Lymphoma Table 4.2. Types of Imaging Tests (continued) Magnetic Resonance Imaging (MRI) ■ An MRI uses magnets and radiofrequency waves to acquire images from different angles throughout the body. ■ An MRI can provide important information about tissues and organs, particularly the bones and nervous system that is not available from other imaging techniques. ■ MRI scans cannot replace CT scans, because they do not provide clear images of lymph nodes as well as CT scans do. Positron Emission Tomography (PET) ■ A PET scan evaluates HL activity in all parts of the body. ■ Radioactive fluorodeoxyglucose (a type of sugar) is injected into the body. A positron camera is then used to detect the radioactivity and produce cross-sectional images of the body. This test relies on the fact that cancer cells metabolize sugar faster than normal cells, so that more “uptake” on a PET scan indicates more metabolic activity, suggesting the presence of the malignant cells. ■ While CT scans provide information about the size of a lymph node, PET scans can better indicate whether the lymph node contains active HL cells. ■ PET scans help distinguish active tumors from scar tissue and may be used to assess a patient’s response to treatment. ■ PET and CT scans are often combined into a single test (PET-CT), in which the CT procedure is slightly modified from that described above. Learning the Basics 36 Part 1 Why Is Heart Function Evaluated? Before beginning some types of lymphoma treatment, the doctor may measure the patient’s baseline heart function to make sure that the patient’s body can withstand treatment. This is especially important because certain lymphoma treatments can occasionally make heart function worse. Depending on the treatment used, the patient’s heart function may be evaluated again during treatment to make sure the heart is tolerating the treatment. Two tests are used to evaluate heart function: an echocardiogram (ECHO) or a multigated acquisition (MUGA) scan. An ECHO is an ultrasound of the heart. An instrument called a transducer is placed on the chest and releases high-frequency sound waves, which are converted into moving images of the heart. This test evaluates the function of the cardiac muscle and provides information about the heart valves. An ECHO can be performed while the patient is resting or after exercise. A MUGA scan creates video images of the ventricles (lower chambers of the heart) to measure how well they are pumping blood. During the procedure, a tracer (radioactive material) that attaches to red blood cells is injected into the arm. As the tracer moves through the bloodstream, a special camera takes pictures to see how efficiently the heart is pumping the blood. Why Is Lung Function Evaluated? Some lymphoma treatments, especially the chemotherapy drug bleomycin (Blenoxane), can put stress on the lungs. For this reason, the doctor may order pulmonary (lung) function tests (PFTs) before beginning treatment and again during treatment to make sure the patient’s lungs are working properly. Three types of PFTs are typically used. Spirometry measures the amount of air a patient breathes in and out. For this test, the patient is fitted with a mouthpiece and a nose clip and is asked to breathe normally. 37 Understanding Hodgkin Lymphoma Patients may also be told to inhale and exhale as deeply and/or as rapidly as they can for several seconds. Plethysmography measures the volume of air in the lungs. For this test, the patient sits or stands in a small booth and breathes into a mouthpiece. The pressure in the booth is measured to determine lung volume. A third test, called diffusing capacity of the lungs for carbon monoxide (DLCO), measures how well the lungs transfer gas from inhaled air to red blood cells. Patients are asked to inhale air containing a very small amount of carbon monoxide, hold their breath for 10 seconds, and then exhale. How Is HL Staged? Staging is used to describe how widely the lymphoma has spread in patients with HL. Doctors use the stage of disease, along with test results and other factors, to decide the best time to begin treatment and what treatments are likely to be the most effective for each patient. For