  $Objective:$ Information on the metabolism of tissues in both healthy and
diseased states plays a significant role in the detection and understanding of
tumors, neurodegenerative diseases, diabetes, and other metabolic disorders.
Hyperpolarized carbon-13 magnetic resonance imaging ($^{13}$C-HPMRI) and
deuterium metabolic imaging ($^2$H-DMI) are two emerging X-nuclei used as
practical imaging tools to investigate tissue metabolism. However due to their
low gyromagnetic ratios ($\gamma_{13C}$ = 10.7 MHz/T; $\gamma_{2H}$ = 6.5
MHz/T) and natural abundance, such method required a sophisticated dual-tuned
radiofrequency (RF) coil. $ Methods:$ Here, we report a dual-tuned coaxial
transmission line (CTL) RF coil agile for metabolite information operating at
7T with independent tuning capability. The design analysis has demonstrated how
both resonant frequencies can be individually controlled by simply varying the
constituent of the design parameters. $Results:$ Numerical results have
demonstrated a broadband tuning range capability, covering most of the
X-nucleus signal, especially the $^{13}$C and $^2$H spectra at 7T. Furthermore,
in order to validate the feasibility of the proposed design, both dual-tuned
$^1$H/$^{13}$C and $^1$H/$^2$H RF coils are fabricated using a semi-flexible
RG-405 .086" coaxial cable and bench test results (scattering parameters and
magnetic field efficiency/distribution) are successfully obtained.
$Conclusion:$ The proposed dual-tuned RF coils reveal highly effective magnetic
field obtained from both proton and heteronuclear signal which is crucial for
accurate and detailed imaging. $Significance:$ The successful development of
this new dual-tuned RF coil technique would provide a tangible and efficient
tool for ultrahigh field metabolic MR imaging.
