An Image-based Approach to Understanding the Physics of MR Artifacts

Published Online:https://doi.org/10.1148/rg.313105115

Principles of physics that underlie propagation of common MR imaging artifacts are explained through a review of clinical images to help readers recognize artifacts, understand their origins, and identify the best methods for reducing them.

As clinical magnetic resonance (MR) imaging becomes more versatile and more complex, it is increasingly difficult to develop and maintain a thorough understanding of the physical principles that govern the changing technology. This is particularly true for practicing radiologists, whose primary obligation is to interpret clinical images and not necessarily to understand complex equations describing the underlying physics. Nevertheless, the physics of MR imaging plays an important role in clinical practice because it determines image quality, and suboptimal image quality may hinder accurate diagnosis. This article provides an image-based explanation of the physics underlying common MR imaging artifacts, offering simple solutions for remedying each type of artifact. Solutions that have emerged from recent technologic advances with which radiologists may not yet be familiar are described in detail. Types of artifacts discussed include those resulting from voluntary and involuntary patient motion, magnetic susceptibility, magnetic field inhomogeneities, gradient nonlinearity, standing waves, aliasing, chemical shift, and signal truncation. With an improved awareness and understanding of these artifacts, radiologists will be better able to modify MR imaging protocols so as to optimize clinical image quality, allowing greater confidence in diagnosis.

