If you are preparing for a brain scan or exploring advanced mental health treatment options, you may come across two similar-sounding terms: MRI and fMRI. Although they use related technologies, they serve different purposes and provide various types of information about the brain.
Understanding the difference between MRI and fMRI can help you feel more confident about your care, especially if you are considering brain-based treatments such as transcranial magnetic stimulation (TMS).
Here, we explain how MRI and fMRI scans work, how they differ, and why fMRI plays an important role in personalized brain-based treatment.
What is an MRI?
Magnetic resonance imaging (MRI) is a medical imaging technique that creates detailed pictures of the structures inside your body using magnetic fields and radio waves. Unlike CT scans or X-rays, MRI does not use ionizing radiation.
In brain imaging, MRI is commonly used to visualize anatomy. It can show the size, shape, and structure of the brain, helping clinicians identify physical changes such as tumors, lesions, bleeding, or signs of injury. MRI is also effective for imaging soft tissues, including the brain, spinal cord, blood vessels, and discs.
Because MRI focuses on structure rather than activity, it provides crucial information about what the brain looks like, but not how different areas of the brain are functioning or communicating with one another.
What is an fMRI?
Functional magnetic resonance imaging (fMRI) is a specialized type of MRI that measures brain activity rather than structure alone.
An fMRI scan detects subtle changes in blood oxygen levels, known as blood-oxygen-level-dependent (BOLD) signals, which reflect how different areas of the brain become active and interact with each other. These changes occur when neurons are working and require more oxygen.
Instead of showing only anatomy, fMRI reveals patterns of brain function. It can help clinicians understand how neural networks communicate, which areas are underactive or overactive, and how different regions work together to support mood, cognition, and behavior.
At Neurotherapeutix, fMRI data is used as part of functional MRI–based computational brain mapping to support precision-guided, personalized TMS therapy.
Key differences between MRI and fMRI
Although MRI and fMRI use the same underlying technology, the information they provide is fundamentally different.
MRI focuses on structure. It shows detailed images of brain anatomy and helps identify physical abnormalities or changes in tissue. It answers the question: What does the brain look like?
fMRI focuses on function. It measures brain activity and connectivity by tracking changes in blood oxygen levels. It answers the question: How is the brain working?
Another important distinction is clinical application. MRI is widely used for diagnosis across many medical specialties. fMRI is typically used when understanding brain function, connectivity, and network activity is essential, such as in neurological research or advanced brain-based treatment planning.
Both scans are non-invasive and do not involve radiation exposure.
Why fMRI matters for brain-based treatment
Many psychiatric and neurological conditions are not caused by visible structural damage, but by disruptions in how brain networks communicate. In these cases, structural imaging alone may not provide enough information to guide treatment.
fMRI allows clinicians to see how specific brain circuits function and interact. This insight is especially important for treatments like TMS, where accurate targeting of neural circuits plays a central role.
By using functional MRI–based computational brain mapping, clinicians can design more personalized treatment plans that reflect each individual’s unique brain connectivity patterns. This precision-driven approach supports informed treatment planning and ongoing evaluation over time.
If you are interested in how fMRI compares with other functional imaging approaches, you can also explore our detailed comparison of rsfMRI vs SPECT imaging.
Learn more about advanced brain imaging at Neurotherapeutix
Understanding the difference between MRI and fMRI can help you make informed decisions as you explore advanced mental health care options.
At Neurotherapeutix, we use functional MRI–based computational brain mapping to guide individualized, non-invasive TMS therapy for psychiatric and neurological conditions.
If you are preparing for imaging or want to learn how fMRI supports precision-guided treatment, you can request an appointment to speak with our team.
FAQs about MRI and fMRI
What is the main difference between MRI and fMRI?
MRI shows the physical structure of the brain, while fMRI shows how the brain is functioning. MRI focuses on anatomy, whereas fMRI measures brain activity and connectivity using changes in blood oxygen levels.
What does an fMRI scan measure?
An fMRI scan measures changes in blood oxygenation associated with neural activity. These changes provide information about which areas of the brain are active and how different regions communicate with one another.
Is fMRI safe?
Yes. fMRI uses magnetic fields and radio waves and does not involve ionizing radiation. It has a strong safety record when performed according to established medical guidelines.
How long does an fMRI scan take?
The length of an fMRI scan can vary depending on the type of study being performed. In general, scans may take anywhere from 30 minutes to an hour. Your care team can provide more specific guidance based on your situation.
Why is fMRI important for TMS therapy?
TMS therapy relies on accurate identification of the brain circuits involved in symptoms. fMRI provides detailed information about brain function and connectivity, helping clinicians personalize stimulation targets rather than relying on standardized anatomical locations.
