Performance of PROPELLER FSE T 2 WI in reducing metal artifacts of material porcelain fused to metal crown: a clinical preliminary study

This study aimed to compare MRI quality between conventional fast spin echo T 2 weighted imaging (FSE T 2 WI) with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) FSE T 2 WI for patients with various porcelain fused to metal (PFM) crown and analyze the value of PROPELLER technique in reducing metal artifacts. Conventional FSE T 2 WI and PROPELLER FSE T 2 WI sequences for axial imaging of head were applied in participants with different PFM crowns: cobalt-chromium (Co–Cr) alloy, pure titanium (Ti), gold–palladium (Au–Pd) alloy. Two radiologists evaluated overall image quality of section in PFM using a 5-point scale qualitatively and measured the maximum artifact area and artifact signal-to-noise ratio (SNR) quantitatively. Fifty-nine participants were evaluated. The metal crown with the least artifacts and the optimum image quality shown in conventional FSE T 2 WI and PROPELLER FSE T 2 WI were in Au–Pd alloy, Ti, and Co–Cr alloy order. PROPELLER FSE T 2 WI was superior to conventional FSE T 2 WI in improving image quality and reducing artifact area for Co-Cr alloy (17.0 ± 0.2% smaller artifact area, p < 0.001) and Ti (11.6 ± 0.7% smaller artifact area, p = 0.005), but had similar performance compared to FSE T 2 WI for Au–Pd alloy. The SNRs of the tongue and masseter muscle were significantly higher on PROPELLER FSE T 2 WI compared with conventional FSE T 2 WI (tongue: 29.76 ± 8.45 vs. 21.54 ± 9.31, p = 0.007; masseter muscle: 19.11 ± 8.24 vs. 15.26 ± 6.08, p = 0.016). Therefore, the different PFM crown generate varying degrees of metal artifacts in MRI, and the PROPELLER can effectively reduce metal artifacts especially in the PFM crown of Co-Cr alloy.