If you have searched for a “triple phase PET scan”, you have probably found very little that answers the question — and some of what you found may have confused you further.
There is a good reason for that. “Triple phase” is not a PET technique. It is a CT contrast technique. And once you understand that single point, everything about the scan, the preparation and the cost becomes clear.
This guide explains what a triple phase study actually is, what happens when it is combined with a PET scan, which clinical questions it exists to answer, why it matters particularly in liver disease, how to prepare, and what to ask before you book.
If your prescription says “triphasic”, “triple phase”, “CECT triple phase” or “PET CT with triple phase CT”, this page is written for you.
The core confusion, cleared up
A PET CT is two scans running in one machine.
The PET part maps metabolic activity. A radiotracer is injected, and the scan shows where it accumulates — telling the doctor how tissue is behaving.
The CT part maps anatomy. It shows where things are, how big they are, and what shape they are.
“Triple phase” describes how the CT part is acquired. Instead of taking one set of images, the scanner takes images at three different moments after intravenous contrast is injected — because different tissues light up at different times as contrast travels through the body.
So a “triple phase PET scan” is really a PET/CT in which the CT component is acquired as a multiphasic contrast study. Some prescriptions say exactly that. Others simply say “triphasic”, and the centre works out the rest.
It is also entirely possible that your prescription is for a triple phase CT alone, with no PET at all. That is a very common investigation in its own right. If you are not sure which you have been advised, do not guess — send the prescription and let the centre identify it.
What the three phases actually are
Contrast injected into a vein does not reach every organ at once. It arrives in arteries first, then fills the venous system and the organs, then washes out. Imaging at three separate moments captures three different pictures of the same anatomy.
Phase one — arterial
Images taken shortly after injection, while contrast is predominantly in the arteries. Lesions with a rich arterial blood supply appear bright at this moment and can stand out clearly against surrounding tissue.
Phase two — portal venous
Images taken a little later, once contrast has passed through into the venous system and the organs are well opacified. In the liver, this is when the normal liver parenchyma is at its brightest.
Phase three — delayed
Images taken several minutes after injection, once contrast is clearing. Some lesions retain contrast at this stage; others lose it faster than the surrounding tissue and appear relatively darker — a behaviour radiologists describe as washout.
Why three pictures beat one
The diagnosis frequently lies in the change between phases, not in any single image.
A lesion that lights up brightly in the arterial phase and then washes out on the later phases behaves in a characteristic way. A lesion that fills in slowly from the edges over the three phases behaves differently. A lesion that stays uniformly bright behaves differently again.
A single-phase CT sees one frame of that sequence. A triple phase study sees the pattern. In several conditions, the pattern is the diagnosis.
Why this matters most in the liver
The liver is the organ where multiphasic imaging earns its reputation, because of an unusual feature of its blood supply.
Most of the normal liver receives blood from the portal vein rather than the hepatic artery. Many liver tumours, on the other hand, develop their own arterial blood supply.
That difference is what the phases exploit. In the arterial phase, an arterially-supplied lesion becomes bright while the normal liver — still waiting for its portal blood — remains relatively dark. Later, when the normal liver has filled with contrast, the lesion may wash out and appear darker against it.
This pattern of arterial enhancement followed by washout is a well-recognised imaging behaviour in hepatocellular carcinoma, and it is precisely why a plain or single-phase CT of the liver is often not enough.
The point that makes this genuinely important with PET
Here is the part patients are rarely told, and it explains why some prescriptions ask for both.
Well-differentiated hepatocellular carcinoma is frequently not FDG-avid. That is, it may not light up on the PET component at all. A patient who has only an FDG PET, without a properly acquired multiphasic CT of the liver, can receive a reassuring-looking scan while a lesion goes uncharacterised.
This is not a failure of PET. It is a limitation of one tracer for one tumour type — and it is exactly why the CT component is acquired multiphasically when the liver is the question. The two parts of the study answer different halves of the problem.
So when a prescription asks for a PET CT with triple phase liver CT, it is usually not padding. It is one scan doing two jobs.
When a triple phase study is typically requested
The decision belongs to your treating doctor. These are the situations where multiphasic imaging is commonly used.
Characterising a liver lesion
When something has been found on an ultrasound or a plain CT and the question is what is it rather than is it there. Distinguishing between different lesion types often depends on enhancement pattern.
