Objetivos pedagógicos

After reading this chapter, you should be able:

  • To state the consequences of increasing the magnetic field on signal-to-noise ratio, relaxation times, SAR, artifacts, acoustic noise
  • Describe the necessary adaptations in sequence parameters and equipment
  • Set out the advantages and disadvantages of increasing magnetic field
  • List the potential fields of application of ultra high field MRI

Pontos principais

  3,0 T vs
 1,5 T
Advantages & Applications Disadvantages & Solutions
SNR ↑ image quality
↑ speed
↑ spatial resolution
T1 ↑ ~

↑ blood/tissue contrast




 ↓ Gadolinium doses

↑ TR or ↓ signal
 Modification of tissue contrasts


Magnetization preparation (inversion, MP…)

T2 ?

Drop in signal


↓ TE

SAR ↑↑

RF energy deposited (SAR limit)


Parallel acquisition
 ↓ flip angle, echo train, number of slices
 ↑ TR

Chemical shift

↑ differences in resonance frequency


Better fat suppression

Chemical shift artifacts


↑ bandwidth
 Fat signal suppression
 Adaptation of in-phase / out-of-phase TE

Magnetic susceptibility ↑↑

Greater sensitivity to magnetic susceptibility


Better detection of hemorrhages
 Perfusion MRI (DSC MRI)
 Functional MRI (BOLD)

Magnetic susceptibility artifacts




Parallel acquisition
 ↓ TE

Dielectric effects

RF heterogeneities, variable signal loss in the image


Optimization of coils,
Parallel RF transmission

Acoustic noise Vacuum magnet housing
Headphones, gradient downgrade


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  2. Tanenbaum. Clinical 3T MR imaging: mastering the challenges. Magnetic resonance imaging clinics of North America. 2006 Feb;14(1):1-15.
  3. Heidemann, Seiberlich. Perspectives and limitations of parallel MR imaging at high field strengths. Neuroimaging clinics of North America. 2006 May;16(2):311-20, xi.
  4. Voss, Zevin. Functional MR imaging at 3.0 T versus 1.5 T: a practical review. Neuroimaging clinics of North America. 2006 May;16(2):285-97, x.
  5. Merkle and Dale. Abdominal MRI at 3.0 T: the basics revisited. Ajr. 2006 Jun;186(6):1524-32.
  6. Mosher. Musculoskeletal imaging at 3T: current techniques and future applications. Magnetic resonance imaging clinics of North America. 2006 Feb;14(1):63-76.
  7. Gutberlet, Noeske. Comprehensive cardiac magnetic resonance imaging at 3.0 Tesla: feasibility and implications for clinical applications. Investigative radiology. 2006 Feb;41(2):154-67.