MRI: Basic Principle
MRI, or Magnetic Resonance Imaging, uses a powerful magnetic field and radio waves to generate detailed images of the body. It exploits the natural magnetic properties of hydrogen atoms within water in our tissues.
Hydrogen Atoms Alignment
When placed in a magnetic field, hydrogen protons in the body align with the field. The strength of this field is measured in teslas; most clinical MRIs operate at 1.5 or 3 teslas.
Radio Frequency Pulses
A short radio frequency (RF) pulse is then applied, disrupting this alignment. When the RF pulse is turned off, protons realign with the magnetic field, releasing energy detectable by the MRI sensors.
Resonance Signals Capture
The energy released as protons realign emits a signal that is captured by coils. Each tissue type sends back a slightly different signal, allowing for the differentiation of tissue contrast in the final image.
Image Construction
Computers process these signals to create cross-sectional images. By compiling multiple slices, a detailed 3D representation of the scanned area can be produced, revealing structures not visible with other imaging methods.
Functional MRI Insights
Functional MRI (fMRI) measures brain activity by detecting changes in blood flow. When an area of the brain is more active, it consumes more oxygen and blood flow to that area increases, which can be imaged.
MRI Safety and Uses
MRI is non-invasive and doesn't use ionizing radiation, unlike X-rays. It's invaluable for diagnosing conditions across the body, particularly in the brain, spine, joints, and soft tissues.
What does MRI stand for?
Magnetic Resonance Imaging
Magnetic Radio Imaging
Motion Resonance Imaging
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