Nuclear medicine is used mainly to
allow visualization of organs and regions within organs that cannot be seen on
conventional x-ray images. Space occupying lesions (injury or abnormality), especially
tumors, may stand out on nuclear medicine images. Generally, these lesions
are seen as areas of reduced radioactivity (called a "coldspot"); however, in
some instances, like bone scanning, areas of increased activity (called a
"hotspot") represent disease or injury (pathology).
Bone scanning
Bone scanning with nuclear
medicine can be an important step in diagnosing and assessing treatment of various kinds of cancer, including breast
cancer, because it can reveal whether the cancer has spread (metastasized) beyond its
primary site and developed secondary cancer growths in the bones. On an x-ray one might
see that the bone is not broken, but on a bone scan, physicians can see metabolic changes
caused by fine fractures, small tumors, or degenerative diseases such as arthritis.
This nuclear medicine bone scan is
normal and shows no pathology.
Heart Disease
Nuclear medicine is also an important
component in the diagnosis and treatment of heart disease.
For example, cardiac angiography yields excellent images of the beating heart and the
blood vessels (coronary arteries) that supply the heart muscle (myocardium) with blood.
However, a stress thallium nuclear medicine study provides additional information by
showing the function of the myocardium.
In a stress thallium study, two data
acquisitions are performed during a stress thallium study. First, the patient is
vigorously exercised on a treadmill or stationary bicycle to elevate cardiovascular
activity and "stress" the heart. This is followed immediately by a nuclear
medicine examination. The patient is then given a period of time to rest. When the
patient's heart activity has again become normal (or "at rest"), a second
nuclear medicine study is completed. The physician then compares the images and function
of the heart at rest to the heart under stress. Areas of the heart which may have been
previously damaged by myocardial infarction (heart attack) or may have insufficient blood
supply due to a blockage of a coronary artery will not show the proper function in the
stress image. Another common cardiac application of nuclear medicine is the MUGA scan
(electrocardiographic MUltiple Gated Acquisition) which allows study of the heart's
muscular wall motion and study of the heart's chambers.
Cardiac "stress thallium"
nuclear medicine study comparing the heart under stress (upper row) to the heart at rest
(lower row). Study shows normal cardiac function.
Nuclear Medicine Can Image
and/or Show the Function a Variety of Organs and Body Parts to Diagnose a Number of
Medical Conditions Including:
abdomen (example given, to check for
gastrointestinal bleeding)
brain (e.g., to look for tumors or
aneurysms (blood vessel disease) or evaluate stroke)
blood (e.g., to test for various blood
cell disorders)
breast (e.g., to image breast cancers)
hepatobiliary system (e.g., to check
gallbladder and bile duct function)
heart (e.g., to look for coronary artery
disease, myocardial infarction, valve disease or heart attack; to detect heart transplant
rejection; check the effectiveness of bypass surgery; to select patients for angioplasty
or bypass surgery)
kidneys (e.g., to check renal function;
to detect renal tumors; to test for renal transplant rejection)
liver/spleen (e.g., to check for
chirrhosis or metastatic cancer)
lung (e.g., to check for pulmonary
embolism (blood clot), check for lung transplant rejection or test for smoke inhalation
injury in burn patients)
lymphatic system (e.g., to detect if
cancer has spread to the lymph nodes)
skeletal system (e.g., to check for
metastatic cancer or to test for hidden bone trauma in sports injuries)
stomach (e.g., to check for stomach
function and to confirm ulcers or cancer)
thyroid and parathyroid (e.g., to check
for tumor or abnormal function)
This nuclear medicine study shows
normal breast anatomy and no abnormalities in this patient.
Updated: June 10, 2008
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