Knowledge Bank

Diagnostic Imaging Cheat Sheet

Imaging 101 checklist

While any medical imaging procedure generates a certain amount of anxiety, being well-informed will help things go as smoothly as possible on the day of your appointment. Whether your doctor wants you to get a CT scan, an MRI or an ultrasound, it’s a good idea to bring a list of questions to ask in advance as you may forget once you arrive. You should also carry a list of your medical history — including any medications you are taking — any time you visit a hospital or clinic. 

Here’s what you can expect before, during and after your procedure and some questions you may want to ask along the way.

General questions to ask prior to any diagnostic imaging test

  • Why do I need this procedure?
  • What information will it provide?
  • Is this the best way to determine my condition?
  • Do I have any other imaging test options?
  • How will the results affect my treatment?
  • What are the risks?
  • Do the benefits of this procedure outweigh any risks?
  • Will my insurance cover this test?

CT scans

Computed Tomography (more commonly known as a CT scan) is a non-invasive, diagnostic imaging test that uses X-rays and a computer to diagnose a variety of illnesses and injuries. The doughnut-shaped machine quickly rotates around the body while taking multiple cross-sectional images, or slices, of a patient’s body. A computer stacks these slices into three-dimensional images to give radiologists a clear look inside the body. 

CT scans are particularly useful for investigating:

  • Muscle and skeletal structures (for things such as bone tumours, fractures and disorders)
  • Arteries, veins and soft tissues (for internal bleeding, infection, clots and tumours) 
  • Organs, including the heart, lungs and brain (for injury, internal bleeding, nodules and tumours)

Before a CT scan

Some questions to ask your doctor

  • Can I eat or drink prior to the procedure?
  • Should I continue to take my regular medications?
  • Are there any new medications I need to take?
  • Will my exam involve a contrast agent?
  • Do I need someone to accompany me to my appointment?
  • Is there anything else I need to know or do?

Depending on the area of the scan, there may be very little to do in advance. You may be asked to change into a gown but should still wear comfortable clothes to the appointment. Leave jewelry and other metal objects at home as they may interfere with the scan. 

Your doctor or technologist may also discuss some of the following with you:

Contrast agent — Some CT scans require the use of a dye, taken orally or intravenously, to better differentiate the body’s internal structures and provide clearer images. A tiny percentage of people are allergic to this dye and your doctor may order a blood test in advance to be on the safe side.

Dietary requirements — You may be required to fast for a few hours ahead of time.

Medication — Most medications are fine to take as usual — unless you are informed otherwise — but it is always a good idea to bring a list of your medications and past medical procedures with you.

Pregnancy — Although low doses of radiation are used, it is important to let your doctor know if you are pregnant as another scan may be used instead. 

The day of a CT scan

Some questions to ask your technologist

  • How long will this procedure take?
  • What should I do if I feel claustrophobic or unwell?
  • How do I alert you if there is any other problem?
  • Will I have any limitations afterwards?
  • Is there anything else I need to know?

The entire process generally takes around 30 minutes with the scan itself only taking a few minutes. You will be asked to lie flat and very still on a table that slides through the doughnut-shaped part of the machine. Because CT scans use X-rays, you will be alone in the room but will be monitored and able to communicate with a technologist via intercom. The machine may make soft whirring noises as it rotates and captures images.

After a CT scan

Some questions to ask your technologist

  • Is there anything I need to do when I get home?
  • When will the results be ready? Will they be available by phone or on PocketHealth?

You may be monitored for a brief period but will most likely be able to immediately go about your day. If a contrast agent was used, you will be instructed to drink plenty of water throughout the day to clear the dye from your system. Results are usually ready in a few days.

MRI scans

Magnetic Resonance Imaging (better known as an MRI scan) is a non-invasive, diagnostic imaging test that uses a strong magnetic field and radio waves to provide clear images of the internal structures of the body. The machine is doughnut shaped — similar to a CT scanner — but longer, allowing a greater section of the body to be scanned at the same time. MRIs are generally better than CT scans at examining the brain and detecting certain types of cancer, such as prostate and uterine.

MRI scans are particularly useful for investigating:

  • The brain (for things such as multiple sclerosis, Alzheimer’s disease, epilepsy, stroke and injury)
  • Muscle and skeletal structures (for arthritis, cancer, lower back pain and joint and spine damage)
  • Arteries, veins and soft tissues (for internal bleeding, infection, clots and tumours) 
  • Breasts (cancer)
  • Organs, including the heart, lungs, kidney and liver (for heart attack, heart disease, nodules, tumours and cancer)

Before an MRI scan

Some questions to ask your doctor

  • Can I eat or drink prior to the procedure?
  • Should I continue to take my regular medications?
  • Are there any new medications I need to take?
  • Will my exam involve a contrast agent?
  • Will my tattoos (if applicable) be an issue?
  • Do I need someone to accompany me to my appointment?
  • Is there anything else I need to know or do?

