Clinical Application Of Magnetic Resonance Metal Artifact Reduction Sequences For Bone Tumor After Joint Replacement

Objective:(1)To compare the effect of syngo-WARP sequences and simple parameter adjusted sequences in metal artifacts reduction on MR images of prosthesis.(2)To investigate the diagnostic value of MR imaging with metal artifact reduction sequences in local recurrence of malignant bone tumor after joint replacement.(3)To explore the value of magnetic resonance follow-up in the diagnosis and treatment of local recurrent osteosarcoma after joint replacement for primary tumor.Methods:(1)MR scans with syngo-WARP sequences,simple parameter adjustment sequences and FSE sequences were performed on 3prosthesis phantoms and 22 patients after joint replacement.The artifact area of the prosthesis on MR images and the MR image quality of patients was evaluated and compared on each sequences.(2)Ninety-four patients with malignant bone tumor who had undergone joint replacement received MR scans with metal artifact reducing syngo WARP sequences and FSE sequences.The sensitivity,specificity,consistency rate,and Kappa value of syngo WARP sequences and FSE sequences in diagnosing local recurrence of malignant bone tumors was compared.The consistency of recurrent tumor size measuring between MR images and pathology was assessed.(3)We enrolled thirty-nine patients who were diagnosed with local recurrent osteosarcoma after joint replacement and received surgery for recurrence.Patients were divided into control group and MR follow-up group according to whether they received MR follow-up after joint replacement for primary tumor.The progression-free survival from primary surgery to recurrence,the maximum diameter of the recurrent lesions,the limb salvage rate and the extent of surgical resection was compared between two groups.Results:(1)The artifact area of the prosthesis phantom was largest in the FSE sequences,the artifact area in the simple parameter adjusted sequences was the second,the artifact area in the syngo-WARP sequences was the smallest.The image quality of patients after joint replacement in syngo-WARP sequences and simple parameter adjusted sequences were significantly better than FSE sequence.The image quality of transverse STIR in the syngo-WARP sequences was better than the simple parameter adjusted sequences(P=0.004).And there was no statistical difference in the image quality of the coronal T1WI(P=0.642)and coronal STIR(P=0.337)between the syngo-WARP sequences and the simple parameter adjusted sequences.(2)Local recurrence of malignant bone tumor mainly presented as soft tissue masses and bone destruction on MR images.The sensitivity,specificity,coincidence rate and Kappa value of syngo WARP sequences in the diagnosis of local recurrence of malignant bone tumors were 93.9%,91.8%,92.6%,and 0.840,which were all higher than FSE sequences.MR images showed high consistency with pathology in evaluating the maximal long diameters and short diameters of recurrent lesions.(3)There was no statistical difference of progression-free survival time between MR follow-up group and control group(P=0.064).The maximum diameter of the recurrent lesions in MR follow-up group were significant shorter than control group(P=0.041).The limb salvage rate in MR follow-up group was higher than control group(P=0.033),with smaller extent of surgical resection(P=0.020).Conclusion: Syngo-WARP sequences and simple parameter adjusted sequences are both effective in metal artifact reduction.MR MARS have good accuracy and consistency in diagnosing local recurrence of malignant bone tumors after joint replacement,and can measure the extent of recurrent tumors accurately.Patients with osteosarcoma receiving MR follow-up after joint replacement helps to early diagnosis and limb salvage.Therefore,MR MARS can play an important role in clinical diagnosis and treatment.