PSMA PET/CT

PET/CT examination with 68Ga -PSMA ligands

In order to detect tumor lesions in patients with prostate cancer more accurately, a new, highly sensitive marker for PET/CT has been introduced at the Department of Nuclear Medicine of the Saarland University Hospital in Homburg. The radioactive substance gallium-68-PSMA ligand binds to prostate specific membrane antigen (PSMA) on the surface of tumor cells and thus enables imaging with very high contrast. In some cases, the smallest tumor metastases can be detected that could escape conventional imaging.

How does the examination work?

A small amount of the gallium-68 labeled PSMA ligand (68Ga-PSMA) is injected into a vein for examination. Following the injection, 68Ga-PSMA reaches the diseased tissue via the blood vessel system and accumulates significantly more in the diseased cells than in normal tissues. In order to observe and visualize its distribution in the body, the PSMA is labeled with a short-lived radioactive substance (gallium-68). Its physical half-life is only 68 minutes.

The diseased tissue will show increased accumulation of PSMA. Using the radiation of gallium-68 and the PET/CT scanner, the enrichment site can be localized and the desired tissue can be visualized. In order to enable a reliable assignment to known structures (lymph nodes, soft tissues), computed tomography (CT) is additionally performed and the 68Ga-PSMA PET images are superimposed on the CT images (PET/CT). Thereby, the locations found in the PET can be precisely assigned to the respective anatomical structures.

Documents

Please bring all relevant documents with you to the examination (especially images and findings from preliminary examinations, preferably also in digital form on CD and doctor's letters). For the possible intravenous administration of contrast media within the scope of CT (computed tomography), you should have your general practitioner determine the creatinine level in your blood as soon as possible - ideally within the week before the examination. The result of the blood test should be the provided on the day of examination.

Examination procedure

• During a detailed discussion with one of our doctors you will be asked a brief review of your complaints, as well as the examinations and treatments carried out so far and you will be informed in detail about the planned examination.
• A low-level radioactive substance (68 Ga-PSMA) will be then injected into your arm vein, which accumulates in metabolically active prostate tissue and metastases of prostate cancer, if there is any.
• You will stay approx. 60 min. in our waiting area; you have to drink sufficient amount of water, that is provided.
• You will then be taken to the PET/CT scanner for a whole body acquisition.

You will be lying on your back on a flat table for the examination, which takes will last for about 20-30 minutes. During the examination you will be supervised by our technical and medical staff.

Following the acquisition the results of the examination will be reviewed by the responsible nuclear medicine physician and will be discussed with you.

The PET-CT scanner is open upwards (towards the head) and downwards (towards the legs) but cannot be compared to a tube.

With a pronounced "claustrophobia", a premedication may be necessary or advisable to relieve anxiety. Remember that with such an anxiolytic medication you are not fit to drive on the day of the examination!

If there is no persistent "claustrophobia" (99% of cases), no such medication is required and you can drive your vehicle (before and after the examination).

Side effects

No side effects are to be expected from the injection of the radioactive tracer itself.

Side effects can result from the administration of iodine-containing contrast media within the scope of the CT (intolerance reaction, hyperthyroidism, intensification of a pre-existing renal insufficiency). In the consultation with our physicians, please make sure to point out if you have experienced a contrast agent reaction in the past (reddening of the skin, itching, swelling, shortness of breath, etc.).

Radiation exposure

The radiation exposure (radiation exposure) through one injection of gallium-PSMA is approximately in the range of twice the amount of natural annual radiation dose (approx. 4-6 mSv). It is below the radiation dose of most conventional CT examinations. Acute and/or chronic radiation damage from gallium PSMA is not to be expected or ever observed.

Important:

Before each PET/CT examination, your family doctor should take a blood sample and determine the values for "creatinine" and "TSH". We kindly ask you to bring these with you for the examination.

You do not have to be in a fasting state on the day of the examination. You may have a light breakfast. The radiopharmaceutical is manufactured for patients and cannot be stored. It is absolutely necessary to keep your appointment or to inform us reasonably early if you will not be able to show up.