Similar to a CT scan, there is usually very little you need to do to prepare for this test. You may be asked to change into a gown but should wear comfortable clothes to the appointment. Metal is a concern because of the large magnet used during the scan. Jewelry should be left at home and you will be asked about any metal that might be inside of your body — such as pins, screws or pacemakers — as they may be affected. A small percentage of people experience claustrophobia during an MRI and you may be prescribed Ativan to help you relax during the procedure. 

Your doctor or technologist may also discuss some of the following with you:

Dietary requirements — Patients can eat or drink as usual prior to a scan unless otherwise instructed.

Contrast agent — Some MRI scans require the use of a dye, taken orally or intravenously, to better differentiate the body’s internal structures and provide clearer images. A tiny percentage of people are allergic to this contrast agent and your doctor may order a blood test in advance.

Medication — Most medications are fine to take as usual — unless you are informed otherwise — but it is always important to bring a list of your medications and past medical procedures with you.

Pregnancy — Even though MRIs do not use X-rays, they are generally not used on pregnant people, particularly during the first trimester. Be sure to inform your doctor if you think you might be pregnant.

Tattoos — Some body art contains metallic particles that can heat up during an MRI. It is important to let the technologist know if you think this might be a concern.

The day of an MRI scan

Some questions to ask your technologist

  • How long will this procedure take?
  • What should I do if I feel claustrophobic or unwell?
  • How do I alert you if there is any other problem?
  • Can I listen to music during the procedure?
  • Will I have any limitations afterwards?
  • Is there anything else I need to know?

An MRI typically takes between 15 minutes and an hour and you should be prepared to hear the machine make a lot of loud noises as the scan is performed. You will be asked to lie flat and very still on a table that slides through the doughnut-shaped part of the machine. 

After an MRI scan

Some questions to ask your technologist

  • Is there anything I need to do when I get home?
  • When will the results be ready? Will they be available by phone or on PocketHealth?

You may be monitored for a brief period after the exam but will most likely be able to immediately go about your day. If a contrast agent was used you will be instructed to drink plenty of water throughout the day to clear the dye from your system. If Ativan was taken, you should have someone there to take you home. Results are usually ready in a few days.

Angiogram 

An angiogram encompasses a series of diagnostic tests that use X-rays to generate images of the body’s blood vessels. During the procedure, a long tube called a catheter may be inserted into an artery — usually in the arm, groin or neck — and threaded through blood vessels to help diagnose any issues.

Angiograms are particularly useful for investigating:

  • Arteries and veins (for things such as blood vessel abnormalities, narrowing or blockages of arteries, heart disease, stroke, aneurisms, tumours and many forms of vascular disease)

Before an angiogram

Some questions to ask your doctor

  • Can I eat or drink prior to the procedure?
  • Should I continue to take my regular medications?
  • Are there any new medications I need to take?
  • Will my exam involve a contrast agent?
  • Do I need someone to accompany me to my appointment?
  • Is there anything else I need to know or do?

Unlike CT scans and MRIs, angiograms are invasive tests and you will be given specific instructions prior to the procedure. You will be asked to change into a gown but should have comfortable clothes to change into after the appointment. Jewelry and other metal objects should be left at home. 

Your doctor or technologist may also discuss some of the following with you:

Dietary requirements — You will likely be asked to fast after midnight the night before the procedure.

Contrast agent — A dye is required for a coronary angiogram, the most common form of the procedure, meaning you may be required to have a blood test ahead of time to ensure you are not allergic to the agent and that your blood is able to clot properly.

Medications — Be sure to follow your doctor’s instructions prior to an angiogram as some medications must not be taken before certain procedures. It is always important to bring a list of your medications and past medical procedures with you.

Pregnancy — Although very low doses of radiation are used, you should let your doctor know if you are pregnant as another scan may be used instead. 

Support — Patients should arrange to have someone take them to and from their appointment.

The day of an angiogram

Some questions to ask your technologist

  • How long will this procedure take?
  • How will you enter my body to perform the angiogram?
  • What will happen if a blockage is discovered?
  • Under what circumstances might an immediate angioplasty or stenting be required?
  • Will I have any limitations afterward?
  • Is there anything else I need to know?

