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Frequently Asked Questions
FAQs for CT Scan | FAQs for MRI Scan | FAQs for Vein Care | FAQs for CT Virtual Colonoscopy
Computerized Axial Tomography (CT)
What is a CT Scan?
How does CT work?
Why are CT Scans performed?
How do I prepare for a CT Scan?
Are there any risks involved?
What will I experience during a scan?
How long does the scan take?
What is contrast?
When will I get the results?
What is a CT Scan?
CT or CAT is short for Computerized (Axial) Tomography. This is an x-ray procedure that combines multiple x-ray images, with the aid of a computer, to generate cross-sectional views or picture slices of your internal organs. If you were to imagine yourself as a loaf of bread, the CT scanner is able to take individual pictures of you just like the individual slices in a loaf of bread. By examining each slice and/or combining the slices into three dimensional (3D) images, the radiologist can diagnose normal or abnormal structures within the body and help your doctor diagnose or follow any disease process.
How does CT work?
The CT scanner is made up of three main parts:
- First, there is the table that you lie on. As the images are taken, the table slides you in and out of the scanner taking x-ray images as you move.
- The gantry -or doughnut-shaped machine-that the table moves through contains the x-ray source and a large array of detectors that receive the fine beams of x-ray.
- The information gathered from these detectors is then fed into the third part of the scanner, the computer. The computer is able to take all of this information and transform it into many images that come up on the screen.
The LifeDiagnostics CT Scanner is able to scan up to 40 slices at one time.
Why are CT scans performed?
A conventional x-ray relies on how much radiation is able to pass through a given body part to be imprinted onto an x-ray film. Soft tissue structures allow a higher percentage of x-rays through them than does bone. However, a problem arises on conventional x-rays in that most soft tissues look the same and it's hard to distinguish between the many organs in the body.
The differences in CT physics and in how the images are created allow for a much improved differentiation between tissues and the ability to not superimpose multiple organs on one another, in one picture. CT scans are performed for various reasons depending on the area of the body being scanned. CT's are not generally used for breast diagnosis or obstetrics, and usually not for looking at the soft tissue structures of joints, although they are excellent for looking at the bones of a joint.
Most often, CT scans are used to look at:
- Traumatic Injuries to the head such as blood clots or skull fractures
- Brain tumors, infections or bleeding into the brain
- Spinal imaging to look at the bony structures of the vertebrae as well as the anatomy of the intervertebral disc spaces and the spinal cord
- Chest or abdominal tumors, cysts, or infections
- Complicated bone fractures
- Blood vessel disease or injury
CT has become the screening test of choice for kidney stones, diverticulitis, and appendicitis. CT of the pulmonary arteries has become an important tool to diagnose life-threatening blood clots or emboli to the lungs.
Our CT scanner can take up to 40 slices at one time. This shortens your exam time and improves the quality of the pictures. We can provide many very detailed images in the shortest amount of time.
We can also use this technology to perform CTA (Computed Tomographic Angiography), a way to look at the arteries in the body without having to go through the more invasive conventional angiography procedures. The procedures can now be completed in 5-15 minutes, usually in just a few breath holds.
How do I prepare for a CT Scan?
At the time your scan is scheduled, our staff will tell you or your doctor's office how you need to prepare for the exam. The procedures are grouped into two categories: without contrast or with contrast. The use of contrast material, or "dye," can help to define anatomy and help delineate abnormal structures in the body.
There are two kinds of contrast commonly used for CT scans: oral and IV. The oral contrast is given by mouth and is mixed with water or clear fruit juice. This contrast is used for certain abdominal scans and is given 1½ - 2 hours prior to the procedure. This contrast is used to highlight your stomach and intestinal track. The IV contrast is given by placing an IV in your arm and injecting the contrast into the veins. This contrast contains iodine. Because some people are allergic to iodine, we will ask you some pertinent questions in advance. Occasionally, a preventative allergy medication will be given ahead of time. IV contrast is most often used to look for tumor, infection, or to look at the blood vessels.
Regardless of whether or not a contrast is used, it is recommended that you not eat or drink anything, except the oral contrast if given, for four hours before your CT scan. You may take prescribed medication with small sips of water. For the colon screening or Virtual Colonoscopy exam, you will need to follow a bowel prep prior to the procedure. This will include a special diet the day before and a laxative to clear the stool from the intestinal track.
For more information about preparing for your CT Scan, access the CT Exam preparation page.
Are there any risks involved?
The overall risks of Computed Tomography are minimal.
One risk of a CT scan is radiation, the same risk that is involved with all x-ray tests. LifeDiagnostics physicians and personnel make sure that the least amount of radiation is used to provide the best images needed to make an accurate diagnosis.
If an intravenous contrast (IV contrast) is used, a small number of patients may experience a minor reaction to the contrast. Some of these reactions are due to allergy, some are not. The IV contrast often makes you feel hot for a short period of time and may give you a funny taste in your mouth for a short time. These are normal reactions and are not allergy. Patients who are allergic to the iodine in the contrast usually have only a minor reaction; major allergic reactions are rare.The staff will have you fill out a questionnaire prior to your procedure and can answer any questions you may have.
