Tackling SNR at low-field: a review of hardware approaches for point-of-care systems

Andrew Webb1, Thomas O’Reilly1
1Department of Radiology, C.J. Gorter MRI Center, Leiden University Medical Center, Leiden, The Netherlands

Tóm tắt

To review the major hardware components of low-field point-of-care MRI systems which affect the overall sensitivity. Designs for the following components are reviewed and analyzed: magnet, RF coils, transmit/receive switches, preamplifiers, data acquisition system, and methods for grounding and mitigating electromagnetic interference. High homogeneity magnets can be produced in a variety of different designs including C- and H-shaped as well as Halbach arrays. Using Litz wire for RF coil designs enables unloaded Q values of ~ 400 to be reached, with body loss representing about 35% of the total system resistance. There are a number of different schemes to tackle issues arising from the low coil bandwidth with respect to the imaging bandwidth. Finally, the effects of good RF shielding, proper electrical grounding, and effective electromagnetic interference reduction can lead to substantial increases in image signal-to-noise ratio. There are many different magnet and RF coil designs in the literature, and to enable meaningful comparisons and optimizations to be performed it would be very helpful to determine a standardized set of sensitivity measures, irrespective of design.

Tài liệu tham khảo

Edelstein WA, Glover GH, Hardy CJ, Redington RW (1986) The intrinsic signal-to-noise ratio in NMR imaging. Magn Reson Med 3(4):604–618 Hoult DI, Lauterbur PC (1979) Sensitivity of the zeugmatographic experiment involving human samples. J Magn Reson 34(2):425–433 Vanheteren JG, Henkelman RM, Bronskill MJ (1987) Equivalent-circuit for coil patient interactions in magnetic-resonance-imaging. Magn Reson Imaging 5(2):93–99 Vanheteren JG, Henkelman RM, Bronskill MJ (1987) Application of an equivalent-circuit to signal-to-noise calculations in MRI. Magn Reson Imaging 5(2):101–108 Gadian DG, Robinson FNH (1979) Radiofrequency losses in NMR experiments on electrically conducting samples. J Magn Reson 34(2):449–455 Redpath TW, Hutchison JM (1984) Estimating patient dielectric losses in NMR imagers. Magn Reson Imaging 2(4):295–300 Hayden ME, Bidinosti CP, Chapple EM (2012) Specific absorption rates and signal-to-noise ratio limitations for MRI in very-low magnetic fields. Concept Magn Reson A 40A(6):281–294 Bandettini WP, Shanbhag SM, Mancini C, Henry JL, Lowery M, Chen MY, Xue H, Kellman P, Campbell-Washburn AE (2021) Evaluation of myocardial infarction by cardiovascular magnetic resonance at 0.55-T compared to 1.5-T. JACC Cardiovasc Imaging 14(9):1866–1868 Bandettini WP, Shanbhag SM, Mancini C, McGuirt DR, Kellman P, Xue H, Henry JL, Lowery M, Thein SL, Chen MCY, Campbell-Washburn AE (2020) A comparison of cine CMR imaging at 0.55 T and 1.5 T. J Cardiovasc Magn Reson. https://doi.org/10.1186/s12968-020-00618-y Bhattacharya I, Ramasawmy R, Javed A, Chen MY, Benkert T, Majeed W, Lederman RJ, Moss J, Balaban RS, Campbell-Washburn AE (2021) Oxygen-enhanced functional lung imaging using a contemporary 0.55 T MRI system. NMR Biomed 34(8):e4562 Bhattacharya I, Ramasawmy R, Javed A, Lowery M, Henry