What Imaging Tests are Used to Diagnose Blood Cancer?
Imaging tests are a variety of assessments that use medical equipment to create pictures of the body. There are several different imaging tests that may be used during diagnosis or staging of blood cancer, or as follow-up tests to see how well a treatment has worked or if the cancer has returned.
Magnetic resonance imaging (MRI) is a test that uses powerful magnets and radio waves to generate pictures of the internal structures of the body. MRI scans are useful for viewing soft tissues, the brain and spinal cord, blood vessels, and bones. During an MRI, the patient may have to lie inside a tube, although some newer MRI machines are open.2-4
Computed tomography (CT) scans use special x-ray equipment to make cross-sectional views of the inside of the body. The patient typically lies flat on a table while the CT scanner rotates around the body, taking pictures at different angles or in a spiral pattern. Modern CT scans create three-dimensional (3-D) pictures of the inside of the body, enabling doctors to view abnormalities.1,2 A CT scan may be used to see if blood cancer has caused any lymph nodes or other organs (like the spleen) to become enlarged.3
Positron emission tomography (PET) scans may be used in diagnosing or staging blood cancer, or to see if a particular treatment is working. Prior to the scan, the patient is given an intravenous (IV) injection of a radioactive substance called a tracer. The tracer is absorbed into organs and other parts of the body. Cancerous cells, which often have a higher metabolism rate than healthy cells, may absorb more of the tracer, making them identifiable on the images. During the scan, the patient lies flat on a table, which slides into a large tunnel-shaped scanner. The computer creates 3-D images on a monitor. Most PET scans are performed in conjunction with a CT scan and the combined scan is called a PET/CT scan.1-3
X-ray machines use a type of radiation to send particles through the body and capture the image of the body on a computer or film. Dense structures, such as bone, appear white, while muscle and fat appear in shades of gray. A chest x-ray takes an image of the chest, lungs, heart, large arteries, ribs, and diaphragm, and it may be used if a doctor suspects a lung infection or to view any potentially enlarged lymph nodes in the chest.2,3
Ultrasound uses high-frequency sound waves to produce an image. Ultrasound can be useful in viewing lymph nodes or potentially enlarged organs in the abdomen, like the kidneys, liver, or spleen.3,4
An echocardiogram uses sound waves to view the heart while it is beating.2 Echocardiograms may be used to check on heart function before choosing a treatment plan, as some treatments for blood cancer may potentially damage the heart.5
A multigated acquisition (MUGA) scan evaluates the pumping function of the ventricles, which are the lower two chambers of the heart. A small amount of radioactive tracer is injected into a vein, and a gamma camera identifies the radiation given off by the tracer and produces moving images of the beating heart. A MUGA scan may be used to determine if the heart can sustain certain treatments or to identify changes to the heart during treatment.6
Bone scans can be used during the staging of blood cancer to determine if the cancer has spread to the bones, generally when other imaging doesn't offer clear results. Prior to the bone scan, the patient is given an intravenous (IV) injection of a radioactive substance called a tracer. The images capture how much of the radioactive tracer collects in the bones, which helps identify changes in the bones. These changes may represent spread of cancer to the bone.2