Shoulder CT scan
CAT scan - shoulder; Computed axial tomography scan - shoulder; Computed tomography scan - shoulder; CT scan - shoulderA computed tomography (CT) scan of the shoulder is an imaging method that uses x-rays to create cross-sectional pictures of the shoulder.
How the Test is Performed
You will be asked to lie on a narrow table that slides into the center of the CT scanner.
Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam without stopping.)
A computer creates separate images of the shoulder area. These are called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of the shoulder area can be created by adding the slices together.
You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time.
The scan should take only 10 to 15 minutes.
How to Prepare for the Test
Certain exams require a special dye, called contrast, to be delivered into the body before the test starts. Contrast helps certain areas show up better on the x-rays.
- Contrast can be given through a vein (IV). If contrast is used, you may also be asked not to eat or drink anything for 4 to 6 hours before the test.
- Let your health care provider know if you have ever had a reaction to contrast. You may need to take medicines before the test in order to safely receive this substance.
- Before receiving the contrast, tell your provider if you take the diabetes medicine metformin (Glucophage) because you may need to take extra precautions.
If you weigh more than 300 pounds (135 kilograms), find out if the CT machine has a weight limit. Too much weight can cause damage to the scanner's working parts.
You will be asked to remove jewelry and wear a hospital gown during the study as metal can affect the CT images.
How the Test will Feel
Some people may have discomfort from lying on the hard table.
Contrast given through an IV may cause a slight burning sensation, a metallic taste in the mouth, and a warm flushing of the body. These sensations are normal and most often go away within a few seconds.
Why the Test is Performed
CT rapidly creates detailed pictures of the shoulder. The test may help diagnose or detect:
- A dislocation, fracture, or other shoulder injury
Dislocation
A dislocation is a disruption of the normal position of the ends of two or more bones where they meet at a joint. A joint is the place where two bon...
Read Article Now Book Mark ArticleFracture
If more pressure is put on a bone than it can stand, it will split or break. A break of any size is called a fracture. If the broken bone punctures...
Read Article Now Book Mark Article - Soft tissue problems such as damage to the rotator cuff tendons
- Abscess or infection
Abscess
An abscess is a collection of pus in any part of the body. In most cases, the area around an abscess is swollen and inflamed.
Read Article Now Book Mark Article - The cause of pain or other problems in the shoulder joint when MRI cannot be done
MRI
A magnetic resonance imaging (MRI) scan is an imaging test that uses powerful magnets and radio waves to create pictures of the body. It does not us...
Read Article Now Book Mark Article - Masses and tumors, including cancer
- Healing problems or scar tissue following surgery
- Help planning for your surgical treatment
This test may also help a surgeon perform a biopsy or plan surgical treatment to the shoulder.
Normal Results
Results are considered normal if the shoulder being examined is normal in appearance.
What Abnormal Results Mean
Abnormal results may be due to:
- Abscess (collection of pus)
Abscess
An abscess is a collection of pus in any part of the body. In most cases, the area around an abscess is swollen and inflamed.
Read Article Now Book Mark Article - Bone tumors or cancer
- Dislocated shoulder
Dislocated
A dislocation is a disruption of the normal position of the ends of two or more bones where they meet at a joint. A joint is the place where two bon...
Read Article Now Book Mark Article - Shoulder fracture
- Rotator cuff tears
- Failure to heal or development of scar tissue after surgery
Risks
Risks of CT scans include:
- Being exposed to radiation
- Allergic reaction to contrast dye
- Birth defect if done during pregnancy
CT scans do expose you to more radiation than regular x-rays. Having many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. You and your provider should weigh this risk against the benefits of getting a correct diagnosis for a medical problem.
Some people have allergies to contrast dye. Let your provider know if you have ever had an allergic reaction to injected contrast dye.
- The most common type of contrast given into a vein contains iodine. If a person with an iodine allergy is given this type of contrast, nausea or vomiting, sneezing, itching, or hives may occur.
Nausea or vomiting
Nausea is feeling an urge to vomit. It is often called "being sick to your stomach. "Vomiting or throwing-up forces the contents of the stomach up t...
Read Article Now Book Mark ArticleSneezing
A sneeze is a sudden, forceful, uncontrolled burst of air through the nose and mouth.
Read Article Now Book Mark ArticleItching
Itching is a tingling or irritation of the skin that makes you want to scratch the area. Itching may occur all over the body or only in one location...
Read Article Now Book Mark ArticleHives
Hives are raised, often itchy, red bumps (welts) on the surface of the skin. They can be an allergic reaction to food or medicine. They can also ap...
Read Article Now Book Mark Article - If you absolutely must be given such contrast, you may need to get antihistamines (such as Benadryl) or steroids before the test.
- The kidneys help remove iodine out of the body. Those with kidney disease or diabetes may need to receive extra fluids after the test to help flush the iodine out of the body.
Rarely, the dye may cause a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.
Anaphylaxis
Anaphylaxis is a life-threatening type of allergic reaction.
Read Article Now Book Mark ArticleReferences
Kapoor G, Toms AP. Current status of imaging of the musculoskeletal system. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic Radiology. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 38.
Perez EA. Fractures of the shoulder, arm, and forearm. In: Azar FM, Beaty JH, eds. Campbell's Operative Orthopaedics. 14th ed. Philadelphia, PA: Elsevier; 2021:chap 57.
Sheah K, Bredella MA. Shoulder. In: Haaga JR, Boll DT, eds. CT and MRI of the Whole Body. 6th ed. Philadelphia, PA: Elsevier; 2017:chap 61.
Review Date: 4/24/2023
Reviewed By: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.