MRI artefacts and fat suppression near implants: A Multi-material Comparative evaluation at 0.31, 0.55, 1.5 and 3...

Metallic implants frequently induce MRI artefacts, impairing diagnostic accuracy. Conventional reduction methods such as VAT and SEMAC mitigate artefacts but increase acquisition times and image blurring. Recent technological advances have renewed interest in low-field MRI as a potential alternative.

Three custom-designed phantoms containing four implants (ceramic femoral head, cobalt-chromium femoral head, titanium screw, stainless steel screw) were scanned at 0.31 T, 0.55 T, 1.5 T, and 3 T. Protocols included T1-FSE, T2-FSE, and STIR sequences with/without VAT and SEMAC. Six blinded readers (radiologists, radiographers, physicist) assessed artefact size, distortion, blurring, noise, and fat suppression using a 5-point Likert scale. Quantitative artefact areas were measured using MATLAB-based segmentation, expressed as absolute values and relative reductions compared with 3 T.

Fifty-four sequences (1968 scores) were analysed. Artefact size decreased by 63-80 % at 0.31 T and 0.55 T compared with 3 T and by 60-77 % compared with 1.5 T. Fat suppression was consistently effective at low fields but less so at 1.5 T and 3 T unless VAT or SEMAC was used. These sequences further reduced artefacts at high fields but introduced blurring and increased acquisition times. Qualitative and quantitative findings were concordant across all readers.

Low-field MRI markedly reduces metal-induced artefacts while preserving clinically acceptable scan times and fat suppression performance. Integrating low-field systems into clinical workflows could complement standard 1.5 T and 3 T imaging, especially for patients with metallic implants.