Diagnostic Imaging

Diagnostic Imaging

Diagnostic Imaging
Diagnostic imaging includes ultrasounds, X-rays, CT scans and MRIs. These create images of different parts of the body and aid in diagnosing diseases and conditions allowing for a course of treatment to be prescribed. Learn more about diagnostic imaging from our experts.

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    A kidney scan, also called a renal scan, often means an ultrasound scan of the kidneys, the fist-sized organs located below the ribcage and on either side of the spine that filter blood and produce urine to carry waste out of the body. A kidney scan is used to monitor kidney function and to diagnose problems like tumors, blood clots, cysts, or kidney stones or blockages, to look for infection, swelling, or signs of injury, or determine if there is fluid retention or complications from a kidney transplant. In an ultrasound, a device called a transducer sends sound waves into the body to create an image of the organs on a screen.

    Another type of kidney scan is a nuclear medicine test to check the structure and function of the kidneys. A small amount of a radioactive substance called a tracer is injected into a vein in the arm. The substance travels through the bloodstream and collects in the kidneys, enabling a special camera to take pictures of the kidneys and surrounding structures. A computer reviews the pictures and provides detailed information to the doctor about the size, position, shape and functioning of the kidneys. The scan takes about 30-60 minutes. It can be used to measure blood pressure in the renal arteries, or determine if kidneys can be saved following injury or other problems. 
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    Bone scans are used if a doctor wants to see if islet cell tumors have spread to nearby bone. During the test, a small amount of radioactive material is injected into a vein. The radioactive material builds up in areas of the bone where cellular activity is very high, such as in a tumor. A special camera is then used to take pictures of the body. Areas where the radioactive material has built up will show up as dark spots in the pictures, indicating a possible tumor.

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    A bone scan is a technique to create images of bones on a computer screen or on film. A small amount of radioactive material is injected into a blood vessel and travels through the bloodstream; it collects in the bones and is detected by a scanner.

    This answer is based on source material from the National Cancer Institute.  

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    A , Oncology, answered
    For a PET scan, a form of radioactive sugar (known as fluorodeoxyglucose or FDG) is injected into the blood. The amount of radioactivity used is very low. Cancer cells in the body grow rapidly, so they absorb large amounts of the radioactive sugar. After about an hour, you will be moved onto a table in the PET scanner. You lie on the table for about 30 minutes while a special camera creates a picture of areas of radioactivity in the body. The picture is not finely detailed like a CT or MRI scan, but it provides helpful information about your whole body.
    A PET scan can help give the doctor a better idea of whether an abnormal area seen on another imaging test is a tumor or not. If you have already been diagnosed with cancer, your doctor may use this test to see if the cancer has spread to lymph nodes or other parts of the body. A PET scan can also be useful if your doctor thinks the cancer may have spread but doesn't know where.
    Some newer machines are able to perform both a PET and CT scan at the same time (PET/CT scan). This allows the doctor to compare areas of higher radioactivity on the PET with the more detailed appearance of that area on the CT.
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    Positron emission tomography (PET) is used to diagnose cancer. During a PET scan, you will have a small amount of radioactive sugar injected into a vein (intravenously). Any cancer cells will absorb this material. A special camera spots the cells that soaked up the sugar. PET is based on the idea that cancerous tissue uses more sugar than normal tissue, leading cancers to "light up" on the scans. The technique is very sensitive and even very small cancerous tumors can show up easily.

    The test can be used to determine if cancer has spread to lymph nodes or other distant places. It is also used to tell if a shadow on your chest x-ray is cancer or not. Most insurance companies cover expenses for PET imaging, including Medicare. However, false-positive and false-negative PET findings may occur. That means the scan shows what looks like cancer, but it really isn't. Or, it doesn't show a cancer when one really exists. So, it's important that the scans be interpreted very carefully.

