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Pediatric Radiology

, Volume 38, Issue 10, pp 1099–1104 | Cite as

A paradoxical signal intensity increase in fatty livers using opposed-phase gradient echo imaging with fat-suppression pulses

  • Robert V. Mulkern
  • Sandra Loeb Salsberg
  • Marta Ramon Krauel
  • David S. Ludwig
  • Stephan Voss
Technical Innovation

Abstract

With the increase in obese and overweight children, nonalcoholic fatty liver disease has become more prevalent in the pediatric population. Appreciating subtleties of magnetic resonance (MR) signal intensity behavior from fatty livers under different imaging conditions thus becomes important to pediatric radiologists. We report an initially confusing signal behavior—increased signal from fatty livers when fat-suppression pulses are applied in an opposed-phase gradient echo imaging sequence—and seek to explain the physical mechanisms for this paradoxical signal intensity behavior. Abdominal MR imaging at 3 T with a 3-D volumetric interpolated breath-hold (VIBE) sequence in the opposed-phase condition (TR/TE 3.3/1.3 ms) was performed in five obese boys (14±2 years of age, body mass index >95th percentile for age and sex) with spectroscopically confirmed fatty livers. Two VIBE acquisitions were performed, one with and one without the use of chemical shift selective (CHESS) pulse fat suppression. The ratios of fat-suppressed over non-fat-suppressed signal intensities were assessed in regions-of-interest (ROIs) in five tissues: subcutaneous fat, liver, vertebral marrow, muscle and spleen. The boys had spectroscopically estimated hepatic fat levels between 17% and 48%. CHESS pulse fat suppression decreased subcutaneous fat signals dramatically, by more than 85% within regions of optimal fat suppression. Fatty liver signals, in contrast, were elevated by an average of 87% with CHESS pulse fat suppression. Vertebral marrow signal was also significantly elevated with CHESS pulse fat suppression, while spleen and muscle signals demonstrated only small signal increases on the order of 10%. We demonstrated that CHESS pulse fat suppression actually increases the signal intensity from fatty livers in opposed-phase gradient echo imaging conditions. The increase can be attributed to suppression of one partner of the opposed-phase pair that normally contributes to the destructive interference between water and fat. The result is a paradoxical increase in signal from fatty liver that will depend on both fat content and the relative longitudinal relaxation times of fat methylene protons and water.

Keywords

Fatty liver Opposed phase Dixon Paradoxical signal increase Gradient echo imaging 

Notes

Acknowledgements

The authors wish to thank the excellent technologists working at the Children’s Hospital Waltham MRI facility, in particular Arnold Cyr and Stephanie Zajac, for their help in acquiring the spectra and images used in this work. We also wish to thank John P. Mugler III, PhD, for helpful discussions regarding Siemens’ receiver technology.

This work was supported in part by a grant from the Allen Foundation, grant M01 RR02172 from the National Center for Research Resources to the General Clinical Research Center at Boston Children’s Hospital, and NIH grant K08CA093554-04.

