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Radiology Exams and Procedures

Johns Hopkins Medical Imaging offers a range of radiology exams using the latest technology. Please call 443-997-7237 if you have additional questions about your exam.

DEXA

Bone Densitometry (DEXA)

A bone density scan, also called DEXA, uses an X-ray to measure the bone mineral content and density. A DEXA scan produces more detailed images than a standard X-ray and helps to identify fragile bones before they break. A DEXA measures the bone density of spine, pelvis, lower arm and thigh. Learn more about bone density exams in the Johns Hopkins Health Library.

How do I prepare for a DEXA?+

PRECAUTIONS: Notify the technologist if you are pregnant or think you may be pregnant. Ensure that you have not had a barium or nuclear medicine exam within the past 72 hours.

EAT/DRINK: Do not take calcium supplements the day of your exam.

CLOTHING: In some cases, you may stay dressed but will be asked to remove all metallic objects such as belt buckles, zippers, coins, keys and jewelry. In other cases, you will be given a gown to wear so that no buttons, zippers or hooks will interfere with the imaging process.

Based on your medical condition, your health care provider may request other specific preparations.

What happens during a DEXA?+

  • You will be positioned on a table, lying flat on your back. Your legs will be supported on a padded box which serves to flatten the pelvis and lumbar spine.
  • Under the table, a photon generator will pass slowly beneath you, while an X-ray detector camera will pass above the table parallel to the photon generator beneath, projecting images of the lumbar spine and hip bones onto a computer monitor.
  • After the scan of the lumbar spine and hip bones is complete, your foot will be inserted into a brace that moves your non-dominant hip (the side you use the least) into a rotated position.
  • The next imaging procedure may involve the radius, one of the two bones of the lower arm. The non-dominant arm (the arm you use the least) is usually examined, unless there is a history of a fracture of that arm.
  • The computer will calculate the amount of photons that are not absorbed by the bones to determine the bone mineral content. The bone mineral density will then be calculated by a radiologist.

Read more about what happens during a bone densitometry exam.

What happens after a DEXA?+

There is typically no special type of care after a DEXA scan. You may resume your normal diet and activities, unless your doctor advises you differently. Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

CT

Computerized Tomography (CT)

Computed tomography is commonly referred to as a CT scan. CT uses X-rays to produce pictures or images of inside the body. The CT machine moves an X-ray around the patient to produce multiple detailed images at different angles. CT provides greater detail of soft tissue such as organs or blood vessels than a traditional X-ray. CT can also be used for a tissue or fluid biopsy. Learn more about CT scans in the Johns Hopkins Health Library.

How do I prepare for a CT scan?+

If you are having a computed tomography angiography (CTA) or a virtual colonoscopy, you will be given specific instructions when you make your appointment.

PRECAUTIONS: If you are pregnant or think you may be pregnant, please check with your doctor before scheduling the exam. We will discuss other options with you and your doctor.

CLOTHING: You may be asked to change into a patient gown. If so, a gown will be provided for you. A locker will be provided to secure all personal belongings. Please remove all piercings and leave all jewelry and valuables at home.

CONTRAST MEDIA: CT scans are most frequently done with and without a contrast media. The contrast media improves the radiologist’s ability to find structures that are abnormal and understand normal anatomy better too.

  • Some patients should not have iodine-based contrast media. If you have problems with your kidney function, please inform us in advance. We may be able to perform the scan without the contrast media, or may be able to find an alternate imaging exam.
  • You will be asked to sign a consent form that will detail the risks and side-effects associated with contrast media injected through an intravenous (IV) line (small tube placed in a vein).
  • The most common type of CT scan with contrast is the double contrast study that will require you to drink a contrast media before your exam begins in addition to the IV contrast. The more contrast you are able to drink, the better the images are for the radiologist to visualize your digestive tract.

ALLERGY: Please inform the access center representative when you schedule your scan if you have had an allergic reaction to any contrast media. IV contrast will not be administered if you have had a severe or anaphylactic reaction to any contrast media in the past. Mild to moderate reactions warrant a plan that includes taking medication prior to the CT examination. These plans will be discussed with you in detail when you schedule your exam. Any known reactions to a contract media should be discussed with your personal physician.

EAT/DRINK: If your study was ordered without contrast you can eat, drink and take your prescribed medications prior to your exam. If your doctor orders a CT scan with contrast, do not eat anything three hours prior to your CT scan. We encourage you to drink clear liquids. You may take your prescribed medications prior to your exam.

DIABETICS: Diabetics should eat a light breakfast or lunch three hours prior to the scan time. Depending on your oral medication for diabetes, you may be asked to discontinue use of the medication for 48 hours after the CT examination. Detailed instructions will be given following your examination.

MEDICATION: All patients can take their prescribed medications as usual.

