- For Patients

Glossary of terms

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A non-steroidal anti-inflammatory drug (NSAID) available over-the-counter.

A surgical procedure to attach the ileum (a portion of the small intestine) to an opening made in the abdomen.

The third portion of the small intestine.

image recording plate
Part of an electronic detector used in a digital imaging system. An x-ray machine produces a small burst of radiation that passes through the body, recording an image either on photographic film or, in a digital system, on the image recording plate of an electronic detector, a device that converts the x-rays into digital signals which are in turn sent to a computer to produce images.

image-guided biopsy
The use of imaging modalities, such as ultrasound, CT, x-ray or MRI, to assist in targeting a lesion too small to be felt so that cells can be removed from the suspicious area and examined under a microscope to determine whether the abnormality is cancerous.

image-guided radiation therapy (IGRT)
A technique for external beam therapy in which more precise radiation doses are delivered to a malignant tumor or even specific areas within the tumor. Often used in conjunction with intensity-modulated radiation therapy (IMRT). For details see the IGRT page.

immunoreactive trypsinogen (IRT)
A chemical released by the pancreas. High levels of IRT can be an indication of cystic fibrosis.


  1. The practice of giving small amounts of an allergy-producing substance in order to stimulate the formation of antibody that will neutralize it.
  2. Use of the body's immune system to fight tumors.


  1. A tooth compressed between the jaw and another tooth that fails to fully erupt through the surface of the gums.
  2. An immobile mass of stool that does not easily pass from the rectum.

A painful condition that occurs when the tendons of the rotator cuff muscles and the bursa, or fluid-filled sacs, in the shoulder joint become irritated and inflamed due to compression of soft tissues. Impingement can result in weakness and loss of movement at the shoulder.


  1. To graft or insert.
  2. Material inserted or grafted into tissues.
  3. In dentistry, a graft or insert set in or onto the tooth socket prepared for its insertion.
  4. In orthopedics, a metallic or plastic device employed in joint reconstruction.

implanted cardiac defibrillator (ICD)
See defibrillator.

implanted port
A quarter-sized disk that is placed either surgically or by an interventional radiologist just beneath the skin in the chest or abdomen. The disk is connected to a catheter that is inserted into a large vein. Fluids, drugs, or blood products can be infused or blood drawn through a needle that is inserted into the disk through the skin. Examples of manufacturer's names: Port-o-cath, Infusaport, Lifeport.

Inability of the male to maintain erection and engage in sexual intercourse.

in situ breast cancer
The early stage of cancer when it is confined to the ducts of the breast where it began and has not invaded the surrounding fatty tissues.

incentive spirometer
A breathing apparatus that helps patients inflate their lungs and exercise breathing muscles to prevent the onset of pneumonia following surgery.

incisional biopsy
A type of surgical biopsy in which part of a lesion or abnormal group of cells is removed.

Inability to prevent the discharge of urine or feces.

Slow to develop or progress.

The death of tissue in the body caused by an obstruction in the tissue's blood supply, a lack of oxygen or both factors.

inferior vena cava
The large vein that returns blood from the legs and abdomen to the heart.

inferior vena cava (IVC) filter
A device that is implanted in the inferior vena cava, the large vein that returns blood from the legs to the heart, to prevent blood clots in the lower body from traveling to the heart or lungs.

The protective response of body tissues to irritation or injury. Signs include redness, heat, swelling and pain.

inflammatory bowel disease (IBD)
A group of inflammatory conditions affecting the colon and small intestine. The two major types are Crohn’s disease and ulcerative colitis.

Manufacturer's name. See implanted port.

Introduction of a fluid, nutrient, or medication directly into a vein by means of gravity flow.

infusion catheter
A catheter that is inserted into a large vein or artery directly into the bloodstream. Fluids, drugs or blood products can be infused or blood drawn through the catheter.

institutional review board (IRB)
A review body established to protect the welfare of human participants recruited for biomedical research.

intensity-modulated radiation therapy (IMRT)
A delivery technique for external beam therapy that uses special devices called collimators to regulate the intensity of the radiation beams, allowing different areas of a tumor and nearby tissues to receive different doses of radiation. For details see the IMRT page.

A drug used in biologic therapy to affect the division of cancer cells and slow tumor growth.

internal jugular vein
One of a pair of neck veins that collect blood from the brain and face and convey it toward the heart.

internal radiation therapy
See brachytherapy.

