CT scans use X-rays for fast imaging, ideal for bones, emergencies, and bleeding, while MRIs use magnets and radio waves for detailed soft tissue views (brain, spinal cord, muscles), avoiding radiation but taking longer and posing risks for metal implants, with the choice depending on urgency and the specific medical question. CTs excel in speed and bone detail, MRIs in soft tissue contrast, with neither being universally "better," but rather suited for different diagnostic needs.
Generally, CT scans are better at spatial resolution, while MRIs are better at contrast resolution. That means CT scans are good at showing us where the edges of things are — where this structure ends and that other one begins.
A CT scan may be recommended if a patient can't have an MRI. People with metal implants, pacemakers or other implanted devices shouldn't have an MRI due to the powerful magnet inside the machine. CT scans create images of bones and soft tissues.
A CT (Computed Tomography) scan uses X-rays and computers to create detailed 2D or 3D images, showing bones, soft tissues, and blood vessels to diagnose injuries, tumors, infections, blood clots, heart disease, stroke, and organ issues, guiding treatments and monitoring diseases like cancer. It provides clearer images than standard X-rays, helping doctors see internal damage, inflammation, and abnormalities in any body part, from the brain to the abdomen, often in emergencies to save lives.
You will only have to spend a few minutes getting a CT scan instead of potentially more than an hour in a tight MRI tube. Additionally, the larger scanning tube used for CT scans reduces any feelings of claustrophobia.
It is a good idea to close your eyes and keep them closed before you are brought into the scanner and during the entirety of the scan, so you can picture yourself just sleeping on your own bed. In contrast, an open MRI is ideal for claustrophobic or anxious patients, pediatric patients, or patients who are large.
CT scans are painless, and most take only a few minutes. You'll lie on a narrow table, which gently glides into the center of a donut-shaped CT scanner. Inside the tunnel, a ring will rotate around you, taking X-ray pictures.
CT scans are very good at showing many tumors and enlarged lymph nodes, but they can still miss small or early cancers, especially in soft tissues or areas that are difficult to image. That is why doctors often combine CT with other imaging tests, lab work and, when needed, a biopsy to confirm a diagnosis.
While CT provides much more detail of damage and disease of internal organs, bones and blood vessels than some other imaging technologies, it can't show everything. Some types of cancer, for example, prostate cancer, uterine cancer and some liver cancers, may be harder to image using computed tomography.
If you have a contrast agent, you will be requested to fast (ie avoid eating) for 2-4 hours before your scan. As explained previously, this is because eating before a CT scan with a contrast agent may increase your risk of nausea and vomiting.
MR imaging of the body evaluates: organs in the abdomen—including the liver, kidneys, spleen, bowel, pancreas, and adrenal glands. pelvic organs including the bladder and the reproductive organs. blood vessels (this may require a specific type of MRI called MR Angiography or MR venogram)
MRIs are more expensive than CT scans. Most insurance companies, however, will cover the bulk of any necessary imaging tests and only require patients to pay a copay or small portion of the exam.
Doctors use CT scans to evaluate all major parts of the body, including the abdomen, back, chest, and head. A CT scan is an excellent way to view the organs inside your abdomen. It is especially useful for looking at solid organs, such as the liver, pancreas, spleen, kidneys, and adrenal glands.
Safety: MRI scans do not involve the use of ionizing radiation, making them a preferred choice over CT scans, especially for children and patients requiring multiple imaging examinations.
Information about common scans. This includes X-rays, a CT scan, an MRI scan and ultrasound scans.
CT scans detect various types of cancer, including bladder cancer, kidney cancer, lung cancer, ovarian cancer, stomach cancer, and colon cancer. These imaging studies enable early detection by capturing detailed images of affected areas, even in the absence of symptoms.
Incurable cancers are those that current treatments cannot completely eliminate, often because they are advanced (spread) or have returned after initial treatment, but they are not necessarily untreatable; treatments like chemo, radiation, and new targeted therapies aim to control the disease, slow growth, relieve symptoms, and improve quality of life. Common examples of cancers often considered incurable include pancreatic, liver, brain, esophageal, and certain advanced lung cancers, but research continuously offers new hope, with many patients living longer with ongoing management.
It's a good idea to wear loose comfortable clothes, as you may be able to wear these during the scan. Try to avoid wearing jewellery and clothes containing metal (such as zips), as these will need to be removed.
The projected cancer risks per CT scan were higher in children than adults, and highest in children younger than 1 year.
It usually takes about 24 to 48 hours to get the results of your CT scan. In an emergency setting, like a hospital or emergency room, healthcare providers often receive results within an hour.
CT scans are particularly good at: Lung Nodules – CT sees these tissue growths at over 5x smaller than MRI. Most lung cancers start as nodules, but most nodules are not cancerous. Bone Fractures: CT Scans are especially useful for finding tricky or hidden fractures, catching what regular X-rays might miss.
If you're receiving contrast, you'll have an IV line placed. This is a small needle that goes into a vein in your arm to deliver the contrast during the scan. You'll be taken to a special CT room that has the scanner.
It is standard practice for the CT technologist to make sure everyone is outside the room or wearing lead if inside the room during imaging. However, we know procedures are not always followed. If you were in the room without lead during the imaging, your radiation exposure would have been very low.
Preparation for a CT scan
We will require your bowel to be empty for this examination. We will have given you a bowel cleansing agent, which has an aniseed flavour, called gastrografin to help us see your bowel in the abdomen on the scan. You will need to drink this aniseed drink the day before your procedure.