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Primer on Commonly Occurring MRI Artifacts and How to Overcome Them

2022; Radiological Society of North America; Volume: 42; Issue: 3 Linguagem: Inglês

10.1148/rg.210021

1527-1323

Chikara Noda, Bharath Ambale‐Venkatesh, Jennifer D. Wagner, Yoko Kato, Jason Ortman, João A.C. Lima,

Advanced X-ray and CT Imaging

HomeRadioGraphicsVol. 42, No. 3 PreviousNext PhysicsFree AccessRadioGraphics FundamentalsPrimer on Commonly Occurring MRI Artifacts and How to Overcome ThemChikara Noda, Bharath Ambale Venkatesh, Jennifer D. Wagner, Yoko Kato, Jason M. Ortman, João A. C. Lima Chikara Noda, Bharath Ambale Venkatesh, Jennifer D. Wagner, Yoko Kato, Jason M. Ortman, João A. C. Lima Author AffiliationsFrom the Divisions of Cardiology (C.N., Y.K., J.M.O., J.A.C.L.) and Radiology (B.A.V.), Johns Hopkins University School of Medicine, 600 N Wolfe St, Blalock 524, Baltimore, MD 21287; and Canon Medical Research USA, Cleveland, Ohio (J.D.W.).Address correspondence to J.A.C.L. (e-mail: [email protected]).Chikara NodaBharath Ambale VenkateshJennifer D. WagnerYoko KatoJason M. OrtmanJoão A. C. Lima Published Online:Apr 22 2022https://doi.org/10.1148/rg.210021MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In AbstractThe full digital presentation is available online.TEACHING POINTS■ By learning the most common causes of each type of artifact, the impact on image quality can be mitigated.■ System conditions, patient physiology, and tissue characteristics contribute to the appearance of artifacts at MRI.■ Each artifact reduction strategy has pitfalls and trade-offs.Various artifacts can occur at MRI. To avoid confusion when dictating reports, radiologists must be aware of these artifacts. In addition, MRI technologists must be able to identify artifacts and understand their causes and solutions to produce consistently high-quality images. This online presentation reviews the artifacts that are commonly encountered at MRI. For each artifact, there is a description of the phenomenon and its cause, as well as suggestions of how to mitigate or avoid similar artifacts. The presentation is targeted toward MRI technologists and trainees, but it can also serve as a useful reference for physicians who review MR images. However, it is assumed that the reader already has a basic knowledge of MR physics.MRI artifacts can be caused by software, hardware, pulse sequences, or factors related to the patient (eg, tissue heterogeneity or movement) (Fig 1). Multiple factors may contribute to a single artifact. Many artifacts can be minimized or completely eliminated by changing the imaging parameters (Fig 2).Figure 1. Overview of commonly occurring artifacts at routine MRI. PI = parallel imaging, RF = radiofrequency.Figure 1.Download as PowerPointOpen in Image Viewer Figure 2. Minimizing artifact by changing imaging parameters. (A) Axial T2-weighted MR image shows chemical shift artifact as high signal intensity (arrowhead) in the orbit. The principal imaging parameters were a matrix of 256 × 256 and a bandwidth of 140 Hz/pixel. The phase-encoding direction was right to left. The fat-saturation pulse was turned off. (B–D) Axial T2-weighted MR images that were obtained after increasing the bandwidth from 140 Hz/pixel to 488 Hz/pixel (B), after increasing the frequency matrix from 256 to 512 (C), and after adding the fat-saturation pulse (D) demonstrate how chemical shift artifact can be minimized.Figure 2.Download as PowerPointOpen in Image Viewer Zipper noise and spike noise are caused by hardware. These artifacts are often eradicated by eliminating the noise source (eg, the charger for a contrast agent injector), but in severe cases, service personnel may need to inspect the system.Aliasing, also called fold-over, wraps signals from outside the field of view into the image. At two-dimensional imaging, this artifact can be avoided by carefully planning both the field of view and the phase-encoding direction. At three-dimensional imaging, wrapping also occurs in the section direction. Therefore, it is necessary to increase the slab thickness or oversampling to the section direction in consideration of wrapping.Streak artifacts are unique to sequences that rely on radial sampling. The cause of these artifacts is the radial dispersion of motion or aliasing, the intensity of which depends on the amount of data sampling. It is necessary to optimize these scan parameters carefully.Susceptibility artifacts due to metal are primarily displayed as localized signal loss, although high signal intensity (often called pile-up) may be seen along the periphery of the signal void. Removing the metallic material eliminates the artifact, but for items that cannot be removed (eg, cerebral artery clip, embolic coil, or pacemaker), some level of artifact typically remains evident, even if the parameters are properly modified.Motion artifacts can be caused by periodic motion (eg, heartbeat or breathing) and random motion (eg, peristalsis or eye movement) during the scan. For periodic movements, artifacts can be reduced by using gated scan techniques (eg, cardiac gating or respiratory gating). There is no complete solution for artifacts that occur because of random motion. However, radial sampling and motion-corrected techniques may reduce the impact of patient motion on the image. When these are not available, it may be easier to read images by switching the phase-encoding direction. If the phase-encoding matrix can be lowered, it is also possible to reduce the severity of motion artifacts by acquiring the image in a shorter time. Finally, to minimize artifacts caused by patient movement, proper immobilization and good communication between the technologist and the patient are critical.Disclosures of conflicts of interest.— J.D.W. Employed by Canon Medical Research, USA.AcknowledgmentsWe gratefully acknowledge the work of past and present members of our laboratory.Supported by a National Institutes of Health grant (133032) to Johns Hopkins University.Recipient of a Cum Laude award for an education exhibit at the 2020 RSNA Annual Meeting.J.D.W. has reported disclosures (see end of article); all other authors have disclosed no relevant relationships.Suggested Readings Hirokawa Y, Isoda H, Maetani YS, Arizono S, Shimada K, Togashi K . MRI artifact reduction and quality improvement in the upper abdomen with PROPELLER and prospective acquisition correction (PACE) technique. AJR Am J Roentgenol 2008;191(4):1154–1158. Crossref, Medline, Google Scholar Huang SY, Seethamraju RT, Patel P, Hahn PF, Kirsch JE, Guimaraes AR . Body MR Imaging: Artifacts, k-Space, and Solutions. RadioGraphics 2015;35(5):1439–1460. Link, Google Scholar Runge M, Ibrahim EH, Bogun F, et al . Metal Artifact Reduction in Cardiovascular MRI for Accurate Myocardial Scar Assessment in Patients With Cardiac Implantable Electronic Devices. AJR Am J Roentgenol 2019;213(3):555–561. Crossref, Medline, Google Scholar Stadler A, Schima W, Ba-Ssalamah A, Kettenbach J, Eisenhuber E . Artifacts in body MR imaging: their appearance and how to eliminate them. Eur Radiol 2007;17(5):1242–1255. Crossref, Medline, Google Scholar Tsuchihashi T . Artifact of MRI [in Japanese]. Nippon Hoshasen Gijutsu Gakkai Zasshi 2003;59(11):1370–1377. Crossref, Medline, Google ScholarArticle HistoryReceived: Feb 1 2021Revision requested: Apr 20 2021Revision received: June 29 2021Accepted: July 9 2021Published online: Apr 22 2022Published in print: May 2022 FiguresReferencesRelatedDetailsCited ByPostsurgical Evaluation of the Pediatric Foot and AnkleMaria PilarAparisi Gómez, AlbertoBazzocchi, PaoloSimoni, Emilio J.Inarejos Clemente2022 | Seminars in Musculoskeletal Radiology, Vol. 26, No. 06Accompanying This ArticlePrimer on Commonly Occurring MRI Artifacts and How to Overcome ThemApr 22 2022Default Digital Object SeriesRecommended Articles Invited Commentary on "Optimizing Diffusion-Tensor Imaging Acquisition for Spinal Cord Assessment," with Response from Dr Martín Noguerol et alRadioGraphics2020Volume: 40Issue: 2pp. 428-431Validation of Software Gating: A Practical Technology for Respiratory Motion Correction in PETRadiology2016Volume: 281Issue: 1pp. 239-248MRI Techniques to Decrease Imaging Times in ChildrenRadioGraphics2020Volume: 40Issue: 2pp. 485-502Respiratory Motion Management in Abdominal MRI: Radiology In TrainingRadiology2022Volume: 306Issue: 1pp. 47-53Impact of Data-driven Respiratory Gating in Clinical PETRadiology2016Volume: 281Issue: 1pp. 229-238See More RSNA Education Exhibits A Primer on Commonly Occurring MRI Artifacts and How to Overcome ThemDigital Posters2020Up-to-Date Technique for Improvement of CT and MRI Imaging Quality in the Head and Neck: Theory, Clinical ApplicationsDigital Posters2019The Magnet is Sometimes "Off" - Practical Strategies for Optimizing Challenging Musculoskeletal MR ImagingDigital Posters2019 RSNA Case Collection Orbital blowout fractureRSNA Case Collection2020Metastatic invasive lobular breast carcinomaRSNA Case Collection2021Pulmonary SequestrationRSNA Case Collection2022 Vol. 42, No. 3 Slide PresentationMetrics Altmetric Score PDF download