J, Mancini C, Machado T, Jones A, Julien-Williams P, Lederman RJ, Balaban RS, Chen MY, Moss J, Campbell-Washburn AE (2022) Assessment of lung structure and regional function using 0.55 T MRI in patients with lymphangioleiomyomatosis. Invest Radiol 57(3):178–186 Campbell-Washburn AE, Jiang Y, Korzdorfer G, Nittka M, Griswold MA (2021) Feasibility of MR fingerprinting using a high-performance 0.55 T MRI system. Magn Reson Imaging 81:88–93 Campbell-Washburn AE, Malayeri AA, Jones EC, Moss J, Fennelly KP, Olivier KN, Chen MY (2021) T2-weighted lung imaging using a 0.55-T MRI system. Radiol Cardiothorac Imaging 3(3):200611 Campbell-Washburn AE, Mancini C, Conrey A, Edwards L, Shanbhag S, Wood J, Xue H, Kellman P, Bandettini WP, Thein SL (2022) Evaluation of hepatic iron overload using a contemporary 0.55 T MRI system. J Magn Reson Imaging 55(6):1855–1863 Campbell-Washburn AE, Ramasawmy R, Restivo MC, Bhattacharya I, Basar B, Herzka DA, Hansen MS, Rogers T, Bandettini WP, McGuirt DR, Mancini C, Grodzki D, Schneider R, Majeed W, Bhat H, Xue H, Moss J, Malayeri AA, Jones EC, Koretsky AP, Kellman P, Chen MY, Lederman RJ, Balaban RS (2019) Opportunities in interventional and diagnostic imaging by using high-performance low-field-strength MRI. Radiology 293(2):384–393 Campbell-Washburn AE, Suffredini AF, Chen MY (2021) High-performance 0.55-T lung MRI in patient with COVID-19 infection. Radiology 299(2):E246–E247 Kolandaivelu A, Bruce CG, Ramasawmy R, Yildirim DK, O’Brien KJ, Schenke WH, Rogers T, Campbell-Washburn AE, Lederman RJ, Herzka DA (2021) Native contrast visualization and tissue characterization of myocardial radiofrequency ablation and acetic acid chemoablation lesions at 0.55 T. J Cardiovasc Magn Reson 23(1):50 Qin C, Murali S, Lee E, Supramaniam V, Hausenloy DJ, Obungoloch J, Brecher J, Lin R, Ding H, Akudjedu TN, Anazodo UC, Jagannathan NR, Ntusi NAB, Simonetti OP, Campbell-Washburn AE, Niendorf T, Mammen R, Adeleke S (2022) Sustainable low-field cardiovascular magnetic resonance in changing healthcare systems. Eur Heart J Cardiovasc Imaging 23(6):e246–e260 Yildirim DK, Bruce C, Uzun D, Rogers T, O’Brien K, Ramasawmy R, Campbell-Washburn A, Herzka DA, Lederman RJ, Kocaturk O (2021) A 20-gauge active needle design with thin-film printed circuitry for interventional MRI at 0.55T. Magn Reson Med 86(3):1786–1801 Marques JP, Simonis FFJ, Webb AG (2019) Low-field MRI: an MR physics perspective. J Magn Reson Imaging 49(6):1528–1542 MAGNETOM Free.Max special issue RSNA Edition 2020 Sarracanie M, LaPierre CD, Salameh N, Waddington DEJ, Witzel T, Rosen MS (2015) Low-cost high-performance MRI. Sci Rep. https://doi.org/10.1038/srep15177 Tsai LL, Mair RW, Li CH, Rosen MS, Patz S, Walsworth RL (2008) Posture-dependent human He-3 lung imaging in an open-access MRI system: initial results. Acad Radiol 15(6):728–739 Tsai LL, Mair RW, Rosen MS, Patz S, Walsworth RL (2008) An open-access, very-low-field MRI system for posture-dependent He-3 human lung imaging. J Magn Reson 193(2):274–285 Koonjoo N, Shen S, Sappo C, Rosen MS (2020) Optimized quadrature head coil improves SNR in the brain at 6.5mT. Sydney, Australia Straney D, Cooley CZ, Rosen MS (2020) An improved power handling active transmit/receive switch for low field