AI Overview · plain answer
Words such as suspicious, indeterminate and likely inflammatory mean the doctor who read the scan could not be sure what a spot is. ‘Suspicious’ means the reader is concerned it could be disease, ‘likely inflammatory’ leans away from cancer, and ‘indeterminate’ means it could go either way. None of them is a diagnosis.
The European (EANM) guideline says uncertain findings should be discussed by your doctors when the answer would change treatment. The usual ways to settle them are further tests, a biopsy, or watching with a repeat scan.[1]
Important
This page explains what these report words usually mean in general. It is patient education, not medical advice. It cannot tell you what a spot on your own scan is. Please discuss your report with the doctor who is treating you.
A PET-CT report often cannot give a definite answer. The European guideline asks the reader to state a definite diagnosis when possible, and otherwise to give how likely each possible cause is, and to suggest further tests if needed.[1] The words below are how readers express that uncertainty.
What the words usually mean
| Words in the report |
What the reader usually means |
| Consistent with, diagnostic of |
The reader is sure, or almost sure |
| Suspicious for, likely, probably |
Leans towards that cause, but not certain |
| Indeterminate, equivocal, may represent |
Could go either way; the scan alone cannot say |
| Likely inflammatory, likely infective, likely reactive |
Leans towards a non-cancer cause |
| Unlikely, cannot be ruled out (excluded) |
Probably not, but not ruled out; ask how likely |
Some hospitals give these words set meanings. For example, the radiology department at Mass General Brigham in the US uses this scale:[3]
- ‘Most likely’: more than 90%
- ‘Likely’: 75 to 90%
- ‘May represent’: 25 to 75%
- ‘Unlikely’: 5 to 25%
- ‘Very unlikely’: less than 5%
Not every hospital uses such a scale, so ask your doctor what the words mean in your report.
Why the words confuse people
Patients and doctors do not always read these words the same way. In one US study, patients and radiologists were asked how likely cancer was for different report phrases. Patients rated ‘probably metastatic disease’ (cancer that has spread) as the most likely, while radiologists rated ‘diagnostic for metastatic disease’ as the most likely. Both groups rated ‘cannot exclude cancer’ as the least likely.[2]
So if a word in your report worries you, it is reasonable to ask: “How likely do you think this is?”
When it is likely inflammation
FDG, the tracer used in most PET scans, is taken up by cancers but also by infection, inflammation and healing tissue.[1] Recent treatment or a vaccine is a common reason:
| Recent event |
What the guidance says |
| Surgery |
Wait at least 6 weeks if the scan is to look at the operated area[1] |
| Radiotherapy |
Inflammation can show for 2 to 3 months; waiting 2 to 3 months is appropriate[1] |
| Chemotherapy |
At least 10 days after the last treatment is generally considered enough when the scan is to measure response[1] |
| Vaccine (for example COVID-19) |
Lymph nodes can react, usually on the side of the injection; tell the scan centre the date and the arm[4] |
If the report says ‘likely inflammatory’, your doctor may still suggest a repeat scan later to check that the spot has settled. Read more: what else can make a spot light up →
‘Clinical correlation recommended’
This common phrase asks your treating doctor to compare the scan finding with your symptoms, examination, blood tests and other scans. On its own, the phrase does not mean something is wrong; what matters is the finding it is attached to. The European guideline notes that PET-CT is more useful when read together with other scans and clinical information, and that comparison with earlier scans should be part of the report.[1]
What usually happens next
The European guideline, drawing on UK Royal College of Radiologists advice, says an uncertain finding should be discussed by the doctors, and at a team meeting of specialists where needed, if a clearer answer would change your treatment. It lists four ways to settle the question:[1]
- Discussion among your doctors, including the doctors who read the scan.
- Further tests, such as another scan, a different PET tracer or blood tests.
- A procedure, usually a biopsy, to take a sample.
- Watching with a repeat scan after an agreed time.
Questions to ask your doctor
- How likely do you think this is to be cancer, infection or something else?
- Was it compared with my earlier scans?
- Could recent surgery, radiotherapy, chemotherapy or a vaccine explain it?
- Would the answer change my treatment? If yes, which test would settle it?
- If we wait, when should the scan be repeated?
How often does a second reading change the opinion?
In one US cancer-centre study of 240 PET-CT scans done at other centres, specialist re-reading gave a different opinion about cancer for 31 scans (13%). Where the final answer was later known, the re-read was right in 25 of 28 of those cases. Most re-reads (209 of 240) agreed with the first report about cancer.[5]
PET-CT Second Read · an independent reading of your scan
If your report uses uncertain words and you would like another specialist opinion, Dr. Ishita B. Sen and Dr. Dharmender Malik, nuclear medicine physicians at TPPL, Gurugram, would be happy to review the scan itself. The report gives their reading of the scan, including how likely each possible cause is. It does not recommend a treatment; your treating team decides what happens next. You receive a structured, digitally signed report within 72 hours of us receiving the complete scan and information. The fee is ₹2,500 for patients in India and USD 100 for international patients.
