What to expect during a CT scan

St. Joseph’s Hospital CT technologist answers six questions about Computed Tomography

When you are sick or injured, your healthcare team will use many tools to find out what’s wrong in order to get you better. Sometimes that includes imaging diagnostic machines to get an inside look of your anatomy. One such device is a CT scan.

CT stands for Computed Tomography. Essentially, it’s a more intuitive X-ray machine, producing multiple 2D images as opposed to one-dimensional images a traditional X-ray produces, explains Chelsea De La Cruz, team lead of the CT department at St. Joseph’s Hospital.

Using a computer, all images taken are combined to produce a detailed look at the body’s anatomy. A CT scan can look at everything from head to toe including every organ in the body, the vascular system, bone abnormalities, brain bleeds, blood clots, masses/tumors and infections, De La Cruz says.

At St. Joseph’s/Candler, we offer the latest technology in imaging, including the GE Revolution CT Scanner, one of the quickest imaging machines available. We offer CT scanning at four imaging locations:

• St. Joseph’s Hospital (two in imaging and a third in the emergency department)
• Candler Hospital (three between inpatient and outpatient imaging)
• SJ/C Imaging Center – Pooler
• SJ/C Imaging Center – Bluffton

With more and more people needing CT scans, it’s important to have a good understanding of the machine and not fear it. Here are six things you should know about CTs:

1. Who needs a CT scan?
   A physician will request a CT scan to view the inside anatomy of a patient. Sometimes, insurance companies will require an X-ray before a CT scan. When physicians need more detailed images, a CT scan is ordered. CT scans are often the first imaging diagnostic tool used in trauma situations, such as stroke or heart attack.
   
   
2. What does it look for?
   CT is a useful imaging tool for almost every part of the body, De La Cruz says. It is most commonly used in imaging the heart, brain, abdomen and bowel (gallbladder and appendix, for example), spine and other organs of the body. CT images can show blood clots, aneurysms, lung nodules, masses, calcium scoring and narrowing of blockages in the vessels around the heart. Additionally, CT can be used for procedures, such as drainages and biopsies, De Le Cruz adds. For example, radiologists use a feature called fluoroscopy which uses real-time imaging to guide a needle or catheter within the body.
   
   
3. How long does it take?
   Thanks to advances in technology, CT machines are faster than ever. How long a scan lasts depends on the area of the body being scanned. In most cases, scans can last anywhere from two minutes to 10 minutes, De La Cruz says.
   
   
4. Is it safe?
   CT scans do use radiation, but with advancements in technology, patients are exposed to less radiation than previous versions of CT scanners. St. Joseph’s/Candler also uses radiation dose reduction software.
   
   Some CT scans also use contrast. Contrast is an agent that improves the visibility of the anatomy for clearer images. Contrast is safe for most patients. The imaging team of nurses and technologists ensure the patient has no iodine allergy and proper renal function, as contrast could have an impact on weakened kidneys. Some patients experience a warm sensation following a contrast IV, but that feeling typically lasts less than a minute. A few patients may also experience nausea.
   
   Patients are encouraged to drink a lot of fluids following a CT scan to help flush everything out of the kidneys and bladder.
   
   The majority of outpatients can drive following a CT scan. A driver is required when a patient undergoes a procedure that requires sedation, such as drainage or biopsy.

    

5. What is the difference between a CT and MRI?
   Many patients confuse CT and MRI, or Magnetic Resonance Imaging. Both are effective and safe imaging diagnostic tools, but they do have differences. The main difference is CT uses radiation while MRI does not. MRI uses a magnetic field, radio waves and a computer to create images.
   
   Another difference is the sound. Some find a CT scans sound like a washing machine going around and round, De La Cruz describes.  MRI machines tend to be noisier, making a knocking sound; however, patients have several options to reduce the noise they hear.
   
   The feeling of claustrophobia is also a difference. Not all, but some patients may experience claustrophobia during an MRI. A CT machine differs from an MRI in that a CT’s depth is shorter, which De La Cruz compares to a doughnut, in which the bed glides in and out. An MRI machine has a longer opening in which the bed remains during the scan. CT scans also typically are faster than an MRI.
   
   A lot of times it’s the physician’s preference as to whether a patient has a CT, MRI or other imaging tool. Some patients may have an implant or hardware in the body that makes them not a candidate for MRI. If a physician is looking at an ankle or foot, for example, an MRI shows tendons better than a CT.
   
   
6. When do I get my results?
   Following a CT scan, the images are sent to a radiologist, which is a physician trained to read imaging and diagnose and/or recommend treatment. The radiologist’s findings are sent to the ordering physician and available to patients within 24 to 48 business hours. Results from scans at St. Joseph’s/Candler are also made available through the patient portal, De La Cruz adds. Patients – most commonly stroke victims – who have a CT scan in the St. Joseph’s Hospital emergency department have their results faster, typically while they are still in the ED.

Another thing De La Cruz also wants you to know is while the scan itself typically takes less than 10 minutes, the entire appointment will take longer. Outpatients will first meet with a registrar and nurse – which many patients don’t realize, De La Cruz says – to ensure everything is in order before the imaging test.

Additionally, if it’s a scan of your heart, your heart rate has to be at a lower rate, so you may need medication to help lower that before your scan which can prolong you appointment. If you are having a scan of your heart, De La Cruz recommends avoiding caffeine.  

For more information about all of St. Joseph’s/Candler imaging services, visit our website. 

Coming next month: What to expect during an MRI