Dr. Lee & Esther Ellman Center for Imaging

What is a Bone Density Scan (DXA)?
Bone density scanning, also called dual-energy x-ray absorptiometry (DXA) or bone densitometry, is an enhanced form of x-ray technology that is used to measure bone loss. DXA is today's established standard for measuring bone mineral density (BMD).

DXA is most often used to diagnose osteoporosis, a condition that often affects women after menopause, but may also be found in men. Osteoporosis involves a gradual loss of calcium, as well as structural changes, causing the bones to become thinner, more fragile, and more likely to break. DXA is also effective in tracking the effects of treatment for osteoporosis and other conditions that cause bone loss. The DXA test can also access an individual's risk for developing fractures. The risk of fracture is affected by age, body weight, history of prior fracture, family history of osteoporotic fractures and life style issues such as cigarette smoking and excessive alcohol consumption. These factors are taken into consideration when deciding if a patient needs therapy.

This exam is performed by a radiologic technologist and typically takes about 20 minutes. After the technologist has reviewed your medical history, you will be asked to lay flat on the table. You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image. The technologist will walk behind a wall or into the next room to activate the x-ray machine. Bone density tests are a quick and painless procedure. Most insurance companies allow a patient to have one DXA scan every two years however there are instances when they can be done sooner.

How should I prepare for a Bone Density Exam?
On the day of the exam you may eat normally. You should not take calcium supplements for at least 24 hours before your exam. You should wear loose, comfortable clothing, avoiding garments that have zippers, belts or buttons made of metal. Objects such as keys or wallets that would be in the area being scanned should be removed. You may be asked to remove some of your clothing and to wear a gown during the exam. You may also be asked to remove jewelry, removable dental appliances, eye glasses and any metal objects or clothing that might interfere with the x-ray images.

It is important to inform the scheduler if you recently had a barium examination or have been injected with a contrast material for a computed tomography (CT) scan or nuclear medicine scan. These items can cause artifacts on your images so you will have to wait 10 to 14 days before undergoing a DXA test to ensure we perform the best scan possible. Also, women should always inform their physician and x-ray technologist if there is any possibility that they are pregnant.

CT or CAT scan is short for computed axial tomography (CAT). CT scans are special X-ray tests that produce cross-sectional images of the body using X-rays and a computer. These images allow the radiologist, a medical doctor who specializes in interpreting images of the body, to look at the inside of the body. This type of special X-ray, in a sense, takes pictures of slices of the body so the doctor can look right at the area of interest. The CT scanner looks like a large doughnut with a narrow table in the middle. Due to the speed of this advanced imaging procedure, most patients have no claustrophobia. Patients are not placed inside a tunnel. The patient is moved in and out of the opening as the scanner takes the pictures. Depending on the exam you are having, you will lie on your back or stomach and move through the scanner either head first or feet first.

Magnetic resonance imaging (MRI) uses a magnetic field and pulses of radio waves to make pictures of the breast. MRI may show problems in the breast that cannot be seen on a mammogram, ultrasound, or CT scan. The MRI creates image that show your breast's normal structure as well as demonstrates any abnormal tissue. In most cases, a dye (contrast material) may be used so that abnormalities can be seen more clearly from normal breast tissue. The contrast material makes it easier to find problems. MRI is a safe and valuable test for looking at the breast. You will not have pain from the magnetic field or radio waves. The table you lie on may feel hard and the room may be cool. Some people feel anxious (claustrophobic) inside the MRI machine. Your physician may prescribe medicine (sedative) to help you relax.

An MRI technologist will perform your exam. Before your MRI, the technologist will review your medical history and explain the test to you in great detail. You will need to remove all metal objects (such as hearing aids, dentures, jewelry, watches, and hairpins) from your body because these objects may be attracted to the powerful magnet used for the test. You will need to take off your clothes above the waist and any other clothing that may be metal on it. You will be given a gown to cover your shoulders during the test.

During the test, you will lie on your stomach on a table that is part of the MRI scanner. The table will slide into the machine part that holds the magnet. Your breasts will be placed in a device called a coil that issued to pick up the MRI signals. Inside the scanner, you will hear tapping or thumping noises as the MRI scans are taken. You will be given earplugs or headphones with music to lessen the noise. It is very important to hold completely still while the scan is being done. Otherwise, repeat scans may be needed. Also, you may be asked to hold your breath for short periods of time. During the test, the technologist is right outside the door and is watching you through a window. They will be able to hear you and you can talk to her through a speaker.

How should you prepare for your MRI?
Tell your doctor and the MRI technologist if you:

• Have a pacemaker, implantable cardioverter-defibrillator (ICD), artificial limb, any metal parts in your body, tattooed eyeliner or metallic-based tattoos, or any other implanted medical device, such as a medicine infusion pump. Also, tell your doctor if you have worked around metal or if you have recently had surgery on a blood vessel. In some cases you may not be able to have the MRI test
• Are or might be pregnant
• Become very nervous in confined spaces
• Have allergies, especially to any medicines
• Have asthma
• Wear any medicine patches
• Have other health problems, such as kidney problems or sickle cell anemia. Contrast material cannot be used with some health problems.

An ultrasound procedure is a non-invasive (the skin is not pierced) diagnostic procedure used to assess soft tissue structures such as muscles, blood vessels, and organs. Ultrasound uses a transducer that sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed at certain locations and angles, the ultrasonic sound waves move through the skin and other body tissues to the organs and structures within. The sound waves bounce off the organs like an echo and return to the transducer. The transducer picks up the reflected waves, which are then converted by a computer into an electronic picture of the organs or tissues under study.

Since Wilhelm Röntgen's discovery that X-rays can identify bony structures over 100 years ago, X-rays have been developed for their use in medical imaging. Radiology is a specialized field of medicine. This is the most common use of X-ray technology. X-rays are most useful in the detection of pathology, like broken bones. 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 an ileus (blockage of the intestine), free air (from visceral perforations) and some kidney stones.