What is a PSMA PET/CT or PSMA SPECT/CT Scan?
A PSMA (Prostate Specific Membrane Antigen) scan is an advanced imaging test specifically designed to detect prostate cancer cells in your body. This scan can find prostate cancer that has spread beyond the prostate gland, even when other imaging tests might miss it. This scan may be performed using either PET/CT (Positron Emission Tomography) or SPECT/CT (Single Photon Emission Computed Tomography) technology, depending on your specific needs and the equipment available.
How Does a PSMA Scan Work?
The scan uses two key technologies working together:
- Nuclear Medicine Imaging: Detects the radioactive signal from the prostate cancer cells
- PET (Positron Emission Tomography): Uses tracers such as Ga-68 PSMA or F-18 PSMA
- SPECT (Single Photon Emission Computed Tomography): Uses tracers such as Tc-99m PSMA
- A small amount of the appropriate radioactive tracer is injected into your bloodstream
- This tracer specifically binds to PSMA proteins found in high amounts on prostate cancer cells
- Areas with prostate cancer will show up as “hot spots” on the scan
- CT (Computed Tomography): Provides detailed anatomical images
- Helps precisely locate where any cancer might be in your body
- Allows doctors to see exactly where the “hot spots” are located
Why Might I Need This Scan?
Your doctor may recommend a PSMA PET or SPECT scan to:
- Determine if prostate cancer has spread beyond the prostate
- Check if cancer has returned after previous treatment
- Help plan the most appropriate treatment for your specific situation
- Monitor how well treatment is working
What to Expect During Your PSMA PET or PSMA SPECT Scan
Before the Scan
- No special dietary preparation or fasting is required
- You should drink water normally before your appointment
- Wear comfortable clothing without metal objects
- Tell your doctor if you are pregnant, breastfeeding, or have any allergies
During the Scan
- You’ll receive an injection of the radioactive tracer into a vein in your arm
- This injection is similar to a regular blood test and causes minimal discomfort
- The type of tracer used will depend on whether you’re having a PET/CT (Ga-68 PSMA or F-18 PSMA) or a SPECT/CT (Tc-99m PSMA)
- The tracer will not make you feel different or cause side effects
- Waiting period (uptake phase)
- You’ll be asked to sit quietly and relax for 30-60 minutes
- During this time, the tracer circulates through your body and attaches to prostate cancer cells
- You may be encouraged to drink water to help clear the tracer from your urinary system
- Scanning procedure
- You’ll lie on a table that moves through the scanner
- The scanner has a large opening (not enclosed like an MRI)
- The machine makes minimal noise
- You’ll need to lie still during the scanning
- The actual scanning takes approximately 30 minutes for PET/CT or SPECT/CT
- The type of scanner used will depend on your specific situation and what your doctor has ordered
- The entire procedure, including waiting time, typically takes 1.5-2 hours
After the Scan
- You can resume all normal activities immediately
- Drink plenty of fluids to help flush the tracer from your body
- The small amount of radiation from the tracer will naturally leave your body within a day
- A nuclear medicine specialist will analyze your images and send a report to your doctor
- Your doctor will discuss the results with you at your next appointment
Are There Any Risks?
The PSMA PET scan uses a very small amount of radiation. The benefits of the information gained from the scan far outweigh any potential risks from this minimal radiation exposure. The radioactive tracer is eliminated from your body naturally within 24 hours.
If you have any questions or concerns about your PSMA PET scan, please discuss them with your healthcare provider.
