PSMA PET CT

What Is a PSMA PET CT Scan?

A PET CT scan combines positron emission tomography and computed tomography to visualize inflammation, brain disorders, and cancers. In addition, the PET scan is used to visualize regions with an exceptionally high metabolic rate. This is the case, for example, with cancer cells, which divide rapidly and accordingly have a high energy requirement.

In the specific case of the PSMA PET CT procedure, the examination is performed using the tracer substances F18-PSMA or Ga68-PSMA. These are injected into the bloodstream and bind to PSMA, the prostate-specific membrane antigen. PSMA is a protein found on the surface of prostate cells and is produced in increased amounts, especially in malignant prostate diseases.

When Is a PSMA PET Scan Performed?

The PSMA PET scan can be used when a carcinoma of the prostate is suspected. Prostate cancer is the most common malignant cancer in men in Germany and can be noticed, among others, by a significantly increased PSA value in the blood. Therefore, the examination procedure is used, for example, to find the cause of a raised PSA value to confirm or rule out a suspected cancer based on the examination.

It is also used in cases of suspected tumor recurrence and to detect cancer metastases. In addition, it can provide more specific information for a more precise classification of the stage of the disease, known as staging, and can be used to monitor therapy for prostate carcinomas that have already been identified.

The advantage of the procedure is that the entire spectrum of tumor disease can be covered with one examination. In addition, PET CT is superior to pure computed tomography, especially for the detection of metastases, as it provides more accurate results.

For this reason, the examination has become increasingly important in recent years, as it is more sensitive and specific than CT and MRI procedures. In some cases, the examination method can also be used for PSMA therapy using a stronger tracer, Lu-177.

The stronger radiation emitted from the ligand can penetrate the cancer cells and cause them to die from within. At the same time, it has no adverse effect on surrounding tissue due to its short range. This therapy is used when all other therapy methods have been exhausted.

Procedure and Duration

The test is performed in two steps. First, the prepared radiopharmaceutical is injected into the patient's vein. For the tracer to reach its target site, a waiting period of one to two hours is required. Typically, the patient should drink about half a liter to one liter of water to remove excess substances. The subsequent examination time requires approximately fifteen to forty-five minutes. The patient is asked not to move during the entire time to obtain better examination results and avoid inaccurate images.

Are There Any Side Effects?

The examination method is considered very safe, and no side effects or allergic reactions have been described so far. Nevertheless, patients with a known allergy to a contrast agent should mention this in the preliminary review with the examining physician. The overall radioactive exposure is low because the tracers are very short-lived and decay quickly. They have a half-life of approximately one to two hours. Therefore, the absorbed radiation dose of an examination corresponds to about one to two times the natural annual radiation exposure in Germany.

What Does PSMA PET CT Cost?

Private health insurance companies, in particular, cover the costs of the examination in most cases. On the other hand, statutory health insurance companies do not usually pay for the procedure; in this case, an application for cost coverage should be submitted in advance.

If the relevant health insurance company does not cover the examination, patients can pay the amount themselves. Although the costs amount to about one thousand to one thousand five hundred euros, the price may vary somewhat depending on the clinic.

Where Can a PSMA PET CT Be Performed?

Nuclear medicine specialists realize the performance of a PSMA PET CT examination. This can be done by practicing radiologists in outpatient practices but also in the nuclear medicine clinic. Unfortunately, not every clinic or radiology practice has the appropriate equipment with the required devices.

Sources:

• https://www.awmf.org/uploads/tx_szleitlinien/031-055l_S1_PSMA-Liganden-PET-CT-Diagnostik-Prostatakarzinoms_2020-05.pdf
• Langbein T, Eiber M. Einsatz von PSMA-PET/CT beim Prostatakarzinom. Der Nuklearmediziner 2020; 43(04): 289 - 302. doi:10.1055/a-1115-8568
• https://www.prostata-hilfe-deutschland.de/prostata-news/psma-pet-ct