Before a coronary angiogram, the medical team will review your medical history and may check your blood pressure and other vital signs. You will have to change into a gown and empty your bladder before lying on your back on a table. Straps may be fastened around you to prevent you from moving as the table tilts. X-rays of your head and chest may be taken and you will be connected to an IV to receive a sedative to help you relax and deliver any other medications needed. Your heart rate and blood pressure will be continually monitored as an incision is made in your arm, groin or neck for a catheter to enter your artery. You shouldn’t feel any pain as the catheter is slowly threaded through to your heart or coronary arteries to determine the issue. Depending on what is discovered, your doctor may need to insert another catheter or use a stent to open up a narrowed artery. The procedure typically takes between half an hour and two hours.

After an angiogram

Some questions to ask your technologist

  • Is there anything I need to do when I get home?
  • When will the results be ready? Will they be available by phone or on PocketHealth?

You will be required to lie flat and be monitored for a few hours following the procedure to ensure there is no internal bleeding. You will need someone to take you home — usually the same day — and will be required to drink plenty of water to help clear the contrast agent from your system. You may be given other instructions to follow at home. Most people feel fine the day after the procedure and results are usually ready in a few days.

X-ray 

An X-ray is a painless, low-risk procedure that uses electromagnetic energy to generate images of the internal structures of the body. As X-rays pass through a patient they are absorbed in varying degrees (depending on the density of the objects they encounter) before being captured on film or digital media on the other side. Dense objects, such as bones or tumours, appear white on an X-ray, while soft tissues, such as skin, fat and muscle, look grey. 

Depending on the body part being investigated, technicians may take more than one image, targeting structures that are perpendicular to one another to provide as much information as possible.

X-rays are particularly useful for investigating:

  • Bones (for things such as fractures, osteoporosis or bone cancer)
  • The chest (for breast cancer, blocked blood vessels or lung infections)
  • The abdomen (for digestive issues or blockages)

Before an X-ray

Some questions to ask your doctor

  • Can I eat or drink prior to the procedure?
  • Do I need someone to accompany me to my appointment?
  • Will my exam involve a contrast agent?
  • Is there anything else I need to know or do?

There isn’t much patients need to do prepare for an X-ray as the procedure is non-invasive and only takes a few minutes to complete. You may be asked to remove any jewelry that is in the area being scanned. Your doctor or technologist may also discuss some of the following with you:

Dietary requirements — Fasting may be required before the imaging of certain areas, such as the abdominal region, but your doctor will inform you of this ahead of time.

Contrast agent — For some X-rays, a contrast agent, such as barium or iodine, may be used to help provide clearer images of the area of concern. Your doctor will discuss this with you beforehand.

Pregnancy — Although very low doses of radiation are used, you should let your doctor know if you are pregnant as another scan may be used instead. 

The day of an X-ray

Some questions to ask your technologist

  • How long will this procedure take?
  • Will I have any limitations afterwards?
  • Is there anything else I need to know?

Depending on the area being examined, you may or may not be required to change into a gown. The procedure only takes a few minutes and the technologist will help position your body in a way that will facilitate the clearest images. You will be asked to lie still and may be required to hold your breath for a few moments to prevent blurry images.

After an X-ray

Some questions to ask your technologist

  • Is there anything I need to do when I get home?
  • When will the results be ready? Will they be available by phone or on PocketHealth?

It depends on the results of the scan and if further testing is required but you should generally be able to go about your day immediately following the procedure.

Mammogram

A mammography exam, better known as a mammogram, is a cancer screening test that uses X-rays to produce two-dimensional images of the breast. During the procedure, each breast is compressed between two plates, horizontally and then vertically, for about 10 to 15 seconds while images — using film or digital media — are captured. Some hospitals and health clinics also have access to digital tomosynthesis, a more advanced type of mammography that produces three-dimensional images of the breast. Most mammograms produce black-and-white images that radiologists examine for signs of cancer. Dense objects, such as bones or tumours, appear white on a mammogram, while soft tissues, such as skin, fat and muscle, look grey.

Mammograms are particularly useful for investigating:

  • Breast cancer or abnormal growths or changes in breast tissue

Before a mammogram

Some questions to ask your doctor

  • At what age should I start having regular mammograms?
  • What type of mammogram do I need?
  • How often should I have a mammogram?
  • When should I stop having mammograms?
  • Is there anything else I need to know or do?

