What is a CAT Scan?
A CAT scan, also called a CT (computed tomography) scan, is a type of specialized x-ray that takes cross-sectional images of the body (Mayo Clinic, 2022). It combines multiple x-ray images taken from different angles to produce detailed 3D images of internal organs, bones, soft tissues, and blood vessels (WebMD, 2023).
Unlike a standard x-ray that takes one image from the outside, a CAT scan takes images from the inside out, slice by slice. This allows doctors to see a 3D visualization of the inside of the body (Johns Hopkins Medicine).
CAT stands for computed axial tomography. The “computed” refers to the use of a computer to synthesize the images after they are taken. “Axial” refers to the horizontal plane or axis of the body. “Tomography” means imaging by sections or slices.
Why Doctors Order CAT Scans
Doctors order CT scans for a variety of diagnostic reasons. According to the Mayo Clinic, CT scans help doctors diagnose illnesses and injuries, monitor known conditions, and screen for certain cancers or diseases (https://www.mayoclinic.org/tests-procedures/ct-scan/about/pac-20393675).
Some common reasons doctors order CT scans include:
- To look for tumors, abscesses, or internal injuries and bleeding
- To examine blood vessels in the brain, heart, lungs, abdomen, or other areas
- To evaluate for stones or abnormalities in the kidneys, liver, pancreas, or gallbladder
- To check for bone fractures, injuries, or other problems in the spine, joints, or bones
- To look for signs of stroke, aneurysms, or arterial diseases
- To screen for lung, colon, or other cancers
- To guide procedures such as biopsies or radiation therapy
- To monitor infections, tumors, or other conditions over time
Overall, CT scans provide detailed images that can reveal many health issues not visible on regular X-rays or physical exams. Doctors rely on them to make accurate diagnoses and determine the best treatment options for their patients (https://www.healthimages.com/reasons-you-may-need-a-ct-scan/).
Preparing for a CAT Scan
Before having a CAT scan, there are important instructions you must follow for the scan to be done properly. Your doctor will provide specific preparation guidelines, which commonly include:123
You will likely need to avoid eating for 4-6 hours before the scan to prevent food from interfering with the images. Follow your doctor’s specific instructions on fasting. You can drink clear liquids leading up to the scan.
Before entering the scanning room, you will need to remove any metal objects including jewelry, eyeglasses, dental work, and hair accessories. You may also need to change into a hospital gown.
Proper preparation allows the CAT scan images to be clear and detailed, leading to the most accurate results.
What Happens During a CAT Scan?
During a CAT scan, you will lie still on a table that slides into a large, tunnel-like scanner. The CAT scanner consists of an x-ray tube that rotates around your body and takes multiple x-ray images from different angles. As the Mayo Clinic explains, “A computer processes the images, and they’re displayed on a monitor.”
You will need to lie completely still while the CAT scanner table slowly moves through the large tunnel opening. This allows the x-ray tube to rotate and take multiple, cross-sectional x-ray images from all angles around your body (Source). Modern CAT scanners can complete hundreds of images in just a few seconds.
Though you don’t feel anything during the scan other than lying still, the x-ray images provide detailed cross-sectional views inside your body. This allows doctors to see internal organs, blood vessels, bones, soft tissues, and more.
Can You Sleep During a CAT Scan?
Sleeping through a CAT scan is generally not advised. In order to get clear images, it is important to lie perfectly still while the scan is in progress. Any movement, even breathing, can potentially cause blurring or artifacts in the images. For this reason, patients are asked to remain awake and motionless during the procedure.
Sedation is usually not provided for routine CAT scans. The test only takes a few minutes, so most patients are able to stay still and follow instructions from the technician. Children and anxious patients may be given a mild sedative to help them relax, but not enough to make them fall asleep.
If you are worried about being able to hold still, talk to your doctor beforehand. They may be able to provide medication to ease anxiety. Practicing breathing exercises or meditation prior to the scan can also help you remain calm. The technician will coach you through the process and remind you not to move if needed. With preparation and concentration, most patients are able to stay awake and motionless for the short duration of a CAT scan.
