PSMA PET Scan — how it works, what it shows.

What is a PSMA PET scan?

PSMA PET has become the reference-standard scan in prostate cancer for three jobs: staging newly diagnosed intermediate-to-high-risk disease before surgery or radiotherapy, finding recurrence when PSA starts rising again after treatment, and selecting patients for PSMA-targeted radioligand therapy such as Lu-177 PSMA. The same PSMA target that lights up on the scan is the target the therapy attacks — the core idea of theranostics, where we “see it, then treat it.”

At Theranostic Physicians, PSMA PET/CT is performed in the Department of Nuclear Medicine at Fortis Memorial Research Institute (FMRI), Sector 44, Gurugram, with image interpretation led by Dr. Ishita B. Sen and Dr. Dharmender Malik.

How does a PSMA PET scan work?

Most prostate cancers overexpress PSMA on the surface of their cells — with expression tending to rise as the disease becomes more aggressive. A PSMA PET scan exploits that biology in four steps:

• The tracer. A small molecule that binds PSMA with high affinity is labelled with a positron-emitting radionuclide. The most common are Gallium-68 PSMA-11 (the agent used in the proPSMA trial) and the fluorine-18 agents piflufolastat F-18 (PSMA-1007 / DCFPyL). The choice depends on availability and the clinical question.
• Injection. A small intravenous injection delivers the tracer. The amount of the binding molecule is a microdose — far too small to have any pharmacological effect.
• Uptake. Over roughly 50 to 60 minutes the tracer circulates and locks onto PSMA on prostate cancer cells wherever they are — prostate bed, lymph nodes, bone, or soft tissue.
• Imaging. The PET scanner detects the radiation emitted from those sites and builds a three-dimensional map; the CT component adds precise anatomical location. PSMA-avid disease appears as bright “hot spots.”

Some PSMA uptake is normal: the salivary and tear glands, liver, spleen, kidneys, bowel and urinary tract all take up the tracer physiologically. Distinguishing this normal pattern from disease is a core part of expert reporting, and is why interpretation matters as much as the machine.

In the United States, F-18 PSMA agents are marketed as Pylarify (piflufolastat F-18) and Posluma (flotufolastat F-18).

Why is a PSMA PET scan performed?

A PSMA PET scan is recommended in a few well-defined situations. Your urologist or oncologist will usually be the one to request it:

• Staging high-risk prostate cancer. For newly diagnosed intermediate-to-high-risk disease, to check whether cancer has spread to lymph nodes or bone before deciding on surgery or radiotherapy. Accurate staging changes the treatment plan.
• A rising PSA after treatment (biochemical recurrence). When PSA climbs again after surgery or radiotherapy, PSMA PET can pinpoint where the cancer has returned — often while PSA is still low — so treatment can be targeted.
• Selecting and planning radioligand therapy. To confirm a tumour is PSMA-positive before Lu-177 PSMA or Ac-225 PSMA therapy, and to map the disease beforehand.
• Restaging and response assessment. To reassess the extent of disease in advanced prostate cancer, or to see how it is responding.

Before the scan: how to prepare

A PSMA PET scan needs very little preparation. Unlike an FDG PET scan, you do not need to fast. Drink water normally and stay well hydrated. Bring any prior imaging — previous PET, CT, MRI or bone scans — along with recent PSA results and your treatment history, so the reporting physician can compare.

What to bring

• Previous scans and reports, ideally on CD or in digital form
• Recent PSA values, with dates
• A list of current medications
• Your referral letter, if you have one

What to expect before you arrive

• No fasting required
• Continue your usual medications unless told otherwise
• Allow about two hours at the centre in total
• Tell the team beforehand if there is any chance you may need assistance lying still for around 20 minutes

During the scan: what happens

The scan itself is painless. A small intravenous injection delivers the PSMA tracer, then you rest quietly for roughly 50 to 60 minutes while it circulates and binds to prostate cancer cells. You will be asked to empty your bladder, then the PET/CT scan is acquired — usually 20 to 30 minutes, lying still on the scanner bed.

After the scan: results and precautions

You can eat, drink and drive as normal immediately after a PSMA PET scan. There is no sedation and no recovery period. Drinking fluids helps clear the tracer, which leaves the body mainly through the kidneys. The radioactivity decays quickly, but as a routine precaution we suggest limiting prolonged close contact with pregnant women and young children for a few hours.

When you get your results

Your report is issued by the reporting nuclear medicine physician and sent to your referring doctor. If the scan was requested to assess suitability for Lu-177 PSMA or Ac-225 PSMA therapy, the same team that reads the scan is the team that would deliver the therapy.

What does a PSMA PET scan show?

A PSMA PET scan shows where prostate cancer is active throughout the body — including the prostate bed, lymph nodes, bone and soft-tissue or visceral sites — by detecting areas of PSMA expression.

