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Reading your end-of-treatment PET scan in DLBCL | CION Cancer Clinics
On an end-of-treatment PET-CT, a Deauville score of 1, 2 or 3 is usually read as no active lymphoma. A score of 4 or 5 means an area is glowing more than the liver and needs a closer look, often a biopsy, because inflammation can glow too. This page explains each score, the words on the report, and what the scan cannot tell you. At CION Cancer Clinics, our haematology team plans myeloma and lymphoma care with you, discussed at a tumour board and explained in plain words.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- What does the end-of-treatment PET scan tell you?
- What does each Deauville score mean?
- What usually happens after each kind of result?
- How do you prepare for the scan?
- What do the other words on the report mean?
- What do families often misread in this report?
- What can this scan, and this page, not tell you?
- Common questions about end-of-treatment PET in DLBCL
The short answer
What does the end-of-treatment PET scan tell you?
The end-of-treatment PET-CT shows whether any lymphoma is still active after your last cycle of chemotherapy. The report grades each area on the Deauville scale from 1 to 5: a score of 1, 2 or 3 is usually read as no active lymphoma, while 4 or 5 means an area needs a closer look.
Why this scan matters so much in DLBCL
Diffuse large B-cell lymphoma is a fast-growing lymphoma, and the scan at the end of treatment is the main way your team judges how well the chemotherapy worked. It helps decide whether you move to regular follow-up, whether radiotherapy is added to one area, or whether more tests or treatment are needed.
What PET measures, in plain words
Before the scan you receive a small injection of a radioactive sugar. Active lymphoma cells take up sugar quickly and glow on the pictures. The CT part shows exactly where that glow sits. A lump can still be visible on CT and yet not glow at all, which usually means it is scar tissue.
Why the timing is planned
Chemotherapy and radiotherapy both cause short-lived inflammation, and inflamed tissue also takes up sugar. Scanning too soon can make healing tissue look like lymphoma. So the scan is usually booked a few weeks after the last chemotherapy, and longer after radiotherapy.
Reading the score
What does each Deauville score mean?
The score compares each area with two normal reference points in your own body: the blood in the middle of the chest and the liver.
Score
What the report is saying
Deauville 1
No uptake above the background in that area
Deauville 2
Uptake no higher than the blood in the middle of the chest
Deauville 3
Higher than the chest, but no higher than the liver
Deauville 4
Somewhat higher than the liver
Deauville 5
Much higher than the liver, or a new area of disease
Not sure whether this applies to you?
Ask an oncologistAfter the report
What usually happens after each kind of result?
These are the usual directions. Your own plan depends on where the area is, how you started and how you are now.
A clear scan: scores 1 to 3
This is called a complete metabolic response, meaning no active lymphoma is seen. Most people move to follow-up visits with blood tests and examination. Routine repeat PET scans are not usually needed if you stay well.
An uncertain area: score 4
A score of 4 can be lymphoma, or it can be inflammation or infection. The team looks at whether the area has shrunk a lot since the first scan.
Common next steps
- A biopsy of that area
- A repeat scan after a few weeks
- Radiotherapy to that one site
A clearly active area: score 5
This raises real concern that lymphoma remains. A biopsy is usually advised to confirm it before second-line treatment, such as salvage chemotherapy or CAR-T, is planned.
A new spot that was not there before
New areas are taken seriously, but not every new glow is lymphoma. Infections, healing fractures and inflamed joints can all light up. A biopsy is often the only way to be sure.
Getting ready
How do you prepare for the scan?
Book at the right time
Confirm the date with your haematologist, not only the scan centre. Scanning too early after chemotherapy can give a confusing result.
Fasting
You will be asked not to eat for some hours beforehand. Plain water is usually fine. If you have diabetes, ask the centre for its own instructions well before the day.
Bring the first scan
The radiologist compares the new pictures with the scan from diagnosis. Carry the CD or the report link, not only the printed summary.
Mention recent illness
Tell the team about any recent fever, cough, injury, vaccination or growth-factor injections. Each of these can make an area glow for reasons that have nothing to do with lymphoma.
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On your report
What do the other words on the report mean?
- Complete metabolic response
- No active lymphoma is seen. A lump may still be visible, but it is not taking up the sugar.
- Partial metabolic response
- Activity has come down, but some areas are still glowing more than expected.
- SUVmax
- A number for how brightly one spot glows. It helps compare the same spot between scans, but it is not a diagnosis by itself.
