Cardiorenal sodium MRI at 7.0 Tesla using a 4/4 channel ¹H/²³Na radiofrequency antenna array

Abstract

Purpose Cardiorenal syndrome describes disorders of the heart and the kidneys in which a dysfunction of 1 organ induces a dysfunction in the other. This work describes the design, evaluation, and application of a 4/4‐channel hydrogen‐1/sodium (1H/23Na) RF array tailored for cardiorenal MRI at 7.0 Tesla (T) for a better physiometabolic understanding of cardiorenal syndrome. Methods The dual‐frequency RF array is composed of a planar posterior section and a modestly curved anterior section, each section consisting of 2 loop elements tailored for 23Na MR and 2 loopole‐type elements customized for 1H MR. Numerical electromagnetic field and specific absorption rate simulations were carried out. Transmission field (B1+) uniformity was optimized and benchmarked against electromagnetic field simulations. An in vivo feasibility study was performed. Results The proposed array exhibits sufficient RF characteristics, B1+ homogeneity, and penetration depth to perform 23Na MRI of the heart and kidney at 7.0 T. The mean B1+ field for sodium in the heart is 7.7 ± 0.8 µT/√kW and in the kidney is 6.9 ± 2.3 µT/√kW. The suitability of the RF array for 23Na MRI was demonstrated in healthy subjects (acquisition time for 23Na MRI: 18 min; nominal isotropic spatial resolution: 5 mm [kidney] and 6 mm [heart]). Conclusion This work provides encouragement for further explorations into densely packed multichannel transceiver arrays tailored for 23Na MRI of the heart and kidney. Equipped with this technology, the ability to probe sodium concentration in the heart and kidney in vivo using 23Na MRI stands to make a critical contribution to deciphering the complex interactions between both organs.

Recent Advances in Radio‐Frequency Coil Technologies: Flexible, Wireless, and Integrated Coil Arrays

“…50 Lastly, we note that wireless systems that can transfer data at low and high data rates both have potential in MRI as each is highly dependent upon the RF coil array application. For example, an extremely high data rate system is required for high-density neuroimaging coil arrays, 1,2 but a lower data rate system with cheaper electronics would be suitable for a four-channel cardiorenal coil array 51 or the aforementioned eight-channel HIC glove array.…”

A Preliminary Study for Reference RF Coil at 11.7 T MRI: Based on Electromagnetic Field Simulation of Hybrid-BC RF Coil According to Diameter and Length at 3.0, 7.0 and 11.7 T

“…In particular, an EM-field simulation is essential to more accurately predict the safety of RF coils as EM-fields play an important role in the generation of B 1 -fields and SAR distributions . Owing to these problems, various studies have been conducted with an aim to increase the uniformity of the B 1 -field [26][27][28][29][30][31][32][33][34][35][36][37] and to improve the sensitivity of the B 1 -field [38][39][40][41][42][43][44][45] along with RF safety [46][47][48][49][50][51][52][53][54][55][56][57].…”

Multi‐ and dual‐tuned microstripline‐based transmit/receive switch for 7‐Tesla magnetic resonance imaging

“…Four T/R switches are used to receive the signals from four 23Na RF coils of oval shape working at 7‐Tesla torso MRI 7 . A 4/4 1H/23Na RF coil is designed for cardiorenal 7‐Tesla MRI 8 . In that work, four T/R switches are used with 1H and four T/R switches are tuned for 23Na, all switches were from Stark Contrast, Erlangen, Germany.…”