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Question: What is the difference between a CT scan and an MRI?

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Answer: For starters, you’ll choose different codes for CTs and MRIs. CPT^® organizes the codes for both tests by body part, so the CT and MRI codes appear throughout the Radiology (70010-79999) section of the CPT^® code book.

As for the clinical differences, CT scans look for structural abnormalities and differences in tissue density. They are often used to evaluate a patient for trauma, tumors, fractures, bleeding, or organ abnormalities, said Angie Davis CPC, CDEO, during her HEALTHCON 2026 presentation on coding different types of scans.

During a CT scan, “rotating X-ray beams produce cross-sectional images and evaluate anatomy and tissue density,” explained Davis.

Codes: CT scan codes for each anatomical area will typically include several coding options to account for:

• The presence/absence of contrast material
• The taking of further sequences (sets of images taken with different timing or settings than the original)
• The taking of further sections (the cross-sectional images that make up each CT scan)

For example, you’ll choose from the following codes for CT of the head/brain:

• 70450 (Computed tomography, head or brain; without contrast material)
• 70460 (… with contrast material(s))
• 70470 (.. without contrast material, followed by contrast material(s) and further sections)

An MRI, on the other hand, focuses on soft-tissue composition and structural detail. It uses strong magnetic fields and radiofrequency pulses to detect signals from hydrogen protons in tissues, said Davis. This produces high-contrast soft tissue images that are commonly used for brain and spinal cord imaging, as well as the evaluation of ligament injuries, tumors, and musculoskeletal disorders.

Just as with CT scans, MRI codes for each anatomical area will typically include several options to answer questions about contrast material and further sequences and sections. For example, you’ll choose from the following codes for MRI of the neck:

• 70540 (Magnetic resonance (eg, proton) imaging, orbit, face, and/or neck; without contrast material(s))
• 70542 (… with contrast material(s))
• 70543 (… without contrast material(s), followed by contrast material(s) and further sequences).

Chris Boucher, MS, CPC, Senior Development Editor, AAPC