A physician specializing in the diagnosis and treatment of disorders of the internal organs.

interstitial lung disease
A respiratory disorder causing shortness of breath on effort. In time the lung tissue may become severely scarred. While some patients recover, others develop respiratory failure or heart failure.

The scaffolding of the lung that supports the tiny air sacs (alveoli) in the lung.

interventional radiologist
A radiologist who specializes in the use of fluoroscopy, CT, and ultrasound to guide passage through the skin by needle puncture, including introduction of wires and catheters for performing procedures such as biopsies, draining fluids, inserting catheters, or dilating or stenting narrowed ducts or vessels.

interventional radiology
The clinical subspecialty that uses fluoroscopy, CT, and ultrasound to guide percutaneous (through the skin) procedures such as performing biopsies, draining fluids, inserting catheters, or dilating or stenting narrowed ducts or vessels.

intervertebral disks
Disk-shaped pads of fibrous tissue that are interposed between the vertebrae.

intestinal obstruction
Partial or total blockage of movement of food or stool through the intestines.

One of the two innermost layers of the walls of the carotid arteries.

Within the skull.

intracranial aneurysm
A ballooning out of the wall of an artery inside the brain; it may lead the vessel to rupture and bleed heavily.

intracranial pressure (ICP)
The pressure inside the skull, in brain tissue and in the cerebrospinal fluid.

intractable ascites
A condition in which excess fluid continually builds up in the abdominal or peritoneal cavity despite appropriate medical therapy.

During surgery.

intraoperative cryotherapy
Cryotherapy is a minimally invasive treatment that uses extreme cold to freeze and destroy diseased tissue, including cancer cells. In an intraoperative cryotherapy procedure, tissue inside the body is treated by inserting a cryoprobe or a series of small needles through the skin and delivering liquid nitrogen or argon gas to the site of the diseased tissue.

intraoperative radiation therapy
Radiation treatment of cancer or other diseases done during surgery.

Within the mouth.

Situated within, occurring within, or administered by entering a bone.

intraosseous venography
A procedure in which an x-ray, or venogram, is taken of a bone after a special dye is injected into bone marrow, the soft substance that fills the hollow center of most bones.

intraperitoneal therapy
A minimally invasive procedure in which anti-cancer drugs are delivered into the peritoneal cavity through a catheter connected to a peritoneal port, a small reservoir or chamber surgically implanted under the skin near the abdomen.

Within the uterus.

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 pyelography (IVP)
Radiography of kidneys, ureters, and bladder following injection of contrast medium into a peripheral vein. For details see the Intravenous Pyelogram page.

intraventricular hemorrhage (IVH)
Bleeding into the ventricles within the brain.

A serious disorder in which one part of the intestine slides into another part of the intestine, similar to a folding telescope, creating an obstruction and causing swelling and inflammation. For information about diagnosis and treatment see the Therapeutic Enema for intussusception page.

An invasive procedure is typically an "open" operation, such as appendectomy, which requires a surgical incision for exposure of deep structures or organs for performance of an intervention.

invasive breast cancer
Cancer that has spread beyond the layer of tissue in which it first developed and is growing into surrounding, healthy tissues.

involved site radiation
A type of radiation therapy in which a patient receives radiation only to the parts of the body known to be cancerous.

A non-metallic element found in table salt, seawater and in plants and animals that grow in the sea. The human body requires small amounts of iodine for healthy growth and development. This element is present in many radiographic contrast materials.

ionizing radiation
Radiation of sufficient energy to dissociate atoms or molecules into electrically charged atoms or radicals in the irradiated material.


  1. The subjective enlargement of a bright object seen against a dark background.
  2. Exposure to the action of electromagnetic radiation (e.g., heat, light, x-rays).

irritable bowel syndrome
Characterized by abdominal pain and altered bowel function - alternating bouts of constipation and diarrhea.

An inadequate blood supply to an organ or part of the body.

ischemic stroke
A brain event that occurs when a blood vessel carrying blood to the brain is blocked or restricted by severely narrowed arteries or a thickened mass of blood called a blood clot.

One of two or more nuclides that are chemically identical, having the same number of protons, yet differ in mass number, since their nuclei contain different numbers of neutrons; individual isotopes are named with the inclusion of their mass number in the superior position (12C) and the atomic number (nuclear protons) in the inferior position (6C). In former usage, the mass numbers follow the chemical symbol (C-12).