Diagnostics: Which Scan is the Gold Standard?

There are many different diagnostic studies, specifically scans, available to diagnose a medical malady. The attending physician is educated in the indication for each diagnostic test and orders the appropriate study based on the efficacy and safety in each individual case.

However, it is also important for a patient to be educated about the pros and cons of each medical diagnostic scan they undergo so they have a basic knowledge about the scan and any risks or benefits.

Computed Tomography (CT)

This type of scan takes multiple cross-section pictures of the body using a combination of x-ray technology and computer capabilities. Some of the conditions that CT scans are used to diagnose are:

There is a radiation exposure risk associated with having a CT scan. The radiation exposure from a CT scan, particularly for children, is a concern. Some calculate that radiation exposure from a single CT scan might be equivalent to the level of radiation an individual might accrue over three to five years. This is concerning, as higher doses of radiation from powerful CT scans can lead to subsequent brain tumors, leukemia, lung or breast cancer.

A physician is supposed to determine the dose of radiation exposure a patient receives during a CT scan, but the technician operating the scanning machine sets the dose. This means that children can sometimes receive an adult-sized dose of radiation if the scan settings have not been adjusted.

The CT scan is a popular diagnostic tool with more than 60 million tests performed annually in the U.S., according to the American College of Radiology (ACR).

Magnetic Resonance Imaging (MRI)

Radio frequency waves and a large magnet are used to create MRI images. MRI scans are used to diagnose some of these conditions:

  • Tumors
  • Torn ligaments
  • Conditions of the brain and spinal cord

There is no radiation exposure involved in MRI imaging. MRI is expensive, but can sometimes be used as an alternative to other diagnostic scans that involve radiation.

Nuclear Scan

Small dose radioactive material called a tracer is intravenously injected into the patient to help create the images in a nuclear scan. Nuclear scans help to diagnose:

  • Cancer
  • Infections
  • Bone fractures

A bone scan is a form of nuclear scan. The injected tracer collects in areas of the bone that are abnormal. A bone scan is used to diagnose only skeletal problems such as infection, fractures and metastatic bone cancer.

Positron Emission Tomography Scan (PET)

This is a nuclear scan that requires an injection of a radioactive tracer. It provides a 3-D image and is done in conjunction with a CT scan for the most accurate results. PET scans are especially helpful in accurately diagnosing cardiac disease.


While not a scan, ultrasound must be mentioned as a viable option to assess organs like the heart, kidneys and liver. It is also used to examine a developing fetus during pregnancy.

The test is simple and safe as it involves no radiation exposure. Ultrasound uses high-frequency sound waves, which bounce off the targeted organ to create an image.

Which Scan Is the Gold Standard?

MRI, when appropriate, is the gold standard in medical diagnostic testing. There is no radiation involved and the test results are comprehensive.

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