If you or someone in your family has been diagnosed with lymphoma, you will hear the words “PET scan” more often than patients with almost any other cancer. There will be one before treatment starts. Very likely one partway through. Almost certainly one at the end.
That is not over-investigation. Lymphoma is the disease where PET imaging changes treatment decisions more directly than in any other common cancer — and understanding why makes the whole sequence far less bewildering.
This guide explains what each scan is for, what the Deauville score in your report actually means, why the timing of a scan after chemotherapy matters enormously, the specific things that can make a scan look worse than the disease really is, and what to ask before every appointment.
Why lymphoma and PET fit together so well
FDG, the tracer used in most lymphoma scans, is a glucose analogue. Cells consuming a lot of sugar take it up and appear bright.
Most lymphomas are highly glucose-avid. Hodgkin lymphoma and diffuse large B-cell lymphoma in particular light up strongly and consistently. That reliability is what makes PET so useful here: when a site lights up, it usually means something, and when it stops lighting up, that usually means something too.
Compare this with, say, well-differentiated hepatocellular carcinoma or some prostate cancers, where FDG uptake is often low and other tracers are needed. In lymphoma, FDG generally does the job.
But not every lymphoma behaves the same way
This is worth knowing, because it explains why your treatment team may or may not use PET in the way described here.
Consistently FDG-avid: Hodgkin lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma and several others. These are the subtypes where PET-based staging and response assessment are most established.
Variably or less FDG-avid: some indolent subtypes, including certain marginal zone lymphomas and small lymphocytic lymphoma, may show low or inconsistent uptake. In these, CT-based assessment may be used instead, or PET may be used for a specific question rather than routinely.
Your haematologist knows which subtype you have and will have factored this in. If you are curious why your pathway looks different from someone else’s, subtype is usually the answer.
The three scans, and what each one decides
1. The baseline scan — before treatment
Done after diagnosis and before the first cycle. Its job is to map where the disease is: which lymph node groups, whether there is involvement outside the lymph nodes, and whether the bone marrow appears involved.
Two things make this scan more important than patients realise.
It sets the stage, which determines the treatment plan. The number of cycles, whether radiotherapy is added, and the intensity of the regimen all follow from staging.
It becomes the yardstick for everything afterwards. Every later scan is read against it. A baseline that is well acquired and properly documented makes every subsequent comparison meaningful. A missing or poor baseline weakens all of them.
There is a further point worth knowing. In several FDG-avid lymphomas, a good-quality baseline PET can demonstrate bone marrow involvement well enough that a separate bone marrow biopsy is not always required. Whether that applies to you is a decision for your haematologist based on subtype and clinical context — but it is one reason the baseline scan carries weight.
2. The interim scan — partway through
Usually after two cycles, sometimes after three or four depending on the regimen. Often called an interim PET or PET-2.
This is the scan that can change your treatment.
The principle is called response-adapted therapy. If the disease has responded strongly and early, some regimens allow treatment to be de-escalated — fewer cycles, or dropping a drug associated with particular toxicity. If the response is poor, the team may escalate to a more intensive regimen rather than completing a course that is not working.
In other words, this scan is not a progress report you receive after the fact. It is an input into a decision your team is about to make. That is why the timing matters so much, and why it is worth telling the centre when your next cycle is due.
3. The end-of-treatment scan
Done after the planned course is complete, to assess the final response and establish whether remission has been achieved.
Timing here is particularly important, and is covered below.
The Deauville score — reading the number in your report
If you have had a lymphoma PET, your report almost certainly contains a Deauville score. Patients see a number between 1 and 5 and understandably try to read it as a grade of how bad things are. It is not quite that.
The Deauville score is a visual comparison. The reporting physician compares uptake at the disease site against two internal reference points in your own body: the mediastinal blood pool, and the liver.
What each score means
- Score 1 — No uptake above background at the site.
- Score 2 — Uptake present, but less than or equal to the mediastinal blood pool.
- Score 3 — Uptake greater than mediastinum, but less than or equal to the liver.
- Score 4 — Uptake moderately higher than the liver.
- Score 5 — Uptake markedly higher than the liver, or new sites of disease.
How the scores are generally interpreted
Scores 1 and 2 are generally regarded as a complete metabolic response.
Score 3 is the one that causes anxiety, and it deserves explanation. In most treatment protocols a score of 3 is also considered a good response — but it sits close enough to the threshold that interpretation depends on the clinical context, the subtype, the treatment regimen and where in the course you are. Your haematologist reads it in that context, which is exactly why the number alone should not be interpreted at home.
