High-resolution imaging of the excised porcine heart at a whole-body 7 T MRI system using an 8Tx/16Rx pTx coil

Maxim Terekhov1, Ibrahim A. Elabyad1, David Lohr1, Ulrich Hofmann2, Laura M. Schreiber1
1Comprehensive Heart Failure Center (CHFC), Department of Cardiovascular Imaging, University Hospital Würzburg, Am Schwarzenberg 15, 97078, Würzburg, Germany
2Department of Internal Medicine I / Cardiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany

Tóm tắt

Abstract Introduction MRI of excised hearts at ultra-high field strengths ($${\mathrm{B}}_{0}$$ B 0 ≥7 T) can provide high-resolution, high-fidelity ground truth data for biomedical studies, imaging science, and artificial intelligence. In this study, we demonstrate the capabilities of a custom-built, multiple-element transceiver array customized for high-resolution imaging of excised hearts. Method A dedicated 16-element transceiver loop array was implemented for operation in parallel transmit (pTx) mode (8Tx/16Rx) of a clinical whole-body 7 T MRI system. The initial adjustment of the array was performed using full-wave 3D-electromagnetic simulation with subsequent final fine-tuning on the bench. Results We report the results of testing the implemented array in tissue-mimicking liquid phantoms and excised porcine hearts. The array demonstrated high efficiency of parallel transmits characteristics enabling efficient pTX-based B1+-shimming. Conclusion The receive sensitivity and parallel imaging capability of the dedicated coil were superior to that of a commercial 1Tx/32Rx head coil in both SNR and T2*-mapping. The array was successfully tested to acquire ultra-high-resolution (0.1 × 0.1 × 0.8 mm voxel) images of post-infarction scar tissue. High-resolution (isotropic 1.6 mm3 voxel) diffusion tensor imaging-based tractography provided high-resolution information about normal myocardial fiber orientation.

Từ khóa


Tài liệu tham khảo

Van de Moortele PF, Akgun C, Adriany G, Moeller S, Ritter J, Collins CM, Smith MB, Vaughan JT, Ugurbil K (2005) B(1) destructive interferences and spatial phase patterns at 7 T with a head transceiver array coil. Magn Reson Med 54(6):1503–1518

Ibrahim TS, Lee R, Abduljalil AM, Baertlein BA, Robitaille PM (2001) Dielectric resonances and B(1) field inhomogeneity in UHFMRI: computational analysis and experimental findings. Magn Reson Imaging 19(2):219–226

Xin SX, Huang QH, Gao Y, Li BG, Xu YK, Chen WF (2013) Fetus MRI at 7 T: B-1 shimming strategy and SAR safety implications. IEEE Trans Microw Theory Tech 61(5):2146–2152

Ibrahim TS (2006) Ultrahigh-Field MRI whole-slice and localized RF field excitations using the same RF transmit array. IEEE Trans Med Imaging 25(10):1341–1347

Mao W, Smith MB, Collins CM (2006) Exploring the limits of RF shimming for high-field MRI of the human head. Magn Reson Med 56(4):918–922

Collins CM, Liu W, Swift BJ, Smith MB (2005) Combination of optimized transmit arrays and some receive array reconstruction methods can yield homogeneous images at very high frequencies. Magn Reson Med 54(6):1327–1332

Yoo H, Gopinath A, Vaughan JT (2012) A method to localize RF B-1 field in high-field magnetic resonance imaging systems. IEEE Trans Biomed Eng 59(12):3365–3371

Elabyad IA, Herrmann T, Bruns C, Bernarding J, Erni D (2018) RF shimming and improved SAR safety for MRI at 7 T with combined Eight-element stepped impedance resonators and traveling-wave antenna. IEEE Trans Microw Theory Tech 66(1):540–555

Metzger GJ, Snyder C, Akgun C, Vaughan T, Ugurbil K, Van de Moortele PF (2008) Local B1+ shimming for prostate imaging with transceiver arrays at 7T based on subject-dependent transmit phase measurements. Magn Reson Med 59(2):396–409

Adriany G, Van de Moortele PF, Wiesinger F, Moeller S, Strupp JP, Andersen P, Snyder C, Zhang X, Chen W, Pruessmann KP, Boesiger P, Vaughan T, Ugurbil K (2005) Transmit and receive transmission line arrays for 7 tesla parallel imaging. Magn Reson Med 53(2):434–445

