Development and assessment of an ex vivo imaging protocol for dental-dedicated MRI systems: A pilot study

This study proposes an ex vivo imaging protocol using a dental-dedicated magnetic resonance imaging (ddMRI) system and qualitatively and quantitatively evaluates the effects of phosphate-buffered saline (PBS) washing on image quality.

Four half-maxillae and 4 half-mandibles from human cadaveric donors were scanned using a ddMRI system with a dental-specific coil. Two pulse sequences ("anatomy" and "inflammation") were applied. Each specimen was imaged at 4 time points: immediately after PBS immersion and after 24, 48, and 72 hours of washing, totaling 64 images. Image quality was evaluated using signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and conspicuity of anatomical structures: cortical bone, medullary bone, root contour, soft tissue, and the sinus floor/mandibular canal. Conspicuity was rated by 3 observers and analyzed using the Cochran Q test (α=0.05).

Cortical bone, medullary bone, and the sinus floor were depicted in all images; root contours (91.1%) and soft tissue (85.9%) were visible in most images. PBS washing did not significantly impact conspicuity (P>0.05). Signal intensity was higher in "anatomy" than "inflammation." In the "anatomy" sequence, both SNR and CNR initially declined, then stabilized from 24 hours onward. CNR between medullary bone and soft tissue showed the greatest improvement with extended PBS washing, especially for the "inflammation" sequence.

The proposed ddMRI protocol enabled consistent visualization of dentomaxillofacial structures in ex vivo samples. PBS represented a suitable carrier. Although PBS washing did not influence conspicuity, at least 24 hours of washing may improve image quality, as reflected by SNR and CNR.