What is a CAT scan?
A CAT scan, also known as a CT or computed tomography scan, is a specialized X-ray test that produces cross-sectional images of the body using X-rays and a computer (1). It allows doctors to see detailed images of the bones, muscles, fat, organs, and blood vessels in the body.
During a CAT scan, the patient lies on a table that slides into a large donut-shaped machine. X-rays spin around the body, taking images from different angles. The images are processed by a computer, which combines them to create cross-sectional views of the body. The computer stacks the images together to build a 3D model of the body.
CAT scans are used to diagnose diseases and injuries. They can detect abnormalities like tumors, bone fractures, blood clots, and internal bleeding. They are also used to plan radiation therapy for cancer treatment. CAT scans provide more detailed images than regular X-rays and are often the preferred method for examining the chest, abdomen, head, spine, and pelvis.
History of the CAT scan
The CAT scan was invented in the 1970s by Godfrey Hounsfield and Allan Cormack. Hounsfield worked for EMI Laboratories in England and started developing the first CAT scan machine in 1967. According to the National Inventors Hall of Fame, Hounsfield built the first prototype in 1971 and installed the first scanner at a hospital in London in 1972 (1).
The first CAT scan machine was a large, cumbersome device that required patients to lie still for several minutes to get a scan. The scan data was processed by a large computer next to the machine. Despite the primitive technology, doctors immediately recognized the immense diagnostic potential of CAT scans. The non-invasive scans allowed doctors to see inside patients in a way that wasn’t possible before.
By the late 1970s and into the 1980s, CAT scanners became a standard fixture in hospitals and medical facilities around the world. The technology rapidly improved over the decade, allowing faster scan times and better image resolution. CAT scans became an essential tool for cancer screening and diagnosis, detection of abnormalities, and assessment of head trauma, strokes, and other conditions.
(1) https://www.invent.org/inductees/godfrey-newbold-hounsfield
What does a CAT scan see?
A CAT scan, also known as a CT or computed tomography scan, provides much more detailed images of the body than a regular X-ray. The scanning machine takes multiple X-ray images from different angles around the body and uses computer processing to create cross-sectional images, or “slices,” of the bones, blood vessels and soft tissues (source).
These detailed images allow doctors to see the internal structures in different parts of the body very clearly. CAT scans are especially useful for imaging the brain, chest, abdomen, pelvis, arms and legs. They can detect abnormalities in these areas that may be difficult to see on a regular X-ray. A CAT scan can help diagnose tumors, infections, blood clots, fractures and more by giving doctors a detailed look at the bones, organs, tissues and blood vessels (source).
Limitations of CAT Scans
Although CAT scans provide detailed views of bones, blood vessels, and organs, they have some limitations compared to other imaging exams like MRI. CAT scans utilize X-rays and thus expose patients to ionizing radiation (FDA, 2023). While the amount used in modern scanners is relatively low, it can still damage DNA and potentially increase cancer risk, especially with repeated scans.
CAT scans also do not provide the same detailed imaging of soft tissues like the brain and muscles compared to MRI. The soft tissue contrast in MRI is superior for detecting abnormalities like tumors, inflammation, and nerve damage (Fred, 2004). Additionally, CAT scans may fail to detect very small lung nodules or subtle ventricular bleeding in the brain.
For these reasons, doctors may order an MRI scan instead of or in addition to a CAT scan depending on the diagnostic information needed. However, CAT scans have the advantage of very rapid image acquisition and are useful when a quick exam is required for trauma, strokes, or unstable patients who cannot remain still for longer MRI exams. Overall, being aware of the limitations of CAT scans can help patients and doctors determine when alternative imaging modalities could provide additional diagnostic value.
Preparing for a CAT scan
There is often no special preparation needed for a CAT scan. However, in some cases, you may need to take a few steps to prepare:
You may need to avoid eating or drinking for a few hours before the scan if you are receiving contrast dye. Fasting helps improve the quality of the images.[1] Contrast dye, which helps highlight blood vessels and organs, is sometimes injected prior to the scan.[2]
You will need to remove any metal objects like jewelry or glasses before the scan, since they can interfere with the images and machinery.[3]
Your doctor may also recommend avoiding caffeine or nicotine before the scan to get clearer images.
Other than fasting and removing metals, no major preparation is required. The CAT scan procedure is quick, taking just 10-30 minutes for most people.
