Topic Index

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Topic Index - s

• safe, MR
  • defined
• safety
  • available guidelines
• sampling time
  • for a whole k-space line (T_line)
  • one point in k-space (ΔT_s)
• SAR (specific absorption rate)
  • defined
  • calculation of
  • temperature sensitive body parts
  • relationship to B₀
  • relationship to flip angle
  • pulse sequence with high SAR
  • reduction of
  • limits, whole body
  • limits, local
  • when calculated
  • user input for calculating
• saturation recovery
  • equation
• scan percentage
  • omitting peripheral k-space lines
• scan time
  • a calculation
  • partial flip angles decrease
• screening
  • unresponsive / unconscious patients
  • RF, see RF screen
• SENSE (SENSitivity Encoding)
  • multi element coil array
  • SENSE factor
• shielding
  • and location of 0.2T line
  • passive and active
  • of monitor / VDU
• shimming
  • passive and active
• signal
  • source in MRI
  • measured in the transverse plane
• signal-to-noise ratio, see SNR
• slew rate
  • described
• slice selection
  • mechanism of
  • setting ω₀
  • truncated sinc RF pulse
  • slice location
  • slice orientation
  • and the RF excitation pulse
  • gradient timing
• slice thickness
  • changing, mechanism of
  • and transmitted bandwidth
  • changing, SNR effect
• SMASH (SiMultaneous Acquisition of Spatial Harmonics)
  • multi element coil array
• SNR (signal-to-noise ratio)
  • equation
  • effect of changing operator selectable parameters see various questions
  • valuable QA measurement
  • how to measure
  • sources of noise
  • small MRI signal
  • statistical fluctuations
  • most likely causes in change of
  • reduction in parallel imaging (SMASH, SENSE)
  • noise in k-space
  • conjugate symmetry and
• sounds, see acoustic noise
• spatial frequencies
  • described
  • contrast
  • resolution
• spatial misregistration
  • synthesizer
  • chemical shift artefact
  • reducing chemical shift artefact
• SPECIAL, see spectral fat suppression
• spectral fat suppression
  • described (SPECIAL, SPIR)
• spin
  • source of MRI signal
  • of nucleons vs. nuclei
  • intrinsic angular momentum
  • quantized angular momentum
  • quantum mechanics necessary?
  • polarisation
• spin echo
  • black blood
  • pulse sequence diagram
  • vs. gradient echo
  • sensitivity to susceptibility effects
• spin-spin relaxation time, see T2 and T2*
• spin-up and spin-down
  • alignment of spins
  • not to be confused with Zeeman splitting
• SPIR (SPectral Inversion Recovery), see spectral fat suppression
• spoiling
  • RF and gradient spoiling
  • instance of gradient spoiling
• static magnetic field (B₀)
  • limits of exposure, patients
  • limits of exposure, staff
  • limits of exposure, public
• steady state
  • in GE with short TRs
  • in turbo gradient echo (TGE)
• stents (implants)
  • coils, stents and filters
• STIR (Short TI Inversion Recovery)
  • described
  • reduction of chemical shift artefact
  • different from SPIR
• superconducting magnet
  • details
  • vs. other types, pros / cons
• surface coils, see RF coils
• susceptibility effects
  • SE and GE sensitivity to
• synthesizer
  • source of transmit RF
  • role in demodulation
  • drift
• system architecture
  • interactive diagram

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