You will need: a DICOM link of the PET-CT (most scan centres give one on request), the original report, any earlier scans, a biopsy report if you have one, and a short clinical summary. How the Second Read works →
Request a Second Read · WhatsApp +91 8800 988936
When a Second Read can’t help
- Some findings stay uncertain. A second reading may also say ‘indeterminate’; a biopsy or a repeat scan may still be needed.
- It cannot prove a spot is harmless or cancer on its own. That usually needs a sample (biopsy) or follow-up.
- It needs the actual images (a DICOM link), not only the PDF report.
- It is not for emergencies. New severe pain, breathlessness, weakness or bleeding needs your doctor or a hospital now.
- It does not replace your treating doctor. The report is written for them to use.
For patients & families
Frequently asked questions
Q01What does suspicious mean on a PET-CT report?
It means the doctor who read the scan thinks the spot could well be disease, often cancer, but cannot be sure from the scan alone. It is not a diagnosis. A biopsy, another test or a repeat scan is usually needed to confirm or rule it out.
Q02What does indeterminate or equivocal mean?
It means the scan does not show clearly what the spot is. It could be harmless or it could need treatment. The European (EANM) guideline says uncertain findings should be discussed by the doctors when the answer would change treatment, and resolved by further tests, a biopsy or watching with a repeat scan.
Q03What does likely inflammatory or likely infective mean?
It means the reader thinks the spot is more likely to be inflammation or infection than cancer. FDG, the tracer used in most PET scans, is also taken up by infection, inflammation and healing tissue. Recent surgery, radiotherapy or a vaccine can cause this. Your doctor may still suggest a repeat scan to be sure.
Q04What does clinical correlation recommended mean?
It asks your treating doctor to compare the scan finding with your symptoms, examination, blood tests and other scans. On its own, the phrase does not mean something is wrong; what matters is the finding it is attached to. The European guideline notes that PET-CT is more useful when read together with other scans and clinical information.
Q05What does cannot be ruled out mean?
It means the reader cannot say for certain that a disease is absent, even if it is not likely. In one US study, both patients and radiologists rated ‘cannot exclude cancer’ as the least likely of the phrases they were asked about. If the phrase worries you, ask your doctor how likely they think it is.
Q06Do I need a biopsy?
Not always. It depends on how likely the finding is to be serious, whether it can be reached safely, and whether the answer would change your treatment. The options are usually a discussion among your doctors, another test, a biopsy, or watching with a repeat scan.
Q07How long after surgery or radiotherapy should a repeat PET scan be done?
The European (EANM) guideline suggests waiting at least 6 weeks after surgery if the scan is to look at the operated area, and 2 to 3 months after radiotherapy, because healing and inflammation can light up. After chemotherapy, at least 10 days after the last treatment is generally considered enough when the scan is to check how well it has worked. Your doctor will choose the timing for you.
Q08Can I get my PET scan read again by another specialist?
Yes. The PET-CT Second Read service reviews a scan you already have. You send a DICOM link of the scan, the original report, any earlier scans, a biopsy report if you have one and a short clinical summary. The fee is ₹2,500 for patients in India and USD 100 for international patients. The report is sent within 72 hours of receiving complete information, and it is written to be shared with your treating doctor.
Evidence & references
[1] Boellaard R et al. FDG PET/CT: EANM procedure guidelines for tumour imaging, version 2.0. Eur J Nucl Med Mol Imaging 2015 (PMID 25452219) — reporting, indeterminate findings, timing after treatment, and causes of FDG uptake.
View source ↗[2] Mityul MI et al. Interpretive differences between patients and radiologists regarding the diagnostic confidence associated with commonly used phrases in the radiology report. AJR Am J Roentgenol 2018;210:123–126 (PMID 29023151).
View source ↗[3] Shinagare AB et al. Diagnostic Certainty Scale. Department of Radiology, Mass General Brigham (RAD-ASSIST), 2020 — an example of set meanings for report phrases.
View source ↗[4] Becker AS et al. Radiology 2021 (PMID 33625298) — recommendations for imaging lymph nodes after COVID-19 vaccination.
View source ↗[5] Ulaner GA et al. Nucl Med Commun 2017 (PMID 28291158) — specialist re-reading of 240 PET-CT scans performed at other centres.
View source ↗
About the Author
Dr. Ishita B. Sen
MBBS · DRM · DNB (Nuclear Medicine) · Senior Director & Head, Department of Nuclear Medicine and Molecular Imaging
Dr. Sen leads the nuclear medicine and theranostics programme in Gurugram, with a focus on PSMA and DOTATATE imaging and Lu-177 and Ac-225 radioligand therapy. Together with Dr. Dharmender Malik, she reviews the PET-CT scans sent to the Second Read service.