Eight-channel transceiver RF coil array tailored for ¹H/¹⁹F MR of the human knee and fluorinated drugs at 7.0 T.
The purpose of this study was to evaluate the feasibility of an eight-channel dual-tuned transceiver surface RF coil array for combined (1)H/(19)F MR of the human knee at 7.0 T following application of (19)F-containing drugs. The (1)H/(19)F RF coil array includes a posterior module with two (1)H loop elements and two anterior modules, each consisting of one (1)H and two (19)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 (19)F MRS was conducted with 47 and 101 mmol/L of flufenamic acid (FA) – a (19)F-containing non-steroidal anti-inflammatory drug – to determine T1 and T2 and to study the (19)F signal-to-dose relationship. The suitability of the proposed approach for (1)H/(19)F MR was examined in healthy subjects. Reflection coefficients of each channel were less than -17 dB and coupling between channels was less than -11 dB. Q(L)/Q(U) was less than 0.5 for all elements. MRS results demonstrated signal stability with 1% variation. T1 and T2 relaxation times changed with concentration of FA: T1 /T2 = 673/31 ms at 101 mmol/L and T1 /T2 = 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(2) achieved in a total scan time of approximately three minutes, which is well suited for translational human studies. This study shows the feasibility of combined (1)H/(19)F MRI of the knee at 7.0 T and proposes T1 and T2 mapping methods for quantifying fluorinated drugs in vivo. Further technological developments are necessary to promote real-time bioavailability studies and quantification of (19)F-containing medicinal compounds in vivo.
Berlin Ultrahigh Field Facility (BUFF), Max Delbrück Center for Molecular Medicine, Berlin, Germany.|Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon, Lisbon, Portugal.
Yiyi
Y
Ji
Berlin Ultrahigh Field Facility (BUFF), Max Delbrück Center for Molecular Medicine, Berlin, Germany.|MRI.TOOLS GmbH, Berlin, Germany.
Helmar
H
Waiczies
Berlin Ultrahigh Field Facility (BUFF), Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Lukas
L
Winter
Berlin Ultrahigh Field Facility (BUFF), Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Pavla
P
Neumanova
Berlin Ultrahigh Field Facility (BUFF), Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Daniela
D
Hofmann
MRI.TOOLS GmbH, Berlin, Germany.
Jan
J
Rieger
Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
Ralf
R
Mekle
Berlin Ultrahigh Field Facility (BUFF), Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Sonia
S
Waiczies
Berlin Ultrahigh Field Facility (BUFF), Max Delbrück Center for Molecular Medicine, Berlin, Germany.|Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Thoralf
T
Niendorf
D000328:Adult; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005439:Flufenamic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics*; D066235:Fluorine-19 Magnetic Resonance Imaging / Q000295:instrumentation*; D006801:Humans; D007717:Knee / Q000502:physiology*; D008297:Male; D057054:Molecular Imaging / Q000295:instrumentation* / Q000379:methods; D066244:Proton Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers; D055815:Young Adult
D000893:Anti-Inflammatory Agents; D005439:Flufenamic Acid
MRI; RF coil; drug monitoring; fluorine magnetic resonance; magnetic resonance; non-steroidal anti-inflammatory drug; ultrahigh field MRI