If you are going for your first mammogram, there is a chance that you may be asked to return to the clinic for additional imaging. This is a normal part of the process and not an indication that there is something wrong but that radiologist may need more information as there are no previous results with which to compare results. According to the American Cancer Society, only about two to four screening mammograms out of 1,000 result in a cancer diagnosis. 

Your doctor or technologist may also discuss some of the following with you:

Perfume, deodorant and lotions — Some substances may show up as white spots on a mammogram so it’s best to avoid applying them on the day of your exam.

Pregnancy — Although very low doses of radiation are used, you should let your doctor know if you are breastfeeding or suspect you may be pregnant. 

Scheduling — If you are still menstruating, it’s a good idea to avoid booking your appointment during the week just prior to your period as the procedure can cause discomfort if your breasts are swollen or tender.

The day of a mammogram

Some questions to ask your technologist

  • How long will this procedure take?
  • Will I have any limitations afterwards?
  • Is there anything else I need to know?

If you are visiting a clinic for the first time, it is helpful to bring a list of the other clinics you have visited (and the scans themselves if you subscribe to PocketHealth). Let the technologist know if you have breast implants or have noticed any recent changes in your breast tissue. You will be required to undress from the waist up and will be alone in the examination room with a technologist for the duration of the exam. 

You will be asked to stand in front of the mammogram machine while the technologist places your breast on a lower plate attached to the machine. An upper plate will be lowered to compress your breasts horizontally for 10 to 15 seconds while images are taken. Your breast will then be compressed vertically by two plates while more images are taken. The process is then repeated for your other breast. The entire process should only take around 20 minutes. If you are receiving a digital tomosynthesis (a 3D mammogram) the machine will move in a small arc as it captures images of your breast.

After a mammogram

Some questions to ask your technologist

  • Is there anything I need to do when I get home?
  • When will the results be ready? Will they be available by phone or on PocketHealth?

Patients can generally go about their day as normal following a mammogram.

 

Ultrasound

An ultrasound is a non-invasive procedure that uses high-frequency sound waves to produce images of the inner workings of the body. The imaging technique is considered safer than an X-ray or CT scan because it does not use radiation to produce images. The sound waves are generated by a probe that usually remains outside the body although certain procedures require it to be used internally. After bouncing off organs and other structures, the sound waves return to the probe and are converted into detailed images of the objects they encountered.

Ultrasounds are particularly useful for investigating:

  • Reproductive organs (including the genitals, ovaries, uterus and developing fetuses)
  • Other internal organs (such as the liver, gallbladder, spleen, bladder, pancreas, appendix, kidneys and the heart — including blood vessels and blood flow)
  • Breasts (for lumps or other abnormalities)

Before an ultrasound

Some questions to ask your doctor

  • Can I eat or drink prior to the procedure?
  • Do I need someone to accompany me to my appointment?
  • Will my exam involve a contrast agent?
  • Is there anything else I need to know or do?

Technologists use different types of probes depending on the type of ultrasound and the area of investigation. Pelvic ultrasounds, for example, require the insertion of a transvaginal probe that is not typically painful but may be uncomfortable. You will be asked to remove any jewelry that may interfere with the procedure. Your doctor or technologist may also discuss some of the following with you:

Dietary requirements — For certain types of ultrasounds, patients may be asked to refrain from eating prior to the procedure. For others, they may be asked to arrive with a full bladder to allow for better imaging. Your doctor will provide instructions ahead of time. 

Contrast agent — Certain ultrasounds require the use of a contrast agent to help differentiate the different internal structures of the body. Your doctor may discuss this with you in advance.

Pregnancy — Although no radiation is used, you should let your doctor know if you are pregnant before the procedure as certain precautions may need to be taken. 

The day of an ultrasound

Some questions to ask your technologist

  • How long will this procedure take?
  • Will I have any limitations afterwards?
  • Is there anything else I need to know?

Depending on the area being examined, you may be asked to remove some or most of your clothing and change into a gown. A water-based gel will be applied to inspection site to prevent air pockets that may interfere with the sound waves. The technologist will slowly move the probe along the surface of your skin as it sends out and then collects returning sound waves. Depending on the type of ultrasound, a probe may be inserted into your esophagus, prostate or vagina. The length of the procedure can vary, with abdominal ultrasounds taking around 45 minutes and wrist or ankle ultrasounds only lasting about 20 minutes.

After an ultrasound

Some questions to ask your technologist

  • Is there anything I need to do when I get home?
  • When will the results be ready? Will they be available by phone or on PocketHealth?

Patients should be able to go about their day immediately following the procedure.