| Medical Dictionary |
A Medical Dictionary of Medical Terminology
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Computed tomography (CT) is a type of medical imaging test that uses special x-ray equipment to make detailed pictures of the inside of your body.
A CT scan produces cross-sectional pictures, which are like slices of the body. These images show the size and structure of organs, bones, and other tissues. CT images can also be combined to create 3-dimensional (3D) views.
Health care providers use CT scans to diagnose, treat, and monitor many health conditions.
Who needs a CT scan?Your provider may suggest a CT scan for many reasons, including:
CT scans may also be used to find the best place to perform a biopsy or help guide certain treatments. They may also be used to check for internal bleeding or injury after trauma or to evaluate the brain for certain conditions.
How do you prepare for a CT scan?You may be asked not to eat or drink for a few hours before the scan. Ask your provider if there are any special instructions to follow.
For some CT scans, you may receive a contrast material. Contrast helps certain parts of the body show up more clearly on the images. Depending on what area is being examined, contrast material might be given as:
CT scans use ionizing radiation at levels higher than a standard x-ray, but the amount is kept as low as possible. Always tell your provider if you are pregnant or think you may be pregnant.
How is a CT scan done?You may be asked to change clothes and remove jewelry or other items that could interfere with the scan.
During the scan, you lie still on a table. The table slowly passes through the center of a large donut-shaped machine. The x-ray tube rotates around your body to create images.
You may hear whirring sounds during the scan. You may be asked to hold your breath for short periods. The test is painless.
The scan usually takes a few minutes, but some may last up to 30 minutes, depending on the area being scanned.
What should you expect after a CT scan?Most people can return to normal activities right away. If you were given a contrast material, drinking fluids can help your body clear it.
A specialist called a radiologist reviews the images and shares the results with your provider.
NIH: National Cancer Institute
Heart diseases are the number one killer in the United States. They are also a major cause of disability. If you do have heart disease, it is important to find it early, when it is easier to treat. Blood tests and heart health tests can help find heart diseases or identify problems that can lead to heart diseases. There are several different types of heart health tests. Your health care provider will decide which test or tests you need, based on your symptoms (if any), risk factors, and medical history.
Cardiac CatheterizationCardiac catheterization is a medical procedure used to diagnose and treat some heart conditions. For the procedure, your provider puts a catheter (a long, thin, flexible tube) into a blood vessel in your arm, groin, or neck, and threads it to your heart. The provider can use the catheter to:
A cardiac CT (computed tomography) scan is a painless imaging test that uses x-rays to take detailed pictures of your heart and its blood vessels. Computers can combine these pictures to create a three-dimensional (3D) model of your whole heart. This test can help providers detect or evaluate various heart problems, including:
Before you have the test, you get an injection of contrast dye. The dye highlights your heart and blood vessels in the pictures. The CT scanner is a large, tunnel-like machine. You lie still on a table that slides you into the scanner, and the scanner takes the pictures.
Cardiac MRICardiac MRI (magnetic resonance imaging) is a painless imaging test that uses radio waves, magnets, and a computer to create detailed pictures of your heart. It can help your provider figure out whether you have heart disease, and if so, how severe it is. A cardiac MRI can also help your provider decide the best way to treat heart problems such as:
The MRI is a large, tunnel-like machine. You lie still on a table that slides you into the MRI machine. The machine makes loud noises as it takes pictures of your heart. Sometimes before the test, you might get an injection of contrast dye. The dye highlights your heart and blood vessels in the pictures.
Chest X-RayA chest x-ray creates pictures of the organs and structures inside your chest, such as your heart, lungs, and blood vessels. It can reveal signs of heart failure, as well as lung disorders and other causes of symptoms not related to heart disease.
Coronary AngiographyCoronary angiography (angiogram) is a procedure that uses contrast dye and x-ray pictures to look at the insides of your arteries. It can show whether plaque is blocking your arteries and how severe the blockage is. Providers use this procedure to diagnose heart diseases after chest pain, sudden cardiac arrest (SCA), or abnormal results from other heart tests such as an EKG or a stress test.
