Evaluation of CT Techniques for Reducing Artifacts in the Presence of Metallic Orthopedic Implants

The projectional nature of radiogram limits its amount of information about the instrumented spine. MRI and CT imaging can be more helpful, using cross-sectional view. However, the presence of metal-related artifacts at both conventional CT and MRI imaging can obscure relevant anatomy and disease. We reviewed the literature about overcoming artifacts from metallic orthopaedic implants at high-field strength MRI imaging and multi-detector CT. The evolution of multichannel CT has made available new techniques that can help minimizing the severe beam-hardening artifacts. The presence of artifacts at CT from metal hardware is related to image reconstruction algorithm (filter), tube current (in mA), X-ray kilovolt peak, pitch, hardware composition, geometry (shape), and location. MRI imaging has been used safely in patients with orthopaedic metallic implants because most of these implants do not have ferromagnetic properties and have been fixed into position. However, on MRI imaging metallic implants may produce geometric distortion, the so-called susceptibility artifact. In conclusion, although 140 kV and high milliamperage second exposures are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. MRI artifacts can be minimized by positioning optimally and correctly the examined anatomy part with metallic implants in the magnet and by choosing fast spin-echo sequences, and in some cases also STIR sequences, with an anterior to posterior frequencyencoding direction and the smallest voxel size.

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“…Imaging parameters X-ray kilovolt peak A higher X-ray kilovolt peak can increase the ability of the X-ray beam to penetrate metal [6].…”

Section: Ctmentioning

confidence: 99%

Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

et al. 2009

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“…4,5 Various methods for artefact reduction (AR) on CBCT have been proposed. 6,7 Root fracture (RF) is a complication that leads often to teeth extraction. 8,9 RF is usually iatrogenic and can occur after the insertion of posts or screws in a root after an endodontic treatment.…”

Section: Introductionmentioning

confidence: 99%

Cone beam CT scans with and without artefact reduction in root fracture detection of endodontically treated teeth

Bechara¹,

McMahan²,

Moore³

et al. 2013

Dentomaxillofacial Radiology

109

120

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Objectives: Cone beam CT (CBCT) is used widely to depict root fracture (RF) in endodontically treated teeth. Beam hardening and other artefacts due to gutta-percha may increase the time of the diagnosis and result in an incorrect diagnosis. Two CBCT machines, ProMax ® (Planmeca, Helsinki, Finland) and Master 3D ® (Vatech, Hwaseong, Republic of Korea), have the option of applying an artefact reduction (AR) algorithm. The aim of this study was to determine whether using an AR algorithm in two CBCT machines enhances the accuracy of detecting RFs in endodontically treated teeth. Methods: 66 roots were collected and decoronated. All roots were treated endodontically using the same technique with gutta-percha and zinc oxide cement. One-half of the roots were randomly selected and fractured using a nail that was tapped gently with a hammer until complete fracture resulted in two root fragments; the two root fragments were glued together with one layer of methyl methacrylate. The roots were placed randomly in eight prepared beef rib fragments. Results: The highest accuracy was obtained when the ProMax was used without AR. The lowest accuracy was obtained with the Master 3D when used with AR. For both machines, accuracy was significantly higher without AR than with AR. Both with and without AR, the ProMax machine was significantly more accurate than the Master 3D machine. The same rank ordering was obtained for both sensitivity and specificity. Conclusions: For both machines, AR decreased the accuracy of RF detection in endodontically treated teeth. The highest accuracy was obtained when using the ProMax without AR.

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“…12 In other studies, the effect of increasing the radiation dose was examined by increasing either the milliampere second factor or the peak kilovoltage. [11][12][13] Many post-processing techniques for MAR also have been proposed. [12][13][14][15] In these studies, the amounts of metal artefact was assessed visually.…”

Section: Introductionmentioning

confidence: 99%

Metal artefact reduction with cone beam CT: anin vitrostudy

Bechara¹,

Moore²,

McMahan³

et al. 2012

Dentomaxillofacial Radiology

130

108

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Background: Metal in a patient's mouth has been shown to cause artefacts that can interfere with the diagnostic quality of cone beam CT. Recently, a manufacturer has made an algorithm and software available which reduces metal streak artefact (Picasso Master 3DH machine; Vatech, Hwaseong, Republic of Korea). Objectives: The purpose of this investigation was to determine whether or not the metal artefact reduction algorithm was effective and enhanced the contrast-to-noise ratio. Methods: A phantom was constructed incorporating three metallic beads and three epoxy resin-based bone substitutes to simulate bone next to metal. The phantom was placed in the centre of the field of view and at the periphery. 10 data sets were acquired at 50-90 kVp. The images obtained were analysed using a public domain software ImageJ (NIH Image, Bethesda, MD). Profile lines were used to evaluate grey level changes and area histograms were used to evaluate contrast. The contrast-to-noise ratio was calculated. Results: The metal artefact reduction option reduced grey value variation and increased the contrast-to-noise ratio. The grey value varied least when the phantom was in the middle of the volume and the metal artefact reduction was activated. The image quality improved as the peak kilovoltage increased. Conclusion: Better images of a phantom were obtained when the metal artefact reduction algorithm was used.

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Evaluation of CT Techniques for Reducing Artifacts in the Presence of Metallic Orthopedic Implants

Cited by 109 publications

References 0 publications

Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

Cone beam CT scans with and without artefact reduction in root fracture detection of endodontically treated teeth

Metal artefact reduction with cone beam CT: anin vitrostudy

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