A Soft Tissue Mass MRI is a detailed MRI scan focused on a specific lump or mass found in the soft tissues — the muscle, fat, nerves, and other non-bony tissues of the arms, legs, trunk, or pelvic floor. It uses no radiation.
Doctors request this scan when a lump has been found and they need to know exactly what they are dealing with before doing anything else. The scan helps tell harmless lumps like lipomas apart from sarcomas, shows exactly how deep the mass goes, and maps it for biopsy or surgery.
Why would my doctor ask for a Soft Tissue Mass MRI?
Your doctor may recommend this scan to look closely at a lump, especially if you have:
- A new lump under the skin that is growing, painful, or larger than a few centimetres.
- A deep mass found on physical examination or another scan.
- A known soft tissue tumour that needs to be characterised before treatment.
- A history of a soft tissue tumour, with a need to check for recurrence after surgery.
- A planned biopsy or operation, where the surgeon needs a full map first.
- An unexplained lump in a child that has been growing or changing.
What can a Soft Tissue Mass MRI detect?
This scan helps doctors see:
- The exact size, shape, and depth of the lump.
- Whether the lump is made of fat, fluid, blood, muscle, or solid tumour tissue.
- The relationship of the lump to nearby nerves, blood vessels, and bone.
- Common benign lesions such as lipomas, ganglion cysts, schwannomas, and haemangiomas.
- Features that suggest sarcoma, such as large size, deep location, and irregular blood supply.
- Changes after treatment or signs of recurrence.
Do I need any special preparation for a Soft Tissue Mass MRI?
Preparation is usually minimal:
- You do not need to fast.
- A cannula will be placed in your arm if contrast is planned, which is the case for most masses.
- Wear comfortable clothes with no metal — you will likely change into a hospital gown.
- Remove all jewellery, body piercings, and metal objects before entering the scan room.
- Tell the team about any implants, especially pacemakers or surgical metal.
- If you have a previous scan of the same area, bring it — the radiologist will want to compare.
Will I be injected with dye for this scan?
Usually, yes. Gadolinium contrast helps show how active the lump is, how it takes up blood, and where the most worrying parts are. Some simple-looking masses — for example, a clear lipoma — can be assessed without dye. Your radiologist will decide based on what the lump looks like on the first set of images.
What does the scan feel like?
The scan is painless. You will lie on a padded table that slides into the MRI scanner. Your position depends on where the lump is — for example, on your back for a thigh mass, or face-down for a back mass.
A receiving device (a coil) will be placed over the area being scanned. The scanner makes loud knocking and humming sounds, and earplugs or headphones will be provided. You will be asked to keep the affected limb or body part as still as possible. The radiographer will speak to you between sequences.
Is it safe for pregnant women or children?
The scan uses no radiation and is safe in principle. In pregnancy, contrast is generally avoided, and the scan is performed only when the answer will change immediate care. In children, it is the test of choice for soft tissue masses because it avoids radiation; younger children may need sedation to lie still.
How long does a Soft Tissue Mass MRI take?
The scan usually takes 30 to 60 minutes, depending on the size of the area and whether contrast is used. Including changing and cannula placement, the whole appointment is usually about an hour.
When will I get my results?
A Radiologist — often one with experience in musculoskeletal imaging — will review the images and prepare a detailed report. Results are typically ready within a few days. If the scan suggests a possible sarcoma, your doctor may refer you to a specialist sarcoma centre before any biopsy is done, because the way the biopsy is taken matters for later treatment.
Will the scan tell me if my lump is cancerous?
In many cases, yes — but not always. Some lumps have such clear MRI features that the radiologist can confidently call them benign, like a simple lipoma or a ganglion cyst. Others have clear warning signs that point to sarcoma. A smaller group sits in between, where the scan narrows the possibilities but cannot give a final answer without a biopsy. Your doctor will explain which group your lump falls into.
Why do I need a scan if the doctor can already feel the lump?
Because feeling a lump only tells you part of the story. The scan shows what the lump is made of, how deep it goes, whether it is wrapped around important nerves or vessels, and whether it has features that suggest cancer. A lump that feels small under the skin can have a much larger deep part that only an MRI can reveal — and operating without that information risks an incomplete or unsafe surgery.
What is a biopsy and will I still need one after this scan?
A biopsy is a small procedure where a needle or knife is used to take a tiny sample of the lump for the laboratory to examine under a microscope. The MRI characterises the lump but does not look at its cells. If the scan clearly shows a benign lesion, a biopsy may not be needed. If the scan suggests anything possibly cancerous, a biopsy is usually the next step — and the radiologist's report will often suggest the safest way to take it.
What if I'm nervous about being inside the scanner?
It is normal to feel anxious — especially when the lump itself is already worrying you. The radiographer will be in contact with you the entire time and you can hold a squeeze ball to alert them if you need a break. If you are very claustrophobic, ask your doctor about a mild sedative beforehand.
Sources and further reading
- RadiologyInfo: MRI of the body
- ACR Manual on Contrast Media
- FDA: Gadolinium retention safety communication
Conclusion
A Soft Tissue Mass MRI is the most useful single test for understanding a lump in the soft tissues. For many people it confirms a harmless diagnosis and avoids unnecessary surgery; for others it identifies a worrying lump early, when treatment is most effective. Bring any previous scans of the same area so the radiologist can compare and judge whether the lump has changed.