MRI uses a powerful magnetic field, radiofrequency waves, and a computer to create detailed cross-sectional (2-dimensional) and 3-dimensional images of the inside of your body without using ionizing radiation (like X-rays, computed tomography, or nuclear imaging).The test can show your heart’s structure (muscle, valves and chambers) and how well blood flows through your heart and major vessels. MRI of the heart lets your doctor see if your heart is damaged from a heart attack, or if there is lack of blood flow to the heart muscle because of narrowed or blocked arteries. MRI of the brain is used to diagnose stroke, aneurysm and other brain abnormalities. MRI of the pelvis and legs helps to diagnose peripheral artery disease (PAD).
Computed Tomography (CT) combines X-rays and computer technology to scan the body and produce detailed cross-sectional images of organs, bone, muscle or other tissue. These images, sometimes called “slices” can be horizontal or vertical, because the scanner moves around the body. Multi-slice scanners capture more images per second than conventional CT, resulting in shorter scan times and higher-resolution images.
Radiographs are useful in the detection of pathology of the skeletal system as well as for detecting some disease processes in soft tissue. Some notable examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer, or pulmonary edema, and the abdominal x-ray, which can detect bowel (or intestinal) obstruction, free air (from visceral perforations) and free fluid (in ascites). X-rays may also be used to detect pathology such as gallstones (which are rarely radiopaque) or kidney stones which are often (but not always) visible. Traditional plain X-rays are less useful in the imaging of soft tissues such as the brain or muscle.
Ultrasound uses sound waves and a computer to create images of internal organs and blood vessels and to monitor the progress of pregnancy. A tool called a transducer that emits sound waves is placed over the area of the body being examined. The sound waves bounce off these structures and their echoes are received by the transducer, which then sends the information to a computer. The computer analyzes the information and creates a moving image.
Ultrasound is commonly used to look at:
• The organs and blood vessels in the abdomen (liver, kidneys, spleen, gallbladder, bile ducts, aorta and pancreas)
• The pelvis (uterus, ovaries, bladder and prostate)
• A fetus (to check for gestational age and irregularities)
• Breast, thyroid, scrotum, or other soft tissue mass
• Arteries and veins in the neck, abdomen and legs
Bone density scanning, also called dual-energy x-ray absorptiometry (DEXA) or bone densitometry, is an enhanced form of x-ray technology that is used to measure bone loss.
DEXA is today's established standard for measuring bone mineral density (BMD). An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body.
DEXA has also been called dual energy X-ray absorptiometry, or DXA. DEXA bone density scan provides an estimate of the strength of your bones. DEXA can measure as little as 2 percent of bone loss per year. It is fast and uses very low doses of radiation.