A computed-tomography scan (also known as CT scan) is a radiological imaging method that creates two-dimensional images in the body in horizontal and cross sectional (sliced). CT is often used to diagnose and characterize neck and/or spine conditions.
What is an MRI scanning for the Spine?
Magnetic resonance imaging (MRI), a test that uses a magnet field and pulses radio wave energy to take pictures of the organs and structures within the body, is called magnetic resonance imaging. In many cases, MRI provides information that is not available with the computed tomography scan (CT) scan. MRI may also reveal problems that are not visible with other imaging methods.
An MRI scan is safe and does not cause any side effects. It is painless and you will not feel any discomfort. The procedure is safe and can be repeated. The theoretical risk to the foetus is very low in the first 12 weeks. Therefore, scans during pregnancy are not recommended.
Patients can become claustrophobic because they have to lie in a large cylindrical while scans are taken. Talk to your doctor if you are concerned about this happening. He may prescribe medication to help you relax. Patients may also be uncomfortable by the machine’s banging sound while it is in operation. It can provide a clear view of the spine’s structure.
The following are the benefits of MRI:
- Imaging organs and soft tissue internal structures (see the spine scan image to right)
- Tissue difference between normal tissue and abnormal
- Without radiation imaging
What is CT Scanning the Spine?
A diagnostic medical test called computed tomography (or CAT scan), is a procedure that produces multiple images of the inside of the human body. A CT scan is a painless, quick, 5–20 minute exam that combines X-rays and computers to create 360-degree, cross-sectional views. CT images of the internal organs, bones and soft tissue, as well as blood vessels, provide more detail than traditional xrays, especially of soft tissues. CT shows the bony structure and intervertebral discs of the spine vertebrae. Cross-sectional images from a CT scan can easily be rearranged in different planes and even generated three-dimensional images.
CT is great for:
- Image bone, soft tissue, and blood vessels simultaneously
- Pinpointing bony structures (injuries).
- Evaluation of chest and lung issues (see the lung scan image to right).
- Cancer detection
- Imagine patients with metal (no magnet).
What is the difference between an MRI or a CT SCAN and what are their differences?
A MRI is different from a CAT scan, also known as a CT scan or a computed axial tomography scan. It does not use radiation. MRI scans can be used to image water-containing tissues better than traditional x-rays. An MRI scan can detect abnormalities in the spinal cord, bulging discs, small disc herniations, pinched nerves, and other soft tissue issues. MRIs can also be used when X-rays are not appropriate, such as in pregnant women. Due to the magnetic field generated by the test, people with metallic implants might not be able undergo an MRI. For imaging calcified tissue, such as bones, a CT scan is more accurate than an MRI. The CT scans can be used to diagnose fractures and osteoarthritis.
A CT scan may reveal spinal conditions that could be identified.
A spinal CT scan can help diagnose neck or back pain by showing details of bones, muscles and organs.
- Vertebral fractures
- Spinal degenerative changes
- Vertebral instability
- Spinal osteomyelitis
- Spinal mass and tumors
The CT procedure allows the entire cervical spine (neck) or the entire spine to be properly visualized. This type of view is often preferred by emergency departments to assess trauma injuries in detail. Because of the metal nature of the bullet, CT is the preferred imaging method for gunshot wounds. It provides clear details that cannot be seen with other specialized scans such as a magnetic resonance imaging scan (MRI) scan. Computed tomography might not capture enough tendons, ligaments and spinal cords. This makes conditions related to these structures less obvious on a CT scan.
Anatomy and structure of the spine
- The spinal column is composed of 33 vertebrae, which are separated by spongy discs and then classified into distinct areas.
- Seven vertebrae make up the cervical area.
- There are 12 vertebrae located in the chest region of the thoracic area.
- Five vertebrae are located in the lower back of the lumbar region.
- Five small fused vertebrae make up the sacrum.
- The four coccygeal vertebrae fuse together to form one bone called the tailbone or coccyx.
- The vertebral canal houses the spinal cord, which is a major component of the central nervous systems. It stretches from the base of the skull to the upper portion of the lower back. The spine bones and cerebrospinal fluid surround the spinal cord. The spinal cord transmits sense and movement signals from the brain to many reflexes.
What are the causes of a CT scan on the spine?
A CT scan of your spine can be used to evaluate the condition of your spine, including for any herniated disc, tumors or other lesions, the extent and severity of injuries, structural anomalies, spina bifida (a type congenital defect of spine), blood vessel malformations or other conditions. This is especially useful when other types of examinations such as X Rays or physical examinations are not conclusive. A CT scan of the spine can also be used for evaluation of the effects of spine treatment, such as surgery or another therapy. Your doctor may recommend a CT scan to examine the spine for other reasons.
What are the potential risks associated with a CT scan
Ask your doctor about the radiation exposure during the CT procedure, and any risks that may be associated with your situation. Keep a record of any radiation exposure you have had, including previous CT scans or other X-rays. This will allow you to inform your doctor. Radiation exposure can be linked to radiation exposure if you have had multiple X-rays or treatments in a short time.
You should inform your doctor if you become pregnant or suspect you might be pregnant. Radiation exposure in pregnancy can cause birth defects. Special precautions will be taken to reduce radiation exposure to the fetus if you need a CT scan of the spine. Before breastfeeding, nursing mothers should wait 24 hours after the injection of contrast material.
Contrast media can cause allergic reactions. Patients who are sensitive or allergic to medication should inform their doctor. Research shows that 85 percent of people will not have an adverse reaction to iodinated color. However, it is important to inform your doctor if you have had any reactions to contrast media or any kidney problems. An allergy to seafood is not considered a contraindication to iodine.
