Investigative Magnetic Resonance Imaging

  • 제16권2호
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  • Pages.103-114
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  • 2012
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  • 2384-1095(pISSN)
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  • 2384-1109(eISSN)
대한자기공명의과학회 (Korean Society of Magnetic Resonance in Medicine)
권호 표지

7T 악관절 MRI를 위한 4 채널 스파이럴 RF 코일의 성능개선

Improvement of a 4-Channel Spiral-Loop RF Coil Array for TMJ MR Imaging at 7T

  • 투고 : 2012.04.04
  • 심사 : 2012.08.16
  • 발행 : 2012.08.31
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초록

목적: 7T 악관절 자기공명상의 개선을 위해 제안된 4 채널 스파이럴 코일과 그를 구동시키기 위한 회로는 자기장의 분포, 송신 전용필드, 신호 대 잡음 비, 그리고 악관절 영상에 대하여 일반적인 단일 루프 형태의 코일과 비교되었다. 대상과 방법: 단일 채널 그리고 4 채널 스파이럴 코일은 단일 루프 형태의 코일에 대해 전자기장 시뮬레이션으로 자기장의 분포 및 송신 전용 필드에 대해서 비교 되었고, 7T에서 이를 평가하고자 송신전용 필드와 더불어 자기장의 분포 역시 비교 평가되었다. 결과: 전자기장 시뮬레이션의 결과와 7T 자기공명영상에서 4 채널 스파이럴 코일은 기존에 사용되는 일반적인 구조인 단일 루프 코일에 비해 상대적으로 우수한 자기장의 분포 및 송신 전용 필드를 보였다. 결론: 7T에서는 코일의 구조에 비해 상대적으로 영상화되는 물질의 특성에 더욱더 의존적이나, 각각의 코일은 다른 필드 분포를 나타냄으로써 최적화된 코일은 악관절 영상과 같은 특정 용도로 사용될 수 있음을 확인하였다.

Purpose : In an attempt to further improve the radiofrequency (RF) magnetic ($B_1$) field strength in temporomandibular joint (TMJ) imaging, a 4-channel spiral-loop coil array with RF circuitry was designed and compared with a 4-channel single-loop coil array in terms of $B_1$ field, RF transmit (${B_1}^+$), signal-to-noise ratio (SNR), and applicability to TMJ imaging in 7T MRI. Materials and Methods: The single- and 4-channel spiral-loop coil arrays were constructed based on the electromagnetic (EM) simulation for the investigation of $B_1$ field. To evaluate the computer simulation results, the $B_1$ field and ${B_1}^+$ maps were measured in 7T. Results: In the EM simulation result and MRI study at 7T, the 4-channel spiral-loop coil array found a superior $B_1$ performance and a higher ${B_1}^+$ profile inside the human head as well as a slightly better SNR than the 4-channel single-loop coil array. Conclusion: Although $B_1$ fields are produced under the influence of the dielectric properties of the subject rather than the coil configuration alone at 7T, each RF coil exhibited not only special but also specific characteristics that could make it suited for specific application such as TMJ imaging.