Suspected hepatocellular carcinoma
Particularly in patients with cirrhosis or chronic hepatitis, where surveillance findings need characterisation.
Assessing the extent of liver disease before treatment
Surgical planning, or planning for locoregional treatments, needs clear delineation of lesions and their relationship to vessels.
Pancreatic assessment
Pancreatic protocols use multiphasic contrast timing to define a lesion and its relationship to surrounding arteries and veins — information that directly affects whether surgery is feasible.
Renal lesion characterisation
Enhancement behaviour across phases helps distinguish between different kinds of renal lesions.
Vascular questions
Where arterial anatomy needs to be mapped, an arterial-phase acquisition is used — this is where the term “angio” on a prescription usually comes from.
Neuroendocrine tumours
Some neuroendocrine lesions are strongly arterial and are best seen on arterial-phase imaging. In these patients a DOTANOC PET may be combined with multiphasic CT, because the two answer different questions — receptor expression on one hand, and precise anatomical and vascular detail on the other.
What your prescription might say, and what each means
- “Triple phase CT abdomen” or “CECT abdomen triple phase” — a CT study with three contrast phases. No PET involved.
- “Triphasic liver” — the same, focused on the liver.
- “Triphasic / Angio” — multiphasic acquisition including an arterial phase for vascular assessment.
- “PET CT with triple phase CT” or “PET/CT triphasic” — a PET study where the CT component is acquired multiphasically.
- “FDG PET CT + triphasic liver” — explicitly both, usually where a liver lesion needs characterising alongside a metabolic survey.
If your slip says something that is not on this list, or the handwriting is unclear, photograph it and send it rather than guessing. Booking the wrong protocol means the study may not answer the question — and you pay for the correct one afterwards.
Preparation — and why it is stricter than a plain scan
A triple phase study involves intravenous contrast, which adds requirements that a plain scan does not have. This is where most rescheduling happens, and almost all of it is avoidable.
Kidney function
Iodinated contrast is cleared by the kidneys. Your centre will usually want a recent kidney function test — commonly serum creatinine — before administering it. If you have any history of kidney disease, reduced kidney function, or are on dialysis, this must be disclosed when you book.
Carry any recent blood reports you have. Turning up without them is one of the most common reasons a contrast study is delayed.
Allergies and previous contrast reactions
Tell the centre if you have ever had a reaction to contrast, iodine or any medication. This changes what is done and what precautions are taken. Do not assume it is not relevant because it was years ago.
Medication
Tell the centre what you take, particularly if you are on metformin or other diabetes medication. Specific guidance around metformin and iodinated contrast depends on your kidney function and your treating doctor’s advice — this is a conversation to have at booking, not a decision to make on your own. Do not stop or change any medication without being told to.
Hydration
Being well hydrated before and after a contrast study is generally advised unless your doctor has restricted fluids for another reason. Ask the centre what applies to you.
Fasting
Some fasting is usually required. If the study includes a PET component with FDG, fasting requirements are stricter — typically around 6 hours, with plain water allowed and encouraged, and no tea, coffee, juice, sweets or chewing gum, because FDG is a sugar analogue and circulating glucose competes with it.
Blood sugar, if PET is involved
Checked before the injection. Diabetic patients should raise this at the time of booking so medication timing can be planned rather than improvised on the morning.
Pregnancy and breastfeeding
Tell the centre before anything is injected. This is important and it changes what is done.
What to bring
- The prescription, with the clinical indication written on it
- Recent kidney function reports
- All previous scans and reports — earlier CTs, MRIs, ultrasounds, PET CTs, biopsy results
- A list of current medications
- Insurance or reimbursement papers, if you plan to file a claim
- Photo identification
Those previous scans matter more here than almost anywhere else. A liver lesion that has been stable for three years and one that appeared six months ago are entirely different clinical situations — and only your old films can tell the reporting doctor which one you have.
What happens on the day
If it is a triple phase CT alone
Registration and paperwork, kidney function check if not already available, then a cannula is placed in a vein in the arm. You lie on the table and a plain set of images may be taken first. Contrast is then injected through a pump, and the three acquisitions are taken at defined intervals — the arterial set within seconds, then the portal venous set, then the delayed set a few minutes later.
You will feel a warm sensation spreading through the body as the contrast goes in, and often a metallic taste. Both are expected and pass within a minute. You will be asked to hold your breath briefly for each acquisition — following those instructions precisely is what keeps the images sharp.
