CT scans are noninvasive medical tests that help our doctors diagnose certain conditions.
A CT scan, also known as a computerized tomogram or CAT scan, is a noninvasive type of X-ray that helps doctors diagnose medical conditions that may not be visible on other types of imaging technology.
Using a CT scan allows radiologists the ability to see more than what a regular X-ray can provide. NYU Langone radiologists review and interpret CT scans to diagnose a variety of illnesses, including abdominal, cardiac, musculoskeletal, neurological, spine-related, and thoracic conditions.
A CT scanner is a doughnut-shaped machine that uses advanced X-ray technology to take pictures of your body. A computer in the scanner reconstructs the data into cross-sectional pictures of your body, called slices or sections.
Unlike an MRI, a CT scanner is an open machine—you are not enclosed and can see completely around yourself.
NYU Langone offers patients the most advanced CT scanner technology available, providing images of exceptional quality, while using the lowest possible radiation dose to keep you safe. Learn more about radiation safety at NYU Langone.
Why Doctors Order a CT Scan
CT scans enable doctors to see cross-sectional images of your internal organs. CT scans can potentially help your doctor see the cause of your symptoms, diagnose certain diseases, and evaluate treatment response. Critical information can be provided to your doctor, often more quickly and economically compared with other tests.
Compared to MRI, CT provides a better evaluation of certain elements such as air, blood, and calcifications. This means that air-containing structures such as the lungs are better studied using CT.
Preparing for a CT Scan
You may be asked not to eat or drink anything for up to three hours before your CT scan, especially if a contrast material is going to be used in your exam. You should inform your doctor of any medications that you are taking and if you have any allergies. You can take your medications before the CT scan.
Talk with your doctor before the CT scan for any specific instructions. Also, please inform your doctor of any recent illnesses or other medical conditions, such as a history of heart disease, asthma, diabetes, kidney disease, or thyroid problems.
When you schedule your appointment, our scheduling associate tells you how early to arrive. Depending on the type of exam, it may be 30 to 60 minutes before your scheduled appointment. This allows time for registration and to complete all necessary paperwork, forms, and questionnaires. Be sure to bring your prescription, insurance card, and any related insurance forms or precertifications.
If you require a precertification for the study and you do not bring it with you, you will likely be delayed until it is on file in our department. It may be helpful to confirm that the doctor referring you for the exam has secured the precertification and has faxed it to our department.
You should wear comfortable, loose-fitting clothing to your exam. Certain exams may require you to wear a gown, which is provided. We have private dressing rooms with lockers for your clothes and valuables, although we suggest that you leave your valuables at home.
Metal objects including jewelry, eyeglasses, dentures, and hairpins may affect the CT images and should be left at home or removed prior to your exam. You may also be asked to take out hearing aids and removable dental work.
Some abdominal CT scans require the administration of water or oral contrast material to allow the radiologist to evaluate your bowel and also to separate the bowel from other important organs and tissues.
If you are having a CT scan of your abdomen or pelvis, you need to arrive one hour before your appointment. You will be asked to drink some type of oral contrast agent; either dilute or very dilute barium, dilute iodine, or water. During this period of time, you can fill out your forms and other paperwork.
Your physician and radiologist may determine that intravenous (IV) contrast material is needed for your CT scan. IV contrast material containing iodine is used to highlight organs and blood vessels that are otherwise difficult to visualize. If required, a small IV is placed in your arm or hand prior to the CT scan.
IV contrast material is safe for most patients, but there is a small chance of a reaction in a very small percentage of patients. Before your scan, you will be interviewed by one of our physician assistants or nurse practitioners. All of the possible consequences related to IV contrast will be explained to you. If, during that interview, it is found that you have certain medical conditions that make IV contrast not safe, we will modify the way we perform the scan. We will also check your serum creatinine level if no recent value is in your medical record during the pretest evaluation within the department.
Allergic reactions can occur following IV contrast administration. The likelihood for an allergic reaction is increased if you have a history of active uncontrolled asthma, if you’ve had a prior allergic reaction to contrast, or if you have a history of a life-threatening reaction to any allergen or medication.
Please notify your referring physician prior to scheduling your CT scan appointment if you have any of these risk factors or a known allergy to contrast material. Your doctor may prescribe medications to reduce the risk of an allergic reaction.
During a CT Scan
Our CT technologist takes you into the CT scanner room and positions you on the table, which moves into the doughnut-shaped portion of the scanner. At this point, the CT technologist exits the room. You and the technologist are able to speak with each other through an intercom system.
The technologist lets you know when the pictures are going to be taken—during this time you need to hold still, as moving causes the images to be blurry. The technologist gives you specific breathing instructions; for example, you may be asked to hold your breath or to breathe quietly. As the scanner takes the pictures, the table slides through the scanner and then back out.
The exam length depends on the type of scan that has been ordered for you. Most people are on the scanning table for less than 10 minutes. A technologist communicates with you throughout the exam and lets you know if additional images need to be taken.
After a CT Scan
When your scan is completed, you may resume your regular diet and activities. We recommend that you drink plenty of non-alcoholic, decaffeinated fluids, such as water or juice, to help your body flush out any IV or oral contrast material.
After your CT scan, our radiologists read the images and dictate a report that is sent to your doctor, who contacts you with the results.
Questions or Comments about Your Visit
Your experience is important to us. If you have questions or comments about your visit, please email firstname.lastname@example.org or call our ombudsman at 212-263-5222.
Plan Your Visit
NYU Langone Radiology—Faculty Practice Radiology
530 First Avenue
New York, NY 10016
NYU Langone Radiology—Gramercy Diagnostic Radiology
380 Second Avenue
New York, NY 10010
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