GLOSSARY

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Angiography
A procedure performed to view blood vessels after injecting them with a radioopaque dye that outlines them on x-ray. This technique can be usefully used to look at arteries in many areas of the body, including the brain, neck (carotids), heart, aorta, chest, pulmonary circuit, kidneys, gastrointestinal tract, and limbs.

Arteriosclerosis
Hardening and thickening of the walls of the arteries. Arteriosclerosis can occur because of fatty deposits on the inner lining of arteries (atherosclerosis), calcification of the wall of the arteries, or thickening of the muscular wall of the arteries from chronically elevated blood pressure (hypertension).

Barium solution
A liquid containing barium sulfate. The barium shows up on x-rays. It outlines organs of the body such as the intestine so they can be seen on x-ray film.

Benign
Not cancer. Not malignant. A benign tumor does not invade surrounding tissue or spread to other parts of the body.

Biopsy
The removal of a sample of tissue for examination under a microscope to check for cancer cells.

Bone density
Bone densitometry, often called bone density testing, is a screening exam for osteoporosis. The exam measures bone mineral density, or bone mass, and compares the results with a reference population of similar age, gender, and racial background.

Chest film
Most common X-ray used to detect abnormalities in or within the thoracic cage, such as the lungs, heart, aorta, and the bones of the chest. Extra metallic objects, such as jewelry are removed from the chest and neck areas for a chest x-ray to avoid interference with x-ray penetration and improve accuracy of the interpretation.

Computed tomography (CT)
Computed tomography (CT) is a medical imaging technique that combines conventional x-ray imaging with computer technology to produce cross-sectional images of the human body. CT scans are capable of creating detailed views of the body’s soft tissues, including blood vessels, muscle tissue, and organs, providing valuable diagnostic information.

Computed tomography angiography (CTA)
A method of examining blood vessels utilizing x-rays and injection of iodine-containing contrast medium.

Contrast agent, contrast material, contrast medium
Any internally administered substance that has a different opacity from soft tissue on radiography or computed tomography; includes barium, used to make opaque parts of the gastrointestinal tract; water-soluble iodinated compounds, used to make opaque blood vessels or the genitourinary tract; may refer to air occurring naturally or introduced into the body; also, paramagnetic substances used in magnetic resonance imaging.

Creatinine
A chemical waste molecule that is generated from muscle metabolism. Creatinine is produced from creatine, a molecule of major importance for energy production in muscles. Approximately 2% of the body's creatine is converted to creatinine every day. Creatinine is transported through the bloodstream to the kidneys. The kidneys filter out most of the creatinine and dispose of it in the urine. Although it is a waste, creatinine serves a vital diagnostic function. Creatinine has been found to be a fairly reliable indicator of kidney function. As the kidneys become impaired the creatinine will rise. Abnormally high levels of creatinine thus warn of possible malfunction or failure of the kidneys, sometimes even before a patient reports any symptoms. It is for this reason that standard blood and urine tests routinely check the amount of creatinine in the blood.

Diagnostic ultrasound
The use of ultrasound to obtain images for medical diagnostic purposes.

Doppler ultrasonography
An application of diagnostic ultrasound used to detect moving blood cells or other moving structures and measure their direction and speed of movement. The Doppler effect is used to evaluate movement by measuring changes in frequency of the echoes reflected from moving structures. Doppler ultrasound permits real-time viewing of blood flow that cannot be obtained by other methods. Doppler ultrasound aids in the evaluation of the major arteries and veins of the body, the heart, and in obstetrics for fetal monitoring.

Embolization
The movement of a blood clot, piece of tissue, or pocket of air or gas from where it forms through the bloodstream until it lodges in place, cutting off the flow of blood with its oxygen and tissue nutrients. Catheter embolization is the deliberate introduction of foreign ("embolic") material such as gelatin sponge or metal coils to stop bleeding or cut off blood flowing to a tumor or arteriovenous malformation.

Fibroid
A benign tumor of the uterus and the single most common indication for hysterectomy. Fibroids can be present and be inapparent. However, they are clinically apparent in up to 25% of women and cause significant morbidity, including prolonged or heavy menstrual bleeding, pelvic pressure or pain, and, in rare cases, reproductive dysfunction. Both the economic cost and the effect of fibroids on quality of life are substantial. Fibroids are not cancerous. Drugs that manipulate the levels of steroid hormones are effective in treating fibroids but side-effects limit their long-term use. Fibroids may be removed if they cause discomfort or if they are associated with uterine bleeding. Surgery is the mainstay of fibroid treatment. In addition to hysterectomy and abdominal myomectomy, various minimally invasive procedures have been developed to remove fibroids. A fibroid is also medically known as a leiomyoma or simply a myoma of the uterus.