MRI using reed relays. p 1395 Zhu B, Liu JZ, Cauley SF, Rosen BR, Rosen MS (2018) Image reconstruction by domain-transform manifold learning. Nature 555(7697):487–492 Cooley CZ, McDaniel PC, Stockmann JP, Srinivas SA, Cauley SF, Sliwiak M, Sappo CR, Vaughn CF, Guerin B, Rosen MS, Lev MH, Wald LL (2021) A portable scanner for magnetic resonance imaging of the brain. Nat Biomed Eng 5(3):229–239 O’Reilly T, Teeuwisse WM, de Gans D, Koolstra K, Webb AG (2021) In vivo 3D brain and extremity MRI at 50 mT using a permanent magnet Halbach array. Magn Reson Med 85(1):495–505 Yushchenko M, Sarracanie M, Salameh N (2022) Fast acquisition of propagating waves in humans with low-field MRI: toward accessible MR elastography. Sci Adv 8(36):eabo5739 Broche LM, Ross PJ, Davies GR, Macleod MJ, Lurie DJ (2019) A whole-body Fast Field-Cycling scanner for clinical molecular imaging studies. Sci Rep. https://doi.org/10.1038/s41598-019-46648-0 Nakagomi M, Kajiwara M, Matsuzaki J, Tanabe K, Hoshiai S, Okamoto Y, Terada Y (2019) Development of a small car-mounted magnetic resonance imaging system for human elbows using a 0.2 T permanent magnet. J Magn Reson 304:1–6 Srinivas SA, Cauley SF, Stockmann JP, Sappo CR, Vaughn CE, Wald LL, Grissom WA, Cooley CZ (2022) External dynamic interference estimation and removal (EDITER) for low field MRI. Magn Reson Med 87(2):614–628 Liu YL, Leong ATL, Zhao YJ, Xiao LF, Mak HKF, Tsang ACO, Lau GKK, Leung GKK, Wu EX (2021) A low-cost and shielding-free ultra-low-field brain MRI scanner. Nat Commun. https://doi.org/10.1038/s41467-021-27317-1 He Y, He W, Tan L, Chen F, Meng F, Feng H, Xu Z (2020) Use of 2.1 MHz MRI scanner for brain imaging and its preliminary results in stroke. J Magn Reson 319:106829 Huang SY, Ren ZH, Obruchkov S, Gong J, Dijkstra R, Yu W. Portable low-cost MRI system based on permanent magnets/magnet arrays. arXiv:181210474 2018 Ren ZH, Mu WC, Huang SY (2019) Design and optimization of a ring-pair permanent magnet array for head imaging in a low-field portable MRI system. IEEE Trans Magn 55(1):1–8 Podol’skii A (2002) Permanent-magnet assemblies for magnetic resonance Imaging devices for various purposes. IEEE Trans Magn 38(3):1549–1552 Ryu JS, Yao YY, Koh CS, Shin YJ (2006) 3-D optimal shape design of pole piece in permanent magnet MRI using parameterized nonlinear design sensitivity analysis. IEEE Trans Magn 42(4):1351–1354 Terada Y, Kono S, Ishizawa K, Inamura S, Uchiumi T, Tamada D, Kose K (2013) Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children. J Magn Reson 230:125–133 Prabhat AM, Crawford AL, Mazurek MH, Yuen MM, Chavva IR, Ward A Jr, Hofmann WV, Timario N, Qualls SR, Helland J, Wira C, Sze G, Rosen MS, Kimberly WT, Sheth KN (2021) Methodology for low-field, portable magnetic resonance neuroimaging at the bedside. Front Neurol. https://doi.org/10.3389/fneur.2021.760321 Mallinson JC (1973) One-sided fluxes—magnetic curiosity. IEEE Trans Magn 4:678–682 Halbach K (1980) Design of permanent multipole magnets with oriented rare-earth cobalt material. Nucl Inst Methods 169(1):1–10 Halbach K (1979) Strong rare-earth cobalt quadrupoles. Bull Amer Phys Soc 24(2):183–183 Samofalov VN, Belozorov DP, Ravlik AG (2006) Optimization of systems of permanent magnets. Phys Met