Magnetic resonance imaging of intraoral hard and soft tissues using an intraoral coil and FLASH sequences

Abstract

Objectives: To ascertain the feasibility of MRI as a non-ionizing protocol for routine dentomaxillofacial diagnostic imaging. Wireless coils were used for MRI of intraoral hard and soft tissues. Methods: FLASH MRI was applied in vivo with a mandible voxel size of 250 × 250 × 500 μm3, FOV of 64 × 64 × 28 mm3 and acquisition time of 3:57 min and with a maxilla voxel size of 350 μm3 and FOV of 34 cm3 in 6:40 min. Ex vivo imaging was performed in 4:38 min, with a resolution of 200 μm3 and FOV of 36.5 cm3. Cone beam (CB) CT of the mandible and subjects were acquired. MRI was compared to CBCT and histological sections. Deviations were calculated with intraclass correlation coefficient (ICC) and coefficient of variation (cv). Results: A high congruence between CBCT, MRI and specimens was demonstrated. Hard and soft tissues including dental pulp, periodontium, gingiva, cancellous bone and mandibular canal contents were adequately displayed with MRI. Conclusions: Imaging of select intraoral tissues was achieved using custom MRI protocols with an easily applicable intraoral coil in a clinically acceptable acquisition time. Comparison with CBCT and histological sections helped demonstrate dimensional accuracy of the MR images. The course of the mandibular canal was accurately displayed with CBCT and MRI. Key points: • MRI is a clinically available diagnostic tool in dentistry • Intraoral hard and soft tissues can be imaged with a high resolution with MRI • The dimensional accuracy of MRI is comparable to cone beam CT