• Staging. In the randomised proPSMA trial, PSMA PET/CT was 27% more accurate than CT plus bone scan for staging high-risk prostate cancer (92% versus 65%), with fewer uncertain results and less radiation exposure.
• Recurrence. When PSA rises after treatment, PSMA PET localises the cancer even at low PSA values where conventional imaging is usually blank — finding disease in a meaningful share of patients with PSA below 0.5 ng/mL.
• Impact on decisions. Because it finds disease earlier and maps it more completely, PSMA PET changes the management plan in a substantial proportion of cases.

PSMA PET vs bone scan and CT

For detecting metastatic prostate cancer, PSMA PET is substantially more accurate than the conventional combination of CT and bone scan. In the randomised proPSMA trial, PSMA PET/CT was 27% more accurate for staging high-risk prostate cancer — 92% versus 65% — with fewer equivocal results and less radiation exposure.

What PSMA PET does not replace: a multiparametric MRI of the prostate remains the test for assessing the gland itself and guiding biopsy. The two answer different questions and are often used together. For the wider picture of how molecular PET differs from anatomical scans, see PET scan vs CT scan.

What happens after a PSMA PET scan?

A PSMA PET scan is not only diagnostic — it is the doorway to treatment. This is the heart of theranostics: the very same PSMA receptor that the scan lights up is what a PSMA-targeted therapy binds to and irradiates.

If the scan shows PSMA-positive disease, you may be a candidate for Lu-177 PSMA therapy — the radioligand treatment (brand name Pluvicto) that delivers radiation directly to PSMA-expressing prostate cancer. In selected patients with aggressive or progressing disease, Ac-225 PSMA alpha therapy is the next option. A PSMA-positive scan, read alongside your clinical picture, is what makes that pathway possible.

If you already have PSMA PET images from elsewhere and want an independent expert opinion before deciding, our Second Read service provides a formal re-read of your existing study.

How much does a PSMA PET scan cost in India?

A PSMA PET-CT scan at Fortis Memorial Research Institute, Sector 44, Gurugram costs approximately ₹25,900. This is the hospital counter price, with no commission added for booking or coordination. The final figure depends on the tracer used (Ga-68 PSMA-11 or an F-18 PSMA agent) and is confirmed in writing before your appointment.

Is a PSMA PET scan safe? Side effects explained

A PSMA PET scan is very safe and side effects are rare. The tracer is given as a microdose, far too small to have a pharmacological effect, and does not cause the reactions associated with iodinated CT contrast. The radiation dose is low — comparable to other routine diagnostic PET/CT studies.

Tracer & side effects

• The PSMA tracer is given in a microdose; allergic or adverse reactions are rare and usually mild.
• There is no sedation and none of the contrast-dye reactions associated with iodinated CT contrast.
• You can eat, drink and drive as normal afterwards. Drinking fluids helps flush the tracer, which is cleared mainly through the kidneys.

Radiation

• The radiation dose is low — in the range of other routine diagnostic PET/CT studies, and a small fraction of any therapeutic dose.
• The radioactivity decays quickly. As a routine precaution we may advise limiting prolonged close contact with pregnant women and young children for a few hours after the scan.

Pregnancy & breastfeeding

• Tell the team beforehand if there is any possibility of pregnancy or if you are breastfeeding, so appropriate precautions can be taken. (PSMA PET is a prostate-cancer test and so this applies in specific contexts only.)

Where to get a PSMA PET scan in Gurugram

PSMA PET/CT is performed at the Department of Nuclear Medicine, Fortis Memorial Research Institute, Sector 44, Gurugram — the single centre where we deliver scans — with interpretation led by Dr. Ishita B. Sen and Dr. Dharmender Malik. Our team coordinates directly with the department so you skip the phone queues, and can usually secure a priority slot on a best-effort basis.

Already have PSMA PET images from another centre? You can request an independent expert opinion through our Second Read service without travelling.

Who reads your scan?

Every PSMA PET study at this centre is interpreted by Dr. Ishita B. Sen, Director of Nuclear Medicine and Molecular Imaging at Fortis Memorial Research Institute and President of the Association of Nuclear Medicine Physicians of India, together with Dr. Dharmender Malik, Senior Consultant.

A PSMA PET result depends on two things working together: a good machine to acquire a clean, high-resolution study, and a good reader — an experienced nuclear medicine physician — to interpret it correctly. Two readers looking at the same images on the same scanner can reach different conclusions; in prostate cancer, that interpretation steers the diagnosis, the staging, and whether a patient is offered Lu-PSMA therapy.

• The institution. Scans are performed at Fortis Memorial Research Institute, Sector 44, Gurugram — a leading tertiary hospital with a dedicated Department of Nuclear Medicine and modern PET/CT imaging.
• The reader. Every study is interpreted by Dr. Ishita B. Sen and Dr. Dharmender Malik, whose years of focused theranostics experience are exactly what a borderline or complex PSMA scan needs — distinguishing true disease from the normal PSMA uptake seen in salivary glands, bowel and the urinary tract.

A scan is only ever as reliable as the equipment that acquires it and the physician who reads it. We hold both to the same standard.