Metallogr 102(5):494–505 Jensen JH, Abele MG (1996) Maximally efficient permanent magnet structures. J Appl Phys 79(2):1157–1163 Ni Mhiochain TR, Weaire D, McMurry SM, Coey JMD (1999) Analysis of torque in nested magnetic cylinders. J Appl Phys 86(11):6412–6424 Raich H, Blumler P (2004) Design and construction of a dipolar Halbach array with a homogeneous field from identical bar magnets: NMR Mandhalas. Concept Magn Reson B 23b(1):16–25 Soltner H, Blumler P (2010) Dipolar halbach magnet stacks made from identically shaped permanent magnets for magnetic resonance. Concept Magn Reson A 36a(4):211–222 Chen JZ, Xu CY (2007) Design and analysis of the novel test tube magnet as a device for portable nuclear magnetic resonance. IEEE Trans Magn 43(9):3555–3557 Kustler G (2010) Computation of NdFeB-halbach cylinders with circular and elliptical cross sections in three dimensions. IEEE Trans Magn 46(9):3601–3607 Turek K, Liszkowski P (2014) Magnetic field homogeneity perturbations in finite Halbach dipole magnets. J Magn Reson 238:52–62 Danieli E, Perlo J, Blumich B, Casanova F (2013) Highly stable and finely tuned magnetic fields generated by permanent magnet assemblies. Phys Rev Lett. https://doi.org/10.1103/PhysRevLett.110.180801 Blumler P, Casanova F (2015) Hardware developments: Halbach magnet arrays. Mobile NMR and MRI: developments and applications. Royal Society of Chemistry, Cambridge, pp 133–157 O’Reilly T, Teeuwisse WM, Webb AG (2019) Three-dimensional MRI in a homogenous 27 cm diameter bore Halbach array magnet. J Magn Reson 307:106578 Tewari S, O’Reilly T, Webb A (2021) Improving the field homogeneity of fixed- and variable-diameter discrete Halbach magnet arrays for MRI via optimization of the angular magnetization distribution. J Magn Reson 324:106923 Nielsen KK, Insinga AR, Bahl CRH, Bjork R (2020) Optimizing a Halbach cylinder for field homogeneity by remanence variation. J Magn Magn Mater 514:167175 Purchase AR, Vidarsson L, Wachowicz K, Liszkowski P, Sun HW, Sarty GE, Sharp JC, Tomanek B (2021) A short and light, sparse dipolar halbach magnet for MRI. IEEE Access 9:95294–95303 Uberruck T, Blumich B (2019) Variable magnet arrays to passively shim compact permanent-yoke magnets. J Magn Reson 298:77–84 Lopez HS, Liu F, Weber E, Crozier S (2008) Passive shim design and a shimming approach for biplanar permanent magnetic resonance imaging magnets. IEEE Trans Magn 44(3):394–402 McDowell A, Conradi M (2017) Thin high-order shims for small dipole NMR magnets. J Magn Reson 281:7–16 Parker AJ, Zia W, Rehorn CWG, Blumich B (2016) Shimming Halbach magnets utilizing genetic algorithms to profit from material imperfections. J Magn Reson 265:83–89 Wenzel K, Alhamwey H, O’Reilly T, Riemann LT, Silemek B, Winter L (2021) B-0-shimming methodology for affordable and compact low-field magnetic resonance imaging magnets. Front Phys. https://doi.org/10.3389/fphy.2021.704566 Wang Y, Xu YJ, Wang F, Zhang JH, Peng BW, Yu P, Yu YC, Yang XD (2022) A passive shimming method for Halbach magnet based on magnetic sheet arrays. J Magn Reson 339:107210 Gilbert KM, Scholl TJ, Chronik BA (2008) RF coil loading measurements between 1 and 50 MHz to guide field-cycled MRI system design. Concept Magn Reson B 33b(3):177–191 Hoult DI, Richards