Novel MR imaging method – MAVRIC – for metal artifact suppression after joint replacement in musculoskeletal tumor patients

Abstract

BackgroundStandard imaging modality for the follow-up after prosthetic replacements for musculoskeletal tumor patients has been conventional radiography. This technique is effective in detecting subtle changes in bone adjacent to metal implants, but in many cases, radiographs do not lead to definitive diagnosis of postoperative adverse events such as acute infection, local recurrence of soft tissue tumor or soft tissue local recurrence of osseous sarcoma. Conventional MRI sequences have not been effective due to metal artifacts. In this study, we tried to elucidate the effectiveness of metal artifact suppression using novel sequence, multiacquisition variable-resonance image combination (MAVRIC), after musculoskeletal tumor surgeries.MethodsWe retrospectively analyzed 5 cases of malignant bone and soft tissue sarcoma patients who were reconstructed with metal prosthesis after wide resection of tumors. Images obtained using MAVRIC and short tau inversion recovery (STIR) were compared side by side. The paired MAVRIC and STIR images were qualitatively compared independently by two specialists for 4 parameters: visualization of bone - implant interface, visualization of surrounding soft tissues, image blurring, and overall image quality. Quantitatively, paired images were reviewed to identify the slice where the metal artifact was maximal, and a region of interest encompassing the implant and surrounding artifact was drawn using Advantage Workstation (GE Healthcare, Japan).ResultsThere were no local recurrences that were detected. By utilizing MAVRIC, visualization of the bone - implant interface and visualization of the surrounding soft tissue were significantly improved in MAVRIC compared to STIR. Although blurring was worse on the MAVRIC acquisitions, the overall image quality was still better on MAVRIC. Quantitatively, the area of metal artifact measured using MAVRIC was markedly less compared to STIR (61.4 cm2 vs 135.9 cm2).ConclusionDespite the relatively small number of cases in the present study, our observation strongly suggests that MAVRIC is able to improve the quality of images by decreasing the artifact caused by endoprosthesis, frequently utilized in reconstruction of musculoskeletal tumor patients. Further installments of conventional imaging sequences with the addition of gadolinium - enhancement will enable increased accuracy in diagnosing local recurrences of sarcoma patients.

Metal artifact reduction in 68Ga-PSMA-11 PET/MRI for prostate cancer patients with hip joint replacement using multiacquisition variable-resonance image combination

“…Metal implant- induced signal voids can be corrected by iterative metal artifact reduction algorithms (Schabel et al, 2017;van der Vos et al, 2017) but also semiautomated inpainting artifacts in the pelvis with soft tissue prior to MR-based AC (Torrado-Carvajal et al, 2018), providing so an accurate quantitative activity distribution (Ladefoged et al, 2013). Our results are in line with the study of Susa et al suggesting that MAVRIC-SL is able to improve image quality by decreasing signal voids caused by endoprothesis and therefore helping to detect joint abnormalities after joint replacement in patients with musculoskeletal tumors (Susa et al, 2015).…”

Advances in MRI around metal

“…Nonimplant associated soft‐tissue abnormalities may be found on MARS sequences, such as cartilage defects, tendon tears, muscle atrophy and fatty infiltration, meniscal or labral lesions, disc abnormalities, spinal canal stenosis, neural injury, or pathology . Recurrence of a tumor or a newly developed tumorous formation is another important clinical entity where MARS sequences may be utilized, both for detection and classification of findings …”

The Effect of Susceptibility Artifacts Related to Metallic Implants on Adjacent-Lesion Assessment in Simultaneous TOF PET/MR

“…Several advanced MR techniques to reduce metallic artifacts are also commercially available. Some, such as the multiacquisition variable-resonance image combination and short-echo-time imaging, are already available for PET/MR and have shown potential in metallic artifact correction (17)(18)(19)(20)(21). Correcting the metallic artifacts on the MR image also improves the AC map and thus the PET image.…”