Computed tomography (CT) uses X-rays to create numerous cross-sectional pictures of the body (tomography is imaging by sections or “slices” of tissue). The CT scanner sends X-ray pulses through the body area being studied. Each pulse takes a picture of a thin slice of the organ or area. Pictures, which can be taken from different positions, are saved on a computer. The scanner can generate multiple two- and three-dimensional cross-sections of tissue. Certain CT examinations require patients to receive an injection of contrast (“dye”) or drink a fluid prior to the scan.
CT is used to diagnose disease and injury in many areas of the body. It is used in:
- Trauma care to quickly assess the severity of illness and injuries
- Oncology to evaluate the extent of cancer (staging) and a patient’s response to cancer therapy
- Gastrointestinal (GI) care to detect inflammatory bowel disease and other disorders of the GI tract
- Postoperative evaluation to look for leaks or obstructions following surgery
- Chest disorders to detect a pulmonary embolism (blocked artery in the lung), emphysema, lung cancer, fibrotic lung tissue and other diseases
- Orthopaedics to exam bones for fractures and tumors and to aid in planning for surgery.
CT neuro-angiography (CTA)
CT neuro-angiography is a neuro-imaging technique that combines CT with X-rays and the injection of a contrast material to examine blood vessels in the brain. X-rays are passed through the area of interest from several different angles to create cross-sectional images, which are then assembled by into a 3-D picture by a computer.
Froedtert Hospital was the first in the world to use a 64-slice volume computed tomography scanner. It is available 24-hours a day and can scan the entire body in less than 10 seconds, giving surgeons more immediate information for determining treatment, ultimately providing you faster care.
Angiography uses a special form of X-ray and a “dye” that is injected into the bloodstream to see the detailed anatomy of the blood vessels in the body. At Froedtert & the Medical College of Wisconsin, diagnostic angiography is performed almost exclusively with the 64-slice VCT scanner. This includes studies of the carotid artery/brain circulation, thoracic and abdominal aorta, abdominal imaging of the liver, pancreas, spleen, kidneys, and intestine, and upper and lower extremity angiography. Compared to the previous technique that involves using an invasive catheter, CT angiography is less invasive (intravenous injection), faster, more convenient for patients, and provide a high-resolution image. The VCT scanner enables angiograms to be performed at acceptable radiation dose with relative low volumes of contrast medium.
Major national and international clinical trials are demonstrating that CT angiography of the coronary arteries performed with an intravenous injection of “dye” provides comparable images to invasive, catheter-based coronary angiography in patients at low to intermediate risk of heart disease. In addition, cardiac CT can demonstrate the structure and function of cardiac valves and chambers in a manor comparable to echocardiography and MRI.