What will I experience during the scan?
The technologist will interview you prior to the procedure. If IV contrast is going to be used, a small needle will be placed in your arm and risk factors will be discussed. You will be asked to lie on the comfortable, padded table on your back or stomach depending on the procedure being performed. You may be asked to drink a small amount of the additional oral contrast just prior to lying down. The table will move in and out of the gantry as necessary and you will be asked to hold your breath so that the pictures are motion free.
Each exam is tailored to individual requirements. Don't be alarmed if the procedure is somewhat different than one you've had before. Let the technologist know if you are uncomfortable. After the procedure the technologist will make sure that all the required images have been completed. You can get dressed and leave and go about your everyday activities with no restrictions. The technologist will advise you to drink plenty of liquids to clear the contrast out of your system.
How long will the scan take?
The 40-slice CT scanner is very fast. The procedure is painless and will take 5-15 minutes. If an oral contrast is needed for your procedure, you will begin drinking the contrast 1½ to 2 hours ahead of time. Upon arrival you will be registered and interviewed for the procedure. This usually takes about 10 - 15 minutes. After the procedure the technologist will check that all the pertinent images have been acquired. You may then get dressed and the technologist will give you instructions for care after the procedure.
What is contrast?
There are two kinds of contrast commonly used for CT scans: oral and IV. Oral contrast is mixed with water or clear fruit juice and is taken by mouth 1 1/2 - 2 hours prior to the procedure. This contrast is used to highlight your stomach and intestinal track. IV contrast is injected into your veins through an IV placed in your arm. This contrast contains iodine. Because some people are allergic to iodine, we will ask you some pertinent questions in advance. IV contrast is most often used to look for tumors, infections, or to look at the blood vessels.
When will I get the results?
The exam will be reviewed by your LifeDiagnostics Radiologist shortly after the completion of your exam. Some procedures require post processing and can take some time to complete, so a report is not always immediately available. The radiologist will dictate a report that will be sent to your referring or primary physician within 24 hours of the procedure.
Complimentary cd-rom images of the exam are available to you or your doctor.
Magnetic Resonance Imaging (MRI)
What is an MRI and how does it work?
Why are MRI scans performed?
How do I prepare for a MRI scan?
Are there any risks involved?
What will I experience during a scan?
How long does the scan take?
When will I get the results?
What is an MRI and how does it work?
MRI stands for Magnetic Resonance Imaging. Unlike other radiology procedures that use x-ray radiation, MRI uses magnetism, radio waves, and a computer to help produce the images of the body. The MRI scanner is able to produce images in any direction with such detail that it has revolutionized medical imaging.
The patient lies on a long table and the large magnetic field surrounds the table. The magnetic field causes the hydrogen protons in the body to align themselves with this magnetic field. A radio frequency is then transmitted through the body causing the hydrogen protons to move. When the radio frequency is turned off, the protons stop moving. As this happens the protons give off a slight signal, which in turn is measured by the computer and transformed into images. Thousands of these signals are measured and processed during a single scan series.
When are MRI Scans performed?
MRI scans can be used as an extremely accurate method of diagnosing diseases in many areas of the body. The exquisite detail produced by these images has made MRI the gold standard for imaging the extremities, especially the joints. In the head, MRI is used to look for tumors, strokes, aneurysms, and nervous system diseases such as Multiple Sclerosis. MRI is considered to be the best exam to look at the entire spine and neck.
Although CT still dominates imaging of the chest and abdomen, MRI is continually coming up with new applications for these body areas and now can be used to evaluate the structures of the heart and aorta as well as the arteries of the abdomen and legs. MRI's ability to look at soft tissue structures has made it one of the newest tools to look at the breast for implant rupture or newly diagnosed breast cancer.
How do I prepare for an MRI Scan?
Most MRI exams do not require any fasting before the procedure. Abdomen exams require the patient to not eat or drink for four hours before the test. When you are scheduled for an MRI, it is important to know whether you have any metal objects that have been implanted in the body. The MRI staff will ask you or the scheduler about such things as aneurysm clips and pacemakers.
- Abdomen - Nothing to eat or drink for 4 hours before test.
- MRCP - Nothing to eat or drink for 4 hours before test.
- Pelvis - Nothing to eat or drink for 4 hours before test.
- Abdomen MRA - Nothing to eat or drink for 4 hours before test.
- Pelvis MRA - Nothing to eat or drink for 4 hours before test.
- Lower Extremity Run-off MRA - Nothing to eat or drink for 4 hours before test.
- All other procedures do not require preparation.
Are there any risks involved?
MRI is a painless radiology procedure that has the advantage of not using any x-ray radiation. There are no known side effects of the scan.
However, since the MRI scanner is a large magnet, it is very important to notify the technologist of metal implants and it is necessary to remove all metal objects such as keys and watches before entering the scan room. A screening form must be completed before starting a scan. In some cases, the exam cannot be performed due to certain implants. The most common contraindications for scanning are:
- Cardiac pacemaker
- Implanted defibrillator
- Brain aneurysm clips
- Metal in the eyes
- Implanted devices, such as insulin pumps
- Certain types of ear implants
The technologist will give you a more complete list and can answer any questions you may have before the scan.