Scores 4 and 5 indicate uptake above the liver, which generally suggests residual metabolically active disease — although, as the next section explains, not every bright area is lymphoma.
The most important thing to understand about Deauville
It is a comparison against your own baseline and your own reference organs — not an absolute measure. Which is why comparison with your previous scans matters so much, and why carrying your earlier films and reports is not a formality.
Timing: the single biggest cause of a misleading lymphoma PET
This section is worth reading twice, because families frequently push for a scan sooner and inadvertently make it less useful.
After chemotherapy
Chemotherapy causes inflammation in treated tissue. Inflammatory cells consume glucose — which means they take up FDG and can appear bright on a scan even where no lymphoma remains.
Scanning too soon after a cycle can therefore produce uptake that reflects treatment effect rather than residual disease. Protocols generally allow a defined interval after the last cycle before assessment, commonly around three weeks, though the exact interval depends on the regimen and your team’s practice.
After radiotherapy
Radiation produces inflammatory change that can persist considerably longer. The interval before an assessment scan after radiotherapy is usually substantially longer than after chemotherapy — often a couple of months or more.
After G-CSF injections
This one catches many patients out.
Growth factor injections given to support blood counts stimulate the bone marrow. A stimulated marrow takes up FDG intensely, and the spleen often does too. On a scan, this can appear as diffuse marrow and splenic uptake that has nothing to do with lymphoma.
An experienced reporting physician recognises this pattern — but only if they know the injections were given. Tell the centre if you have had growth factor injections, and when. It is one of the most useful things you can mention at booking.
After surgery or a biopsy
Recent surgical sites and biopsy tracks show inflammatory uptake. Mention any recent procedure and its date.
The practical rule
If your team has scheduled the scan for a particular date, that date is usually part of the protocol rather than an administrative delay. Bringing it forward can reduce the reliability of the answer.
Other things that can light up and are not lymphoma
Understanding these prevents unnecessary alarm when you read your own report.
Infection. Active infection produces intense FDG uptake. Patients on chemotherapy are more prone to infection, so this is not rare. Tell the centre if you have had fever, a chest infection, a urinary infection or any active infection recently.
Recent vaccination. A vaccine can cause reactive uptake in the lymph nodes on that side, and sometimes at the injection site. If you have been vaccinated recently, say so and say in which arm.
Thymic rebound. In younger patients particularly, the thymus can become metabolically active again after chemotherapy ends. This appears as uptake in the front of the chest and is a recognised benign pattern.
Brown fat. Activated by cold, brown fat in the neck, above the collarbones and around the spine takes up FDG intensely and can be mistaken for nodal disease if the pattern is not recognised. This is why you are asked to stay warm before the scan — it is not a comfort instruction.
Muscle activity. Muscles worked before the scan, or activated during the uptake period by walking or talking, take up FDG.
None of these means a report cannot be trusted. It means the reporting physician needs the clinical information to interpret what they see — which is why the questions asked at registration are not bureaucracy.
Preparation for a lymphoma PET
Standard FDG preparation applies, with a few points that matter particularly here.
Fasting
Usually around 6 hours. Plain water is allowed and encouraged. No tea, coffee, juice, milk, sweets or chewing gum. Sugar-free gum is also generally discouraged, because chewing activates jaw muscles.
Blood sugar
Checked before injection. Circulating glucose competes with the tracer. If you are diabetic, tell the centre when you book so medication timing can be planned. Do not skip medication on your own initiative.
Steroids are part of many lymphoma regimens and can raise blood sugar. If you are on steroids, mention it — it is relevant to both scheduling and interpretation.
Avoid exertion
No strenuous exercise for around 24 hours beforehand. This includes heavy physical work and long walks.
Stay warm
Particularly in the cooler months, because of brown fat. Carry a shawl or jacket, and stay warm in the waiting area as well as during the uptake period.
The uptake period
Roughly 45 to 60 minutes of genuinely quiet rest after the injection. Not much talking, no walking about, phone on silent. Muscle activity during this window appears on the images.
Tell the centre these five things when you book
- Your lymphoma subtype, if you know it
- Where you are in treatment — baseline, after which cycle, or end of treatment
- The date of your last chemotherapy cycle
- Whether you have had G-CSF injections, and when
- Any recent infection, fever, vaccination, surgery or biopsy
These five pieces of information materially change how your scan is interpreted. Volunteering them is more useful than any question you could ask.
