Scalable and modular 8‐channel transmit and 8‐channel flexible receive coil array for 19F MRI of large animals. Issue 3 (13th October 2022)

• Record Type: Journal Article
• Authors: Özen, Ali Caglar; Spreter, Felix; Schimpf, Waldemar; Fischer, Johannes; Ilbey, Serhat; Reiss, Simon; Maier, Alexander; von Elverfeldt, Dominik; Heidt, Timo; von zur Mühlen, Constantin; Bock, Michael
• Is Part Of: Magnetic resonance in medicine. Volume 89:Issue 3(2023)
• Page Start: 1237
• Page End: 1250
• Publication Date: 2022-10-13
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.29490
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: To introduce an RF coil system consisting of an 8‐channel transmit (Tx) and 8‐channel receive (Rx) coil arrays for 19 F MRI of large animals. Methods: The Tx efficiency and homogeneity of the 8‐element loop coil array (loop size: 6 × 15 cm 2 ) were simulated for two different pig models rendered from MR images. An 8‐channel Rx coil array consisting of a flexible 6‐channel posterior and a 2‐channel planar anterior array was designed to fit on the abdomen of an average‐sized pig in supine position. Measurements were performed in a grid phantom and ex vivo on a pig model with perfluoroctylbromide (PFOB)–filled tubes inserted in the thorax. Results: Measured and simulated Tx efficiency and homogeneity for the 8‐channel and 5‐channel arrays were in good agreement: 1.87 ± 0.22μT/√kW versus 1.96 ± 0.29μT/√kW, and 2.29 ± 0.39μT/√kW versus 2.41 ± 0.37μT/√kW. An isolation of 38 ± 8 dB is achieved between the 19 F Tx and Rx elements, and over 30 dB between the 1 H and 19 F elements. The PFOB‐filled vials could be clearly identified within the cadaver abdomen with an SNR of 275 ± 51 for a 3D gradient‐echo sequence with 2‐mm isotropic resolution and 12 averages, acquired in 9:52 min:s. Performance of the Tx array was robust against phase and amplitude mismatches at the input ports. Conclusions: A modular and scalable Tx array offers improved Tx efficiency in 19 F MRI of large animals with various sizes. Although conventional birdcage coils have superior Tx efficiency within the target region of interest, scalability of the Tx array to animal size is a major benefit. The described 19 F coil provides homogeneous excitation and high sensitivity detection in large pig models.