As of the latest update, Google Chrome and Microsoft Edge have made a breaking change to how file uploads are handled. Once your system installs this update, you will not be able to upload new images. Please use another browser until we can get it fixed.

Functional MRI

Functional magnetic resonance imaging (fMRI) is a technique used to obtain functional information by visualizing cortical activity. fMRI detects subtle alteration in blood flow in response to stimuli or actions. It is used in two broad ways:

  1. clinical practice
    • typically in presurgical patients 
  2. research 
    • often cohort of patients (often normals)
    • aimed at elucidating novel neural networks

fMRI is technically-challenging to perform as the techniques used to visualize cortical activity (most commonly BOLD imaging) rely on minute changes in a low signal-to-noise ratio (SNR) environment. 

  • 1.5 T or higher field strength MRI
  • excellent quality assurance
  • appropriate software
  • appropriate paradigms and ability to deliver visual and auditory stimuli and record motor response
  • co-operative patients

Two testing designs are employed most commonly:

Block design uses repeated blocks of activity (paradigm) separated by blocks of inactivity or alternative activity. This is by far the most frequently used study design in clinical fMRI.

Event-related design involves individual events rather than blocks, and can be randomly distributed during the study. 

The activity performed or stimulus received by the patient is termed a paradigm, and each is designed to elicit a specific cortical response. Numerous paradigms have been developed of various complexity. In the clinical setting four paradigms (with modifications according to the clinical situation) suffice for most indications. 

  • visual paradigm
  • motor paradigm
  • speech paradigm
  • memory paradigm
Imaging technology
Share article

Article information

rID: 12364
Tag: refs, fmri, refs
Synonyms or Alternate Spellings:
  • Functional MR
  • Functional MRI (fMRI)
  • fMRI
  • Functional magnetic resonance imaging (fMRI)

Support Radiopaedia and see fewer ads

Cases and figures

  • Figure 1: motor paradigm
    Drag here to reorder.
  • Figure 2: language paradigm
    Drag here to reorder.
  • Figure 3: fMRI block design
    Drag here to reorder.
  • Case 1: low grade astrocytoma
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.