Intraoral Coil Arrays for Single-Tooth Dental MRI

MRI offers superior contrast to x-ray and CBCT that can play an important role in diagnosing dental pathologies. Current extraoral RF coils for MRI in dentistry provide only limited SNR, thus limiting spatial resolution. We propose an intraoral coil (IOC) array that can provide high SNR to achieve a 250 μm isotropic resolution and enable parallel imaging.

A capacitively decoupled 2-channel IOC array with a buccal and a lingual element was placed on a bite form covered with silicon putty for subject-specific fixation. Phantom and in vivo measurements were performed at 3 T to compare the performance of the IOC array to an external single channel loop coil and a single-channel IOC in terms of sensitivity, image SNR, and g-factor for 2-fold acceleration.

IOC array improves SNR by up to 20-fold compared to the tight-fit extraoral loop coil (Ø = 4 cm), provides more uniform sensitivity and allows parallel imaging with a g-factor of less than 1.07 for 2-fold acceleration. (250 μm)³ isotropic resolution of premolar and molar teeth could be realized using a T₁-SPACE protocol within 2 min.

Intraoral coil arrays are feasible and offer higher homogeneity and SNR compared to an extraoral loop coil. Moreover, they allow for parallel imaging, which significantly reduces total acquisition time, thereby improving diagnostic potential.