What to expect during the scan
During the scan, you will lie still on a table that slides into the CT scanner, which looks like a large donut. The scanning machine will rotate around you as you move through the scanner (Mayo Clinic). You will hear whirring or clicking sounds from the machine as it takes images. The test is painless, though the noises can be loud and startling.
The actual scan typically takes only 5-10 minutes to complete (WebMD). You will need to hold still while the images are being taken to avoid blurring the pictures. Some facilities will ask you to hold your breath at certain points during the exam. The technologist operating the machine will give you instructions over an intercom.
Overall, the CT scan process is fast, painless, and straightforward. While the machine can be noisy, the test will be over before you know it.
After the CAT scan
After undergoing a CAT scan, most patients can return to their normal activities. There are usually no restrictions unless specifically advised by a doctor (Stanford Health Care, 2022). The radiologist will analyze the images from the scan and send a report to your doctor. However, the radiologist does not discuss results directly with patients.
It is important to follow up with your physician after the CAT scan. The doctor will explain the results of the scan, whether it showed any areas of concern, and recommend any next steps in treatment or additional testing if needed (Mayo Clinic, 2022). Do not hesitate to ask any questions about the findings and what they mean for your health during this follow-up appointment.
Overall, a CAT scan is a quick, painless procedure. Within a day or two, your doctor can explain the results and what they found. With modern CAT scan technology, detailed images of the body provide valuable information to accurately diagnose medical conditions.
Risks and side effects
CAT scans use radiation to generate images, so there is a small amount of radiation exposure. However, the radiation exposure from a single scan is quite low. According to the Mayo Clinic, the amount of radiation is comparable to the natural radiation exposure from living for a few months. The benefits of the diagnostic information from a CAT scan generally outweighs this small risk.
Some patients can have an allergic reaction to the contrast dye used in some CAT scans. This reaction is rare and mild, causing hives or itchiness. More severe reactions are extremely rare but can cause low blood pressure or difficulty breathing. Patients should tell their doctor ahead of time if they have any allergies or have reacted to contrast dye in previous scans.
The confined space inside the CAT scan machine can cause anxiety for some patients. Patients who are claustrophobic may feel anxious or have difficulty remaining still during the scan. However, CAT scan machines have become less confining in recent years. Patients can also ask their doctor for medication to help them relax.
Cost and insurance coverage
A CT scan is an expensive medical test, with the average cost ranging around $1,200. Exact pricing can vary dramatically based on the facility, your location, and whether contrast dye is used. According to GoodRx, CT scan costs typically range from $300 on the low end up to $6,750 on the high end, with some specialized scans costing over $20,000.
Fortunately, CT scans are usually covered by health insurance plans, as long as they are deemed medically necessary. Your exact out-of-pocket costs will depend on your individual plan’s deductibles, copays, and coinsurance. Those with government insurance like Medicare or Medicaid will also have coverage, but may be responsible for copays or coinsurance. Uninsured patients can expect to pay the full cash price, which can easily amount to thousands of dollars for a single scan.
To reduce costs, it’s recommended to use in-network providers and imaging centers when possible. You may also want to inquire about discounted cash prices if paying without insurance. Some facilities offer more affordable self-pay options. Overall, CT scans are an expensive but sometimes vital medical test that most insurance plans will cover, but always be sure to check benefits and pre-authorization requirements first.
Future advances in CAT scans
CAT scan technology is rapidly evolving to provide improved image quality, faster scan times, reduced radiation exposure, and enhanced 3D imaging capabilities. Some key areas of innovation include:
Improved image quality and faster scan times – New CT scanners like the Revolution CT from GE Healthcare use next-generation detectors and reconstruction algorithms to capture higher resolution images while reducing scanning time. These advances produce more detailed scans that can be completed in just one second rather than several minutes (https://www.cassling.com/blog/whats-new-in-ct-systems-and-scanner-technology-2023-edition).
Reduced radiation exposure – Researchers are developing photon-counting CT scanners that use detectors to analyze each individual photon of X-ray light. This allows the dose to be tuned more precisely to the patient’s size while still producing high quality images (https://www.nibib.nih.gov/news-events/newsroom/two-monumental-milestones-achieved-ct-imaging). Lower radiation is safer, especially for pediatric patients.
Enhanced 3D imaging – Dual energy CT scanners can differentiate multiple tissue types in a single scan, allowing detailed 3D models to be constructed. This advancement aids surgical planning and diagnosis.
