Design and Characterization of a Fully Flexible Dipole Antenna for Intraoral MRI

Dental magnetic resonance imaging (MRI) has been improved through the development of an intraoral antenna that increases the signal-to-noise ratio (SNR) and image quality. This study aimed to design a fully flexible coaxial dipole antenna for intraoral applications at 3 T. The dipole design is characterized by its open distal end, which allows for a lack of restriction on the movement of the tongue, and also offers an increased depth of sensitivity that allows for dental roots. The finite element method (FEM) and finite-difference time-domain (FDTD) simulations were used to optimize the antenna performance and identify the optimum gaps in the shield that ensure a uniform current distribution at the desired frequency band. Finally, a fabricated prototype was evaluated in minced pork to measure the reflection coefficient in open- and closed-mouth scenarios. The optimal configurations were determined with gaps on both sides of the fully flexible dipole antenna at small and large curvatures. Furthermore, the implementation of the dipole antenna has led to improvement in the $\text{B}_{1}^{+}$ field homogeneity, resulting in higher transmit and specific absorption rate (SAR) efficiency. In addition, the magnetic resonance (MR) images obtained by the proposed dental coil exhibited high sensitivity of the dental roots, teeth, and surrounding mouth. Finally, safety considerations were considered when analyzing the performance of the intraoral antenna under MRI. A novel intraoral flexible antenna and its advantages are described to overcome the challenges associated with intraoral radio frequency (RF) coils.