Fluoroscopy
An x-ray procedure that makes it possible to see internal organs in motion. Fluoroscopy uses x-ray to produce real-time video images. After the x-rays pass through the patient, instead of using film, they are captured by a device called an image intensifier and converted into light. The light is then captured by a TV camera and displayed on a video monitor.

Gadolinium
An element used in contrast media for magnetic resonance imaging.

Gantry
A frame housing the x-ray tube, collimators, and detectors in a CT machine, with a large opening into which the patient is inserted; a mechanical support for mounting a device to be moved in a circular path.

Guidewire
A device used to correctly position an intravenous catheter.

Interventional radiology
The use of image guidance methods to gain access to the deepest interior of most organs and organ systems. Through a variety of techniques, interventional radiologists can treat certain conditions through the skin (percutaneously) that might otherwise require surgery. The technology includes the use of balloons, catheters, microcatheters, stents, therapeutic embolization (deliberately clogging up a blood vessel), and more.

Intravenous
Inside a vein. Frequently a needle will be placed in a vein, often a large arm vein, to deliver fluids and medications, withdraw blood samples, and transfuse blood.

Intravenous pyelogram (IVP)
An x-ray of the kidneys and urinary tract. Structures are made visible by the injection of a substance that blocks x-rays.

KUB film
An X-ray showing the kidney, ureter, and bladder. This is in reality a plain abdominal X-ray and includes other structures such as the diaphragm above and the pelvis below.

Magnetic resonance imaging (MRI)
MRI is a special imaging technique designed to image internal structures of the body, especially the soft tissues. An MRI uses the influence of a large magnet to polarize hydrogen atoms in the tissues and then monitor the summation of the spinning energies within living cells. MRI images are clear, particularly with soft tissue, brain and spinal cord, abdomen and joints.

Magnetic resonance angiogram (MRA)
MRA is a general term that refers to various noninvasive imaging techniques that are used to visualize the blood vessels blood vessels of certain size in the head and neck by using magnetic resonance.

Mammogram
Mammography is a medical imaging technique that combines low-dose radiation and high-contrast, high-resolution film for examination of the breast and screening for breast cancer. A screening mammogram is one done in women who have no signs of breast cancer. It usually involves two x-rays of each breast. The aim of a screening mammogram is to detect a tumor that cannot be felt. Most mammograms that are performed are screening mammograms. A diagnostic mammogram takes longer and involves correspondingly more radiation exposure than a screening mammogram because it involves more x-rays. Diagnostic mammograms are done to evaluate any abnormalities that have been seen or suspected on a prior screening mammogram.

Modality
A form of application or employment of a therapeutic agent or regimen.

Neuroradiology
The clinical subspecialty concerned with the diagnostic radiology of diseases of the central nervous system, head, and neck.

Noninvasive
Denoting a procedure that does not require insertion of an instrument or device through the skin or a body orifice for diagnosis or treatment.

Nuclear medicine
The clinical discipline concerned with the diagnostic and therapeutic uses of radionuclides (an isotope of artificial or natural origin that exhibits radioactivity), excluding the therapeutic use of sealed radiation sources. Certain imaging procedures, including PET scanning, employ radionuclides to provide real-time visuals of biochemical processes.

Osteoporosis
Thinning of the bones with reduction in bone mass due to depletion of calcium and bone protein. Osteoporosis predisposes a person to fractures, which are often slow to heal and heal poorly. It is more common in older adults, particularly post-menopausal women; in patients on steroids; and in those who take steroidal drugs. Osteoporosis can be detected by using tests that measure bone density.

Radiation
Rays of energy. The term "radiation" also refers to the use of energy waves to diagnose or to treat disease. Gamma rays and X-rays are two of the types of energy waves often used in medicine.

Radiography
Film records (radiographs) of internal structures of the body. Radiography is made possible by X-rays passing through the body to act on a specially sensitized film.

Radiologist
A physician specialized in radiology, the branch of medicine that uses ionizing and nonionizing radiation for the diagnosis and treatment of disease. Like other physicians, a radiologist must have graduated from an accredited medical school or school of osteopathy, passed a licensing examination, and completed at least 4 years of graduate medical or osteopathic education (residency). Radiologists are usually board certified, that is, they have taken and passed an examination and thus are approved to practice in the field of radiology by either the American Board of Radiology (for a medical doctor) or the American Osteopathic Board of Radiology (for an osteopathic doctor).