The scanning itself is quick. Most of the appointment is preparation, cannula placement and the waiting between phases.
If it is a PET CT with triple phase CT
The same, with the PET sequence around it: registration, blood sugar check, tracer injection, then a quiet uptake period of roughly 45 to 60 minutes during which you must sit still and talk as little as possible, because muscle activity in that window shows on the images. The scan follows, with the multiphasic CT acquired as part of the study.
Plan for two to three hours at the centre for the combined study.
Afterwards
You can usually eat and resume your routine. Drink plenty of water to help clear both the contrast and, if PET was involved, the tracer. If a tracer was used, keep some distance from pregnant women and young children for the rest of the day as a standard precaution.
If you notice any rash, itching, breathlessness or swelling after contrast, tell the centre immediately rather than going home and waiting.
Understanding the report
A multiphasic report reads differently from a plain CT report, because it describes behaviour across time.
You will see phrases describing what a lesion did in each phase — whether it enhanced in the arterial phase, whether it washed out later, whether it filled in progressively. These descriptions are the substance of the report, not decoration.
If a PET component was included, the report will also describe metabolic activity, often with an SUV value. Remember that SUV is not a cancer score: infection and inflammation can raise it, and some tumours — well-differentiated HCC among them — show low uptake. It is most meaningful when compared against a previous study.
The impression at the end is the reporting physician’s summary, and it is the part your treating doctor reads first. If anything in it is unclear, ask the doctor who ordered the scan — they read it alongside everything else they know about your case.
What decides the cost of a triple phase study
Our PET rates are published openly, and a triple phase study is listed among them — FDG whole body with triple phase is Rs 13,499. The figure includes the scan, the tracer and the reporting.
What it depends on:
- Whether PET is included — a triple phase CT alone and a PET CT with triple phase CT are very different studies
- Which tracer, if PET is included — FDG and the Gallium-68 tracers such as DOTANOC differ substantially
- The contrast itself — this is a contrast-enhanced study by definition, so a plain-study rate never applies
- The region covered — liver, whole abdomen, or whole body
- Whether additional views or delayed imaging are needed
Our CT scan rates are published openly on our CT page, study by study, including triple phase studies — so if a CT alone has been advised, you can see the figure for your specific study rather than having to ring and ask.
For comparison, the all-inclusive rates for other PET studies are FDG whole body Rs 7,999, PSMA Rs 15,999, DOTANOC Rs 19,999 and FAPI Rs 21,999, with nothing added at the counter. Send the prescription and we will confirm the complete figure for your exact study in writing, before you book.
Ask these before you pay anywhere
- Is contrast included in the figure you just quoted? For a triple phase study this is not optional — it is the study.
- Is the tracer included, if PET is part of it?
- Is reporting included?
- Are consumables and cannula charges included?
- What is the total I will pay at the counter? Ask for it in writing.
- Do you need a kidney function report before the appointment?
- Who reports the study, and when will the report be ready?
- If the study has to be repeated for a preparation reason, what happens?
Where saving money backfires on this particular study
Accepting a single-phase CT instead. If the clinical question depends on enhancement pattern across phases, a single acquisition cannot answer it. You will pay for both.
Turning up without kidney function reports. The commonest cause of a wasted trip for a contrast study.
Not mentioning a previous contrast reaction. This is a safety matter, not an administrative one.
Leaving old scans at home. For liver lesions especially, comparison with previous imaging often changes the interpretation entirely.
Not disclosing kidney disease or diabetes medication. Both change what should be done.
Where Neurad fits
Neurad Diagnostic and Healthcare LLP is a dedicated PET-CT and nuclear medicine centre at B-3, opposite Metro Pillar No. 233, near Paschim Vihar West Metro Station, New Multan Nagar, Paschim Vihar, New Delhi-110056. Monday to Saturday, 8:00 AM to 5:00 PM.
Triphasic and angio CT studies are part of our CT service, with rates published on our CT page.
PET CT with multiphasic CT where the prescription calls for both, so the metabolic and the anatomical question are answered in one visit rather than two appointments.
An in-house 68Ga generator, so DOTANOC, PSMA, FAPI, Exendin and Trivehexin studies are scheduled on working days rather than held until an outside tracer supply is arranged — relevant when a neuroendocrine lesion needs both receptor imaging and multiphasic CT.
