PET/CT examinations of the brain

 

In determination of agressivity of certain brain tumors or in assessment of therapeutic efficacy, the cerebral PET (positron emission tomography) or the CT (computer tomography) can be very effective.
Before the cerebral PET examination we give the patient a radioactive substance, grape sugar with radioactive fluorine isotope or amino acid, the component of proteins (C11-methionine) in the form of an intravenous injection. After this the patient has to wait in a silent waiting room and should not speak. Afterwards the imaging is performed. To reduce the feeling of claustrophoby it is worth closing the eyes. Additionally it is very important that the patient has to lie still during the examination. If the patient is not capable of this, he/she has to indicate it to the examining physician.
We perform cerebral PET-CT examinations with 2 types of tracer substances: with F18-FDG (in Budapest and in Debrecen) and with C11-methionine (only in Debrecen).

The full examination lasts for 10 minutes with F18-FDG and for 20 minutes with C11-methionine. Besides the PET examination we take CT images as well every time with the same camera, but it does not increase the examination time.

General preparations

In 6 hours prior to the examination patients are not allowed to eat. They can only drink water, because every other fluid and food contains sugar that significantly reduces the efficacy of the examination. If the patient suffers from diabetes it is especially important to inform the physician requesting the examination. Patients are informed by our colleagues on the phone about preparations in details when they are called with an appointment.

Radiation load

The radiation load of the examination is low, it is similar to the CT examinations’. So after the examination patients can freely go to community and use toilets without any substantive risk for others.

Pregnancy

About pregnancy, suspicion of pregnancy and about breast-feeding the patient has to inform the therapist, who discusses the further duties with the nuclear medicine specialist.

 

18F-FDG PET/CT examination of the brain

The clinical application of 18F-FDG PET/CT examination extends to detection of brain tumors and determination of the degree of malignancy. But imaging of glucose distribution in the brain provides an opportunity to diagnosing dementia and epileptogenic foci.

Preparation of the patient

The patient should arrive to the examination having spent 4-6 hours on an empty stomach. After recording data and taking medical history the blood glucose level is measured. After administration of the radiopharmacon the patient has to lie in complete rest and if possible in half light for an additional 40 minutes. During time of waiting the patient does not have to consume fluid or diluted contrast medium. The actual examination starts in the 45th minute (+/-5 minutes) after administration of the radiopharmacon. First we perform a low-dose CT examination of the skull and after that we are collecting PET data that lasts for 10 minutes.

 

Cerebral 11C-methionine PET/CT examination

The aim of the 11C-methionine PET/CT examination is to detect the viable cerebral cancer tissue based on the increased amino acid transport of cancer cells, to detect the exact extent of cerebral cancer processes, to assign the site of sample excision in case of heterogenous tumors and to detect early recurrence after therapy.

Preparation of the patient

After at least 4 hours spent with an empty stomach, the PET is performed with injecting the radiopharmacone manually into a peripheral vein. After administration of the radiopharmacon the patient has to spend 2-3 more minutes with resting. During time of waiting the patient does not have to consume fluid or diluted contrast medium. Prior to the examination the patient does not have to urinate. The actual examination starts in the tenth minute (+/-2-3 minutes) after administration of the radiopharmacon. First we perform a low-dose CT examination of the skull and after that for 20 minutes we are collecting PET data.