- Mediastinal blood pool
- The blood in the large vessels in the middle of the chest, used as a normal reference for the score.
- Residual mass
- Something still visible on CT after treatment. Often it is scar tissue rather than lymphoma.
Commonly believed
What do families often misread in this report?
"The report says a lump is still there, so the treatment did not work."
A large mass often leaves a scar that stays visible on CT for a long time. What matters is whether it still takes up the sugar. A visible but inactive lump is a common and usually reassuring finding.
"Score 3 is a middle score, so it must be half bad."
In most standard reporting, a score of 3 after treatment counts with 1 and 2 as a complete response. The scale is not a percentage. Ask your haematologist how your team reads a 3, because some treatment plans handle it more cautiously.
"Score 4 or 5 means the lymphoma is back for certain."
Not for certain. Infection and inflammation can also glow brightly. That is why a biopsy is so often advised before any big change in treatment. Deciding on a single score alone can lead to treatment that was never needed.
"A clear scan means we can stop all check-ups."
A clear scan is very good news, but follow-up visits still matter. They pick up late effects of treatment and any return of symptoms early. Keep every appointment your team gives you.
Being straight with you
What can this scan, and this page, not tell you?
A PET score is not a diagnosis and not a forecast. It describes how brightly areas glow on one day. It cannot tell you how long a response will last, or what your outlook is. Those depend on the type of DLBCL, its stage, your first scan and your general health.
Who the scale works less well for
The Deauville scale was built for lymphomas that take up sugar strongly, like DLBCL. It is less reliable when the liver itself is unusual, when there is active infection, or soon after growth-factor injections that make the bone marrow glow. Your team will factor these in.
Reading the report before the appointment
Many families receive the report before they see the doctor, and read the worst into a line written for another specialist. Bring the report and your questions instead. CION's haematology team reviews scan reports alongside the biopsy and the first scan, and a tumour board discusses any result that is not clear-cut.
Questions we are asked
Common questions about end-of-treatment PET in DLBCL
My mother's report says Deauville 3. Is that good?
In most standard reporting, a score of 3 at the end of treatment is read as a complete metabolic response, meaning no active lymphoma is seen. Some plans handle a 3 more cautiously, so ask her haematologist how they are reading it. The score is always considered with her symptoms and the first scan.
Why wait after chemotherapy before doing the scan?
Treatment leaves behind inflammation that also takes up the radioactive sugar. Scanning too early can make healing tissue look like lymphoma and lead to worry or tests that were not needed. Your haematologist sets the timing so the result is as reliable as possible.
Will I need a biopsy if the score is 4 or 5?
Often, yes. A biopsy is the only sure way to tell lymphoma apart from inflammation or infection. Second-line treatments are intensive, so teams usually want proof before starting them. In some cases a repeat scan or radiotherapy to one small area is chosen instead.
Is a PET scan safe to repeat?
Each PET-CT involves some radiation, so scans are done when they will change a decision rather than as routine. After a clear end-of-treatment scan, most people with no symptoms do not need repeat PET scans. Your team will explain when another scan would be useful.
Can I hold my grandchildren after the scan?
The radioactive sugar leaves the body quickly. As a simple precaution, many centres suggest keeping a little distance from babies, young children and anyone pregnant for the rest of that day. Follow the written advice the scan centre gives you.
Does a clear scan mean the lymphoma will not come back?
A clear scan is a strong, positive sign, but no scan can promise the future. Very small numbers of cells can be below what any scanner sees. That is why follow-up visits continue. Tell your team early about new lumps, fevers, night sweats or weight loss.
What if the scan shows something outside the lymph nodes?
PET often picks up things unrelated to lymphoma, such as a thyroid nodule, an inflamed bowel or a healing injury. The report may suggest further tests. Your haematologist will decide which findings need follow-up and which are expected after treatment.
Can CION review a PET report done elsewhere?
Yes. Bring the report, the scan images on a CD or link, the first diagnosis scan and the biopsy report. CION's haematology team reviews them together, discusses unclear results at a tumour board and explains the options and next steps to you and your family.
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Sources
- National Cancer Institute — Adult Non-Hodgkin Lymphoma Treatment (PDQ) - Health Professional Version
- Cancer Research UK — PET-CT scan
- American Cancer Society — Non-Hodgkin Lymphoma
- Leukemia & Lymphoma Society — Non-Hodgkin Lymphoma
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
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Have a PET report you want explained?
Share the report with CION's haematology team. We will review it with your first scan and biopsy and explain the next step. One helpline serves every CION centre.