What to bring
- The prescription, with the clinical indication written on it
- Your baseline PET and every subsequent PET — films or CD, not just reports. Deauville is a comparison
- Previous CT or MRI scans
- Biopsy and histopathology reports
- Recent blood counts, if you have them
- A list of current medications, including steroids
- Insurance or reimbursement papers, if you plan to file a claim
- Photo identification
What happens on the day
Registration and blood sugar check. This is also when the questions about recent treatment, injections and infections are asked. Answer them fully.
The injection. Through a vein in the arm, like a routine blood test. If you have a PICC line or port, mention it.
The uptake period. 45 to 60 minutes of quiet rest, kept warm.
The scan. Typically 20 to 30 minutes, lying on a table that moves slowly through a ring that is open at both ends. Considerably quieter than an MRI.
Afterwards. You can normally eat and resume your routine. Drink water to help clear the tracer, and keep some distance from pregnant women and young children for the rest of the day.
Plan for two to three hours in total.
After remission — should you keep having PET scans?
This question matters financially and emotionally, and the honest answer surprises many families.
Routine surveillance PET scanning in patients who are in remission and have no symptoms is generally not recommended in most lymphoma protocols. The reasoning is that in a healthy, asymptomatic patient the chance of a bright spot representing something benign — infection, inflammation, brown fat — is relatively high compared with the chance of it representing recurrence. That leads to further tests, further anxiety and further cost, often for nothing.
Follow-up after remission is therefore usually based on clinical review, examination, blood tests and symptoms, with imaging done when there is a specific reason.
This is one of the few places in oncology where the guidance points towards fewer scans rather than more. If you are being offered routine surveillance PET without a specific clinical question, it is entirely reasonable to ask your haematologist what it is expected to add.
How many scans, and planning for them
A typical lymphoma course involves a baseline scan, at least one interim scan and an end-of-treatment scan. Additional scans may be added if the clinical picture changes.
Two practical suggestions:
Ask your haematologist at the start how many are anticipated and when. Even an approximate answer transforms your ability to plan, financially and logistically.
Try to have them at one centre. Deauville scoring is a comparison, and comparison is more reliable when the earlier studies were acquired with the same protocol on the same scanner and read by the same team. If you do change centres, carry every previous study — films, CDs and reports, not summaries.
What decides the cost
Lymphoma studies are usually FDG whole body, which is Rs 7,999 all-inclusive — the figure includes the scan, the tracer and the reporting, and nothing is added at the counter. Contrast or additional views are occasionally required by the protocol; send the prescription and we will confirm the complete figure for your exact study in writing.
The final figure depends on whether the study is whole body, whether the CT component uses contrast, whether additional imaging is required, and the clinical indication.
Ask these before you book
- Is the tracer included in the figure you quoted?
- Is contrast included, if my protocol needs it?
- Is reporting included?
- What is the total I will pay at the counter? In writing.
- Will my baseline and previous PET scans be compared, and will the report state a Deauville score?
- Can the report be ready before my next cycle on [date]?
- Who reports the study, and what are their qualifications?
Question five is the one specific to lymphoma. A report that does not compare against your previous scans is worth considerably less in this disease than in most others.
Insurance — start before the scan
Lymphoma treatment involves several scans, so getting the coverage process right once saves repeating a mistake three times.
- Ask your treating hospital’s insurance or TPA desk whether PET CT is covered for your indication
- Ask whether it is covered as an outpatient investigation or only during an admission
- Ask what paperwork is needed and who raises it
- Ask whether repeat scans within the same treatment course are handled differently
- Make sure every prescription states the indication — for example, “FDG PET CT whole body for interim response assessment, Hodgkin lymphoma, post 2 cycles ABVD” rather than simply “PET CT”
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.
Reported by our own nuclear medicine team, not outsourced — which across a lymphoma course means the same team reading your progression rather than a different reporter each time.
Your previous scans compared, provided you bring them. If your earlier scans were done here, they are already in the system.
Written preparation instructions specific to your study, sent every time you book — including the reminder to stay warm, which matters more in lymphoma imaging than most patients realise.
Blood sugar checked before injection as standard, with diabetic patients and patients on steroids planned in advance.
Timing planned around your cycles. Tell us your next cycle date at booking so the scan and report can be arranged around the decision your haematologist has to make.
Complimentary pickup and drop within 3 km; beyond that, Rs 50 per km. Across three or four scans, that is three or four round trips you do not have to arrange.
