Magnetic resonance imaging artifacts: mechanism and clinical significance.

Pusey, E; Lufkin, Robert B.; Brown, Richard K.J.; Solomon, Marc; Stark, D D; Tarr, R W; Hanafee, William N.

doi:10.1148/radiographics.6.5.3685515

Cited by 81 publications

(38 citation statements)

References 9 publications

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“…7 Metallic artifacts arise from distortions in the main magneticˆeld caused by ferromagnetic materials. 29 Even nonferromagnetic materials create moderate artifacts. 30 The nonferromagnetic vascular clip has been depicted as a central area of extreme signal void adjacent to an asymmetric high-intensity border that is several times the size of the clip.…”

Section: Discussionmentioning

confidence: 99%

Artifacts of Vena Cava Filters ex vivo on MR Angiography

2003

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Section: Discussionmentioning

confidence: 99%

Artifacts of Vena Cava Filters ex vivo on MR Angiography

2003

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“…15 These are patchy areas of increased or decreased signal intensity. This artefact is produced by variations in RF energy required to tip protons 90 or 180 degrees within the selected slice volume.…”

Section: Rf Noise 1415mentioning

confidence: 99%

“…Gradient field artefacts (B1 inhomogeneity) 15 Magnetic field gradients are used to spatially encode the location of signals from excited protons within the volume being imaged. The slice select gradient defines the volume (slice).…”

mentioning

confidence: 99%

“…If correction is not achieved, the cause might be either a damaged gradient coil or an abnormal current passing through the gradient coil. 15 Variation in intensity across the image may be due to the failure of the RF coil, non-uniform B1 field, nonuniform sensitivity of the receive only coil (spaces between wire in the coil, uneven distribution of wire), or presence of non-ferromagnetic material in the imaged object.…”

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confidence: 99%

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A short overview of MRI artefacts

et al. 2004

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Many different artefacts can occur during magnetic resonance imaging (MRI), some affecting the diagnostic quality, while others may be confused with pathology. An artefact is a feature appearing in an image that is not present in the original object. Artefacts can be classified as patientrelated, signal processing-dependent and hardware (machine)-related. This article presents an overview of MRI artefacts and possible rectifying methods. IntroductionArtefacts remain a problematic in magnetic resonance imaging (MRI). Some affect the quality of the examination, while others may be confused with pathology.An artefact is a feature appearing in an image that is not present in the original object. Depending on their origin, artefacts are typically classified as patient-related, signal processingdependent and hardware (machine)-related.It is important to recognise these artefacts and have a basic understanding of their origin, especially those mimicking pathology. In this article emphasis is placed on recognition of artefacts and possible rectifying methods. Patient-related MR artefacts Motion artefactsMotion is one of the most common artefacts in MR imaging, causing either ghost images or diffuse image noise in the phase-encoding direction. The reason for mainly affecting data sampling in the phase-encoding direction is the significant difference in the time of acquisition in the frequency-and phase-encoding directions. Frequency-encoding sampling in all the rows of the matrix (128, 256 or 512) takes place during a single echo (milliseconds). Phase-encoded sampling takes several seconds, or even minutes, owing to the collection of all the k-space lines to enable Fourier analysis. Major physiological movements are of millisecond to seconds duration and thus too slow to affect frequency-encoded sampling, but they have a pronounced effect in the phase-encoding direction.Periodic movements such as cardiac movement and blood vessel or CSF pulsation cause ghost images, while non-periodic movement causes diffuse image noise (Fig. 1). Ghost image intensity increases with amplitude of movement and the signal intensity from the moving tissue.Several methods can be used to reduce motion artefacts, including patient immobilisation, 1 cardiac and respiratory gating, 2 signal suppression of the tissue causing the artefact, 1 choosing the shorter dimension of the matrix as the phase-encoding direction, view-ordering or phase-reordering methods 3 and swapping phaseand frequency-encoding directions 1 to move the artefact out of the field of interest. FlowFlow can manifest as either altered intravascular signal (flow enhancement or flow-related signal loss), or flow-related artefacts (ghost images or spatial misregistration).Flow enhancement, also known as inflow effect, is caused by fully magnetised protons entering the imaged slice while the stationary protons have not fully regained their magnetisation. A short overview of MRI artefacts L J Erasmus MB ChB D Hurter MB ChB M Naudé MB ChB H G Kritzinger MB ChB

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“…Sagittal and axial sequences were also checked to exclude true radial tears. We excluded the first consecutive image immediately after the insertion site of following transverse ligament of anterior horn of the medial meniscus, which could cause an artifact at the meniscal tip due to partial volume (9). The following were evaluated: 1) the presence of pseudoradial tear at the anterior horn to body of the medial meniscus 2) the incidence according to age group 3) the location of blunted tip 4) the number of consecutive images on which a pseudoradial tear was present in each case.…”

Section: Introductionmentioning

confidence: 99%