    Today, there are newer machines available that can perform a PET and computed tomography (CT) scan at the same time (PET/CT scan). This test allows doctors to compare areas of higher radioactivity on the PET scan with the appearance of the same areas on the CT scan so they can better diagnosis any problems or uncertain findings.
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    The most common gallbladder scan is an ultrasound. This is done with a small probe that is gently scanned over your abdomen. The probe sends sound waves through the body and creates images using these sound waves. Your doctor or a technician can perform the ultrasound scan. It is not invasive and does not use radiation. Other scans include a computed tomography (CT) scan, which uses x-rays to scan the body and produce images, and a hepatobiliary iminodiacetic acid (HIDA) scan, which looks at how the gallbladder functions after you receive an injection of a drug that is taken up by the liver and gallbladder and then emptied into the intestines.
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    A gallbladder scan is an imaging procedure that provides a view of the gallbladder to check its structure and function. The gallbladder is a small organ attached to the liver that stores bile and then releases the bile into a duct to be transferred into the intestine. There are different means of scanning the gallbladder, but the most common is an ultrasound. In an ultrasound, a device called a transducer sends sound waves into the body to create an image of the organ on a screen. A gallbladder scan may be used to diagnose problems in the gallbladder and surrounding structures including:
    • a blocked or abnormal bile duct
    • bile leaks
    • gallbladder infection
    • gallstones
    • tumors
    • abscesses
    • cysts
    • blood clots
    • malfunctions of the gallbladder
    Another type of gallbladder scan, called a gallbladder radionuclide scan, is a type of nuclear medicine scan used to check the structure and function of the gallbladder. A radioactive substance called a tracer is injected into a vein in the arm. The tracer is processed through the liver and gallbladder, while a special camera takes images of the structures and tissues through which the tracer travels. The radionuclide scan may be used to check an infection of the gallbladder, blockage of a bile duct, or to determine the function of a transplanted liver. 
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    After a diagnosis of hyperthyroidism is made, a thyroid scan helps health professionals know the reason for the excess thyroid hormone in the body in order to prescribe treatment. For this test, you will be injected with a radioactive isotope. A camera takes images of your thyroid. This test reveals how and where iodine goes in your thyroid gland. It helps reveal hyperfunctioning thyroid nodules or other thyroid irregularities.

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    A , Endocrinology Diabetes & Metabolism, answered
    There are several kinds of x-ray or imaging studies that can be used in the evaluation of thyroid disease.  The most common is an ultrasound which uses high-frequency sound waves to give a 3 dimensional image.  This is useful for checking for the presence of solid thyroid nodules--growths  within the thyroid gland--which may be solid or fluid filled (cysts).  In most cases a thyroid ultrasound gives the most precise information about the anatomy of the thyroid.  To get functional information, the best test is a thyroid scan.
    Actually, when we say a "thyroid scan," we usually really mean two separate tests:  a thyroid scan and radioactive iodine uptake.  These tests are done together  and the results are interpreted together.  The proper interpretation of a thyroid scan and radioactive iodine uptake is often helpful in the diagnosis of many thyroid disorders.
    The thyroid scan gives information functional information in a pictorial sense.  The test uses a radioactive material--usually technetium, though iodine can be used---to tell whether the thyroid gland is functioning uniformly or whether some areas are making too much thyroid hormone or not enough.  The resulting images give a 2 dimensional picture of how the radioactive material is distributed throughout  the thyroid  gland.  An area that has increased amount  of the radioactive material is said to be "hot," and an area with diminished radioactive material is said to be "cold."  In most cases this information is important for the evaluation of a thyroid nodule.  A "hot nodule" may be the source of increased amounts of thyroid hormone in the blood (hyperthyroidism) while a cold nodule may require a fine needle biopsy to exclude cancer.
    The radioactive iodine uptake is a quantitative test.  Instead of a picture, a number is generated.  A high uptake indicates overall increased metabolic activity in a gland.  The  most common use for this is to distinguish among causes of hyperthyroidism.  For example, Graves' disease, which results from overall increased thyroid activity on the basis of an immune problem, usually results in a very high iodine uptake, while Hashimoto's disease, which sometimes results in hyperthyroidism early on, typically would have a very low value.
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    A thyroid scan is a way for your doctor to see the shape of your thyroid. Your doctor will inject a radioactive isotope into a vein of your arm. This isotope then travels through the bloodstream to the thyroid. A camera then takes a photo of your thyroid, which is more visible than usual due to the isotope.