Tests for Soft Tissue Sarcomas

A CT scan uses x-rays to make detailed images of your body. This test is often done if the doctor suspects a soft tissue sarcoma in the chest, abdomen (belly), or the retroperitoneum (the back of the abdomen). This test is also used to see if the sarcoma has spread to the lungs, liver, or other organs.

CT scans might be used to guide a biopsy needle into a tumor inside the body. This is called a CT-guided needle biopsy. You lie on the CT scanning table while a radiologist moves a biopsy needle toward the tumor.

MRI uses radio waves and strong magnets (not x-rays) to take pictures of the inside of the body. MRI scans are often part of the workup of any tumor that could be a sarcoma. They're often better than CT scans in evaluating sarcomas in the arms or legs.

MRIs can show your health care team many things about the tumor, like where it is, how big it is, and sometimes the type of tissue it comes from, like bone, fat, or muscle. MRIs are also very helpful in examining the brain and spinal cord.

Ultrasounds use sound waves and their echoes to look inside the body. For this test, a small, wand-like instrument called a transducer is moved around on the skin, which creates an image that can be seen on a computer screen. The test uses no radiation and does not cause any pain.

An ultrasound might be done before a biopsy to see if a lump is a cyst (a non-cancerous fluid-filled lump) or more likely a tumor. This test is often not needed if a CT or MRI scan is done.

PET scans aren't often used for soft tissue sarcomas, but can be helpful in some cases. For a PET scan, a slightly radioactive form of sugar, known as FDG, is injected into the blood and collects mainly in cancer cells. These areas of radioactivity can be seen on a PET scan using a special camera.

A PET scan is useful when your doctor thinks the cancer has spread but doesn't know where. 

PET/CT scan: Some machines can do both a PET and CT scan at the same time. This lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed picture of that area on the CT scan.