A radiologist can also subspecialize. Subspecialties in radiology listed by the American College of Radiology include:

•  Breast Imaging
•  Cardiovascular
•  Chest
•  Computed Tomography
•  Diagnostic Radiology
•  Emergency
•  Gastrointestinal
•  Genitourinary
•  Head and Neck
•  Interventional
•  Magnetic Resonance Imaging
•  Musculoskeletal
•  Neuroradiology
•  Nuclear Medicine
•  Pediatric Radiology
•  Radiological Physicist
•  Radiobiology
•  Ultrasound
•  Radiation Oncology

Radiology
The branch of medicine that uses ionizing and nonionizing radiation for the diagnosis and treatment of disease. Historically, radiology involved the use of ionizing radiation including X rays for the diagnosis of disease and X rays and gamma rays for the treatment of disease. More recently, radiology has also embraced the use of radioactive isotopes and of nonionizing radiation such as ultrasound waves and nuclear magnetic resonance imaging (MRI). Radiology is also known as roentgenology after Wilhelm Conrad Roentgen who discovered X-rays in 1895.

Radiopaque
Anything that does not let X-rays or other types of radiation penetrate. Radiopaque objects block radiation. A metal object, for example, is typically radiopaque. If a child swallows a coin and it goes down into the stomach, it is easily visible in the stomach on an X-ray because it is radiopaque. Radiopaque dyes are used in radiology to enhance the X-ray pictures of selected internal anatomic structures.

Roentgen
An international unit of X-radiation or gamma-radiation. (A roentgen is abbreviated R). Named for Wilhelm Roentgen who greatly expanded our diagnostic and treatment capabilities by discovering radiology.

Scan
The image, record, or data obtained by scanning, usually identified by the technology or device employed; e.g., CT scan, radionuclide scan, ultrasound scan, etc.

Sonographer
An allied health professional who has been specifically trained to perform ultrasound examinations. Many sonographers are certified by a registry of sonographers, provided they meet strict training requirements and pass examinations in basic ultrasound science and clinical applications.

Sonography
The location, measurement, or delineation of deep structures by measuring the reflection or transmission of high frequency or ultrasonic waves. Computer calculation of the distance to the sound reflecting or absorbing surface plus the known orientation of the sound beam gives a two- or three-dimensional image.

Spiral CT Scan
A spiral CT scan is a new specialized CT scan technique that involves continuous movement of the patient through the scanner with the ability to scan faster and with higher definition of internal structures. Helical CT scanning can permit greater visualization of blood vessels and internal tissues, such as those within the chest cavity. This form of scanner may be particularly helpful in the rapid evaluation of severe trauma injuries, such as those sustained in automobile accidents. A spiral CT scan is also referred to as helical CT scan.

Stent
A tube designed to be inserted into a vessel or passageway to keep it open. Stents are inserted into narrowed coronary arteries to help keep them open after balloon angioplasty. The stent then allows the normal flow of blood and oxygen to the heart. Stents placed in narrowed carotid arteries (the vessels in the front of the neck that supply blood to the brain) appear useful in treating patients at elevated risk for stroke. Stents are also used in other structures such as the esophagus to treat a constriction, the ureters to maintain the drainage of urine from the kidneys, and the bile duct to keep it open.

Tomography
Making a radiographic image of a selected plane by means of reciprocal linear or curved motion of the x-ray tube and film cassette; images of all other planes are blurred ("out of focus") by being relatively displaced on the film.

Transducer
An instrument that converts electrical energy into mechanical energy. A transducer can also act as a transmitter and receiver of ultrasound information.

Transvaginal Ultrasound
A technique in which sound waves are sent out by an ultrasound probe that has been inserted in the vagina. The waves go through the vaginal wall and bounce off the ovaries, and a computer uses the ultrasound echoes to create a picture (a sonogram). Transvaginal ultrasound is also referred to as TVS. Ovarian cancer is difficult to detect before it reaches an advanced stage when it carries a poor prognosis (outlook). TVs has been reported to be effective as a screening tool to detect ovarian cancer while it is still in an early, curable stage.

Ultrasound
A test in which high-frequency sound waves (ultrasound) are bounced off tissues using special devices and the echoes are converted into a picture (sonogram). Ultrasound imaging, referred to as ultrasonography, allows physicians and patients to get an inside view of soft tissues and body cavities, without using invasive techniques. Ultrasound is often used to examine a fetus during pregnancy. There is no convincing evidence for any danger from ultrasound during pregnancy.

Virtual Colonoscopy
A method for examining the colon by taking a series of x-rays (a CT scan) and then using a computer to reconstruct 2-D and 3-D pictures of the interior surfaces of the colon from these x-rays. The pictures can be saved, manipulated to better viewing angles, and reviewed at any time after the procedure.

X-ray
High-energy radiation; radiation with waves shorter than those of visible light. It is used in low doses for making images that help to diagnose diseases, and in high doses to treat cancer.

•  X-ray, AP
An X-ray picture in which the beams pass from front-to-back (anteroposterior). An AP film is as opposed to a PA (posteroanterior) film in which the rays pass through the body from back-to-front.

•  X-ray, lateral
An X-ray picture taken from the side.

•  X-ray, PA
An X-ray picture in which the beams pass from back-to-front (posteroanterior). By contrast an AP (anteroposterior) film is one in which the rays pass through the body from front-to-back.