Susceptibility artifacts in 2DFT spin-echo and gradient-echo imaging: The cylinder model revisited

Bakker, Chris J.G.; Bhagwandien, Rohit; Moerland, Marinus A.; Fuderer, Miha

doi:10.1016/0730-725x(93)90473-q

Cited by 95 publications

(70 citation statements)

References 13 publications

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“…Slice thickness variations may be complex and account for significant signal loss and image distortion, particularly adjacent to metal devices with a complex threedimensional geometry [26]. For imaging in the vicinity of a metal device, slice thickness should be minimized as much as possible because small voxel size in MRI in the vicinity of metal increases image quality.…”

Section: Sequence Parametersmentioning

confidence: 99%

“…The magnitude of local misregistration artifact is also inversely proportional to the frequency encoding (readout) gradient strength used in the imaging acquisition [25]. Misregistration artifacts occur only in the frequency encoding direction and are not seen in the phase encoding direction [4,16,[26][27][28]. Orientation of the frequency and phase encoding gradients can be selected such that misregistration artifacts are directed away from areas of anticipated clinical diagnostic interest.…”

Section: Pulse Sequence Selectionmentioning

confidence: 99%

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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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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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Section: Sequence Parametersmentioning

confidence: 99%

Section: Pulse Sequence Selectionmentioning

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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“…Susceptibility artifacts have been studied extensively and are well understood (23)(24)(25). These artifacts arise when objects like metallic implants, having a considerably larger magnetic susceptibility than human tissue, are brought into or near the imaging plane.…”

Section: Susceptibility Artifactsmentioning

confidence: 99%

Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Bartels

Bakker

Viergever

2001

Magnetic Resonance in Med

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In this study, a method is proposed for MRI of the lumen of metallic vascular implants, like stents or vena cava filters. The method is based on the reduction of artifacts caused by flow, susceptibility, and RF eddy currents. Whereas both flow artifacts and susceptibility artifacts are well understood and documented, RF artifacts are not. Therefore, the present study comprises an in-depth theoretical explanation of the factors governing the severity of these RF artifacts. It is explained that the RF caging inside cage-like implants is caused by disturbances of the send and receive sensitivities due to coupling between the loops in the implant and the MR scanner's send and receive coils. A scaled excitation angle model describing the behavior of the signal intensity inside the implants as a function of the applied nominal excitation angle is introduced. This theoretical model was validated in phantom experiments. Reduced signal from within implants due to the caging problem could be restored by increasing the applied RF power in the excitation pulse, without exceeding the generally accepted SAR safety limits. For all these applications the imaging of regions of the body containing metallic vascular implants, like stents and vena cava filters, is troublesome because of the artifacts provoked by these implants. In particular, MRA of stented vessels is hampered inside and near the stent. Often signal void is seen at these locations, rendering evaluation of the stent lumen and detection of possible restenosis inside the stent impossible (9 -11).Several authors have studied the artifacts caused by various commonly used stents in . The application of contrast enhanced (CE) MRA techniques has been shown to provide some improvement in stent visualization, but still it was found that the extent to which the images are distorted depends strongly on the type of stent used. For older stent types, often made from stainless steel alloys, the artifacts are mainly due to local differences in magnetic volume susceptibility between the stent and its surroundings. For this reason, stents made of ferromagnetic materials show larger susceptibility artifacts than stents made of so-called MR-compatible materials like tantalum or nitinol. Recently however, it was observed that stents made from the same material, thereby having the same magnetic susceptibility, can provoke significantly different degrees of signal loss in their lumen (17,21,22). These differences were attributed to small variations in susceptibility (16) and to differences in the design of the wire mesh. RF caging of the stent lumen by the metallic cage-like construction of the implant plays an important role here. The extent to which this caging takes place is obviously different for different cage constructions, which accounts for the observed differences in signal disturbance inside the stents.Whereas both flow artifacts and susceptibility artifacts are well understood and documented, RF artifacts are not. Therefore, an in-depth study of the factors governing the seve...

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“…Metallic hardware-induced MR susceptibility artifacts are mainly the sum of local field inhomogeneities (due to spin resonance differences between metal and surrounding soft-tissues) altering both phase and frequency of local spins. These result in subsequent image formation misregistration in the form of signal loss within the metallic object, distortion of the shape of the metallic object along the axes of frequency encoding and section selection as well as high signal intensity appearing around the metallic object ( Figure 6A) [59][60][61][62] . As mentioned with CT, the production of metal-related artifacts in MRI is a result of both hardware-related factors such as hardware composition, geometry (shape), as well as location (orientation to the main magnetic fields) and MRI technical factors including magnetic field strength used, type of pulse sequences applied and the sequence parameters, including voxel size (determined by field of view, image matrix, and section thickness), and echo train length [62][63][64] .…”

Section: Magnetic Resonance Imagingmentioning

confidence: 99%

Spinal fusion-hardware construct: Basic concepts and imaging review

Nouh¹

2012

WJR

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The interpretation of spinal images fixed with metallic hardware forms an increasing bulk of daily practice in a bus�� imaging department. Radio�ogists are required to be familiar with the instrumentation and operative options used in spinal fixation and fusion procedures, especia�� in his or her institute. This is critica� in eva�uat-ing the position of imp�ants and potentia� comp�ications associated with the operative approaches and spinal fixation devices used. Thus, the radiologist can play an important role in patient care and outcome. This review out�ines the advantages and disadvantages of common�� used imaging methods and reports on the best yield for each modality and how to overcome the problematic issues associated with the presence of metallic hardware during imaging. Baseline radiographs are essentia� as the�� are the base�ine point for eva�uation of future studies shou�d patients deve�op s��mptoms suggesting possib�e comp�ications. The�� ma�� justif�� further imaging workup with computed tomography, magnetic resonance and/or nuc�ear medicine studies as the eva�u-ation of a patient with a spinal implant involves a multimodality approach. This review describes imaging features of potential complications associated with spinal fusion surgery as well as the instrumentation used. This basic knowledge aims to help radiologists approach ever��da�� practice in c�inica� imaging.

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Susceptibility artifacts in 2DFT spin-echo and gradient-echo imaging: The cylinder model revisited

Cited by 95 publications

References 13 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

Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Spinal fusion-hardware construct: Basic concepts and imaging review

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