On larger, highly 18F-FDG–avid lesions, the metallic implants had only a limited effect.
Furthermore, our study indicated that simulated susceptibility artifacts related to metallic implants have a significant effect on small, moderately 18F-FDG–avid lesions near the implant site that possibly may go unnoticed without TOF information. There was also a significant qualitative improvement in image quality in these locations. Conclusion: Qualitatively, there was a significant reduction of artifacts in the femoral head, sternum, and spine. The mean percentage error was −3.5% for TOF and −4.8% for non-TOF reconstructions, meaning that the inclusion of TOF information reduced the percentage error in SUV max by 28.5% ( P < 0.01). It also improved image quality in these locations ( P = 0.02, 0.01, and 0.01, respectively). The inclusion of TOF information significantly reduced artifacts due to simulated implants in the femoral head, sternum, and spine ( P = 0.01, 0.01, and 0.03, respectively). In 40 and 50 of these cases (non-TOF and TOF, respectively), the detectability of the lesions did not change in 9 and 1 cases, the detectability changed and in 2 non-TOF cases, the lesions were no longer visible after the introduction of metallic artifacts. Results: In total, 51 lesions were assessed. All reconstructed images were qualitatively and quantitatively assessed and compared with the baseline images.
Reconstruction was repeated after the introduction of artificial signal voids in the AC map to simulate metallic implants in standard anatomic areas. Baseline non-TOF and TOF PET images were reconstructed. In all patients, a clinically indicated whole-body 18F-FDG PET/MR scan was acquired. Methods: We included 27 patients without implants but with confirmed 18F-FDG–avid lesions adjacent to common implant locations. The purpose of this study was to evaluate the effect of susceptibility artifacts related to metallic implants on adjacent metabolically active lesions in clinical simultaneous PET/MR scanning for both time-of-flight (TOF) and non-TOF reconstructed PET images. Metalic implants may affect attenuation correction (AC) in PET/MR imaging.
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