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Q. What is the need for cardiac CT? |
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Coronary Artery disease (CAD) is the leading cause of death in the industrialized world.
n “Screening” is a widely accepted strategy to combat CAD for early detection of stenosis of the coronary artery lumen.
n Exclusion of stenosis in non- symptomatic high risk patients.
n Prior to major (non-cardiac) Surgery.
n Atypical (unstable) chest pain.
n Refractory chest pain with doubtful coronary origin.
n Non-conclusive stress tests.
n As a substitute to conventional coronary angiography prior to percatareous coronary intervention and in high risk patient like aortic disease.
n Adjuvant to coronary Angio for Plaque characterization ,Complicated coronary intubation., Total coronary occlusion.
n Follow-up in -Percutaneous coronary intervention-Bypass Surgery.
n Evaluation of coronary anomalies.
n Evaluation of chest pain at emergency department.
n Evaluation of lifestyle, dietary or pharmacological interventions on progression /regression of coronary atherosclerosis.
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Q. How is the procedure performed? |
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n Prior appointment taken (at any convenient time for the patient).
n To come 4 hours fasting for the examination (to take all medicines as per schedule) with all previous cardiac-related information.
n Stabilization of heart rate with an oral β-blocker (if required).
n If pulse rate low and regular, the patient is taken for the examination.
n An IV line is put into a peripheral vein in the arm.
n Breathing rehearsal for approximately 12 second breath-hold.
n CT calcium scoring study is performed with a non contrast scan, in a single breath hold.
n Contrast is injected and angiogram performed with a single breathhold study.
n The patient is ready to leave for normal daily routine.
n There is absolutely no pain, no hospitalization, and noninvasive.
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Q. How is it performed? |
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During a CT scan, you lie on a table inside a doughnut-shaped machine called a gantry. An X-ray tube inside the machine rotates around your body and sends small doses of radiation through it at various angles. As X-rays pass through your body, different tissues absorb different amounts. Detectors inside the gantry measure the radiation leaving your body and convert the radiation into electrical signals. A computer gathers these signals and assigns them a color ranging from black to white depending on signal intensity. The computer then assembles the images and displays them on a computer monitor.
n Calcium scoring - we do a plain scan for calcium content evaluation of the coronary arteries.
n Coronary Artery Lumen evaluation with non invasive CT coronary angiography.
n Argus Function evaluation of the ventricular muscle mass.
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Q. What are the dangers of CT scanning? |
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n Though it involves x-ray radiation, there are no dangers in practice. Only in pregnant women, it should be done after weighing all the risks of exposing your fetus to radiation and benefits (like any other CT investigation).
n Dangers of contrast medium.
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Q. What is a ‘contrast’ medium? |
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A contrast is a iodinated compound injected intravenously (peripherally) to opacify the vessels and enhances the ability of CT scans to pick up abnormalities
Only the very safest contrast (non-ionic) is used for all the patients in our centre. This gives better compliance with patients, as compared to ionic contrast, which is cheaper but gives more adverse reactions.
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Q. What is a ‘contrast’ medium? |
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A contrast is a iodinated compound injected intravenously (peripherally) to opacify the vessels and enhances the ability of CT scans to pick up abnormalities
Only the very safest contrast (non-ionic) is used for all the patients in our centre. This gives better compliance with patients, as compared to ionic contrast, which is cheaper but gives more adverse reactions.
Dangers of contrast medium
Though not so common, the contrast medium involved in a CT scan poses a slight risk of allergic reaction.
n Most reactions result in hives or itchiness.
n For individuals with asthma who become allergic to the contrast medium, the reaction can be an asthma attack.
n In very rare instances, an allergic reaction might cause swelling in your throat or other areas of your body.
If you experience hives, itchiness or swelling in your throat during or after your CT exam, immediately tell your technologist or doctor. We keep an emergency kit for all commonly known adverse reactions.
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Q. Who is at ‘ high-risk’ for contrast injection? |
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n Past history of reaction to contrast/any other drugs.
n Bronchial asthma.
n Cardiac/kidney disease /diabetes etc.
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Q. Other indications your doctor may recommend a CT scan to help? |
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n Diagnose muscle and bone disorders, such as bone tumors and fractures.
n Pinpoint the location of a tumor, infection or blood clot.
n Guide procedures such as surgery, biopsy and radiation.
n Detect and monitor diseases such as cancer.
n Detect internal injuries and internal bleeding.
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Q. What can you expect during a CT scan? |
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Expect the exam to last no more than an hour, depending on the preparation needed and whether it includes the use of contrast medium. The scan itself may take just a few minutes.
n During the CT scan you lie on a narrow table that slides through the opening of a large device called the gantry. The table can be raised, lowered or tilted. Straps and pillows may help you stay in position. During a CT scan of the head, the table may be fitted with a special cradle that holds your head still.
n As the X-ray tube rotates around your body, the table slowly moves through the gantry. While the table is moving you may need to hold your breath to
avoid blurring the images. You may hear clicking and whirring noises. Each rotation yields several images of thin slices of your body.
n During this time, a technologist in a shielded room supervises the CT scan and monitors the images as they appear on the computer screen. The
technologist can see and hear you, and you can communicate via intercom.
n If an infant or small child is having the CT scan, you may be allowed to stay with your child during the test. If so, you may be asked to wear a lead apron to shield you from X-ray exposure.
n CT scans are painless. If your exam involves use of an intravenous contrast medium, you may feel a brief sensation of heat or experience a metallic taste
in your mouth. If you receive contrast medium through an enema - to help highlight your lower gastrointestinal region - you may feel a sense of fullness or
cramping.
After the exam you can return to your normal routine. If you were given a contrast medium, your doctor or the radiography staff may give you special instructions. These likely include drinking lots of fluids to help remove the medium from your body.
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