Patients suffering from kidney disease or other problems should inform their doctor. Contrast media may cause kidney damage in some cases. Contrast agents and kidney disease have been more widely discussed in the past decade. Patients with kidney disease are more likely to suffer from kidney damage following contrast exposure. Patients taking metformin (Glucophage), a diabetes medication, should inform their doctor before receiving IV contrast. It may cause metabolic acidosis, a rare condition. Metformin users will need to discontinue taking the drug at the time of surgery and wait 48 hours before they can resume their normal dose. Before you can take metformin again, you may need to have your kidney function checked.
Other risks may exist depending on your medical condition. Before you undergo the procedure, discuss your concerns with your doctor.
How can I prepare for a CT scan
When you make an appointment for a computed Tomography Angiography (CTA), you’ll be given detailed instructions.
PRECAUTIONS: Before scheduling an exam, make sure you check with your doctor if you think or are pregnant. Your doctor will discuss other options with you.
CLOTHING: It is possible that you will be asked to wear a patient gown. A gown will be provided if you are required. To protect personal belongings, a locker will be provided. All piercings must be removed and all valuables and jewelry left at home.
CONTRAST MEDIA: CT scans can be done both with and without contrast media. Contrast media enhances the radiologists’ ability to see inside the body. Contrast media containing iodine should not be used for some patients. When you make an appointment, let the access center representative know if you have any problems with your kidney function. The scan may not require contrast media. You might be eligible for an alternative imaging exam.
A consent form will be required to detail the side-effects and risks associated with contrast media injections through a tiny tube placed in a vein known as an intravenous line (IV). Double contrast CT scans are the most popular. This will require you to consume a contrast media prior to your exam. For the radiologists to see your digestive tract, the more contrast you can drink is better.
ALLERGY: If you have ever had an allergic reaction to contrast media, please inform the access center representative at the time you schedule your CT scan. If you have ever had anaphylactic or severe reactions to contrast media, IV contrast will not likely be administered. You will need to take medication if you have had mild or moderate reactions to contrast media in the past. These plans will be discussed in detail with you when you schedule your exam. Your physician should discuss any known reactions to contrast media.
You can eat and drink if your doctor has ordered a CT scan with no contrast. Do not eat any food three hours before your CT scan if your doctor has ordered contrast. Clear liquids are recommended. Your doctor may ask you to take any prescribed medication before your exam.
DIABETICS: Diabetics should have a light breakfast or lunch at least three hours before the scan. You may need to stop taking your diabetes medication 48 hours after the CT scan, depending on the results of your oral medication. After your CT scan, you will receive detailed instructions.
MEDICATION: All patients are allowed to continue taking their prescribed medication as normal. Your doctor may recommend a different preparation depending on your medical condition.
How CT Scans Work
Computed tomography can be described as an xray study. A series of xrays are rotated in various directions around a particular body part. This creates a sequence of computer-generated images. Contrary to traditional x-rays these sequential images do not overlay and provide excellent detail of the target tissue.
The x-ray data is transmitted to a computer which gathers it and displays it on a monitor as a series of two-dimensional images.
Intraoperative CT
In neurosurgery, intraoperative CT scans are used to provide real-time images either during or after a surgery. Intraoperative CT makes it possible to perform minimally invasive surgery, which prevents the need for extensive or open surgeries. Intraoperative CT aids in precise screw placement for spinal fusion surgery.
Preparing for a Spinal CT
Metal jewelry, clothing, and accessories, as well as surgical clips, can create artifacts in a CT scan. These artifacts can obscure the images. The hospital gown is provided and patients are asked to take off all jewelry prior to the scan. Patients with pacemakers, programmable pumps, or shunts can use a CT scan safely.
Spinal CT Procedure
A spinal CT scan is painless and can be done in any hospital that has a CT machine. The same process is used for neck and back CT scans. It typically follows the following steps:
- The patient lies down on a scanner table, supported by straps and pillows to reduce or stop bodily movement.
- Once the patient is satisfied, the technician will leave the room and control the CT machine from another room.
- The scanner rotates around the scan table as the scanner slides into the large, circular-shaped opening on the CT machine.
- The scanner detects x-ray beams emitted from the machine and absorbed into the body. It transmits them to the scanner in the form of an image that can be viewed on a computer.
Contrast dyes are required for certain types of CT studies such as CT with myelogram. This dye is used to enhance contrast and CT resolution.
What happens following a CT scan
Contrast media may have been used in your procedure. You will be closely monitored for side effects and reactions, including itching, swelling, difficulty breathing, and rash. If you have any of these symptoms, please notify your doctor or the radiology team. You should inform your doctor if you feel any discomfort, pain, or redness at the IV site following your procedure. This could be a sign of an infection. A CT scan of your spine does not require any special care. Unless your doctor advises otherwise, you can resume your normal diet and activities. Your doctor may offer additional or alternate instructions depending on your specific situation.
Spinal CT: The Risks
Exposure to ionizing radiation can cause tissue damage in the CT procedure. Computed Tomography, which is approximately half of all medical radiation, uses 50-1000 times more radiation than traditional x-rays. Pregnant women should not have a CT scan unless there is a clear benefit to the baby. Children under 10 years old should not have a CT scan because of the risk of radiation damage to their developing organs.
CT scans can help diagnose many neck and back conditions. They can also be used prior to, during, or after spinal treatment. The scan’s benefits are often greater than the radiation exposure. CT should not be used if there is high risk of tissue damage and radiation exposure.