Aigner CS, Dietrich S, Schaeffter T, Schmitter S (2022) Calibration-free pTx of the human heart at 7T via 3D universal pulses. Magn Reson Med 87(1):70–84

Schmitter S, DelaBarre L, Wu X, Greiser A, Wang D, Auerbach EJ, Vaughan JT, Ugurbil K, Van de Moortele PF (2013) Cardiac imaging at 7 Tesla: Single- and two-spoke radiofrequency pulse design with 16-channel parallel excitation. Magn Reson Med 70(5):1210–1219

Adriany G, Van de Moortele PF, Ritter J, Moeller S, Auerbach EJ, Akgun C, Snyder CJ, Vaughan T, Ugurbil K (2008) A geometrically adjustable 16-channel transmit/receive transmission line array for improved RF efficiency and parallel imaging performance at 7 Tesla. Magn Reson Med 59(3):590–597

Aigner CS, Dietrich S, Schmitter S (2021) Three-dimensional static and dynamic parallel transmission of the human heart at 7 T. Nmr in Biomedicine 34 (3).

Dietrich S, Aigner CS, Kolbitsch C, Mayer J, Ludwig J, Schmidt S, Schaeffter T, Schmitter S (2021) 3D Free-breathing multichannel absolute B-1(+) Mapping in the human body at 7T. Magn Reson Med 85(5):2552–2567

Schar M, Ding H, Herzka DA (2015) Improvement in B1+ homogeneity and average flip angle using dual-source parallel rf excitation for Cardiac MRI in swine hearts. PLoS ONE 10(10):e0139859

Steensma BR, Voogt IJ, Leiner T, Luijten PR, Habets J, Klomp DWJ, van den Berg CAT, Raaijmakers AJE (2018) An 8-channel Tx/Rx dipole array combined with 16 Rx loops for high-resolution functional cardiac imaging at 7 T. Magn Reson Mater Phys, Biol Med 31(1):7–18

Dietrich S, Aigner CS, Kolbitsch C, Mayer J, Ludwig J, Schmidt S, Schaeffter T, Schmitter S (2020) 3D Free-breathing multichannel absolute B1+Mapping in the human body at 7T. Magn Reson Med. https://doi.org/10.1002/mrm.28602

Niendorf T, Graessl A, Thalhammer C, Dieringer MA, Kraus O, Santoro D, Fuchs K, Hezel F, Waiczies S, Ittermann B, Winter L (2013) Progress and promises of human cardiac magnetic resonance at ultrahigh fields: a physics perspective. J Magn Reson 229:208–222

Niendorf T, Paul K, Oezerdem C, Graessl A, Klix S, Huelnhagen T, Hezel F, Rieger J, Waiczies H, Frahm J, Nagel AM, Oberacker E, Winter L (2016) W(h)ither human cardiac and body magnetic resonance at ultrahigh fields? technical advances, practical considerations, applications, and clinical opportunities. NMR Biomed 29(9):1173–1197

Niendorf T, Schulz-Menger J, Paul K, Huelnhagen T, Ferrari VA, Hodge R (2017) High Field Cardiac Magnetic Resonance Imaging: A Case for Ultrahigh Field Cardiac Magnetic Resonance. Circ Cardiovasc Imaging 10 (6).

Erturk MA, Raaijmakers AJ, Adriany G, Ugurbil K, Metzger GJ (2017) A 16-channel combined loop-dipole transceiver array for 7 tesla body MRI. Magn Reson Med 77(2):884–894

Wu X, Schmitter S, Auerbach EJ, Ugurbil K, Van de Moortele PF (2014) Mitigating transmit B 1 inhomogeneity in the liver at 7T using multi-spoke parallel transmit RF pulse design. Quant Imaging Med Surg 4(1):4–10

Vaughan JT, Snyder CJ, DelaBarre LJ, Bolan PJ, Tian J, Bolinger L, Adriany G, Andersen P, Strupp J, Ugurbil K (2009) Whole-body imaging at 7T: preliminary results. Magn Reson Med 61(1):244–248