키워드

참고문헌

  1. Hoult DI, Richards RE. The signal to noise ratio of the nuclear magnetic resonance experiment. J Magn Reson 1976;24:71-85
  2. Wiesinger F, Van de Moortele PF, Adriany G, Zanche ND, Ugurbil K, Pruessmann KP. Potential and feasibility of parallel MRI at high field. NMR Biomed 2006;19:368-378
  3. Abduljalil AM, Robitaille P-ML. Macroscopic susceptibility in ultra high field MRI. J Comput Assist Tomogr 1999;23:832-841
  4. Abduljalil AM, Kangarlu A, Yu Y, Robitaile P-ML. Macroscopic susceptibility in ultra high field MRI. II: acquisition of spin echo images from the human head. J Comput Assist Tomogr 1999;23:842-844
  5. Bottomley PA, Andrew ER. RF magnetic field penetration, phase shift and power dissipation in biological tissue: implications for NMR imaging. Phys Med Biol 1978;23:630-643
  6. Roschmann P. Radiofrequency penetration and absorption in the human-body: limitations to high-field whole-body nuclear magnetic resonance imaging. Med Phys 1987;14:922-931
  7. Bomsdorf H, Helzel T, Kunz D, Roschmann P, Tschendel O, Wieland J. Spectroscopy and imaging with a 4 tesla whole-body mr system. NMR Biomed 1988;1:151-158
  8. Cho ZH, Kim YB, Kim KN, Hong SM. MRI system RF coil assembly with a birdcage transmit only coil and a pseudo-chainlink receive only coil array. 2010; US 7,733,088 B2
  9. Wald LL, Wiggins GC, Potthast A, Wiggins CJ, Triantafyllou C. Design consideration and coil comparisons for 7T brain imaging. Appl Magn Reson 2005;29:19-37
  10. Eberhard D, Bantleon HP, Steger W. Functional magnetic resonance imaging of temporomandibular joint disorders. Eur J Orthod 2000;22:489-497
  11. Welker KN, Tsuruda JS, Hadley JR, Hayes CE. Radio-frequency coil selection for MR imaging of the brain and skull base. Radiology 2001;221:11-25
  12. Zhang S, Gersdorff N, Frahm J. Real-time magnetic resonance imaging of temporomandibular joint dynamics. The Open Medical Imaging Journal 2011;5:1-7
  13. Vaughan JT, Garwood M, Collins CM, et al. 7T vs. 4T: RF power, homogeneity, and signal-to-noise comparison in head images. Magn Reson Med 2001;46:24-30
  14. Van de Moortele PF, Akgun C, Adriany G, et al. B1 destructive interference and spatial phase patterns at 7T with a head transceiver array coil. Magn Reson Med 2005;54:1503-1518
  15. Alsop DC, Connick TJ, Mizsei G. A spiral volume coil for improved RF field homogeneity at high static magnetic field strength. Magn Reson Med 1998;40:49-54
  16. Mueller MF, Blaimer M, Breuer F, et al. Double spiral array coil design for enhanced 3D parallel MRI at 1.5 Tesla. Concept in Magn Reson Part B 2009;35:67-79
  17. Staewen RS, Johnson AJ, Ross BD, Parrish T, Merkle H, Garwood M. 3D flash imaging using a single surface coil and a new adiabatic pulse, BIR-4. Invest Radiol 1990;25:559-567
  18. Katscher U, Borner P, Leussler C, Van de Brink JS. Transmit SENSE. Magn Reson Med 2003;49:144-150
  19. Adriany G, Van de Moortele PF, Ritter J, et al. A geometrically adjustable 16-channel transmit/receive transmission line array for improved RF efficiency and parallel imaging performance at 7Tesla. Magn Reson Med 2008;59:590-597
  20. Kim KN, Darji N, Herrmann T, et al. Improved B1+ field using 16-channel transmit head array and an 8-channel pTx system at 7T. In: Proceedings of the 20th Annual Meeting of ISMRM, Montreal, 2011, p 3220
  21. Clare S, Alecci M, Jezzard P. Compensating for B1 inhomogeneity using active transmit power modulation. Magn Reson Imaging 2001;19:1349-1352
  22. Mispelter J, Lupu M, Briguet A. NMR probeheads for biophysical and biomedical experiments: theoretical principles & practical guidelines. Imperial College London 2006
  23. Gabriel C. Internet document; URL: http://niremf.ifac.cnr.it/tissprop/#over
  24. Eroglu S, Gimi B, Roman B, Friedman G, Magin RL. NMR spiral surface microcoils: design, fabrication, and imaging. Concepts in Magn Reson Part B 2003;17:1-10
  25. Gimi B, Eroglu S, Leoni L, Desai TA, Magin RL, Roman BB. NMR spiral surface microcoils: applications. Concepts in Magn Reson Part B 2003;18:1-8
  26. Constantinides C, Angeli S, Gkagkarellis S, Cofer G. Intercomparison of performance of RF coil geometries for high field mouse cardiac MRI. Concepts in Magn Reson Part A 2011;38:236-252
  27. De Zwart JA, Ledden PJ, Kellman P, van Gelderen P, Duyn JH. Design of a SENSE-optimized high-sensitivity MRI receive coil for brain imaging. Magn Reson Med 2002;47:1218-1227
  28. Roemer PB, Edelstein WA, Hayes CE, Souza SP, Mueller OM. The NMR phased array. Magn Reson Med 1990;16:192-225
  29. Wang J. A novel method to reduce the signal coupling of surface coils for MRI. In: Proceedings of the 4th Annual Meeting of ISMRM, 1996, p 1434
  30. Deppe MH, Parra-Robles J, Marshall H, Lanz T, Wild JM. A flexible 32-channel receive array combined with a homogeneous transmit coil for human lung imaging with hyperpolarized 3He at 1.5T. Magn Reson Med 2011;66:1788-1797
  31. Morze CV, Tropp J, Banerjee S, et al. An eight-channel, nonoverlapping phased array coil with capacitive decoupling for parallel MRI at 3T. Concepts in Magn Reson Part B 2007;31:37-43
  32. Kraff O, Bitz AK, Kruszona S, et al. An eight-channel phased array RF coil for spine MR imaging at 7T. Invest Radiol 2009;44:734-740
  33. Yang QX, Wang J, Zhang X, et al. Analysis of wave behavior in lossy dielectric samples at high field. Magn Reson Med 2002;47:982-989
  34. Collins CM, Yang QX, Wang JH, et al. Different excitation and reception distribution with a single-loop transmit-receive surface coil near a head-sized spherical phantom at 300 MHz. Magn Reson Med 2002;47:1026-1028
  35. Dole CW. Coaxial cable insertion phase measurement and analysis. Internet document; URL: http://www.belden.com/pdfs/Techpprs/Wireless%20Market%20Web%20Phase%20Paper.pdf, Accessed March 10, 2012
  36. Cunningham CH, Pauly JM, Nayak KS. Saturated double-angle method for rapid B1+ mapping. Magn Reson Med 2006;55:1326-1333
  37. Collins CM, Smith MB. Calculation of B1 distribution, SNR, and SAR for a surface coil adjacent to an anatomically-accurate human body model. Magn Reson Med 2001;45:692-699
  38. Collins CM, Smith MB. Signal-to-noise ratio absorbed power as functions of main magnetic field strength, and definition of "$90^{\circ}$" RF pulse for the head in the birdcage coil. Magn Reson Med 2001;45:684-691
  39. NEMA standards publication MS-2001
  40. Dalkiz M, Pakdemirli E, Beydemir B. Evaluation of temporomandibular joint dysfunction by magnetic resonance imaging. Turk K Med Sci 2001;31:337-343
  41. Maizlin ZV, Nutiu N, Dent PB, et al. Displacement of the temporomandibular joint disk: correlation between clinical findings and MRI characteristics. J Can Dent Assoc 2010;76:a3