CT Test Prep
Note: The following preps are for outpatient care only.
For questions about any of these preps, please contact
the Radiology Reception Desk, at (734) 936-4500 for more information.
What is a CT?
Computed tomography, called CT or CAT scanning is an x-ray system that produces detailed cross-sectional images of the head, spine, chest, pelvis, abdomen and other areas of the body. CT images show organs of interest at selected levels of the body. CT examinations produce detailed organ studies by stacking individual image slices. To produce the scans, you will be asked to lie on a table. The table slides into the doughnut-shaped ring in the center of the scanning machine. There the x-ray tube rotates around the area of interest. Sensors in the ring detect x-rays passing through the body. Information from the sensors is processed by a computer and displayed as an image on a video screen. A radiologist (specialized physician) interprets film copies of the image.
Frequently, a colorless liquid called a contrast agent (commonly called "dye") is used to see the organs being studied. The contrast agent is injected into a vein, usually in the arm or leg. During the injection, many patients feel a warm or flushed sensation and feel some discomfort that usually lasts about two minutes.
Adult patients should not eat 4 hours prior to the appointment time, but may drink clear liquids up until 2 hours prior to the appointment time (unless otherwise instructed). Any medication that is needed should be taken as prescribed with a small amount of water, unless otherwise instructed by the Radiology Department.
Clear Liquids Allowed:
- Tea/black coffee
- Apple or cranberry juice
- Lemon or Lime Jello-O
- Clear Chicken or Beef Broth
- Clear Sodas (7-UP, Sprite, Ginger Ale)
If you have any known allergies to dye or iodine, the CT Department or Radiologist
needs to be aware of the allergy and what type of reaction you have had. This
information will allow the radiologist to arrange for pre-medication for you
through your referring physician or make necessary arrangements. Please call
the Radiology Department at (734) 936-4500 if you have any known
If you are diabetic and taking a medication that contains metformin, it should be discontinued at the time of or prior to your examination. It should not be taken for the 48 hrs. after your examination. At that time, your kidney function should be re-evaluated by your physician, and you should not start taking metformin again until kidney function has been found to be normal. Please refer to the Patient information pages supplied to you with the medicine by your Pharmacy. In the USA, metformin is sold as a generic drug and is also present within drugs named Glucophage, Glucovance, Avandamet, and Metaglip.
Abdominal or Pelvic CT
You will need to arrive one hour prior to your scheduled appointment time for oral preparation. The oral preparation is called Readi-Cat 2. The 60 minute barium administration protocol for an Abdomen/Pelvis CT is as follows: Administer 450ml CT barium suspension 60 minutes before scan, another 300ml 30 minutes before scan, and finally 150ml immediately prior to scan. Occasionally, water will be used as an oral preparation. The 60 minutes water administration protocol for an Abdomen/Pelvis CT is as follows: Administer 480ml of water 60 minutes before scan, another 480ml 30 minutes before scan, and finally 480ml immediately prior to scan. The oral preparation is all completed once the patient has arrived in the CT Radiology department.
Please arrive by your appointment time. You will be asked to lie on a narrow table. Prior to the procedure, more oral contrast may be given or an I.V. may be placed to administer contrast. The technologist will position the area to be studied inside the scanner's doughnut - shaped ring. As the procedure begins, you will hear humming, buzzing or clicking sounds from the CT machine. You may be asked to follow simple breathing instructions. Remaining still helps make the clearest images. All Diagnostic CT exams last from fifteen to forty-five minutes, depending on the extent of the study being performed.
Body CT or Spine CT
You will be instructed to change into a gown or robe (clothing with metal on it will interfere with the exam).
Neck or Chest CT
You will need to remove all necklaces, earrings, hair pins, bras, hearing aids, metal buttons, etc.
CT Guided Biopsy
You will need to have someone accompany you for the procedure. All biopsies are scheduled for a two hour period, but the procedure may take longer or shorter in duration. Sometimes, a medication will be given to help you relax during the procedure. After the biopsy, you will be sent to a recovery area in the Radiology Department for approximately two to six hours.
After the Procedure
The radiologist will send a report to your doctor after the images have been studied. It is best to ask your doctor for the exam results.
A questionnaire needs to be filled out through the CT scheduling office. In addition, blood tests need to be drawn prior to the biopsy. The blood tests consist of : Prothrombin Time (PT), Partial Thromboplastin Time (PTT), Platelet Count (PLT), international Normalized Ratio (INR), Creatinine (CREATE) and Urea Nitrogen (UN).
If you have any questions regarding CT scheduling, please call (734) 936-4500.
Reviewed and Approved:
Joel Platt, MD