Total inhomogeneity correction including chemical shifts and susceptibility by view angle tilting

Cho, Z. H.; Kim, D. J.; Kim, Y. K.

doi:10.1118/1.596162

Cited by 204 publications

(173 citation statements)

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“…Thus, the spins are read out at an angulated view. Cho et al first proposed viewing the slice at a shifted angle [35]. It can cause some blurring, though, which can be countered by using thin sections and large bandwidth.…”

Section: New Metal Artifact Reduction Sequencementioning

confidence: 99%

CT and MRI Techniques for Imaging Around Orthopedic Hardware

Duong

Sutter

Skornitzke

et al. 2017

Fortschr Röntgenstr

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ZUSAMMENFASSUNGOrthopädische Implantate verringern die Bildqualität in der Schnittbildgebung. Bei steigendem Einsatz von orthopädi-schen Implantaten in einer alternden Bevölkerung ist eine Metallartefaktreduktion von zunehmender Bedeutung. Im folgenden Review möchten wir einen Überblick über die wesentlichen Artefakte in der Computertomografie und Magnetresonanztomografie sowie die neuesten Standards zur Verbesserung der Bildqualität geben. Alle Schritte der Bildakquisition von Gerätewahl über Scanvorbereitungen und -parameter bis hin zur Bildverarbeitung beeinflussen das Ausmaß der Metallartefakte. Technische Fortschritte wie die Dual-energy-Computertomografie mit der Option der Virtuellen monochromatischen Bildgebung sowie neue Implantatmaterialien bieten weitere Möglichkeiten der Metallartefaktreduktion in CT und MRT. Dezidierte MetallartefaktSequenzen beinhalten Algorithmen zur Artefaktreduktion und zur Verbesserung der Bildqualität des umgebenden Gewebes und sind essenzielle Werkzeuge in der orthopä-dischen Bildgebung zur frühzeitigen Detektion von postoperativen Komplikationen. ABSTR AC TOrthopedic hardware impairs image quality in cross-sectional imaging. With an increasing number of orthopedic implants in an aging population, the need to mitigate metal artifacts in computed tomography and magnetic resonance imaging is becoming increasingly relevant. This review provides an overview of the major artifacts in CT and MRI and state-ofthe-art solutions to improve image quality. All steps of image acquisition from device selection, scan preparations and parameters to image post-processing influence the magnitude of metal artifacts. Technological advances like dual-energy CT with the possibility of virtual monochromatic imaging (VMI) and new materials offer opportunities to further reduce artifacts in CT and MRI. Dedicated metal artifact reduction sequences contain algorithms to reduce artifacts and improve imaging of surrounding tissue and are essential tools in orthopedic imaging to detect postoperative complications in early stages.

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Section: New Metal Artifact Reduction Sequencementioning

confidence: 99%

CT and MRI Techniques for Imaging Around Orthopedic Hardware

Duong

Sutter

Skornitzke

et al. 2017

Fortschr Röntgenstr

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“…Several techniques are commonly used to reduce the severity of metal susceptibility artifact, including simple concessions such as increasing the frequency encoding bandwidth (BW), or orienting the long axis of the metal along the frequency encoding direction (1). A clever technique still not in common usage is view angle tilting (VAT) (2), which has been demonstrated to be clinically useful for reducing the distortion in images when imaging patients with metal implants (3)(4)(5) and during interventional MRI where inserted needles distort the local magnetic field (6). VAT results in a marked reduction in the severity of the metal susceptibility artifact, and can be employed without increasing the imaging time.…”

mentioning

confidence: 99%

Quantitative evaluation of metal artifact reduction techniques

Kolind

MacKay

Munk

et al. 2004

Magnetic Resonance Imaging

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Purpose: To develop a technique to quantify artifact, and to use it to compare the effectiveness of several approaches to metal artifact reduction, including view angle tilting and increasing the slice select and image bandwidths (BWs), in terms of metal artifact reduction, noise, and blur. Materials and Methods:Nonmetallic replicas of two metal implants (stainless steel and titanium/chromium-cobalt femoral prostheses) were fabricated from wax, and MR images were obtained of each component immersed in water. The differences between the images of each metal prosthesis and its wax counterpart were measured. The contributions from noise and blur were isolated, resulting in a measure of the metal artifact. Several off-resonance artifact reduction techniques were assessed in terms of metal artifact reduction capability, as well as signal to noise ratio and blur.Results: Increasing the image BW from Ϯ16 kHz to Ϯ64 kHz was found to reduce the artifact by an average of 60%, while employing view angle tilting (VAT) alone was found to reduce the artifact by an average of 63%. The metal artifact reduction sequence (MARS), which combines several susceptibility artifact reduction techniques, resulted in the least amount of image distortion, reducing the artifact by an average of 79%. Conclusion:The results indicate that while VAT alone (with an image BW of Ϯ16 kHz) resulted in the smallest amount of total energy and no reduction in the signal-tonoise ratio compared to a conventional spin-echo pulse sequence, MARS resulted in significantly less artifact and dramatically less blur. IMAGE DISTORTIONS caused by differences in magnetic susceptibility have long been a problem in clinical imaging, especially in the presence of metal prostheses. Several techniques are commonly used to reduce the severity of metal susceptibility artifact, including simple concessions such as increasing the frequency encoding bandwidth (BW), or orienting the long axis of the metal along the frequency encoding direction (1). A clever technique still not in common usage is view angle tilting (VAT) (2), which has been demonstrated to be clinically useful for reducing the distortion in images when imaging patients with metal implants (3-5) and during interventional MRI where inserted needles distort the local magnetic field (6). VAT results in a marked reduction in the severity of the metal susceptibility artifact, and can be employed without increasing the imaging time. Unfortunately, it introduces blurring, and only reduces the artifact in one direction. These deficiencies are lessened in the metal artifact reduction sequence (MARS), which involves VAT and increased slice select and image BWs. The effectiveness of MARS in reducing susceptibility artifacts in a clinical scan is illustrated in Fig. 1.It is difficult to evaluate quantitatively the competence of a given metal artifact reduction technique. Each method has drawbacks that can mask its ability to reduce metal artifact, and it is necessary to quantify the disadvantages as well as the advantages ...

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“…To obtain further artifact suppression the fundamental sequence design must be altered, and accordingly, several techniques with such aim have been developed; view angle tilting (VAT) [4,5], slice encoding for metal artifact correction (SEMAC) [6], and Multi-Acquisition VariableResonance Image Combination (MAVRIC) [7]. VAT suppresses geometrical distortions within the imaging plane, whereas SEMAC and MAVRIC correct for the bending of the imaging plane near the metal.…”

Section: Introductionmentioning

confidence: 99%