Whole-body MRI, full-body CT and multi-cancer blood tests are designed to check the whole body. They often report a finding in the chest without identifying what it is. The test that identifies it depends on where in the chest it lies, and choosing the wrong test has led to unnecessary operations. Dr Lawrence Okiror, Consultant Thoracic and Robotic Surgeon (GMC 6150382), reviews the report and the images, explains what the finding is likely to be, and advises whether anything further is needed. Appointments at London Bridge Hospital and The Lister Hospital Chelsea within 2–3 days, including video consultations. Self-referrals welcome.
Last reviewed: October 2026 · Dr Lawrence Okiror FRCS(CTh) FRCSEd(CTh) · GMC 6150382
These scans cover the whole body at a general level of detail. They are good at detecting an abnormality and less good at identifying it. A second, targeted test is usually needed, and the right one depends on where in the chest the finding lies.
CT can make a harmless cyst at the front of the chest look solid. MRI can make a harmless rib lesion look aggressive, and it misses small lung nodules. Knowing these weaknesses is a large part of interpreting the report.
For most people who send me one of these reports, the outcome is reassurance with a set follow-up date, or a single targeted scan. Surgery is arranged only for the few who need it.
When a scan is arranged for a symptom, a risk factor or an abnormal result, the doctor already has a reason to suspect something, and the images are read with that in mind. A scan bought as a health check has no such starting point. You were well and nothing prompted the scan, so the likelihood of serious disease was low beforehand and is usually still low afterwards.
The finding still needs to be assessed properly. It should be interpreted with that low starting likelihood in mind. A report written without this context can sound more definite than the evidence supports, and phrases such as likely represents and cannot be excluded often describe a small possibility.
The sections below set out what these scans and tests do well, where they are weaker, and the sensible next step for each part of the chest. The chest imaging page explains what CT, MRI and PET each contribute and what common phrases in a radiology report mean.
The chest has five main areas. In each one, a different scan is best at identifying a finding, and each scan has its own typical errors.
| Where in the chest | Which scan identifies it |
|---|---|
| Front of the chest and thymus | CT detects it; targeted MRI shows whether it contains fluid or is solid |
| Middle and back of the mediastinum | CT detects it; MRI shows whether it is a benign cyst |
| Ribs, breastbone and spine | CT detects and identifies it; MRI can make it look more serious than it is |
| Lungs | CT detects and identifies it; MRI misses small nodules |
| Chest wall and lining of the lung | CT detects it; MRI or ultrasound identifies it |
Usually less than the word suggests. The thymus lies directly behind the breastbone. It is a normal organ, often still visible in younger adults, and it can enlarge again after illness, physical stress, steroid treatment or chemotherapy. It is therefore seen often on chest imaging, and a scan looking for cancer will often mention it in the report.
Normal thymus is triangular or arrowhead-shaped, with a smooth outline, two symmetrical lobes and no separate lump within it. A thymoma is a distinct rounded or lobulated mass, separate from the surrounding tissue. Age is also relevant: a normal or enlarged thymus is common in younger adults and becomes less common with age.
Shape does not always settle the question, and this is why additional MRI sequences are used. In one published case, a thymoma looked smooth and symmetrical on CT and was reported as an enlarged normal thymus. It was correctly identified only when the additional MRI sequences were performed.
The MRI sequence that answers the question adds a few minutes to the scan. It detects microscopic fat within the tissue. Normal and enlarged thymus contains this fat and a thymoma does not, so the signal drops in normal tissue and stays the same in a thymoma. In published series this separates the two almost completely. The sequence is not part of a whole-body screening protocol, so if your scan has raised the question, the test that answers it has usually not yet been done.
Thymic cysts cause a separate problem. A thymic cyst is a benign fluid-filled sac that needs no treatment. If it contains protein, it can have the same density on CT as a solid tumour, and a small cyst next to the aorta can appear to take up contrast when it has not. This is how unnecessary thymus operations come about, and one targeted MRI usually prevents it.
This is the situation people find hardest. A blood test has reported a cancer signal, a scan has been arranged, and it has found nothing, or found something unrelated. At present there is no agreed answer in medicine on what should happen next.
Two facts help. First, in people without symptoms, a positive result on these tests is more often a false alarm than a true one. This is because serious disease is uncommon in a well population. Even a very accurate test produces more false positives than true positives when it is used in people who are unlikely to be ill.
In the largest published study of a multi-cancer blood test used in this way, resolving a positive result took around two months when a cancer was eventually found, and around five months when no cancer was found. A quarter of people waited eight months or longer. A later and larger study reported shorter times, but false alarms still took longest to resolve.
Published work in this field states that it is not known how closely people should be followed when the first round of tests is negative or inconclusive. A fixed surveillance protocol offered with confidence goes beyond the current evidence.
My role is to deal with the chest. I review the images themselves, decide whether anything in the chest needs further investigation, and give you a set follow-up interval with a clear end point. If nothing in the chest needs further action, I will tell you so.
The test most people have heard of may not be the one they have had. Galleri is the most widely reported multi-cancer blood test and was the subject of a large NHS trial that reported in 2026. For several years it was available in the UK only within that trial. It carries a UKCA mark, and during 2026 it began to be offered privately by a small number of UK providers. It is not available on the NHS. UK clinics also sell several other tests, and a positive result means different things for each. Please bring the actual report rather than the name of the test.
Most people who send me one of these reports do not need an operation. The usual outcome is an explanation, reassurance with a set follow-up date, or one targeted scan. I say this at the start because a surgeon's page can easily be read as a recommendation for surgery.
At the consultation I review the images themselves, not only the report. Reports are written cautiously and often sound less certain than the images are. Going through the images with you and explaining what they show is usually the most useful part of the appointment, and most people have not yet had this done.
If further imaging is needed, it is a single scan aimed at the specific question. If you live at a distance, it can usually be arranged locally and reviewed at a follow-up appointment. Only the few who need an operation come to London, to London Bridge Hospital or The Lister Hospital Chelsea. When surgery is needed, it is usually within a week of completing investigations.
These scans often report findings outside the chest, in the liver, kidneys, adrenal glands, prostate, spine or brain. These are outside my specialty and I do not manage them. I will tell you which of them appear to need a specialist opinion and which are common and harmless.
I also do not comment on whether you should have had the test. Most people choose these tests after careful reading, and my role begins once the result exists.
Appointments at London Bridge Hospital and The Lister Hospital Chelsea are usually available within 2–3 days, including video consultations, and patients are seen from across the UK and abroad. Where a case is uncertain, it is discussed at the chest multidisciplinary team meeting before any decision about surgery. If you have already received an opinion you are unsure about, you can ask for a second opinion.
Clinics and radiologists who reported the finding and wish to refer the patient directly can use the referral route for imaging and screening clinics, which sets out what to send and what is returned.
The figures above are given in plain terms. The underlying data and references are listed below.
Questions people ask after a whole-body scan, a full-body CT or a cancer blood test has reported something in the chest.
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Self-referrals welcome. Appointments at London Bridge Hospital and The Lister Hospital Chelsea within 2–3 days, including video consultations, with outpatient clinics at Canary Wharf and the City of London. Please send the report, the images and any blood test result.
Jo Mitchelson, PA · 020 7952 2882 · pa@lungsurgeon.co.uk
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