Reported by our own nuclear medicine and radiology team, not outsourced.
Written preparation instructions specific to your study, sent when you book — including exactly what blood reports to carry for a contrast study.
Your previous imaging compared, provided you bring it.
Complimentary pickup and drop within 3 km; beyond that, Rs 50 per km.
The all-inclusive figure in writing before you book.
Related reading
- PET CT for colorectal cancer — where liver characterisation matters most
- PET CT for pancreatic cancer — the pancreatic protocol CT and where FAPI helps
- PET CT vs CT vs MRI — when a cheaper scan answers the question
- PET CT scan price in Delhi — what decides your figure, and the nine questions to ask
Frequently asked questions
What is a triple phase PET scan?
Strictly, “triple phase” describes the CT part, not the PET part. It means the CT component is acquired at three separate moments after contrast injection — arterial, portal venous and delayed. A “triple phase PET scan” is usually a PET/CT in which the CT is acquired multiphasically, most often to characterise a liver lesion.
Is a triple phase scan the same as a triphasic scan?
Yes. The terms are used interchangeably. “Triphasic / angio” on a prescription usually means multiphasic acquisition including an arterial phase for vascular assessment.
Why are three sets of images needed?
Because the diagnosis often lies in how a lesion changes between phases rather than in any single image. A lesion that enhances brightly in the arterial phase and then washes out behaves characteristically — a single-phase scan sees only one frame of that sequence.
Why is this used so often for the liver?
Because of the liver’s dual blood supply. Most normal liver tissue is supplied by the portal vein, while many liver tumours develop their own arterial supply. That difference is what makes lesions stand out in the arterial phase and behave differently later.
Can a PET scan alone assess a liver lesion?
Not always. Well-differentiated hepatocellular carcinoma is frequently not FDG-avid, meaning it may not light up on the PET component. This is exactly why the CT component is acquired multiphasically when the liver is the clinical question.
Do I need contrast for a triple phase study?
Yes — contrast is what creates the phases. A triple phase study without intravenous contrast is not possible.
Do I need a blood test before the scan?
Usually a recent kidney function test, because iodinated contrast is cleared by the kidneys. Ask the centre what they need when you book, and carry any recent reports you have.
I am on metformin. What should I do?
Tell the centre at the time of booking and mention your kidney function if you know it. Guidance depends on your individual situation and your treating doctor’s advice. Do not stop or change medication on your own initiative.
What will I feel when the contrast is injected?
A warm sensation spreading through the body, and often a metallic taste. Both are expected and pass within about a minute. Tell the staff immediately if you feel anything else.
How long does the appointment take?
A triple phase CT alone is largely preparation, cannula placement and short waits between phases. If a PET component is included, plan for two to three hours in total.
Is it safe?
Contrast studies are performed routinely, with precautions based on kidney function, allergy history and medication. A PET component adds a small radiation dose from a rapidly decaying tracer. Your doctor orders the study because the information it provides outweighs those considerations for your situation.
How much does a triple phase scan cost?
It depends on whether PET is included, which tracer, the region covered and whether additional imaging is needed. CT rates including triphasic studies are published on our CT page. For PET studies, FDG whole body with triple phase is Rs 13,499 all-inclusive, covering the scan, the tracer and the reporting; send the prescription and we will confirm the complete figure for your exact study in writing before you book.
My prescription just says “triphasic”. Is that CT or PET?
Usually CT — but not always. Photograph the prescription and send it rather than guessing. Identifying the correct study is our job, and booking the wrong protocol means paying for the right one afterwards.
If you are holding the prescription now
Send a photograph to 8368225620 on WhatsApp. We will tell you exactly which study has been advised, what blood reports to carry, the preparation for your specific protocol, the next available slot, and the all-inclusive rate — in writing.
Prefer to speak to someone? Call 8368225620 or 7011968879, Monday to Saturday, 8:00 AM to 5:00 PM.
And if you are unsure whether you have been advised a CT, a PET CT, or both — send it anyway. That is precisely the question we can answer for you in a minute.
This page is general information about multiphasic contrast imaging and how it is used with CT and PET CT. It is not medical advice and must not be used to decide for or against a scan your doctor has advised. Which study you need, and whether contrast is appropriate for you, is a clinical decision made by your treating doctor. A valid prescription is required for all PET CT studies.