Snyder CJ, DelaBarre L, Metzger GJ, van de Moortele PF, Akgun C, Ugurbil K, Vaughan JT (2009) Initial results of cardiac imaging at 7 Tesla. Magn Reson Med 61(3):517–524

Graessl A, Renz W, Hezel F, Dieringer MA, Winter L, Oezerdem C, Rieger J, Kellman P, Santoro D, Lindel TD, Frauenrath T, Pfeiffer H, Niendorf T (2014) Modular 32-channel transceiver coil array for cardiac MRI at 70T. Magn Reson Med 72(1):276–290

Dieringer MA, Renz W, Lindel T, Seifert F, Frauenrath T, von Knobelsdorff-Brenkenhoff F, Waiczies H, Hoffmann W, Rieger J, Pfeiffer H, Ittermann B, Schulz-Menger J, Niendorf T (2011) Design and application of a four-channel transmit/receive surface coil for functional cardiac imaging at 7.T. J Magn Reson Imaging 33(3):736–741

Winter L, Kellman P, Renz W, Gräßl A, Hezel F, Thalhammer C, von Knobelsdorff-Brenkenhoff F, Tkachenko V, Schulz-Menger J, Niendorf T (2012) Comparison of three multichannel transmit/receive radiofrequency coil configurations for anatomic and functional cardiac MRI at 70.T: implications for clinical imaging. Eur Radiol 22(10):2211–2220

Grassl A, Winter L, Thalhammer C, Renz W, Kellman P, Martin C, von Knobelsdorff-Brenkenhoff F, Tkachenko V, Schulz-Menger J, Niendorf T (2013) Design, evaluation and application of an eight channel transmit/receive coil array for cardiac MRI at 7.0 T. Eur J Radiol 82(5):752–759

Thalhammer C, Renz W, Winter L, Hezel F, Rieger J, Pfeiffer H, Graessl A, Seifert F, Hoffmann W, von Knobelsdorff-Brenkenhoff F, Tkachenko V, Schulz-Menger J, Kellman P, Niendorf T (2012) Two-dimensional sixteen channel transmit/receive coil array for cardiac MRI at 7.0 T: design, evaluation, and application. J Magn Reson Imaging 36(4):847–857

Versluis MJ, Tsekos N, Smith NB, Webb AG (2009) Simple RF design for human functional and morphological cardiac imaging at 7tesla. J Magn Reson 200(1):161–166

Avdievich NI, Solomakha G, Ruhm L, Bause J, Scheffler K, Henning A (2020) Bent folded-end dipole head array for ultrahigh-field MRI turns “dielectric resonance” from an enemy to a friend. Magn Reson Med. https://doi.org/10.1002/mrm.28336

Avdievich NI, Solomakha G, Ruhm L, Scheffler K, Henning A (2020) Decoupling of folded-end dipole antenna elements of a 9.4 T human head array using an RF shield. NMR Biomed. https://doi.org/10.1002/nbm.4351:e4351

Oezerdem C, Winter L, Graessl A, Paul K, Els A, Weinberger O, Rieger J, Kuehne A, Dieringer M, Hezel F, Voit D, Frahm J, Niendorf T (2016) 16-channel bow tie antenna transceiver array for cardiac MR at 7.0 tesla. Magn Reson Med 75(6):2553–2565

Paska J, Cloos MA, Wiggins GC (2018) A rigid, stand-off hybrid dipole, and birdcage coil array for 7 T body imaging. Magn Reson Med 80(2):822–832

Elabyad IA, Terekhov M, Stefanescu MR, Lohr D, Fischer M, Schreiber LM (2019) Design and evaluation of a novel symmetric multichannel transmit/receive coil array for cardiac MRI in Pigs at 7 T. IEEE Trans Microw Theory Tech 67(9):3928–3945

Elabyad IA, Terekhov M, Stefanescu MR, Lohr D, Fischer M, Schreiber LM (2019) Design of a novel antisymmetric coil array for parallel transmit cardiac MRI in pigs at 7 T. J Magn Reson 305:195–208

Elabyad IA, Terekhov M, Lohr D, Stefanescu MR, Baltes S, Schreiber LM (2020) A Novel mono-surface antisymmetric 8Tx/16Rx coil array for parallel transmit cardiac MRI in Pigs at 7T. Sci Rep 10(1):3117

