An imaging test allows a physician to see pictures of the inside of the body. Forms of energy such as X-rays, sound waves, radioactive particles, or magnetic fields are sent through the body. The changes in energy patterns made by body tissues create the image, which shows normal and abnormal body structures and functions. The most common imaging tests include the following:
X-ray – emits a short pulse of radiation when the patient is placed in front of an X-ray detector and produces an image on radiographic film or electronically. X-rays are useful for visualizing disorders of the skeletal system and certain diseases of soft tissue such as pneumonia, lung cancer, pulmonary edema, bowel obstructions, or ascites (abdominal fluid). X-rays are less useful for imaging other soft tissue.
CT (computerized tomography) or CAT (computerized axial tomography) scan – emits a series of narrow X-ray beams, producing more detail than standard X-rays. A computer uses the data from these X-rays and generates a 3-dimensional image; sometimes contrast dye is used to enhance the image. CT scans are more useful than standard X-rays for viewing abnormalities in bones or soft tissues. The accuracy and speed of CT scans may be improved with spiral CT, during which the X-ray beam takes a spiral path while scanning and gathers continuous data with no gaps between images.
Ultrasound (sonography) – uses high-frequency sound waves to produce precise images on computer. Most ultrasound tests use a sonar device outside of the body, although some may involve placing the device inside. Sound waves do not travel well through air or bone; thus ultrasound is not effective at imaging parts of the body that have gas or are obscured by bone.
MRI (magnetic resonance imaging) scan – uses a magnetic field and pulses of radio wave energy to form images on a computer. The area of the body being studied is placed inside a machine that contains a strong magnet to produce the magnetic field. Since MRI does not use radiation, it is recommended in preference to CT when either method can yield the same information. MRI is the test of choice for imaging many conditions of the central nervous system (brain and spinal cord) as well as other soft tissues such as tumors. It cannot be used in patients with pacemakers, metal implants, shrapnel, or metallic foreign objects.
PET (positron emission tomography) scan – uses radiation coupled with a biologically active molecule such as water, glucose, or ammonia to form a radiotracer that is placed in the body. Once inside, the radiotracer will go to areas that utilize the biological molecule. The radiotracer produces 3-dimensional color images on a computer that show the functional activity of tumors.
The National Comprehensive Cancer Network (NCCN) in its Clinical Practice Guidelines for WM/LPL (lymphoplasmacytic lymphoma) recommends the use of CT scans of the chest, abdomen, and pelvis as part of the essential diagnostic work up of WM patients to determine the presence and degree of lymphadenopathy (enlarged lymph nodes), splenomegaly (enlarged spleen), and other masses of potential WM cells. WM patients who have symptomatic lymph node and organ enlargement may require follow-up monitoring with scans.