The MRI exam may require an injection of a contrast material. The most common contrast is called gadolinium. This basically does the same thing for MRI as iodine does for CT scans. The complication rate for this contrast is very low.
What will I experience during a scan and how long does the scan take?
You will be asked to lie on a table and this table will slowly move to the center of the magnetic field. The scanner is a long tube open at both ends. The part of the body being scanned must be in the middle of this tube. Some patients find that they can be somewhat claustrophobic during this scan. However, the Philips scanner has a very short bore and claustrophobia is not usually an issue.
The scanner generates loud knocking noises during the scan so the staff will provide earphones during the procedure. You can listen to your favorite radio station or CD. The scan times are very short and every consideration will be taken to make you comfortable during the procedure.
The procedure usually lasts 15 - 30 minutes and you must lie very still. Some patients like to take a light sedative or pain medication before they arrive for the test.
When will I get the results?
The exam will be reviewed by your LifeDiagnostics radiologist shortly after the completion of your exam. Some procedures require post processing and can take some time to complete so a report is not always readily available. The Radiologist will dictate a report that will be sent to your referring or primary physician within 24 hours of the procedure.
A complimentary CD-ROM or x-ray film copies of the exam are available to you or your doctor.
CT Virtual Colonoscopy
What can I expect from a CT Virtual Colonoscopy?
The Virtual Colonoscopy is performed on our CT scanner. It is a minimally invasive procedure so we normally do not need to use any sedatives. This will allow you to resume normal activities immediately following the procedure.
We begin by laying you on your side with your knees bent toward your chest. The technologist will place a small tube into the rectum to fill the colon with carbon dioxide gas. The gas may occasionally cause you to feel some pressure in the abdomen. Please let the technologist know if you feel any discomfort. For the actual exam, we will place you on your back and take a set of images and then turn you on your stomach and take a second set of images. You will be asked to hold your breath during these scans. The entire exam takes about 10 - 15 minutes to complete.
When the exam is complete, most of the gas will be removed through the tube in the rectum. Once we remove the tube, we will escort you to the bathroom. You may pass gas for a few hours after the procedure. Consult your physician if the gas or bloating does not improve on its own.
What do I need to do to prepare for my CT Virtual Colonoscopy?
You will need to pick up this preparation at our office 2 days prior to the procedure or we can make arrangements to have it delivered to you if time permits.
The preparation kit includes the following:
2 days before your exam: (Suggested diet beginning with lunch*)
| Lunch | Dinner |
| Soup | Soup |
| Fish/white meat chicken | Fish/white meat chicken |
| White rice | White rice |
| Bread/cracker | Bread/cracker |
| Dessert/fruit | Dessert/fruit |
* This diet is the suggested diet. If your normal diet is an alternative diet and you have any questions please feel free to contact us at 612-347-7226.
Allowed items on this list:
Limit of 2 cups low fat milk or yogurt (plain) - Plainly prepared fish, poultry, eggs - White rice, spaghetti noodles, macaroni, potato with no skin - White bread, saltine crackers - Clear fruit juices, canned fruit with no seeds, skin or membranes - Bouillon /broth, strained soup, soups made with allowed vegetables and meats - Gelatin, fruit ices, Popsicles - Coffee (Limited), fruit flavored drinks, tea, carbonated beverages (avoid caffeine and chocolate) - Salt, pepper, jelly, sugar, honey, and syrup.
The Day before the exam:
Breakfast and Lunch: One bottle of Tagitol at each meal time. Clear liquids only - Carbonated drinks, coffee and tea without cream or non-dairy creamer, Kool-Aid or fruit drinks like Hi-C, grape, apple, cranberry and cran-apple juices. Plain Jello, popsicles and ices made without milk. Plain hard candy, and Gum (do not Swallow it). Bouillon, clear broth, or strained broth.
DO NOT DRINK: Milk, milk drinks, non-dairy creamer, beer, alcohol, juices with pulp, prune, and tomato juice or apple cider.
DO NOT EAT: any vegetables, meat, cream, or noodle soups.
Dinner (5 pm) Clear liquids (same as Breakfast and Lunch) & the last bottle of Tagitol
| 5:30 p.m. | LoSo Prep Magnesium Citrate (follow package directions) |
| 6:00 p.m. | 8 oz glass water, tea, apple juice, or club soda |
| 7:00 p.m. | 8 oz glass water, tea, apple juice, or club soda |
| 7:30 p.m. | LoSo Bisacodyl Tablets (follow package directions) |
| 8:00 p.m. | 8 oz glass water, tea, apple juice, or club soda |
| 9:00 p.m. | 8 oz glass water, tea, apple juice, or club soda |
| After 9:00 p.m. Nothing to eat or drink | |
The day of the exam:
Do not eat or drink anything.
2 hours before you begin to travel to your appointment, insert the LoSo Prep Bisacodyl Suppository (follow the package directions). Please call if you have any questions or concerns. Phone: 612-347-7226