View-Angle Tilting and Slice-Encoding Metal Artifact Correction for Artifact Reduction in MRI: Experimental Sequence Optimization for Orthopaedic Tumor Endoprostheses and Clinical Application.

Jungmann, Pia M; Ganter, Carl; Schaeffeler, Christoph J; Bauer, Jan S; Baum, Thomas; Meier, Reinhard; Nittka, Mathias; Pohlig, Florian; Rechl, Hans; von Eisenhart-Rothe, Ruediger; Rummeny, Ernst J; Woertler, Klaus

doi:10.1371/journal.pone.0124922

journal article

Title:: View-Angle Tilting and Slice-Encoding Metal Artifact Correction for Artifact Reduction in MRI: Experimental Sequence Optimization for Orthopaedic Tumor Endoprostheses and Clinical Application.
Document type:: Journal Article; Research Support, Non-U.S. Gov't
Author(s):: Jungmann, Pia M; Ganter, Carl; Schaeffeler, Christoph J; Bauer, Jan S; Baum, Thomas; Meier, Reinhard; Nittka, Mathias; Pohlig, Florian; Rechl, Hans; von Eisenhart-Rothe, Ruediger; Rummeny, Ernst J; Woertler, Klaus
Abstract:: MRI plays a major role in follow-up of patients with malignant bone tumors. However, after limb salvage surgery, orthopaedic tumor endoprostheses might cause significant metal-induced susceptibility artifacts.To evaluate the benefit of view-angle tilting (VAT) and slice-encoding metal artifact correction (SEMAC) for MRI of large-sized orthopaedic tumor endoprostheses in an experimental model and to demonstrate clinical benefits for assessment of periprosthetic soft tissue abnormalities.In an experimental setting, tumor endoprostheses (n=4) were scanned at 1.5T with three versions of optimized high-bandwidth turbo-spin-echo pulse sequences: (i) standard, (ii) VAT and (iii) combined VAT and SEMAC (VAT&SEMAC). Pulse sequences included coronal short-tau-inversion-recovery (STIR), coronal T1-weighted (w), transverse T1-w and T2-w TSE sequences. For clinical evaluation, VAT&SEMAC was compared to conventional metal artifact-reducing MR sequences (conventional MR) in n=25 patients with metal implants and clinical suspicion of tumor recurrence or infection. Diameters of artifacts were measured quantitatively. Qualitative parameters were assessed on a five-point scale (1=best, 5=worst): "image distortion", "artificial signal changes at the edges" and "diagnostic confidence". Imaging findings were correlated with pathology. T-tests and Wilcoxon-signed rank tests were used for statistical analyses.The true size of the prostheses was overestimated on MRI (P<0.05). A significant reduction of artifacts was achieved by VAT (P<0.001) and VAT&SEMAC (P=0.003) compared to the standard group. Quantitative scores improved in the VAT and VAT&SEMAC group (P<0.05). On clinical MR images, artifact diameters were significantly reduced in the VAT&SEMAC-group as compared with the conventional-group (P<0.001). Distortion and artificial signal changes were reduced and diagnostic confidence improved (P<0.05). In two cases, tumor-recurrence, in ten cases infection and in thirteen cases other pathologies were diagnosed.Significant reduction of metallic artifacts was achieved by VAT and SEMAC. Clinical results suggest, that these new techniques will be beneficial for detecting periprosthetic pathologies during postoperative follow-up.
Journal title abbreviation:: PLoS ONE
Year:: 2015
Journal volume:: 10
Journal issue:: 4
Pages contribution:: e0124922
Language:: eng
Fulltext / DOI:: doi:10.1371/journal.pone.0124922
Pubmed ID:: http://view.ncbi.nlm.nih.gov/pubmed/25909472
Print-ISSN:: 1932-6203
TUM Institution:: Fachgebiet Neuroradiologie (Prof. Zimmer); Klinik und Poliklinik für Orthopädie und Sportorthopädie
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