Abstract
MR physics can be a challenging subject for practicing pediatric radiologists. Although many excellent texts provide very comprehensive reviews of the field of MR physics at various levels of understanding, the authors of this paper explain several key concepts in MR physics that are germane to clinical practice in a non-rigorous but practical fashion. With the basic understanding of these key concepts, practicing pediatric radiologists can build on their knowledge of current clinical MR techniques and future advances in MR applications. Given the challenges of both the increased need for rapid imaging in non-sedated children and the rapid physiological cardiovascular and respiratory motion in pediatric patients, many advances in complex MR techniques are being applied to imaging these children. The key concepts are as follows: (1) structure of a pulse sequence, (2) k-space, (3) “trade-off triangle” and (4) fat suppression. This review is the first of five manuscripts in a minisymposium on pediatric MR. The authors’ goal for this review is to aid in understanding the MR techniques described in the subsequent manuscripts on brain imaging and body imaging in this minisymposium.
Similar content being viewed by others
References
Pooley RA (2005) Fundamental physics of MR imaging. Radiographics 25:1087–1099
Bitnar R, Leung G, Perng R et al (2006) MR pulse sequences: what every radiologist wants to know but is afraid to ask. Radiographics 26:513–537
IMAIOS (2016) MRI step-by-step, interactive course on magnetic resonance imaging. https://www.imaios.com/en/e-Courses/e-MRI. Accessed 5 Dec 2016
Westbrook C, Kaut Roth C, Talbot J (2011) MRI in practice, 4th edn. Wiley-Blackwell, Hoboken
McRobbie D, Moore E, Graves M et al (2007) MRI from picture to proton, 2nd edn. Cambridge University Press, Cambridge
Melki PS, Mulkern RV, Panych LP et al (1991) Comparing the FAISE method with conventional dual-echo sequences. JMRI 1:319–326
Jones KM, Mulkern RV, Mantello MT (1992) Brain hemorrhage: evaluation with fast spin-echo and conventional dual spin-echo images. Radiology 182:53–58
Chavhan GB, Babyn PS, Jankharia BG et al (2008) Steady-state MR imaging sequences: physics, classification, and clinical applications. Radiographics 28:1147–1160
De Coene B, Hajnal JV, Gatehouse P et al (1992) MR of the brain using fluid-attenuated inversion recovery (FLAIR) pulse sequences. AJNR Am J Neuroradiol 13:1555–1564
Sargent MA, Poskitt KJ (1997) Fast fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging of the brain: a comparison of multi-shot echo-planar and fast spin-echo techniques. Pediatr Radiol 27:545–549
Kellman P, Andrew AE (2012) Cardiac imaging techniques for physicians: late enhancement. JMRI 36:529–542
Grist TM, Thornton FJ (2005) Magnetic resonance angiography in children: technique, indications, and imaging findings. Pediatr Radiol 35:26–39
Goo HW, Yang DH, Park IS et al (2007) Time-resolved three dimensional contrast enhanced magnetic resonance angiography in patients with Fontan operation or bidirectional cavopulmonary connection: initial experience. J Magn Reson Imaging 25:727–736
Herrmann KH, Baltzer PA, Dietzel M et al (2011) Resolving arterial phase and temporal enhancement characteristics in DCE MRA at high spatial resolution with TWIST acquisition. J Magn Reson Imaging 34:973–982
Krishnamurthy R, Bahouth SM, Muthupillai R (2016) 4D contrast-enhanced MR angiography with the keyhole technique in children: technique and clinical application. Radiographics 36:523–537
Feng L, Grimm R, Block KT et al (2014) Golden-angle radial sparse parallel MRI: combination of compressed sensing, parallel imaging, and golden-angle radial sampling for fast and flexible dynamic volumetric MRI. Magn Reson Med 72:707–717
Chandarana H, Block TK, Rosenkrantz AB et al (2011) Free-breathing radial 3D fat- suppressed T1-weighted gradient echo sequence: a viable alternative for contrast-enhanced liver imaging in patients unable to suspend respiration. Investig Radiol 46:648–653
Sodickson DK, Manning WJ (1997) Simultaneous acquisition of spatial harmonics (SMASH): fast imaging with radiofrequency coil arrays. Magn Reson Med 38:591–603
Pruessmann KP, Weiger M, Schiedegger MB et al (1999) SENSE: sensitivity encoding for fast MRI. Magn Reson Med 42:952–962
Glockner JF, Hu HH, Stanley DW et al (2005) Parallel MR imaging: a user’s guide. Radiographics 25:1279–1297
Delfaut E, Beltran J, Johnson G et al (1999) Fat suppression in MR imaging: techniques and pitfalls. Radiographics 19:373–382
Grande F, Santini F, Herzka D et al (2014) Fat-suppression techniques for 3-T MR imaging of the musculoskeletal system. Radiographics 34:217–233
Dixon WT (1984) Simple proton spectroscopic imaging. Radiology 153:189–194
Ma J (2008) Dixon techniques for fat and water imaging. J Magn Reson Imaging 28:543–558
Glover GH, Schneider E (1991) Three-point Dixon technique for true water/fat decomposition with B0 inhomogeneity correction. Magn Reson Med 18:371–383
Rybicki FJ, Chung T, Reid J et al (2001) Fast three-point Dixon MR imaging using low-resolution images for phase correction: a comparison with chemical shift selective fat suppression for pediatric musculoskeletal imaging. AJR Am J Roentgenol 177:1019–1023
Eggers H, Brendel B, Duijndam A et al (2011) Dual-echo Dixon imaging with flexible choice of echo times. Magn Reson Med 65:96–107
Rybicki FJ, Mulkern RV, Robertson RL et al (2001) Fast three-point DIXON MR imaging of the retrobulbar space with low-resolution images for phase correction: comparison with fast spin-echo inversion recovery imaging. AJNR Am J Neuroradiol 22:1798–1802
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflicts of interest
Dr. Chung has received travel and lodging support from Philips Healthcare to participate in the Philips Pediatric MR User Group meeting. Dr. Moore has no conflicts of interest to report.
Additional information
CME activity This article has been selected as the CME activity for the current month. Please visit the SPR Web site at www.pedrad.org on the Education page and follow the instructions to complete this CME activity.
Rights and permissions
About this article
Cite this article
Moore, M.M., Chung, T. Review of key concepts in magnetic resonance physics. Pediatr Radiol 47, 497–506 (2017). https://doi.org/10.1007/s00247-017-3791-3
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00247-017-3791-3