Computed Tomography (CT)

Exam Forms

By logging in to Weill Cornell Connect, eCheck-In makes it easy to save time and complete all safety forms required for your upcoming appointment. 

Exam Preparation

Please notify our staff when scheduling and checking in for your appointment if any of the following apply to you:

  • If there is any possibility that you are pregnant.
  • If you are allergic to contrast.
  • If you have a history of kidney disease, especially if you are on dialysis.
  • If you are diabetic.
  • If you need an interpreter to assist you with your native language.

If you are having a Cardiac CTA (Computed Tomography Angiography of your heart), review the exam preparations by following the link below.

PDF icon How to prepare for your Cardiac CTA exam 

What should I wear to my appointment?

Wearing the right clothing may eliminate the need for you to change into a gown prior to your exam. Suggestions for appropriate clothing include:

  • Wear loungewear, pajamas, or loose-fitting cotton or linen clothing without metal embellishment. Metal can affect the quality of the images.
  • Do not wear clothing or undergarments with metal fasteners, zippers, hooks, under wires or other metal components.
  • Please leave items such as watches and jewelry at home.

Do I need to fast before my exam?

Depending on the type of exam you are having, you may need to fast before your exam or adjust the use of certain medications.

  • CT Enterography: No food or liquids four (4) hours prior to exam.
  • Cardiac CTA: No Phosphodiesterase Type 5 Inhibitor such as VIAGRA®, CIALIS®, LEVITRA®, etc. for two (2) days prior to the exam. Click here for more information on preparing for your Cardiac CTA exam.
  • CT Colonography (Virtual Colonoscopy): Patients should follow the instructions regarding fasting (NO FOOD), clear fluids and the bowel cleansing preparation prescribed by their doctor. Patients must pick up prep at Weill Cornell Imaging, at least two (2) days prior to exam. All of the necessary medication and specific preparation instructions will be provided in this kit. No food or liquids four (4) hours prior to the exam.
  • If you have Diabetes: If you are on oral hypoglycemic such as Glucophage®, you should stop these agents for 48 hours after the CT scan if you received intravenous (IV) contrast.

What should I bring with me on the day of my appointment?

  • A copy of the prescription for your examination if it was given to you.
  • Your insurance information.
  • A list of your current medications.

What can I expect on the day of my appointment?

Patient verification is an important part of your safety and you will be asked to verify your identification and your exam several times during your appointment. Our check-in staff will review your completed registration forms with you.

For many exams you will not have to change into a gown unless you are wearing something that contains metal (see guidelines above).  Some exams do require that you are in a gown. You will be asked to remove and place your electronic devices, wallet, credit cards, metro card, watch, jewelry, belt, hairpins, eyeglasses, hearing aid, or any removable dental pieces into the provided lockers. 

Some CT scans require the use of an iodinated contrast material, also known as "x-ray dye” which is injected through an intravenous (IV) line.  If contrast is required, a skilled nurse or technologist will start this IV line in the arm or hand prior to the examination. The IV will be removed immediately after the exam.

Some CT scans of the abdomen and pelvis require oral contrast. If you are given oral contrast as part of your exam you will have to wait approximately 1 hour after drinking the contrast until the contrast has made it to the part of your bowel that it needs to be.

Before you enter the CT scanning room, a technologist will review the safety questionnaire with you. We understand that this may seem redundant but your safety is our first priority. Once the technologist is assured that it is safe to proceed, he or she will escort you into the scanning room and onto the CT table.

How is a CT performed?

  • You will lie on a scan table that slides into a large, circular opening of the scanning machine.
  • The CT staff will be an adjacent room where the scanner controls are located. However, you will be in constant sight of the staff through a window. Speakers inside the scanner will enable the staff to hear and communicate with you. You will have a call bell so that you can let the staff know if you have any problems during the procedure.
  • As the scan begins, you may hear humming sounds during the procedure as the x-ray tube and detectors rotate and begin to collect information.
  • It is very important that you remain very still during the procedure. You may be asked to hold your breath at various times during the procedure. If you have breathing issues which prevent breath-holds, please let us know prior to the exam.
  • Upon completion, the technologist will escort you outside of the scanning room where you will retrieve your personal belongings and proceed to check-out.
Our staff is available to address any questions or concerns that you might have before, during, or after your appointment. Please call (212) 746-6000 if you wish to speak with us.


Health Library

Computed Tomography (CT or CAT Scan)

What is a Computed Tomography (CT or CAT) Scan?

A CT or CAT scan is a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, organs, and blood vessels. CT scans are more detailed than standard x-rays.

In standard x-rays, an invisible beam of energy is aimed directly at the body part being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle, and other tissue. While much information can be obtained from a regular x-ray, a lot of detail about internal organs and other structures is not available.

During CT scans, the x-ray beam moves in a circle around the body as oppose to a straight line during a general x-ray. This allows many different views of the same organ or structure, and provides much greater detail. The x-ray information is sent to a computer that interprets the x-ray data and displays it in 2-dimensional form on a monitor. Additional advanced technology and computer software makes three-dimensional (3-D) images possible.

CT scans may be done with or without contrast. "Contrast" refers to a substance taken by mouth or injected into an intravenous (IV) line that causes the particular organ or tissue under study to be seen more clearly. Contrast examinations may require you to fast for a certain period of time before the procedure. Your physician will notify you of this prior to the procedure.

You will need to let your physician know if you have ever had a reaction to any contrast dye or if you are allergic to iodine. If you have any medical conditions or recent illnesses, inform your physician. If you are pregnant or think you may be pregnant, you should notify your physician and not proceed with the CT scan unless absolutely necessary.


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