Document Type: Original Research

Authors

1 Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran

2 Medical imaging research center, Shiraz University of medical sciences, Shiraz, Iran

3 Radiation research center, School of Mechanical Engineering, Shiraz University, Shiraz, Iran

4 Radiotherapy and Oncology Department, Shiraz University of Medical Sciences, Shiraz, Iran

5 Radiology department, Faghihi hospital, Shiraz University of medical sciences, Shiraz, Iran

Abstract

Introduction: Proton magnetic resonance spectroscopy (MRS) is a well-known device for analyzing the biological fluids metabolically. Obtaining accurate and reliable information via MRS needs a homogeneous magnetic field in order to provide well-defined peaks and uniform water suppression. There are lots of reasons which can disturb the magnetic field homogeneity which can be corrected by a process known as shimming. This study is intended to recall the importance of shimming and also the significant role of quality control (QC) in achieving an accurate quantification.Material and Method: An acrylic cylindrical quality control phantom was designed as an analog of brain MRS test phantoms in order to control the accuracy of the obtained signal of a 1.5 T Siemens MRI system which belonged to one of Shiraz hospitals. The signal of NAA, Cho, Cr, the combination of these metabolites and also the distilled water, which was used in this study, was evaluated using separate phantoms. A QC test was performed using Siemens QC phantom and a standard test phantom.Results: The spectrum of our home- made phantom had a significant difference with the expected spectrum. The results of checking the spectrum of metabolites separately also confirmed that there was a systemic problem that affects all the signals originated from all metabolites and even the pure distilled water. The MRS system could not pass QC tests, and peak broadening was common in all spectra. The complex spectrum of standard test phantom was not produced successfully by the MRS system.Discussion: By a simple check of the water peak characteristics, lots of information can be obtained, one of which is the status of shimming that has a considerable effect on the accuracy of the spectrum. Thus, performing an automatic or manual shimming is not a criterion of the spectrum accuracy, and performing a periodic quality control using a test phantom by a specialist  is necessary.Conclusion: Briefly, the quality control of MRS and all the other clinical device must be taken seriously. Sometimes QC can be the boundary of a right or a wrong decision for the patient.

Keywords

  1. Blüml S. Magnetic resonance spectroscopy: basics. MR spectroscopy of pediatric brain disorders: Springer; 2013. p. 11-23.
  2. Wuthrich K. Protein structure determination in solution by nuclear magnetic resonance spectroscopy. Science. 1989;243:45-50.
  3. Leary SM, Davie CA, Parker GJ, Stevenson VL, Wang L, Barker GJ, et al. 1H magnetic resonance spectroscopy of normal appearing white matter in primary progressive multiple sclerosis. J Neurol. 1999;246:1023-6. PubMed PMID: 10631633.
  4. Van der Knaap MS, Pouwels P. Magnetic resonance spectroscopy: basic principles and application in white matter disorders. Magnetic resonance of myelination and myelin disorders: Springer; 2005. p. 859-80.
  5. Kurth J, Defeo E, Cheng LL. Magnetic resonance spectroscopy: a promising tool for the diagnostics of human prostate cancer? Urol Oncol. 2011;29:562-71. doi: 10.1016/j.urolonc.2011.05.016. PubMed PMID: 21930088; PubMed Central PMCID: PMC4339019.
  6. Faghihi R, Zeinali-Rafsanjani B, Mosleh-Shirazi M-A, Saeedi-Moghadam M, Lotfi M, Jalli R, et al. Magnetic Resonance Spectroscopy and its Clinical Applications: A Review. Journal of Medical Imaging and Radiation Sciences. 2017.
  7. Stork C, Renshaw PF. Mitochondrial dysfunction in bipolar disorder: evidence from magnetic resonance spectroscopy research. Mol Psychiatry. 2005;10:900-19. doi: 10.1038/sj.mp.4001711. PubMed PMID: 16027739.
  8. Maudsley AA, Govind V, Levin B, Saigal G, Harris L, Sheriff S. Distributions of Magnetic Resonance Diffusion and Spectroscopy Measures with Traumatic Brain Injury. J Neurotrauma. 2015;32:1056-63. doi: 10.1089/neu.2014.3505. PubMed PMID: 25333480; PubMed Central PMCID: PMC4504344.
  9. Öz G. Magnetic resonance spectroscopy of degenerative brain diseases: Springer; 2016.
  10. Chitty KM, Lagopoulos J, Hickie IB, Hermens DF. A longitudinal proton magnetic resonance spectroscopy study investigating oxidative stress as a result of alcohol and tobacco use in youth with bipolar disorder. J Affect Disord. 2015;175:481-7. doi: 10.1016/j.jad.2015.01.021. PubMed PMID: 25679204.
  11. Wright A, Ma R, Hummer T, Francis M, Mehdiyoun N, Dydak U, et al. SU-F-SPS-07: Magnetic Resonance Spectroscopy Findings in Early-Phase Psychosis. Med Phys. 2016;43:3351-.
  12. Drost DJ, Riddle WR, Clarke GD, Group AMT. Proton magnetic resonance spectroscopy in the brain: report of AAPM MR Task Group #9. Med Phys. 2002;29:2177-97. doi: 10.1118/1.1501822. PubMed PMID: 12349940.
  13. Chmurny GN, Hoult DI. The ancient and honourable art of shimming. Concepts in Magnetic Resonance. 1990;2:131-49.
  14. Juchem C, de Graaf RA. B0 magnetic field homogeneity and shimming for in vivo magnetic resonance spectroscopy. Anal Biochem. 2017;529:17-29. doi: 10.1016/j.ab.2016.06.003. PubMed PMID: 27293215; PubMed Central PMCID: PMC5148734.
  15. McLean MA [Internet]. 1D and 2D Quantification Methods. Available from: http://afni.nimh.nih.gov/sscc/staff/rwcox/ISMRM_2006/Syllabus%202006%20-%203340/files/G_04.pdf
  16. Hull WE. NMR Tips for Shimming, Part II. Computerized shimming with the Simplex algorithm Bruker SpinReport. 2004:154-5.
  17. Tkac I, editor Shimming & MRS. Proc Intl Soc Magn Reson Med; 2010.
  18. Schneider E, Glover G. Rapid in vivo proton shimming. Magn Reson Med. 1991;18:335-47. PubMed PMID: 2046515.
  19. de Graaf RA, Juchem C. B0 Shimming Technology. In: Webb AG, editor. Magn Reson Technol Hardw Syst Compon Des. London: Royal Society of Chemistry; 2016. pp. 166–207.
  20. Zhang H, Xue H, Alto S, Hui L, Kannengiesser S, Berthold K, et al. Integrated Shimming Improves Lesion Detection in Whole-Body Diffusion-Weighted Examinations of Patients With Plasma Disorder at 3 T. Invest Radiol. 2016;51:297-305. doi: 10.1097/RLI.0000000000000238. PubMed PMID: 26704452.
  21. O’Reilly T. New Developments in Dielectric Shimming for Neuroimaging in MRI at 7T 2015.
  22. Siemens Healthineers. Syngo MR B19, basic manual- spectroscopy. 2012.
  23. Belkic K. Molecular imaging through magnetic resonance for clinical oncology: Cambridge Int Science Publishing; 2004.