RE (2011) The signal-to-noise ratio of the nuclear magnetic resonance experiment. J Magn Reson 213(2):329–343 Cooley CZ, Stockmann JP, Armstrong BD, Sarracanie M, Lev MH, Rosen MS, Wald LL (2015) Two-dimensional imaging in a lightweight portable MRI scanner without gradient coils. Magn Reson Med 73(2):872–883 de Vos B, Parsa J, Abdulrazaq Z, Teeuwisse WM, Van Speybroeck CDE, de Gans DH, Remis RF, O’Reilly T, Webb AG (2021) Design, characterisation and performance of an improved portable and sustainable low-field MRI system. Front Phys. https://doi.org/10.3389/fphy.2021.701157 LaPierre CD, Sarracanie M, Wald LL, Rosen MS. Parallel imaging and acceleration in the Johnson noise dominated regime. ISMRM2013. p 2772 Chen C-N, Hout DI (1989) Biomedical magnetic resonance technology. Adam Hilger, Bristol Grafendorfer T, Conolly SM, Matter NI, Pauly JM, Scott G (2006) Optimized Litz coil design for prepolarized extremity MRI, p 2613 Resmer F, Seton HC, Hutchison JMS (2010) Cryogenic receive coil and low noise preamplifier for MRI at 0.01 T. J Magn Reson 203(1):57–65 Hoult DI (1978) The NMR receiver: a description and analysis of design. Progress NMR Spectroscopy 12:41–77 Mispelter J, Lupu M, Briguet A (2015) NMR probeheads for biophysical and biomedical experiments. Imperial College Press, London Der E, Volotovskyy V, Sun HW, Tomanek B, Sharp JC (2018) Design of a high power PIN-diode controlled switchable RF transmit array for TRASE RF imaging. Concept Magn Reson B 48(1):e21365 Nacher PJ, Kumaragamage S, Tastevin G, Bidinosti CP (2020) A fast MOSFET rf switch for low-field NMR and MRI. J Magn Reson 310:106638 Hutchison JMS, Edelstein WA, Johnson G (1980) A whole-body NMR imaging machine. J Phys E Sci Instrum 13(9):947–955 Hoult DI (1979) Fast recovery, high sensitivity NMR probe and pre-amplifier for low-frequencies. Rev Sci Instrum 50(2):193–200 Hoult DI (1984) Fast recovery with a conventional probe. J Magn Reson 57(3):394–403 Conradi MS, Fet Q (1977) Switch for pulsed NMR. Rev Sci Instrum 48(3):359–361 Andrew ER, Jurga K (1987) NMR probe with short recovery-time. J Magn Reson 73(2):268–276 Jurga K, Reynhardt EC, Jurga S (1992) NMR transmit-receive system with short recovery-time and effective isolation. J Magn Reson 96(2):302–306 Zhen JZ, O’Neill KT, Fridjonsson EO, Stanwix PL, Johns ML (2018) A resistive Q-switch for low-field NMR systems. J Magn Reson 287:33–40 Peshkovsky AS, Forguez J, Cerioni L, Pusiol DJ (2005) RF probe recovery time reduction with a novel active ringing suppression circuit. J Magn Reson 177(1):67–73 Mandal S, Utsuzawa S, Cory DG, Hurlimann M, Poitzsch M, Song YQ (2014) An ultra-broadband low-frequency magnetic resonance system. J Magn Reson 242:113–125 Hrovat MI, Hersman FW, Patz S, Mair RW, Walsworth RL (2003) Signal correction for narrow bandwidth coils. p 1053 Raad A, Darrasse L (1992) Optimization of Nmr receiver bandwidth by inductive coupling. Magn Reson Imaging 10(1):55–65 Broekaert P, Jeener J (1995) Suppression of radiation damping in NMR in liquids by active electronic feedback. J Magn Reson Ser A 113(1):60–64 Scott G, Conolly SM, Macovski A (1996) Low field preamp matching design for high Q receiver coils. p 396 Kuzmin VV, Nacher PJ (2020) Signal feedback applications in