Sources:
https://www.cuh.nhs.uk/patient-information/ct-computerised-tomography-scan-under-oral-sedation/
https://blog.radiology.virginia.edu/sedation-and-radiology/
Tips for Staying Awake and Still
Staying awake and lying completely still are crucial for getting clear images during your CAT scan. Here are some tips to help:
Come well-rested. Being tired makes it much harder to stay still and keep your eyes open. Get a good night’s sleep before your scan and avoid scheduling it at a time when you tend to feel drowsy.
Bring distractions like music. Listening to soothing music through headphones can help distract you and make the time pass more quickly. Some facilities may provide headphones or let you bring your own.
Focus on your breathing. Take slow, deep breaths and consciously relax each part of your body. This can help minimize fidgeting and provide a meditation-like focus.
Let the technician know if you feel you may fall asleep. They can provide suggestions to help keep you awake. However, avoid excessive conversation during the actual imaging.
With preparation and concentration, most patients can remain awake for a CT scan’s duration. Alert the technician immediately if you feel you cannot hold still, so they can pause the scan and help reposition you.
Risks of Moving During a Scan
It’s crucial to lie perfectly still while the CT scanner is taking images. Any movement can lead to blurred or distorted images.
If the images are distorted due to movement, the radiologist may not be able to make an accurate diagnosis based on the scan. In this case, you may have to come back and redo the scan completely.
Redoing a scan means repeating the radiation exposure from the initial test. According to the American College of Radiology, the standard radiation dose for a CT scan is equivalent to 200 to 6,000 chest X-rays1. Repeated radiation exposure can increase lifetime cancer risk.
To avoid unnecessary radiation and get clear scan results, it’s essential to lie perfectly still during the imaging process.
When Sedation May Be Used
Sedation may need to be used during a CAT scan in certain situations:
For young children:
Young children may have difficulty remaining still for the length of the scan, which can take anywhere from 5 to 30 minutes. Sedating young children helps ensure they stay completely still so the scan images are clear.[1]
For claustrophobic patients:
For adults or older children who have anxiety or claustrophobia regarding medical procedures, sedation can help them relax and avoid panic during the scan.[2] Being sedated allows them to undergo the necessary scan without being distressed.
For patients in pain:
Patients who are in acute pain may be unable to lie still for the scan. Sedation allows them to relax and remain motionless so the scan can be completed and diagnostic information obtained.
Recovering After a CAT Scan
Most patients do not require any recovery time after a CAT scan and can resume normal activities immediately (source). You should be able to drive yourself home or return to work right away. The scanning procedure is not invasive or taxing on the body.
If you received intravenous contrast dye for the scan, your doctor may recommend drinking extra fluids like water or juice afterwards. This helps flush the contrast material out through your urine (source). Staying hydrated can minimize any potential side effects from the contrast dye.
Overall, a CAT scan is a very safe procedure. Aside from possible minor irritation from an IV line, most patients experience no effects after the test is complete. If you feel any concerning symptoms like rashes, trouble breathing, or dizziness, contact your doctor right away. But in most cases, you can go about your regular daily activities immediately.
Results and Follow-Up
After the CAT scan is completed, a radiologist will examine the images and write up a report for your doctor. The radiologist will look for any abnormalities or issues that need further evaluation. According to the Cleveland Clinic, it usually takes about 24 to 48 hours to get the results of your CT scan back from the radiologist.
If any concerning findings are discovered on the scan, your doctor may order additional tests like an MRI or biopsy to further investigate. As the KidsHealth article notes, “In an emergency, the results of a CT scan can be available quickly.”
Once the radiology report is complete, your doctor will schedule a follow-up appointment to go over the results with you. According to WebMD, they will explain if the CT scan revealed any problems and discuss recommendations for next steps in care or treatment.
It’s important to attend this follow-up visit, ask any questions you may have about the test results, and understand your doctor’s advice moving forward after the CAT scan.