You usually have a cardiac catheterization to inject the dye into your coronary arteries. Then the provider will take special x-rays while the dye is flowing through your coronary arteries. The dye lets your provider study the flow of blood through your heart and blood vessels.
EchocardiographyEchocardiography, or echo, is a painless test that uses sound waves to create moving pictures of your heart. The pictures show the size and shape of your heart. They also show how well your heart's chambers and valves are working. Providers use an echo to diagnose many different heart problems, and to check how severe they are.
There are several different types of echocardiography. For transthoracic echocardiography (the most common type), a technician applies gel to your chest. The gel helps sound waves reach your heart. The technician moves a transducer (wand-like device) across your chest. The transducer connects to a computer. It transmits ultrasound waves into your chest, and the waves bounce (echo) back. The computer converts the echoes into pictures of your heart.
Electrocardiogram (EKG), (ECG)An electrocardiogram, also called an ECG or EKG, is a painless test that detects and records your heart's electrical activity. It shows how fast your heart is beating and whether its rhythm is steady or irregular.
An EKG may be part of a routine exam to screen for heart disease. Or you may get it to detect and study heart problems such as heart attacks, arrhythmia, and heart failure.
For the test, you lie still on a table and a nurse or technician attaches electrodes (patches that have sensors) to the skin on your chest, arms, and legs. Wires connect the electrodes to a machine that records your heart's electrical activity.
Stress TestingStress testing looks at how your heart works during physical stress. It can help to diagnose coronary artery disease, and to check how severe it is. It can also check for other problems, including heart valve disease and heart failure.
For the test, you exercise (or are given medicine if you are unable to exercise) to make your heart work hard and beat fast. While this is happening, you get an EKG and blood pressure monitoring. Before or after the test, you might also have an echocardiogram, or other imaging tests such as a nuclear scan. For the nuclear scan, you get an injection of a tracer (a radioactive substance), which travels to your heart. Special cameras detect the energy from the tracer to craeate pictures of your heart. You have pictures taken after you exercise, and then after you rest.
NIH: National Heart, Lung, and Blood Institute
Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special camera that detects radioactivity.
Before the test, you receive a small amount of radioactive material. You may get it as an injection. Sometimes you swallow it or inhale it. Then you lie still on a table while the camera makes images. Most scans take 20 to 45 minutes.
Nuclear scans can help doctors diagnose many conditions, including cancers, injuries, and infections. They can also show how organs like your heart and lungs are working.
An abscess is a pocket of pus. You can get an abscess almost anywhere in your body. When an area of your body becomes infected, your body's immune system tries to fight the infection. White blood cells go to the infected area, collect within the damaged tissue, and cause inflammation. During this process, pus forms. Pus is a mixture of living and dead white blood cells, germs, and dead tissue.
Bacteria, viruses, parasites and swallowed objects can all lead to abscesses. Skin abscesses are easy to detect. They are red, raised and painful. Abscesses inside your body may not be obvious and can damage organs, including the brain, lungs and others. Treatments include drainage and antibiotics.
An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. The tumor usually grows slowly. As it grows, it presses against the hearing and balance nerves. At first, you may have no symptoms or mild symptoms. They can include:
The tumor can also eventually cause numbness or paralysis of the face. If it grows large enough, it can press against the brain, becoming life-threatening.
Acoustic neuroma can be difficult to diagnose, because the symptoms are similar to those of middle ear problems. Ear exams, hearing tests, and scans can show if you have it.
If the tumor stays small, you may only need to have it checked regularly. If you do need treatment, surgery and radiation are options.
If the tumors affect both hearing nerves, it is often because of a genetic disorder called neurofibromatosis.
NIH: National Institute on Deafness and Communication Disorders
Your brain is the control center of your body. It controls your thoughts, memory, speech, and movement. It regulates the function of many organs. It's part of your nervous system, which also includes your spinal cord and peripheral nerves. The nervous system sends signals between your brain and the rest of the body. Your nerves take in information from your senses and send it to the brain to be processed. Your brain and nerves also communicate to help you move and to control your body's functions.
When the brain is healthy, it works quickly and automatically. But when you have a brain disease, it may affect how well you can function and do your daily activities. Some common brain diseases include:
The symptoms of brain diseases vary widely, depending on the specific problem. In some cases, damage is permanent. In other cases, treatments such as surgery, medicines, or therapies such as physical, occupational, and speech therapies, may cure the disease or improve the symptoms.
