A computed tomography (CT) scan of the knee is an imaging method that uses x-rays to create detailed pictures of the knee.
Alternative NamesCAT scan - knee; Computed axial tomography scan - knee; Computed tomography scan - knee
How the test is performedYou will be asked to lie on a narrow table that slides into the center of the CT scanner. You will lie on your back.
Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam in one continuous motion.)
Small detectors inside the scanner measure the amount of x-rays that make it through the knee. A computer takes this information and uses it to create several individual images, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of the knee can be created by stacking the individual slices together.
You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time.
The test should take less than 1 hour.
How to prepare for the testCertain exams require a special dye, called contrast, to be delivered into the body before the test starts. Contrast can highlight specific areas inside the body, which creates a clearer image.
Some people have Allergies to IV contrast and may need to take medications before their test in order to safely receive this substance.
Contrast can be given several ways:
If contrast is used, you may also be asked not to eat or drink anything for 4-6 hours before the test.
If you weigh more than 300 pounds, have your doctor contact the scanner operator before the exam. CT scanners have a weight limit. Too much weight can cause damage to the scanner's working parts.
Since x-rays have difficulty passing through metal, you will be asked to remove jewelry and wear a hospital gown during the study.
How the test will feelSome people may have discomfort from lying on the hard table.
Contrast given through an IV may cause a slight burning sensation, a metallic taste in the mouth, and a warm flushing of the body. These sensations are normal and usually go away within a few seconds.
Why the test is performedCT rapidly creates more detailed pictures of the knee than can be seen on standard x-rays. The test may be used to:
Results are considered normal if the knee being examined is normal in appearance.
What abnormal results meanAbnormal results may be due to:
CT scans and other x-rays are strictly monitored and controlled to make sure they use the least amount of radiation. CT scans do create low levels of ionizing radiation, which has the potential to cause cancer and other defects. However, the risk associated with any individual scan is small. The risk increases as numerous additional studies are performed.
In some cases, a CT scan may still be done if the benefits greatly outweigh the risks. For example, it can be more risky not to have the exam, especially if your health care provider thinks you might have cancer.
The most common type of contrast given into a vein contains iodine. If a person with an iodine allergy is given this type of contrast, nausea or vomiting, sneezing, itching, or hives may occur. Let your doctor know if you have ever had an allergic reaction to injected contrast dye.
If you absolutely must be given such contrast, your doctor may choose to treat you with antihistamines (such as Benadryl) or steroids before the test.
The kidneys help filter the iodine out of the body. Therefore, those with kidney disease or Diabetes should receive plenty of fluids after the test, and be closely monitored for kidney problems. If you have diabetes or are on kidney dialysis, talk to your health care provider before the test about your risks.
Before receving the contrast, tell your health care provider if you take the diabetes medication metformin (Glucophage) because you may need to take extra precautions.
Rarely, the dye may cause a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.
ReferencesBeynnon BD, Johnson RJ, Coughlin KM. Knee. In: DeLee JC, Drez Jr. D. DeLee & Drez's Orthopaedic Sports Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2003:chap 28.
A computed tomography (CT) scan of the knee is an imaging method that uses x-rays to create detailed pictures of the knee.
Alternative NamesCAT scan - knee; Computed axial tomography scan - knee; Computed tomography scan - knee
How the test is performedYou will be asked to lie on a narrow table that slides into the center of the CT scanner.
Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam without stopping.)
A computer creates separate images of the body area, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of the body area can be created by stacking the slices together.
You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time.
The scan should take less than 30 minutes.
How to prepare for the testCertain exams require a special dye, called contrast, to be delivered into the body before the test starts. Contrast helps certain areas show up better on the x-rays.
If you weigh more than 300 pounds, find out if the CT machine has a weight limit. Too much weight can cause damage to the scanner's working parts.
You will be asked to remove jewelry and wear a hospital gown during the study.
How the test will feelSome people may have discomfort from lying on the hard table.
Contrast given through an IV may cause a slight burning sensation, a metallic taste in the mouth, and a warm flushing of the body. These sensations are normal and usually go away within a few seconds.
Why the test is performedCT rapidly creates more detailed pictures of the knee than can be seen on standard x-rays. The test may be diagnose or detect:
A CT scan may also be used to guide a surgeon to the right area during a biopsy.
Normal ValuesResults are considered normal if the knee being examined is normal in appearance.
What abnormal results meanAbnormal results may be due to:
Risks of CT scans include:
CT scans do expose you to more radiation than regular x-rays. Having many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. You and your doctor should weigh this risk against the benefits of getting a correct diagnosis for a medical problem.
Some people have allergies to contrast dye. Let your doctor know if you have ever had an allergic reaction to injected contrast dye.
Rarely, the dye may cause a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.
ReferencesDeLee JC, Drez D Jr, Miller MD, eds. DeLee and Drez's Orthopaedic Sports Medicine. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 23.
Grainger RG, Thomsen HS, Morcos SK, Koh DM, Roditi G. Intravascular contrast media for radiology, CT, and MRI. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 2.
Shaw AS, Dixon AK. Multidetector computed tomography. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 4.
Reviewed ByReview Date: 02/17/2011
Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
No. You can have CT Scan instead.
Can I smoke before ct scan
There are no generally contraindicated medications after a contrast enhanced Ct Scan.
should you eat before having a ct scan of the chest and abdomen
CT scan
cat scan
A CT scan is about $300 to $6750, while a MRI scan is $400 to $12,000.
Yes, it is possible to CT scan a child.
No, you cannot see an ulcer on a ct scan.
Side effect of cervical ct scan?
I looked your question up on google translate and CT scan is "Tomografia computarizada" but just CT is "CT" english to spanish
AXIAL