 


Page revised Friday, May 6, 2011

Content manager: Håkan Geijer

Published by Anita Pettersson

Contact

Associate professor, consultant

Håkan Geijer