Most brain malformations begin long before a baby is born. Something damages the developing nervous system or causes it to develop abnormally. Sometimes it's a genetic problem. In other cases, exposure to certain medicines, infections, or radiation during pregnancy interferes with brain development. Parts of the brain may be missing, abnormally small or large, or not fully developed.
Treatment depends upon the problem. In many cases, treatment only helps with symptoms. It may include antiseizure medicines, shunts to drain fluid from the brain, and physical therapy.
There are head malformations that do not involve the brain. Craniofacial disorders are the result of abnormal growth of soft tissue and bones in the face and head. It's common for new babies to have slightly uneven heads, but parents should watch the shape of their baby's head for possible problems.
NIH: National Institute of Neurological Disorders and Stroke
A brain tumor is a growth of abnormal cells in the tissues of the brain. Brain tumors can be benign, with no cancer cells, or malignant, with cancer cells that grow quickly. Some are primary brain tumors, which start in the brain. Others are metastatic, and they start somewhere else in the body and move to the brain.
Brain tumors can cause many symptoms. Some of the most common are:
Doctors diagnose brain tumors by doing a neurologic exam and tests including an MRI, CT scan, and biopsy. Treatment options include watchful waiting, surgery, radiation therapy, chemotherapy, and targeted therapy. Targeted therapy uses drugs or other substances that attack cancer cells with less harm to normal cells. Many people get a combination of treatments.
NIH: National Cancer Institute
Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should. These extra cells can form a mass called a tumor.
Tumors can be benign or malignant. Benign tumors aren't cancer, while malignant ones are. Cells from malignant tumors can invade nearby tissues. They can also break away and spread to other parts of your body. The spread of cancer from one part of the body to another is called metastasis. Symptoms and treatment depend on the type of cancer and how advanced it is.
What are the types of cancer?There are more than 100 different types of cancer. Cancer can start almost anywhere in your body. Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast.
Cancer may also be described by the type of cell that formed it, such as sarcoma if cancer begins in your bone and soft tissue. Carcinoma is the most common type of cancer. It is formed by epithelial cells, the cells that cover the inside and outside surfaces of your body.
How does cancer develop?Cancer is a genetic disease. That means changes in your genes cause it. Changes in your genes are also called gene variants or mutations. Genes are parts of DNA in your cells that you inherit from your parents. However, only some cancers are caused by genes passed down from your parents.
Genetic changes can occur to your genes over your lifetime that affect how your cells function. Usually, your body gets rid of damaged cells before they turn cancerous, but this ability goes down as you age. Other factors that may affect your risk of developing cancer can include:
Cancer symptoms depend on the type of cancer. For example, some of the symptoms that cancer may cause can include:
Cancer may cause various symptoms but often doesn't cause pain. Don't wait until you're having pain before seeing your health care provider. See your provider if you have symptoms that don't get better in a few weeks.
How is cancer diagnosed?There is no single test that can diagnose cancer. The tests ordered are usually based on your symptoms. Your provider may:
To find out if you have cancer, your provider may order a biopsy. A biopsy is the procedure of removing and examining tissue, cells, or fluids from your body.
What are the treatments for cancer?Treatment depends on the type of cancer and how advanced it is. Most treatment plans may include surgery, radiation, and/or chemotherapy. Some may involve hormone therapy, immunotherapy or other types of biological therapy, or stem cell transplantation.
Can cancer be prevented?It's usually not possible to know exactly why cancer develops in some people but not others. There are some things that you can't control which may increase or decrease your risk of getting cancer, such as inheriting certain genes or your age. But some lifestyle habits may increase your risk of certain types of cancer. Avoid or reduce lifestyle habits such as:
NIH: National Cancer Institute
When you play the piano or hit a tennis ball you are activating the cerebellum. The cerebellum is the area of the brain that controls coordination and balance. Problems with the cerebellum include:
Treatment of cerebellar disorders depends on the cause. In some cases, there is no cure but treatment may help with symptoms.
NIH: National Institute of Neurological Disorders and Stroke