What happens during a CT scan?+

  • If you are to have a CT scan done with contrast, an intravenous (IV) line will be started in the hand or arm for injection of the contrast media. For oral contrast, you will be given a liquid contrast preparation to swallow. In some situations, the contrast may be given rectally.
  • You will lie on a scan table that slides into a large, circular opening of the scanning machine. Pillows and straps may be used to prevent movement during the procedure.
  • The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. Speakers inside the scanner will enable the technologist to communicate with and hear you. You may have a call button so that you can let the technologist know if you have any problems during the procedure.
  • As the scanner begins to rotate around you, X-rays will pass through the body for short amounts of time. You will hear clicking sounds, which are normal.
  • The X-rays absorbed by the body's issues will be detected by the scanner and transmitted to the computer. The computer will transform the information into an image to be interpreted by the radiologist.
  • It will be important that you remain very still during the procedure. You may be asked to hold your breath at various times during the procedure.

Learn more about what happens during a CT scan.

What happens after a CT scan?+

  • If contrast media was used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast dye, such as itching, swelling, rash or difficulty breathing.
  • If you notice any pain, redness, and/or swelling at the IV site after you return home following your procedure, you should notify your doctor as this could indicate an infection or other type of reaction.
  • Otherwise, there is no special type of care required after a CT scan. You may resume your usual diet and activities unless your doctor advises you differently. Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

What CT exams are performed at Johns Hopkins Medical Imaging?+

MRI of the spine

Magnetic Resonance Imaging (MRI)

MRI uses high-powered magnets and radio waves to produce images of organs and structures inside the body. The MRI scanner is shaped like a building block with a very large hole in the middle where the patient lies on a table during the exam. The picture quality is at its best in the center of the magnet. This is why the part of your body that your doctor needs examined is always placed in the center. The information collected by the MRI scanner is sent to a computer and translated into images. MRI can also be used for a tissue or fluid biopsy. Learn more about MRI exams in the Johns Hopkins Health Library.

How do I prepare for an MRI?+

EAT/DRINK: You may eat, drink and take medications as usual, unless your health care provider tells you otherwise.

CLOTHING: You must completely change into a patient gown and lock up all personal belongings. Please remove all piercings and leave all jewelry and valuables at home.

ALLERGY: If you have had an allergic reaction to contrast that required medical treatment, contact your ordering physician to obtain the recommended prescription for Prednisone 40mg by mouth 24, 12 and two hours prior to examination.

ANTI-ANXIETY MEDICATION: If you require anti-anxiety medication due to claustrophobia, contact your ordering physician for a prescription. Please note that you will need someone else to drive you home.

STRONG MAGNETIC ENVIRONMENT: Due to the strong magnetic field, you must inform your doctor prior to the appointment if you have any metal in your body. If you have metal within your body that was not disclosed prior to your appointment, your study might be delayed, rescheduled or cancelled upon your arrival until further information can be obtained.

When you call to make an appointment, please let us know if you have any of the following:

  • You have a pacemaker or have had heart valves replaced
  • You have any type of implantable pump, such as an insulin pump
  • You have metal plates, pins, metal implants, surgical staples or aneurysm clips
  • You are pregnant or suspect you may be pregnant
  • You have any body piercing
  • You are wearing a medication patch
  • You have permanent eye liner or tattoos
  • You have ever had a bullet wound
  • You have ever worked with metal (for example, a metal grinder or welder)
  • You have metallic fragments anywhere in the body
  • You are not able to lie down for 30 to 60 minutes

Specialized MRI studies: Please review the letter confirming your appointment for specific instructions for the following MRI examinations. In some cases you will be contacted prior to the examination to discuss the details of the procedure and how to prepare.

Based on your medical condition, your health care provider may require other specific preparations.

What happens during an MRI?+

  • Your MRI exam takes places inside of a large tube-like structure, open on both ends. You must lie perfectly still for quality images.
  • You will lie on a table that slides into the tunnel of the MRI machine. During the scanning process, a clicking noise will sound as the magnetic field is created and radio waves are sent from the scanner. Because the machine is very loud, you will be given earplugs that are required.

Learn more about what happens during an MRI exam.

What happens after an MRI?+

  • There is typically no special type of care after an MRI. If contrast dye is used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast dye, such as itching, swelling, rash or difficulty breathing.
  • You may resume your normal diet and activities, unless your doctor advises you differently. Your doctor may give you additional or alternate instructions after the procedure depending on your particular situation.

What MRI exams are performed at Johns Hopkins Medical Imaging?+

Mammogram

Mammogram

A mammogram is an X-ray of the breast used to screen for and diagnose breast cancer. A mammography unit can either produce a standard 2-D image or 3-D image. 3-D mammography, or tomosynthesis, produces more detailed images of the breast tissue. Mammograms can also be used for a breast tissue or fluid biopsy. Learn more about a mammogram exam in the Johns Hopkins Health Library.

How do I prepare for a mammogram?+

SCHEDULING: Breasts can be tender the week before and during menstruation, so try to schedule your mammogram for one to two weeks after your period starts. If you have breast implants, please notify the office when you schedule the exam.

