Interference of titanium and zirconia implants on dental-dedicated MR image quality: ex vivo and in vivo assessment.

Objectives: To assess the impact of titanium and zirconia implants on dental-dedicated MR image (ddMRI) quality ex vivo (magnetic field distortion [MFD]) and in vivo (artefacts).

Methods: ddMR images were acquired (MAGNETOM Free.Max, 0.55 T, Siemens Healthineers AG, Forchheim, Germany) using a dental-dedicated coil (Rapid Biomedical, Rimpar, Germany). Ex vivo: three phantoms were manufactured: one agar-embedded titanium implant, one agar-embedded zirconia implant, and one control phantom (agar 1.5%). Field map analysis of images acquired at 0.55 T, 1.5 T, and 3.0 T (MAGNETOM Sola and MAGNETOM Lumina, respectively, Siemens Healthineers AG, Forchheim, Germany) was done to illustrate the extent and severity of MFD caused by the implants. In vivo (0.55 T only): a splint was designed to serve as an implant carrier, allowing diverse implant positions (0, 1, 2, or 5 implants). A volunteer was imaged using multiple pulse sequences. Three blinded observers scored the images twice for the presence, severity, and type of artefacts, illustrated by descriptive statistics and inter- and intra-observer reproducibility (kappa statistics).

Results: Ex vivo: titanium produced more severe MFD than zirconia. MFD extent and amplitude increased with field strength (0.55 T < 1.5 T < 3.0 T). In vivo: titanium produced more artefacts than zirconia, generally as signal voids in tooth crowns close to implants. Inter- and intra-observer reproducibility ranged from 0.28 to 0.64 and 0.32 to 0.57, respectively.

Conclusions: The prevalence of artefacts increased with magnetic field strength. Titanium generated larger MFD than zirconia. For both materials, artefacts were visible mainly in the crown area. Observer reproducibility needs improvement by dedicated ddMRI training.