References

  1. 1.
    Delfaut EM, Beltran J, Johnson G et al (1999) Fat suppression in MR imaging: techniques and pitfalls. Radiographics 19:373–382PubMedGoogle Scholar
  2. 2.
    Earls JP, Krinsky GA (1997) Abdominal and pelvic applications of opposed-phase MR imaging. AJR 169:1071–1077PubMedGoogle Scholar
  3. 3.
    Fishbein MH, Stevens WR (2001) Rapid MRI using a modified Dixon technique: a non-invasive and effective method for detection and monitoring of fatty metamorphosis of the liver. Pediatr Radiol 31:806–809PubMedCrossRefGoogle Scholar
  4. 4.
    Chan TW, Listerud J, Kressel HY (1991) Combined chemical-shift and phase selective imaging for fat suppression: theory and initial clinical experience. Radiology 181:41–47PubMedGoogle Scholar
  5. 5.
    Siegelman ES, Outwater EK, Vinitski S et al (1995) Fat suppression by saturation/opposed-phase hybrid technique: spin echo vs gradient echo imaging. Magn Reson Imaging 13:545–548PubMedCrossRefGoogle Scholar
  6. 6.
    Mitchell DG, Stolpen AH, Siegelman ES et al (1996) Fatty tissue on opposed-phase MR images: paradoxical suppression of signal intensity by paramagnetic contrast agents. Radiology 198:351–357PubMedGoogle Scholar
  7. 7.
    Schuchmann S, Weigel C, Albrecht L et al (2007) Non-invasive quantification of hepatic fat fraction by fast 1.0, 1.5 and 3.0 T MR imaging. Eur J Radiol 62:416–422PubMedCrossRefGoogle Scholar
  8. 8.
    Karcaaltincaba M, Akhan O (2007) Imaging of hepatic steatosis and fatty sparing. Eur J Radiol 61:33–43PubMedCrossRefGoogle Scholar
  9. 9.
    Rofsky NM, Lee VS, Laub G et al (1999) Abdominal MR imaging with a volumetric interpolated breath-hold examination. Radiology 212:876–884PubMedGoogle Scholar
  10. 10.
    Dixon WT (1984) Simple proton spectroscopic imaging. Radiology 153:189–194PubMedGoogle Scholar
  11. 11.
    Hasse A, Frahm J, Hanicke W et al (1985) 1H NMR chemical shift selective (CHESS) imaging. Phys Med Biol 30:341–344CrossRefGoogle Scholar
  12. 12.
    Cali AM, Zern TL, Taksall SE et al (2007) Intrahepatic fat accumulation and alterations in lipoprotein composition in obese patients. Diabetes Care 30:3093–3098PubMedCrossRefGoogle Scholar
  13. 13.
    Scribner KB, Pawlak DB, Ludwig DS (2007) Hepatic steatosis and increased adiposity in mice consuming rapidly vs slowly absorbed carbohydrate. Obesity 15:2190–2199PubMedCrossRefGoogle Scholar
  14. 14.
    Kenchaiah S, Evans JC, Levy D et al (2002) Obesity and the risk of heart failure. N Engl J Med 347:305–313PubMedCrossRefGoogle Scholar
  15. 15.
    Wilson PW, D’Agostino RB, Sullivan L et al (2002) Overweight and obesity as determinants of cardiovascular risk: the Framingham experience. Arch Intern Med 162:1867–1872PubMedCrossRefGoogle Scholar
  16. 16.
    Fontaine KR, Redden DT, Wang C et al (2003) Years of life lost due to obesity. JAMA 289:187–193PubMedCrossRefGoogle Scholar
  17. 17.
    Olshansky SJ, Passaro DJ, Hershow RC et al (2005) A potential decline in life expectancy in the United States in the 21st century. N Engl J Med 352:1138–1145PubMedCrossRefGoogle Scholar
  18. 18.
    Chan DF, Li AM, Chu WC et al (2004) Hepatic steatosis in obese Chinese children. Int J Obesity 28:1257–1263CrossRefGoogle Scholar
  19. 19.
    Franzese A, Vajro P, Argenziano A et al (1997) Liver involvement in obese children. Ultrasonography and liver enzyme levels at diagnosis and during follow-up in an Italian population. Dig Dis Sci 42:1428–1432PubMedCrossRefGoogle Scholar
  20. 20.
    Radetti G, Kleon W, Stuefer J et al (2006) Non-alcoholic fatty liver disease in obese children evaluated by magnetic resonance imaging. Acta Paediatr 95:833–837PubMedCrossRefGoogle Scholar
  21. 21.
    Siegel MJ, Hildebolt CF, Bae KT et al (2007) Total and intraabdominal fat distribution in preadolescents and adolescents: measurement with MR imaging. Radiology 242:846–856PubMedCrossRefGoogle Scholar
  22. 22.
    Thomas EL, Hamilton G, Patel N et al (2005) Hepatic triglyceride content and its relation to body adiposity: a magnetic resonance imaging and proton magnetic resonance spectroscopy study. Gut 54:122–127PubMedCrossRefGoogle Scholar
  23. 23.
    Greenman RL, Shirosky JE, Mulkern RV et al (2003) Double inversion black blood fast spin echo imaging of the human heart: a comparison between 1.5 T and 3.0 T. J Magn Reson Imaging 17:648–655PubMedCrossRefGoogle Scholar
  24. 24.
    Rakow-Penner R, Daniel B, Huanzhou Y et al (2006) Relaxation times of breast tissue at 1.5 T and 3 T measured using IDEAL. J Magn Reson Imaging 23:87–91PubMedCrossRefGoogle Scholar
  25. 25.
    Schindera ST, Merkle EM, Dale BM et al (2006) Abdominal magnetic resonance imaging at 3.0 T: what is the ultimate gain in signal-to-noise ratio? Acad Radiol 13:1236–1243PubMedCrossRefGoogle Scholar
  26. 26.
    de Bazelaire CM, Duhamel GD, Rofsky NM et al (2004) MR imaging relaxation times of abdominal and pelvic tissues measured in vivo at 3.0 T: preliminary results. Radiology 230:652–659PubMedCrossRefGoogle Scholar
  27. 27.
    Mulkern RV, Hung YP, Ababneh Z et al (2005) On the strong field dependence and non-linear response to gadolinium contrast agent of the proton transverse relaxation rate in dairy cream. Magn Reson Imaging 23:757–764PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Robert V. Mulkern
    • 1
  • Sandra Loeb Salsberg
    • 2
  • Marta Ramon Krauel
    • 2
  • David S. Ludwig
    • 2
  • Stephan Voss
    • 1
  1. 1.Department of Radiology, Children’s Hospital BostonHarvard Medical SchoolBostonUSA
  2. 2.Department of Medicine, Children’s Hospital BostonHarvard Medical SchoolBostonUSA

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