low-field NMR and MRI. J Magn Reson 310:106622 Zheng B, Goodwill PW, Dixit N, Xiao D, Zhang WC, Gunel B, Lu KA, Scott GC, Conolly SM (2017) Optimal broadband noise matching to inductive sensors: application to magnetic particle imaging. IEEE Trans Biomed Circ Syst 11(5):1041–1052 Hasselwander CJ, Cao ZP, Grissom WA (2016) gr-MRI: A software package for magnetic resonance imaging using software defined radios. J Magn Reson 270:47–55 Michal CA (2018) A low-cost multi-channel software-defined radio-based NMR spectrometer and ultra-affordable digital pulse programmer. Concept Magn Reson B 48b(3):e21401 Michal CA (2020) Low-cost low-field NMR and MRI: instrumentation and applications. J Magn Reson 319:106800 Wald LL, McDaniel PC, Witzel T, Stockmann JP, Cooley CZ (2019) Low-cost and portable MRI. J Magn Reson Imaging. https://doi.org/10.1002/jmri.26942 Guallart-Naval T, O’Reilly T, Algarin JM, Pellicer-Guridi R, Vives-Gilabert Y, Craven-Brightman L, Negnevitsky V, Menkuc B, Galve F, Stockmann JP, Webb A, Alonso J (2022) Benchmarking the performance of a low-cost magnetic resonance control system at multiple sites in the open MaRCoS community. NMR Biomed 36:e4825 Layton KJ, Kroboth S, Jia F, Littin S, Yu H, Leupold J, Nielsen JF, Stocker T, Zaitsev M (2017) Pulseq: a rapid and hardware-independent pulse sequence prototyping framework. Magn Reson Med 77(4):1544–1552 Li JZ, Nie ZD, Liu YH, Wang L, Hao Y (2017) Evaluation of propagation characteristics using the human body as an antenna. Sensors 17(12):2878 Guallart-Naval T, Algarin JM, Pellicer-Guridi R, Galve F, Vives-Gilabert Y, Bosch R, Pallas E, Gonzalez JM, Rigla JP, Martinez P, Lloris FJ, Borreguero J, Marcos-Perucho A, Negnevitsky V, Marti-Bonmati L, Rios A, Benlloch JM, Alonso J (2022) Portable magnetic resonance imaging of patients indoors, outdoors and at home. Sci Rep. https://doi.org/10.1038/s41598-022-17472-w Walsh DO (2008) Multi-channel surface NMR instrumentation and software for 1D/2D groundwater investigations. J Appl Geophys 66(3–4):140–150 Muller-Petke M (2020) Non-remote reference noise cancellation—using reference data in the presence of surface-NMR signals. J Appl Geophys 177:104040 Trushkin DV, Shushakov OA, Legchenko AV (1994) The potential of a noise-reducing antenna for surface NMR groundwater surveys in the earths magnetic-field. Geophys Prospect 42(8):855–862 Dalgaard E, Auken E, Larsen JJ (2012) Adaptive noise cancelling of multichannel magnetic resonance sounding signals. Geophys J Int 191(1):88–100 Dalgaard E, Christiansen P, Larsen JJ, Auken E (2014) A temporal and spatial analysis of anthropogenic noise sources affecting SNMR. J Appl Geophys 110:34–42 Larsen JJ, Dalgaard E, Auken E (2014) Noise cancelling of MRS signals combining model-based removal of powerline harmonics and multichannel Wiener filtering. Geophys J Int 196(2):828–836 Rearick T, Charvat GL, Rosen MS, Rothberg J (2019) Noise suppression methods and apparatus. USA Ocali O, Atalar E (1998) Ultimate intrinsic signal-to-noise ratio in MRI. Magn Reson Med 39(3):462–473 Lattanzi R, Grant AK, Polimeni JR, Ohliger MA, Wiggins GC, Wald LL, Sodickson DK (2010) Performance evaluation of a 32-element head array with respect to the ultimate intrinsic SNR. NMR Biomed 23(2):142–151