The all-inclusive figure in writing before you book.
Frequently asked questions
What does the Deauville score in my lymphoma PET report mean?
It is a five-point visual scale comparing uptake at disease sites against the mediastinal blood pool and the liver. Scores 1 and 2 are generally regarded as a complete metabolic response; 3 is usually favourable but interpreted in context; 4 and 5 suggest uptake above the liver. Your haematologist interprets it alongside everything else known about your case.
Is Deauville 3 good or bad?
In most protocols it is considered a good response, but it sits near the threshold and interpretation depends on subtype, regimen and where you are in treatment. This is precisely the number not to interpret at home — ask the doctor who ordered the scan.
Why do I need a PET scan in the middle of treatment?
Because the result can change the treatment. Response-adapted protocols use the interim scan to decide whether to de-escalate, continue, or escalate. It is an input into a decision, not a progress report.
Can I have the scan earlier than the date given?
Usually not advisable. Chemotherapy causes inflammation that takes up the tracer, so scanning too soon can show uptake that reflects treatment effect rather than disease. The interval in your schedule is generally part of the protocol.
I had a G-CSF injection. Does that affect the scan?
It can. Growth factor injections stimulate the bone marrow, which then takes up the tracer intensely, often with the spleen too. This is a recognised pattern and reporting physicians allow for it — but only if they know. Always mention it and give the date.
Can a PET scan replace a bone marrow biopsy in lymphoma?
In several FDG-avid subtypes, a good-quality baseline PET can assess marrow involvement well enough that a routine biopsy is not always required. Whether that applies in your case is your haematologist’s decision, based on subtype and clinical context.
Do all lymphomas show up on a PET scan?
Most common subtypes are reliably FDG-avid, including Hodgkin lymphoma and diffuse large B-cell lymphoma. Some indolent subtypes show lower or variable uptake, and your team may use CT-based assessment instead in those cases.
Should I keep having PET scans after remission?
Routine surveillance PET in asymptomatic patients in remission is generally not recommended in most protocols, because benign findings are relatively more likely than genuine recurrence and lead to further tests and anxiety. Follow-up is usually clinical, with imaging when there is a specific reason. Ask your haematologist what a proposed scan is expected to add.
Why do they tell me to stay warm?
Because cold activates brown fat in the neck, above the collarbones and around the spine, which takes up the tracer intensely and can be mistaken for nodal disease. Staying warm genuinely improves the quality of a lymphoma scan.
What if I have an infection or fever before the scan?
Tell the centre. Active infection produces intense uptake and can complicate interpretation. Depending on the situation your team may prefer to reschedule, or the reporting physician may simply need to know.
Why must I bring my old scans?
Because Deauville scoring and response assessment are comparisons. A lymphoma PET read without the baseline answers a much smaller question for the same money.
How many PET scans will I need?
Typically a baseline, at least one interim and an end-of-treatment scan, with more if the clinical picture changes. Ask your haematologist at the start how many are anticipated so you can plan.
What does a lymphoma PET cost?
FDG whole body is Rs 7,999 all-inclusive, covering the scan, the tracer and the reporting. Contrast or additional views are occasionally required by the protocol; send the prescription on WhatsApp and we will confirm the complete figure for your exact study in writing before you book.
Do I need a prescription?
Yes. A valid prescription is required for all PET CT studies, and for insurance purposes it should state the indication and where you are in treatment.
Related reading
- PET CT for lung cancer — nodal staging, and why TB confuses the picture in India
- PET CT for myeloma — another marrow disease, and the G-CSF problem
- How many PET CT scans will you need? — planning interim and end-of-treatment scans
- PET CT scan price in Delhi — what decides your figure, and the nine questions to ask
Booking your scan
Send a photograph of the prescription to 8368225620 on WhatsApp, and include four things: your lymphoma subtype if you know it, where you are in treatment, the date of your last cycle, and the date of your next one.
You will get the all-inclusive rate, a slot planned around your cycle, the written preparation instructions, and a note on which previous scans to carry.
Prefer to speak to someone? Call 8368225620 or 7011968879, Monday to Saturday, 8:00 AM to 5:00 PM.
This page is general information about the role of PET CT in lymphoma. It is not medical advice and must not be used to interpret your own report or to decide for or against a scan. Deauville scores, staging and treatment decisions are made by your treating haematologist, who reads the scan alongside your history, examination, blood work and pathology. A valid prescription is required for all PET CT studies.