Physics and imaging technology: MRI

Knowledge of the physics and imaging technology involved in the production of MRI scans is vitally important for medical imaging specialists.

See also

• physics and imaging technology: x-ray
• physics and imaging technology: ultrasound
• physics and imaging technology: CT
• physics and imaging technology: MRI
• physics and imaging technology: nuclear medicine

Related Radiopaedia articles

Physics and Imaging Technology: MRI

• MRI (introduction)
• MRI physics
  • B0
  • chemical shift
  • dependence of magnetization (proton density, field strength and temperature)
  • echo time
  • eddy currents
  • electromagnetic induction
  • Ernst angle
  • flip angle
  • Larmor frequency
  • magnetic dipole
    • magnetic dipole moment
    magnetic field gradient
    • effect of gradient strength and bandwidth on slice thickness
  • magnetic susceptibility
  • magnetism​
    • diamagnetism
    • ferromagnetism
    • longitudinal and transverse magnetization
    • nuclear magnetization
    • paramagnetism
    • superparamagnetism
  • molecular tumbling rate effects on T1 and T2
  • net magnetization vector (NMV)
    • energy difference between spin up and spin down states
  • relaxation
    • T1 relaxation
      • T1 values (1.5 T)
      • factors affecting T1
    • T2 relaxation
    • T2* relaxation
  • repetition time
  • resonance and radiofrequency (RF)
  • units of magnetism
    • SI units
      • henry
      • tesla
      • weber
    • legacy units
      • gauss
      • maxwell
• MRI hardware 
  • coils
    • gradient coil
    • phased array coil
    • radiofrequency coil
    • volume coil
    • surface coil
  • electronics and data processing
  • magnets
    • quenching
    • magnetic field
  • radiofrequency receiver
  • radiofrequency transmitter
  • 1.5 T vs 3 T
  • ultrahigh field MRI
• signal processing
  • acquisition time
  • Fourier transformation
  • k-space
  • motion compensation
  • spatial resolution
  • temporal resolution
  • signal-to-noise ratio (SNR)
  • trade-offs
  • zero filling interpolation
• MRI pulse sequences (basics | abbreviations | parameters)
  • CSF flow studies
  • diffusion weighted sequences (DWI)
    • apparent diffusion coefficient (ADC)
    • b-values
    • diffusion tensor imaging and fiber tractography​
  • echo-planar pulse sequences
  • fat-suppressed imaging sequences
  • gradient echo sequences
    • in-phase and out-of-phase
    • spoiled gradient echo MRI
    • steady-state free precession
  • inversion recovery sequences
    • short tau inversion recovery (STIR)
    • fluid attenuation inversion recovery (FLAIR)
    • turbo inversion recovery magnitude (TIRM)
    • double inversion recovery (DIR)
  • metal artifact reduction sequence (MARS)
  • perfusion-weighted imaging
    • techniques
      • dynamic susceptibility contrast (DSC) MR perfusion
      • dynamic contrast enhanced (DCE) MR perfusion
      • arterial spin labeling (ASL) MR perfusion
    • derived values
      • cerebral blood flow (CBF)
      • cerebral blood volume (CBV)
      • k-trans
      • mean transit time (MTT)
      • negative enhancement integral (NEI)
      • time to peak (TTP)
  • saturation recovery sequences
  • spin echo sequences
    • T1 weighted image
    • T2 weighted image
    • fast spin echo (FSE)
    • proton density weighted image
  • spiral pulse sequences
  • susceptibility-weighted imaging (SWI)
  • T1 rho
• MR angiography (and venography)
  • contrast-enhanced MRA
  • non-contrast-enhanced MRA
    • phase contrast imaging
    • time of flight angiography
    • TRICKS
• MR spectroscopy (MRS)
  • 2-hydroxyglutarate peak: resonates at 2.25 ppm
  • alanine peak: resonates at 1.48 ppm
  • choline peak: resonates at 3.2 ppm
  • citrate peak: resonates at 2.6 ppm
  • creatine peak: resonates at 3.0 ppm
  • functional MRI (fMRI)
    • BOLD imaging
  • gamma-aminobutyric acid (GABA) peak: resonates at 2.2-2.4 ppm
  • glutamine-glutamate peak: resonates at 2.2-2.4 ppm 
  • Hunter's angle
  • lactate peak: resonates at 1.3 ppm
  • lipids peak: resonates at 1.3 ppm
  • myoinositol peak: resonates at 3.5 ppm
  • MR fingerprinting
  • N-acetylaspartate (NAA) peak: resonates at 2.0 ppm
• MRI artifacts
  • MRI hardware and room shielding
    • central point artifact
    • herringbone artifact
    • inhomogeneity artifact
    • moiré fringes
    • RF overflow artifact
    • zebra stripes
    • zipper artifact
  • MRI software
    • cross-excitation
    • fat-water swapping
    • slice-overlap artifact a.k.a. cross-talk artifact
  • patient and physiologic motion
    • phase-encoded motion artifact
    • entry slice phenomenon
    • flow void
  • tissue heterogeneity and foreign bodies
    • black boundary artifact
    • chemical shift artifact
    • dielectric effect artifact
    • magic angle effect
    • magnetic susceptibility artifact
      • ​blooming artifact
  • Fourier transform and Nyquist sampling theorem
    • aliasing (wrap around) artifact
    • Gibbs (truncation) artifact
    • zero-fill artifact
• MRI contrast agents
  • gadolinium contrast agents
  • gastrointestinal MRI contrast agents
  • reticuloendothelial MRI contrast agents
  • tumor-specific MRI contrast agents
  • intravascular (blood pool) MRI contrast agents
    • chromium-labeled red blood cells
    • Gd-DTPA-labeled dextran
    • Gd-DTPA-labeled albumin
    • gadofosveset trisodium
  • hepatobiliary MRI contrast agents
    • gadoxetate disodium
  • extracellular MRI contrast agents
    • gadobenate dimeglumine
    • gadobutrol
    • gadodiamide
    • gadopentetate dimeglumine
    • gadoterate meglumine
    • gadoteridol
    • gadoversetamide
  • contrast media safety
    • nephrogenic systemic fibrosis (NSF)
    • contrast media and breastfeeding
• MRI safety
  • magnetic shielding