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What Are CT, MRI, CT-Angiogram, PET Scans...

There are so many different types of radiology studies that patients can undergo. I know that as a newer nurse there were many times that I thought to myself, "What is that study going to show?" Here is a brief overview of the most common radiology studies that are performed in the hospital (at least from what I've seen!).

Computed Tomography (CT) Scan

A CT scan is quick and painless for the patient. They are laid on a flat table that moves through a donut-shaped scanner. This scanner essentially takes x-rays of the patient from many different angles. The multiple images are used to visualize cross sections of the patient's body.
According to Radiologyinfo.org, CT imaging is:
  • one of the fastest and most accurate tools for examining the chest, abdomen and pelvis because it provides detailed, cross-sectional views of all types of tissue.
  • used to examine patients with injuries from trauma such as a motor vehicle accident.
  • performed on patients with acute symptoms such as chest or abdominal pain or difficulty breathing.
  • often the best method for detecting many different cancers, such as lymphoma and cancers of the lung, liver, kidney, ovary and pancreas since the image allows a physician to confirm the presence of a tumor, measure its size, identify its precise location and determine the extent of its involvement with other nearby tissue.
  • an examination that plays a significant role in the detection, diagnosis and treatment of vascular diseases that can lead to stroke, kidney failure or even death. CT is commonly used to assess for pulmonary embolism (a blood clot in the lung vessels) as well as for aortic aneurysms.
  • invaluable in diagnosing and treating spinal problems and injuries to the hands, feet and other skeletal structures because it can clearly show even very small bones as well as surrounding tissues such as muscle and blood vessels.

CT scans are very useful for showing obvious internal bleeding. On new onset stroke patients, one of the first interventions that receive for stroke treatment is a head CT scan. This shows if the patient's stroke is hemorrhagic (bleeding in the brain) or ischemic (a clot has clogged a vessel making the brain lose oxygen).

Computed Tomography (CT) Angiogram Scan

This type of radiology scan is performed in the same fashion as a regular CT scan. The main difference is that during the test, the radiology technician will insert dye into the patient's IV. The purpose of this study is to visualize the heart and blood vessels. The CT scan is performed just after the dye is injected. The picture of the dye circulating through the vessels can show blockages, blood clots, aneurysms, abnormal vasculature, or buildup of plaques in the vessel walls.


I think that most people are familiar with what an ultrasound is because of ultrasounds performed during pregnancy. This study uses sound waves to create images and is very non-invasive for the patient. Ultrasound technicians come to the bedside to perform this. Ultrasound can help to evaluate a patient's internal organs or be used to provide visual guidance during procedures.

Magnetic Resonance Imaging (MRI)

An MRI uses a magnetic field, radio waves, and a computer to create a very detailed image of the internal structures of the body. Unlike CT scans and traditional x-rays, MRI does not use ionizing radiation which can be potentially harmful to the patient. It does look similar to a CT scanner in shape. The patient is placed on a flat table and moved through a donut shaped machine. MRI takes much longer to complete than a CT or x-ray scan. As a result, it gives a very detailed picture of the internal structures of the human body.

Medical News Today states that MRI scans are used commonly for the following conditions:
  • Abnormalities of the brain and spinal cord
  • Tumors, cysts, and other abnormalities in various parts of the body
  • Injuries or abnormalities of the joints, such as back pain
  • Certain types of heart problems
  • Diseases of the liver and other abdominal organs
  • Causes of pelvic pain in women (e.g. fibroids, endometriosis)
  • Suspected uterine abnormalities in women undergoing evaluation for infertility
Be prepared to remove anything that you have on your person that is metal when you go into the MRI room. The last time I went to MRI with a patient, I could feel my bobby pins in my hair pulling towards the machine!

Positron Emission Tomography (PET) Scan

A PET scan is a form of nuclear medicine. This is performed by having a radioactive material either injected, swallowed, or inhaled by the patient. This type of scan does not focus on creating exact images of organs (like CT, MRI, or x-ray), but instead shows the amount of energy that is being given off within an organ by the radioactive material. This reconstructs an image of the internal structure as well as where the most energy is being consumed.

Radiologyinfo.org states that PET and PET/CT scans are performed to:
  • detect cancer.
  • determine whether a cancer has spread in the body.
  • assess the effectiveness of a treatment plan, such as cancer therapy.
  • determine if a cancer has returned after treatment.
  • determine blood flow to the heart muscle.
  • determine the effects of a heart attack, or myocardial infarction, on areas of the heart.
  • identify areas of the heart muscle that would benefit from a procedure such as angioplasty or coronary artery bypass surgery (in combination with a myocardial perfusion scan).
  • evaluate brain abnormalities, such as tumors, memory disorders, seizures and other central nervous system disorders.
  • map normal human brain and heart function

This guest blog post by Courtney Tracy first appeared in From New To ICU.

Courtney is an experienced ICU nurse and the creator of From New to ICU. She enjoys helping nurses at all stages of their careers, from getting into nursing school, learning new skills or even searching for their first nursing job! Follow the links to learn and read more from Courtney.


Posted: 1/11/2018 7:47:58 AM
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