Some tests, such as a computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan, are often done to look for the cause of symptoms and to find a tumor (such as a sarcoma). Other tests may be done after a sarcoma is diagnosed to look for cancer spread.
A regular x-ray of the area with the lump may be the first test ordered. A plain chest x-ray may be done after diagnosis to look for spread of sarcoma to the lungs.
Computed tomography scans
The CT scan is an x-ray procedure that produces detailed, cross-sectional images of your body. Instead of taking one picture like a conventional x-ray, a CT scanner takes many pictures as it rotates around you. A computer then combines these pictures into an image of a slice of your body. The machine will create multiple images of the part of your body being studied. A CT scan is often done if the doctor suspects a soft tissue sarcoma in the chest, abdomen, or the retroperitoneum. This test is also used to see if the sarcoma has spread into the lungs, liver or other organs.
A CT scanner has been described as a large donut, with a narrow table in the middle opening. You will need to lie still on the table while the scan is being done. CT scans take longer than regular x-rays, and you might feel a bit confined by the ring while the pictures are being taken
Before any pictures are taken, you may be asked to drink 1 to 2 pints of a liquid called oral contrast. This helps outline the intestine more clearly. You may also receive an IV (intravenous) line through which a different kind of contrast dye (IV contrast) is injected. This helps better outline structures in your body.
The IV contrast dye can also cause some flushing (redness and warm feeling). Some people are allergic and get hives or, rarely, more serious reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays.
CT scans might be done to precisely guide a biopsy needle into a tumor that is inside the body — the chest or abdomen, for example. For this procedure, called aCT-guided needle biopsy, the patient remains on the CT scanning table while a radiologist advances a biopsy needle toward the location of the mass. CT scans are repeated until the doctors are sure the needle is within the mass.
Magnetic resonance imaging scans
Magnetic resonance imaging (MRI) scans use radio waves and strong magnets instead of x-rays to take pictures of the body. The energy from the radio waves is absorbed and then released in a pattern formed by the type of tissue and by certain diseases. A computer translates the pattern of radio waves given off by the tissues into a very detailed image of parts of the body. A contrast material might be injected, just as with CT scans, but is used less often.
MRI scans are often part of the work-up of any tumor that could be a sarcoma. They are often better than CT scans in evaluating sarcomas in the arms or legs. They provide a good picture of the extent of the tumor. They can show your health care team many things about the tumor, including location, size, and sometimes even the type of tissue it comes from (like fat or muscle). This makes MRI scans useful in planning a biopsy.
MRIs are also very helpful in examining the brain and spinal cord.
MRI scans are a little more uncomfortable than CT scans. First, they take longer — often up to an hour. Also, you have to lie inside a long tube, which is confining and can be upsetting. Special “open” MRI machines sometimes are an option for people who have claustrophobia (fear of enclosed spaces), but the drawback is that the pictures are often not as clear. MRI machines also make a thumping noise that you may find disturbing. Some places will provide headphones with music to block this noise out.
Ultrasound uses sound waves and their echoes to produce pictures of parts of the body. A small instrument called a transducer emits sound waves and picks up the echoes as they bounce off the organs. The sound wave echoes are converted by a computer into an image that is displayed on a computer screen.
This is a very easy procedure to have. It uses no radiation, which is why it is often used to look at developing fetuses. For most ultrasounds, you simply lie on a table while a technician moves the transducer over the part of your body being examined. Usually, the skin is first lubricated with gel. This test may be done before a biopsy to see if the lump is a cyst, meaning it contains fluid and is likely benign, or if it is solid and more likely a tumor. This test is often not needed if a CT or MRI was done.
Positron emission tomography scan
In this test, radioactive glucose (sugar) is injected into the patient’s vein to look for cancer cells. Because cancers use glucose (sugar) at a higher rate than normal tissues, the radioactivity will tend to concentrate in the cancer. A scanner can spot the radioactive deposits. A positron emission tomography (PET) scan is useful when your doctor thinks the cancer has spread but doesn’t know where. A PET scan can be used instead of several different x-rays because it scans your whole body. Often the PET scan is used with a CT scan. This helps decide if abnormalities seen on the CT scan are cancer or something else. PET is not often used for sarcoma, but it can be helpful in certain cases.