Karmanos Cancer Institute
CT Scan (Computed Tomography)

CT Scan

At McLaren we use the latest technology and the capabilities of our state-of-the-art scanners play a key role in tailoring each exam to your specific needs and reducing radiation exposure.

What is a CT Scan

A CT (computed tomography) scan is a non-invasive medical test that uses X-rays to produce multiple images or pictures of the inside of the body and a computer to join them together in cross-sectional views of the area being studied. CT scans of internal organs, bone, soft tissue, and blood vessels provide greater clarity than conventional X-ray exams. CT is considered to be the most versatile of all imaging modalities. CT provides clearer, more detailed pictures than traditional X-rays.

Common Uses

CT scanning is commonly used to diagnose problems such as cancers, cardiovascular disease, infectious disease, trauma, and musculoskeletal disorders. It is also used for orthopedic purposes, such as diagnosing bone fractures and preparing for orthopedic surgery.


To protect our patients, we have implemented new precautions for diagnostic tests using contrast.

If you are over 70 or have kidney disease, diabetes, lupus, or multiple myeloma, you'll need a blood test beforehand to make sure the contrast will be safe for you.

Prior to the administration of elective Gadolinium-based MRI contrast agent, a CT (with Contrast), or an IVP appointment, a recent (within the last 30 days) Glomerular Filtration Rate (GFR) will be required for patients ages 60 and older or with a history of one or more of the indications below:

  • Diabetes
  • History of Renal Disease (including solitary kidney, renal transplant, renal tumor)
  • History of Renal Transplant
  • Hypertension
  • Diabetes
  • CHF
  • Multiple Myeloma
  • Dehydration
  • Contrast exposure within the past 72 hours

Before the CT Scan

  • Medications: It is important for you to keep to your regular medication schedule. Please take all medications that have been prescribed to you by your physician. Just let our staff know what medications you have taken prior to your test.

  • Food and drink: You should not eat solid foods for two hours prior to your test. You may, however, drink plenty of fluids, such as water, broth, clear soups, juice, or black decaffeinated coffee or tea. We encourage you to drink plenty of fluids before your arrival to our facility.

  • When to arrive: If you are having a CT scan of your abdomen or pelvis, you need to arrive one hour before your scheduled appointment to allow time for you to drink barium sulfate before your exam and to ensure that the barium fluid completely coats your gastrointestinal tract. The barium helps to highlight body areas for the CT scan. If you are having a scan other than the abdomen, you should arrive at your appointed time.

  • What to wear: You should dress in comfortable clothing. It might be necessary for you to change into a hospital gown if there is metal in your clothing, such as a bra or zipper, within the area of interest of your study. If you are wearing jewelry or anything else that might interfere with your scan, we will ask for its removal. The CT scan is conducted in a very secure environment. It is best, however, if you leave valuable items at home.

  • Diabetic conditions: If you are an insulin-dependent diabetic, please continue to take your insulin as prescribed, but remember to drink extra fruit juices to make up for the fasting of solid foods for the 2-3 hour period that your stomach is empty. Patients who are taking diabetic medications that contain metformin should take the normal prescribed dose, but discontinue the next doses for 48 hours AFTER the CT exam. Patients should notify their primary care physician that they were instructed to discontinue their medication for 48 hours. If you need a substitute medication, please consult with your physician.

  • Intravenous preparation: Many patients receive a contrast agent intravenously (IV) during their CT test. If your physician or the radiologist has determined that this procedure will enhance your CT scan results, the technologist will place an IV in your arm or hand prior to scanning. (Please see the section on "Contrast medium" below.)

During the CT Scan

  • Scanning: Your CT technologist will bring you into the CT scan room where you will lie down on a table. The technologist will position your body so that the area you are having scanned is in the middle of the large doughnut-shaped scanner ring which holds the X-ray tube and an electronic detector. The technologist will leave the room, but will be in full view and communication with you through the observation window in the adjoining room.

    The scanner will not touch you, nor will you feel the X-rays. It will make noise and the table you are lying on may move slightly to make adjustments for a better view. It is important for you to lie very still. At some point you may be asked to briefly hold your breath as the picture is taken. During the scan, a thin beam of X-ray is focused on a specific part of your body. The X-ray tube will move very rapidly around this area, enabling multiple images to be made from different angles to create a cross-sectional picture. The X-ray beam information constructs an image for the radiologist to interpret.

    CT exams require that you lie still in a confined space. Because the scanning time is so short, most people tolerate the experience well.
  • Length of scan: Each CT scan is individualized and tailored to each patient's needs. In general, the actual image-taking is only about one minute and most examinations last approximately 15 - 30 minutes in total.

  • Contrast medium: A contrast medium, or contrast agent, highlights your organs and blood vessels and helps the radiologist see them better. The contrast agents in use today carry a low risk of allergic reaction and cause minimal discomfort for most people.

    The high speed of our state-of-the art scanners means we are able to produce high-quality images using less contrast than in the past. Contrast dilutes fairly quickly into your bloodstream, but our scanners take their pictures before the dilution occurs.

After the CT Scan

  • Instructions: You have no restrictions after having a CT scan and can go about your normal activities. To help eliminate the contrast medium from your body, drink plenty of decaffeinated or non-alcoholic beverages. Water and juices also work well.

  • Exam results: CT exams are interpreted by a radiologist. Under normal circumstances, the reports are available electronically to the ordering physician. Your referring physician will communicate these results to you.

CT Scan Locations Near You