PRECAUTIONS: If you are pregnant or think you may be pregnant, please check with your doctor before scheduling the exam. We will discuss other options with you and your doctor.

BREASTFEEDING: Please notify the technologist if you are currently breastfeeding.

PERSONAL HYGIENE: Do not use any deodorant, powder, lotion or perfume on the day of your exam.

CLOTHING: You must remove your clothing from the waist up and change into a patient gown and lock up all personal belongings. Please remove all piercings and leave all jewelry and valuables at home.

What happens during a mammogram?+

  • You will be asked to remove your clothing from the waist up and any other clothing or jewelry that may interfere with the exam.
  • You will stand in front of the mammography machine and one breast will be placed on the X-ray plate. A separate flat plate will be brought down on top of the breast to compress it against the X-ray plate.

Learn more about what happens during a mammogram exam.

What happens after a mammogram?+

There is typically no special type of care following a mammogram. However, your health care provider may give you additional instructions depending on your specific health condition.

Ultrasound

Ultrasound

An ultrasound, also called a sonogram, uses sound waves to produce images of soft tissues inside the body. Sound waves move through the body and based on the frequency, the signals are translated into images on a computer. Ultrasound can also be used for a tissue or fluid biopsy. Learn more about ultrasound exams in the Johns Hopkins Health Library.

How do I prepare for an ultrasound?+

Based on your medical condition, your health care provider may require other specific preparations.

Abdominal Ultrasound

EAT/DRINK:

  • A.M. appointment: Nothing to eat or drink from midnight the evening before until after the examination. Patient may take medications with a small amount of water.
  • P.M. appointment: Clear liquid breakfast (no milk) before 9 a.m. Do not eat or drink anything after breakfast. Patients may take medications with a small amount of water.

Biophysical Profile Study

EAT/DRINK: Patients should eat a meal one hour prior to appointment, preferably with carbohydrates.

Patients who are having both a biophysical profile study in addition to an obstetric ultrasound are required to follow both preparations.

Gallbladder, Liver and Pancreas Ultrasound

EAT/DRINK:

  • A.M. appointment: Nothing to eat or drink from twelve midnight the evening before until after the examination. Patient may take medications with a small amount of water.
  • P.M. appointment: Clear liquid breakfast (no milk) before 9 a.m. Do not eat or drink anything after breakfast. Patients may take medications with a small amount of water.

Obstetric Ultrasound (Pregnancy Ultrasound)

EAT/DRINK: Drink 24 – 36 ounces of fluid at least one hour before the appointment. Do not urinate until after the exam.

Pelvic Ultrasound

EAT/DRINK: Drink 24 – 36 ounces of fluid at least one hour before the appointment. Do not urinate until after the exam.

Prostate Ultrasound

EAT/DRINK: Drink 24 ounces of fluid at least one hour before the appointment. Do not urinate until after the exam.

Renal Artery Doppler/Duplex

EAT/DRINK:

  • A.M. appointment: Nothing to eat or drink from midnight the evening before until after the examination. Patient may take medications with a small amount of water.
  • P.M. appointment: Clear liquid breakfast (no milk) before 9 a.m. Do not eat or drink anything after breakfast. Patients may take medications with a small amount of water.

Renal and Bladder Ultrasound

EAT/DRINK: Drink 24 ounces of fluid at least one hour before the appointment. Do not urinate until after the exam.

Renal Ultrasound

No specific preparation is needed.

Transvaginal Ultrasound

No specific preparation is needed.

What happens during an ultrasound?+

  • You will be asked to remove any clothing or jewelry that may interfere with the exam. If you are asked to remove clothing, you will be given a gown to wear.
  • You will lie on an exam table on your back, side or stomach, depending on the specific area to be examined.
  • Ultrasound gel is placed on the area of the body that is being examined.

Learn more about what happens during an ultrasound exam.

What happens after an ultrasound?+

There is typically no special type of care following an ultrasound. However, your health care provider may give you additional instructions depending on your specific health condition.

X-ray

X-ray

An X-ray machine uses a small dose of radiation to produce images of structures inside the body. The x-rays pass through the area of the body being examined and are translated into images captured on the other side of the body. Learn more about X-ray exams in the Johns Hopkins Health Library.

How do I prepare for a X-ray?+

  • Notify the technologist if you are pregnant or think you may be pregnant.
  • No other specific exam preparation is typically required.

What happens during an X-ray?+

  • You will be asked to remove any clothing or jewelry that may interfere with the exam. If you are asked to remove clothing, you will be given a gown to wear.
  • The area of your body being examined will determine if you sit, stand or lie down on a table.
  • Areas of the body not being examined may be covered with a lead apron to avoid exposure to the X-rays.

Learn more about what happens during an X-ray.

What happens after an X-ray?+

There is typically no special type of care following an X-ray. However, your health care provider may give you additional instructions depending on your specific health condition.