Elabyad IA, Terekhov M, Bille M, Schreiber LM (2021) Design and implementation of Two 16-element antisymmetric transceiver coil arrays for parallel transmission human cardiac MRI at 7 T. IEEE Trans Microw Theory Tech 69(7):3540–3557

Elabyad IA, Terekhov M, Lohr D, Bille M, Hock M, Schreiber LM (2022) A novel antisymmetric 16-element transceiver dipole antenna array for parallel transmit cardiac MRI in pigs at 7 T. NMR Biomed. https://doi.org/10.1002/nbm.4726:e4726

Lohr D, Terekhov M, Veit F, Schreiber LM (2020) Longitudinal assessment of tissue properties and cardiac diffusion metrics of the ex vivo porcine heart at 7 T: Impact of continuous tissue fixation using formalin. NMR Biomed 33(7):e4298

Lohr D, Terekhov M, Weng AM, Schroeder A, Walles H, Schreiber LM (2019) Spin echo based cardiac diffusion imaging at 7T: An ex vivo study of the porcine heart at 7T and 3T. PLoS ONE 14(3):e0213994

Lohr D, Thiele A, Stahnke M, Braun V, Smeir E, Spranger J, Brachs S, Klopfleisch R, Foryst-Ludwig A, Schreiber LM, Kintscher U, Beyhoff N (2022) Assessment of myocardial microstructure in a murine model of obesity-related cardiac dysfunction by diffusion tensor magnetic resonance Imaging at 7T. Front Cardiovasc Med 9:839714

Kozlov M, Turner R (2009) Fast MRI coil analysis based on 3-D electromagnetic and RF circuit co-simulation. J Magn Reson 200(1):147–152

Elabyad IA, Terekhov M, Hock M, Lohr D, Schreiber LM (2021) Development of a Dedicated Mono-surface 16-Element Transceiver Dipole Antenna Array for Parallel Transmission Cardiac MRI in Pigs at 7 Tesla. Proc Intl Soc Mag Reson Med 1577.

Metzger GJ, Snyder C, Akgun C, Vaughan T, Ugurbil K, Van de Moortele PF (2008) Local B-1(+) shimming for prostate imaging with transceiver arrays at 7T based on subject-dependent transmit phase measurements. Magn Reson Med 59(2):396–409

Chung S, Kim D, Breton E, Axel L (2010) Rapid B1+ mapping using a preconditioning RF pulse with TurboFLASH readout. Magn Reson Med 64(2):439–446

Skare S, Hedehus M, Moseley ME, Li TQ (2000) Condition number as a measure of noise performance of diffusion tensor data acquisition schemes with MRI. J Magn Reson 147(2):340–352

F-C Y. http://dsi-studio.labsolver.org. Accessed April 22 2016

Kotu LP, Engan K, Skretting K, Maloy F, Orn S, Woie L, Eftestol T (2013) Probability mapping of scarred myocardium using texture and intensity features in CMR images. Biomed Eng Online 12:91

Magat J, Ozenne V, Cedilnik N, Naulin J, Haliot K, Sermesant M, Gilbert SH, Trew M, Haissaguerre M, Quesson B, Bernus O (2021) 3D MRI of explanted sheep hearts with submillimeter isotropic spatial resolution: comparison between diffusion tensor and structure tensor imaging. MAGMA 34(5):741–755

Schuster A, Zarinabad N, Ishida M, Sinclair M, van den Wijngaard JP, Morton G, Hautvast GL, Bigalke B, van Horssen P, Smith N, Spaan JA, Siebes M, Chiribiri A, Nagel E (2014) Quantitative assessment of magnetic resonance derived myocardial perfusion measurements using advanced techniques: microsphere validation in an explanted pig heart system. J Cardiovasc Magn Reson 16:82

Chiribiri A, Schuster A, Ishida M, Hautvast G, Zarinabad N, Morton G, Otton J, Plein S, Breeuwer M, Batchelor P, Schaeffter T, Nagel E (2013) Perfusion phantom: an efficient and reproducible method to simulate myocardial first-pass perfusion measurements with cardiovascular magnetic resonance. Magn Reson Med 69(3):698–707

Terekhov M, Elabyad IA, Schreiber LM (2021) Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI. PLoS ONE 16(8):e0255341