Christoph Roser1, Tim Hilgenfeld2, Sinan Sen3, Tobias Badrow2, Sebastian Zingler3, Sabine Heiland2, Martin Bendszus2, Christopher J Lux3, Alexander Juerchott2. 1. Department of Orthodontics and Dentofacial Orthopedics, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. christoph.roser@med.uni-heidelberg.de. 2. Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. 3. Department of Orthodontics and Dentofacial Orthopedics, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
Abstract
OBJECTIVES: Magnetic resonance imaging (MRI) image quality can be severely impaired by artifacts caused by fixed orthodontic retainers. In clinical practice, there is a trend towards using computer-aided design/computer-aided manufacturing (CAD/CAM) retainers. This study aimed to quantify MRI artifacts produced by these novel CAD/CAM retainers. MATERIAL AND METHODS: Three CAD/CAM retainers and a stainless-steel retainer ("Twistflex"; clinical reference standard) were scanned in vitro at 3-T MRI using a high-resolution 3D sequence. The artifact diameters and three-dimensional artifact volumes (AV) were determined for all mandibular (AVmand) and maxillary (AVmax) retainers. Moreover, the corresponding ratio of artifact volume to retainer volume (AV/RVmand, AV/RVmax) was calculated. RESULTS: Twistflex caused large artifact volumes (AVmand: 13530 mm3; AVmax: 15642 mm3; AV/RVmand: 2602; AV/RVmax: 2235). By contrast, artifact volumes for CAD/CAM retainers were substantially smaller: whereas artifact volumes for cobalt-chromium retainers were moderate (381 mm3; 394 mm3; 39; 31), grade-5 titanium (110 mm3; 126 mm3; 12; 12) and nickel-titanium (54 mm3; 78 mm3; 12; 14) both produced very small artifact volumes. CONCLUSION: All CAD/CAM retainers caused substantially smaller volumes of MRI artifacts compared to Twistflex. Grade-5 titanium and nickel-titanium CAD/CAM retainers showed the smallest artifact volumes. CLINICAL RELEVANCE: CAD/CAM retainers made from titanium or nickel-titanium may not relevantly impair image quality in head/neck and dental MRI. Artifacts caused by cobalt-chromium CAD/CAM retainers may mask nearby dental/periodontal structures. In contrast, the large artifacts caused by Twistflex are likely to severely impair diagnosis of oral and adjacent pathologies.
OBJECTIVES: Magnetic resonance imaging (MRI) image quality can be severely impaired by artifacts caused by fixed orthodontic retainers. In clinical practice, there is a trend towards using computer-aided design/computer-aided manufacturing (CAD/CAM) retainers. This study aimed to quantify MRI artifacts produced by these novel CAD/CAM retainers. MATERIAL AND METHODS: Three CAD/CAM retainers and a stainless-steel retainer ("Twistflex"; clinical reference standard) were scanned in vitro at 3-T MRI using a high-resolution 3D sequence. The artifact diameters and three-dimensional artifact volumes (AV) were determined for all mandibular (AVmand) and maxillary (AVmax) retainers. Moreover, the corresponding ratio of artifact volume to retainer volume (AV/RVmand, AV/RVmax) was calculated. RESULTS: Twistflex caused large artifact volumes (AVmand: 13530 mm3; AVmax: 15642 mm3; AV/RVmand: 2602; AV/RVmax: 2235). By contrast, artifact volumes for CAD/CAM retainers were substantially smaller: whereas artifact volumes for cobalt-chromium retainers were moderate (381 mm3; 394 mm3; 39; 31), grade-5 titanium (110 mm3; 126 mm3; 12; 12) and nickel-titanium (54 mm3; 78 mm3; 12; 14) both produced very small artifact volumes. CONCLUSION: All CAD/CAM retainers caused substantially smaller volumes of MRI artifacts compared to Twistflex. Grade-5 titanium and nickel-titaniumCAD/CAM retainers showed the smallest artifact volumes. CLINICAL RELEVANCE: CAD/CAM retainers made from titanium or nickel-titanium may not relevantly impair image quality in head/neck and dental MRI. Artifacts caused by cobalt-chromiumCAD/CAM retainers may mask nearby dental/periodontal structures. In contrast, the large artifacts caused by Twistflex are likely to severely impair diagnosis of oral and adjacent pathologies.
Authors: Tim Hilgenfeld; Marcel Prager; Alexander Heil; Franz Sebastian Schwindling; Mathias Nittka; David Grodzki; Peter Rammelsberg; Martin Bendszus; Sabine Heiland Journal: Eur Radiol Date: 2017-07-11 Impact factor: 5.315
Authors: Alexander Heil; Eduardo Lazo Gonzalez; Tim Hilgenfeld; Philipp Kickingereder; Martin Bendszus; Sabine Heiland; Ann-Kathrin Ozga; Andreas Sommer; Christopher J Lux; Sebastian Zingler Journal: PLoS One Date: 2017-03-23 Impact factor: 3.240
Authors: Christoph Roser; Lutz D Hodecker; Chris Koebel; Christopher J Lux; Dorothee Ruckes; Stefan Rues; Andreas Zenthöfer Journal: Sci Rep Date: 2021-07-19 Impact factor: 4.379