© RSNA, 2011

References

  • 1 Golfieri R, Cherryman GR, Olliff JF, Husband JE. Comparative evaluation of computerized tomography/magnetic resonance (1.5 T) in the detection of brain metastasis [in Italian]. Radiol Med 1991;82(1–2):27–34. MedlineGoogle Scholar
  • 2 Rosenberg ZS, Cheung Y, Jahss MH, Noto AM, Norman A, Leeds NE. Rupture of posterior tibial tendon: CT and MR imaging with surgical correlation. Radiology 1988;169(1):229–235. LinkGoogle Scholar
  • 3 Brazzelli M, Sandercock PA, Chappell FMet al.. Magnetic resonance imaging versus computed tomography for detection of acute vascular lesions in patients presenting with stroke symptoms. Cochrane Database Syst Rev 2009 (4):CD007424. MedlineGoogle Scholar
  • 4 Friedman AC, Seidmon EJ, Radecki PD, Lev-Toaff A, Caroline DF. Relative merits of MRI, transrectal endosonography and CT in diagnosis and staging of carcinoma of prostate. Urology 1988;31(6):530–537. Crossref, MedlineGoogle Scholar
  • 5 Sheldon JJ, Siddharthan R, Tobias J, Sheremata WA, Soila K, Viamonte M. MR imaging of multiple sclerosis: comparison with clinical and CT examinations in 74 patients. AJR Am J Roentgenol 1985;145(5):957–964. Crossref, MedlineGoogle Scholar
  • 6 Gloviczki ML, Glockner J, Gomez SIet al.. Comparison of 1.5 and 3 T BOLD MR to study oxygenation of kidney cortex and medulla in human renovascular disease. Invest Radiol 2009;44(9):566–571. Crossref, MedlineGoogle Scholar
  • 7 Lucht RE, Delorme S, Hei Jet al.. Classification of signal-time curves obtained by dynamic magnetic resonance mammography: statistical comparison of quantitative methods. Invest Radiol 2005;40(7):442–447. Crossref, MedlineGoogle Scholar
  • 8 Eiber M, Beer AJ, Holzapfel Ket al.. Preliminary results for characterization of pelvic lymph nodes in patients with prostate cancer by diffusion-weighted MR-imaging. Invest Radiol 2010;45(1):15–23. Crossref, MedlineGoogle Scholar
  • 9 Voth M, Haneder S, Huck K, Gutfleisch A, Schönberg SO, Michaely HJ. Peripheral magnetic resonance angiography with continuous table movement in combination with high spatial and temporal resolution time-resolved MRA with a total single dose (0.1 mmol/kg) of gadobutrol at 3.0 T. Invest Radiol 2009;44(9):627–633. Crossref, MedlineGoogle Scholar
  • 10 Wood ML, Henkelman RM. MR image artifacts from periodic motion. Med Phys 1985;12(2):143–151. Crossref, MedlineGoogle Scholar
  • 11 Henkelman RM, Hardy PA, Bishop JE, Poon CS, Plewes DB. Why fat is bright in RARE and fast spin-echo imaging. J Magn Reson Imaging 1992;2(5):533–540. Crossref, MedlineGoogle Scholar
  • 12 Fink C, Puderbach M, Biederer Jet al.. Lung MRI at 1.5 and 3 Tesla: observer preference study and lesion contrast using five different pulse sequences. Invest Radiol 2007;42(6):377–383. Crossref, MedlineGoogle Scholar
  • 13 Griswold MA, Jakob PM, Heidemann RMet al.. Generalized autocalibrating partially parallel acquisitions (GRAPPA). Magn Reson Med 2002;47(6):1202–1210. Crossref, MedlineGoogle Scholar
  • 14 Glockner JF, Hu HH, Stanley DW, Angelos L, King K. Parallel MR imaging: a user's guide. RadioGraphics 2005;25(5):1279–1297. LinkGoogle Scholar
  • 15 Runge VM, Case RS, Sonnier HL. Advances in clinical 3-tesla neuroimaging. Invest Radiol 2006;41(2):63–67. Crossref, MedlineGoogle Scholar
  • 16 Attenberger UI, Runge VM, Stemmer Aet al.. Diffusion weighted imaging: a comprehensive evaluation of a fast spin echo DWI sequence with BLADE (PROPELLER) k-space sampling at 3 T, using a 32-channel head coil in acute brain ischemia. Invest Radiol 2009;44(10):656–661. Crossref, MedlineGoogle Scholar
  • 17 Wintersperger BJ, Runge VM, Biswas Jet al.. Brain magnetic resonance imaging at 3 Tesla using BLADE compared with standard rectilinear data sampling. Invest Radiol 2006;41(7):586–592. Crossref, MedlineGoogle Scholar
  • 18 Bailes DR, Gilderdale DJ, Bydder GM, Collins AG, Firmin DN. Respiratory ordered phase encoding (ROPE): a method for reducing respiratory motion artefacts in MR imaging. J Comput Assist Tomogr 1985;9(4):835–838. Crossref, MedlineGoogle Scholar
  • 19 Zhuo J, Gullapalli RP. AAPM/RSNA physics tutorial for residents: MR artifacts, safety, and quality control. RadioGraphics 2006;26(1):275–297. LinkGoogle Scholar
  • 20 Hinks RS, Constable RT. Gradient moment nulling in fast spin echo. Magn Reson Med 1994;32(6):698–706. Crossref, MedlineGoogle Scholar
  • 21 Morelli JN, Runge VM, Feiweier T, Kirsch JE, Williams KW, Attenberger UI. Evaluation of a modified Stejskal-Tanner diffusion encoding scheme, permitting a marked reduction in TE, in diffusion-weighted imaging of stroke patients at 3 T. Invest Radiol 2010;45(1):29–35. Crossref, MedlineGoogle Scholar
  • 22 Reese TG, Heid O, Weisskoff RM, Wedeen VJ. Reduction of eddy-current-induced distortion in diffusion MRI using a twice-refocused spin echo. Magn Reson Med 2003;49(1):177–182. Crossref, MedlineGoogle Scholar
  • 23 Erturk SM, Alberich-Bayarri A, Herrmann KA, Marti-Bonmati L, Ros PR. Use of 3.0-T MR imaging for evaluation of the abdomen. RadioGraphics 2009;29(6):1547–1563. LinkGoogle Scholar
  • 24 Olsen RV, Munk PL, Lee MJet al.. Metal artifact reduction sequence: early clinical applications. RadioGraphics 2000;20(3):699–712. LinkGoogle Scholar
  • 25 Lee MJ, Kim S, Lee SAet al.. Overcoming artifacts from metallic orthopedic implants at high-field-strength MR imaging and multidetector CT. RadioGraphics 2007;27(3):791–803. LinkGoogle Scholar
  • 26 Olsrud J, Lätt J, Brockstedt S, Romner B, Björkman-Burtscher IM. Magnetic resonance imaging artifacts caused by aneurysm clips and shunt valves: dependence on field strength (1.5 and 3 T) and imaging parameters. J Magn Reson Imaging 2005;22(3):433–437. Crossref, MedlineGoogle Scholar
  • 27 Hood MN, Ho VB, Smirniotopoulos JG, Szumowski J. Chemical shift: the artifact and clinical tool revisited. RadioGraphics 1999;19(2):357–371. LinkGoogle Scholar
  • 28 Wood ML, Henkelman RM. Truncation artifacts in magnetic resonance imaging. Magn Reson Med 1985;2(6):517–526. Crossref, MedlineGoogle Scholar

Article History

Received: Apr 22 2010
Revision requested: June 21 2010
Revision received: Sept 20 2010
Accepted: Oct 11 2010
Published online: May 4 2011
Published in print: May 2011