X-nuclei MR

X-nuclei are physiologically relevant nuclei with a nuclear spin I > 0, which can thus be used for signal detection in addition to hydrogen. The requirements for X-nuclei imaging are strongly associated with their atomic properties. Due to the nucleus-specific gyromagnetic ratio the different nuclei have differing resonance frequencies at 7 Tesla (¹H: ca. 297 MHz, ²³Na: ca. 79 MHz, ³⁵Cl: ca. 29 MHz, ³⁹K: ca. 14 MHz). As a result, the MR scanner must support these frequencies in addition to the proton frequency and special coils are required for the respective nuclei (e.g. ²³Na head coil, ²³Na body coil). In collaboration with the research groups '7 Tesla MR: RF Systems and Concepts' and 'Electromagnetic Simulations and RF Safety' we are developing and building MR coils for X-nuclei imaging in-house such as a sodium body coil (Platt et al., Magn Reson Med, 2018).

Furthermore, ¹⁷O, ²³Na, ³⁹K, and ³⁵Cl have a nuclear spin greater than 1/2 and thus exhibit very short relaxation times. This necessitates the use of dedicated pulse sequences such as a density-adapted radial sequence (Nagel et al., Magn Reson Med, 2009). Furthermore, the in vivo concentration of X-nuclei is orders of magnitude lower compared to the concentration of ¹H. X-nuclei imaging therefore greatly benefits from ultrahigh static magnetic fields such as 7 Tesla and X-nuclei MR investigations can be further improved via advanced image reconstruction and post-processing techniques.

• Gast LV, Platt T, Nagel AM, Gerhalter T: Recent technical developments and clinical research applications of sodium (23Na) MRI. Progress in Nuclear Magnetic Resonance Spectroscopy. 2023.
• Platt T, Ladd ME, Paech D: 7 Tesla and beyond: advanced methods and clinical applications in magnetic resonance imaging. Investigative radiology. 2021; 56:705-725.
• Kratzer FJ, Flassbeck S, Schmitter S, Wilferth T, Magill AW, Knowles BR, ... & Nagel AM. 3D sodium (23Na) magnetic resonance fingerprinting for time‐efficient relaxometric mapping. Magnetic Resonance in Medicine. 2021; 86(5):2412-2425.
• Kratzer FJ, Flassbeck S, Nagel AM, Behl NGR, Knowles BR, Bachert P, ... & Schmitter S. Sodium relaxometry using 23Na MR fingerprinting: A proof of concept. Magnetic Resonance in Medicine. 2020; 84(5):2577-2591.
• Lott J, Platt T, Niesporek SC, Paech D, Behl NGR, Niendorf T, ... & Nagel AM. Corrections of myocardial tissue sodium concentration measurements in human cardiac 23Na MRI at 7 Tesla. Magnetic resonance in medicine. 2019; 82(1): 159-173.
• Niesporek SC, Nagel AM, & Platt T. Multinuclear MRI at ultrahigh fields. Topics in Magnetic Resonance Imaging. 2019; 28(3):173-188.
• Platt T, Umathum R, Fiedler TM, Nagel AM, Bitz AK, Maier F, Bachert P, Ladd ME, Wielpütz MO, Kauczor HU, Behl NGR: In vivo self-gated 23Na MRI at 7 T using an oval-shaped body resonator. Magnetic Resonance in Medicine. 2018; 80:1005-1019.
• Nagel AM, Laun FB, Weber MA, Matthies C, Semmler W, Schad LR. Sodium MRI using a density-adapted 3D radial acquisition technique. Magn Reson Med 2009; 62(6):1565-1573. 

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