X-Rays vs. MRI, CT and Ultrasound: Choosing the right imaging test
Medically reviewed by Dr. Betsy Koickel, MD on April 1, 2026
Medical imaging allows healthcare providers to visualize the body’s structures in a non-invasive way in order to diagnose a variety of medical conditions, illnesses or injuries. While X-rays are a common imaging technique you might already be familiar with, there are many others that your provider may recommend depending on your symptoms.
Let’s break down the most common imaging tests to help you understand the difference between MRI vs X-ray vs CT scan vs ultrasound, and when your provider might recommend each type.
X-Rays
X-rays are an imaging technique most people are familiar with, as they are commonly used to evaluate fractures or infections in the lungs.
What they are
X-rays use electromagnetic radiation to create images of the inside of the body, primarily the bones. The radiation is absorbed by dense materials like bone, making them appear white so providers can determine if there is a fracture or injury. Soft tissues don’t absorb quite as much radiation, which is why they appear gray on an X-ray.
Common uses
The most common use for X-rays is detecting bone fractures. But they can also evaluate lung problems, such as pneumonia, find foreign objects in the body, examine teeth or screen for certain types of cancer.
MRI (Magnetic resonance imaging)
An MRI can take more detailed pictures of internal structures than an X-ray by using a powerful magnetic field.
What it is
An MRI uses strong magnetic fields and radio waves to generate detailed images of organs and soft tissues. Unlike X-rays, MRIs do not use radiation and can provide more detailed images of soft tissue that X-rays cannot identify.
Common uses
MRIs are often used to diagnose injuries and musculoskeletal conditions. This may include:
- Cartilage loss
- Joint inflammation
- Nerve compression
- Spinal injuries
- Torn ligaments, tendons or muscles
CT scan (Computed tomography)
A CT scan is similar to an X-ray in that it uses electromagnetic radiation, but there are some key differences between X-ray vs CT scans.
What it is
A CT scan combines multiple X-ray images taken from different angles to create cross-sectional images of the body. This provides more detailed images, which help your provider see injuries or illnesses that may not be seen on standard X-rays.
Common uses
CT scans are often used for assessing internal injuries, detecting cancers and evaluating bone and soft tissue conditions.
Ultrasound
An ultrasound uses sound waves to see inside the body to evaluate tissues or organs.
What it is
An ultrasound, also sometimes called a sonogram, is a technique that uses high-frequency sound waves to create real-time images of organs and tissues. Some can detect movement inside the body, like the beating heart of a fetus.
Common uses
Ultrasounds are most common during pregnancy to monitor the baby’s growth, check the position of the placenta or screen for birth defects. They can be used to evaluate soft tissues, like organs, glands and blood vessels, to diagnose various symptoms. They can also guide procedures such as needle biopsies, helping position the needle accurately.
When to choose each imaging technique
Imaging techniques are usually recommended by a healthcare provider after an evaluation of symptoms and your medical history.
Generally, this is when each type of medical imaging will be recommended:
- X-rays are used first for fast checks of bones or lungs.
- CT scans provide quick, detailed images of the head, chest, abdomen or complex injuries, especially in emergencies.
- MRI offers the best soft-tissue detail for the brain, spine, joints and many tumors without radiation, but takes longer.
- Ultrasound is radiation-free and ideal for pregnancy, pelvic organs, gallbladder, blood vessels and guiding biopsies.
FAQs
Here are frequently asked questions about medical imaging.
What is the primary difference between an X-ray and an MRI?
The primary difference between MRIs vs X-rays is that X-rays use radiation to show bones and dense structures, while MRI uses magnetic fields and radio waves to create detailed images of soft tissues.
When is a CT scan preferred over an MRI?
A CT scan is preferred in emergencies because it is much faster and shows both bone and soft tissue injuries clearly.
Is ultrasound safe for pregnant women?
Yes, ultrasound is safe for pregnant women because it uses sound waves instead of radiation.
Can an MRI detect bone fractures?
MRI can detect some fractures, especially subtle or hidden ones, but X-rays or CT scans are usually used first.
How do I know which imaging test I need?
Your healthcare provider chooses the imaging test based on your symptoms, the body part involved and how quickly results are needed.
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