Eight‐channel transceiver RF coil array tailored for 1H/19F MR of the human knee and fluorinated drugs at 7.0 T. (27th April 2015)

• Record Type: Journal Article
• Authors: Ji, Yiyi; Waiczies, Helmar; Winter, Lukas; Neumanova, Pavla; Hofmann, Daniela; Rieger, Jan; Mekle, Ralf; Waiczies, Sonia; Niendorf, Thoralf
• Is Part Of: NMR in biomedicine. Volume 28:Number 6(2015:Jun.)
• Page Start: 726
• Page End: 737
• Publication Date: 2015-04-27
• Subjects: Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.3300
• Languages: English
• ISSNs: 0952-3480

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The purpose of this study was to evaluate the feasibility of an eight‐channel dual‐tuned transceiver surface RF coil array for combined <sup>1</sup>H/<sup>19</sup>F MR of the human knee at 7.0 T following application of <sup>19</sup>F‐containing drugs.</p> <p>The <sup>1</sup>H/<sup>19</sup>F RF coil array includes a posterior module with two <sup>1</sup>H loop elements and two anterior modules, each consisting of one <sup>1</sup>H and two <sup>19</sup>F elements. The decoupling of neighbor elements is achieved by a shared capacitor. Electromagnetic field simulations were performed to afford uniform transmission fields and to be in accordance with RF safety guidelines. Localized <sup>19</sup>F MRS was conducted with 47 and 101 mmol/L of flufenamic acid (FA) – a <sup>19</sup>F‐containing non‐steroidal anti‐inflammatory drug – to determine <italic>T</italic><sub>1</sub> and <italic>T</italic><sub>2</sub> and to study the <sup>19</sup>F signal‐to‐dose relationship. The suitability of the proposed approach for <sup>1</sup>H/<sup>19</sup>F MR was examined in healthy subjects.</p> <p>Reflection coefficients of each channel were less than −17 dB and coupling between channels was less than −11 dB. <italic>Q</italic><sub>L</sub>/<italic>Q</italic><sub>U</sub> was less than 0.5 for all elements. MRS results demonstrated signal stability with 1% variation. <italic>T</italic><sub>1</sub> and <italic>T</italic><sub>2</sub> relaxation times changed with concentration of FA: <italic>T</italic><sub>1</sub>/<italic>T</italic><sub>2</sub> = 673/31 ms at 101 mmol/L and <italic>T</italic><sub>1</sub>/<italic>T</italic><sub>2</sub> = 616/26 ms at 47 mmol/L. A uniform signal and contrast across the patella could be observed in proton imaging. The sensitivity of the RF coil enabled localization of FA ointment administrated to the knee with an in‐plane spatial resolution of (1.5 × 1.5) mm<sup>2</sup> achieved in a total scan time of approximately three minutes, which is well suited for translational human studies.</p> <p>This study shows the feasibility of combined <sup>1</sup>H/<sup>19</sup>F MRI of the knee at 7.0 T and proposes <italic>T</italic><sub>1</sub> and <italic>T</italic><sub>2</sub> mapping methods for quantifying fluorinated drugs <italic>in vivo</italic>. Further technological developments are necessary to promote real‐time bioavailability studies and quantification of <sup>19</sup>F‐containing medicinal compounds <italic>in vivo</italic>. Copyright © 2015 John Wiley & Sons, Ltd.</p> </abstract>