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MRI Artifacts and Their Remedies/Corrections.pptx
The document discusses MRI image artifacts, which are distortions in MRI images caused by various factors like patient movement and hardware limitations, and emphasizes the importance of managing them for accurate diagnoses. It outlines common types of artifacts such as motion, susceptibility, chemical shift, and zipper artifacts, along with their causes and potential remedies. Recommendations include using faster imaging techniques, increasing receiver bandwidth, and ensuring proper RF shielding to improve image quality.
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Dr. Dheeraj Kumar presents on MRI image artifacts and their management in medical imaging.
MRI image artifacts are distortions affecting diagnosis, caused by various factors like patient movement.
Lists common MRI artifacts: Motion, Susceptibility, Chemical Shift, Aliasing, Gibbs, Truncation, Ghosting, Zebra, and Zipper artifacts.
Motion artifacts cause blurring due to patient movement; remedies include faster sequences and immobilization.
These artifacts result from different magnetic susceptibilities, with remedies including spin-echo sequences.
Chemical shift artifacts arise from misregistration of fat and water signals. Increasing bandwidth helps remedy this.
Aliasing artifacts occur when external signals fold into the image; remedy involves increasing the field of view.
Gibbs artifacts cause oscillations at edges, remedied by increasing matrix size and filtering techniques.
Truncation artifacts manifest as false bands due to inadequate sampling, mitigated by increasing phase encoding.
Ghosting artifacts result from periodic motion; remedies include synchronizing images with patient physiology.
Zebra artifacts show alternating lines due to gradient nonlinearity; remedies involve gradient calibration.
Zipper artifacts are linear lines caused by RF interference, gradient malfunctions, and improper shielding.
To resolve zipper artifacts, ensure proper RF shielding and regular maintenance of equipment is crucial.
Citations provided include key literature in magnetic resonance imaging relevant to artifacts.
Concluding remarks from Dr. Dheeraj Kumar, indicating the end of the presentation.
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MRI Artifacts and Their Remedies/Corrections.pptx
- 1. MRI Image Artifactsand Their Remedies Presenter: Dr. Dheeraj Kumar MRIT, Ph.D. (Radiology and Imaging) Assistant Professor Medical Radiology and Imaging Technology School of Health Sciences, CSJM University, Kanpur
- 2. MRI Image Artifacts:Definition • MRI Image Artifacts are distortions or errors in the MRI images that do not represent the true anatomy or pathology of the subject being imaged. • These artifacts can be caused by a variety of factors including patient movement, hardware limitations, specific properties of the tissues being imaged, and the parameters set during the scanning process. • Understanding and managing these artifacts is crucial for accurate diagnosis and treatment planning. MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 2
- 3. Types of MRIArtifacts • Common Types of MRI Artifacts Content: • Motion Artifacts • Susceptibility Artifacts • Chemical Shift Artifacts • Aliasing (Wrap-Around) Artifacts • Gibbs (Ringing) Artifacts • Truncation Artifacts • Ghosting Artifacts • Zebra Artifacts • Zipper Artifacts MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 3
- 4. Motion Artifacts Blurring orghosting due to patient movement. • Causes: Voluntary or involuntary patient movement, respiration, cardiac motion. • Remedies: • Use of faster imaging sequences • Patient immobilization • Breath-hold techniques • Motion correction algorithms MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 4
- 5. Susceptibility Artifacts Distortion orsignal loss at tissue interfaces with different magnetic susceptibilities. • Causes: Metal implants, air-tissue interfaces. • Remedies: • Use of spin-echo sequences • Decrease echo time (TE) • Remove metal objects if possible • Use of higher bandwidth MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 5
- 6. Chemical Shift Artifacts Misregistrationof fat and water signals. • Causes: Difference in precessional frequencies of fat and water. • Remedies: • Increase receiver bandwidth • Use fat suppression techniques • Adjust echo time (TE) MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 6
- 7. Aliasing (Wrap-Around) Artifacts Signalfrom outside the field of view (FOV) folds into the image. • Causes: Inadequate FOV. • Remedies: • Increase FOV • Use anti-aliasing techniques • Apply presaturation bands MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 7
- 8. Gibbs (Ringing) Artifacts Oscillationsat sharp boundaries. • Causes: Finite sampling of high- frequency data. • Remedies: • Increase matrix size • Use of filtering techniques MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 8
- 9. Truncation Artifacts False bandsor lines parallel to edges. • Causes: Inadequate data sampling. • Remedies: • Increase number of phase encoding steps • Apply apodization filters MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 9
- 10. Ghosting Artifacts Replicated imagesor echoes. • Causes: Periodic motion, gradient imperfections. • Remedies: • Synchronize imaging with the patient's physiology (gating) • Use of navigator echoes MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 10
- 11. Zebra Artifacts Alternating darkand bright lines. • Causes: Gradient nonlinearity. • Remedies: • Use of gradient shimming • Ensure proper gradient calibration MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 11
- 12. Zipper Artifacts Zipper Artifactsare a type of MRI artifact characterized by linear, zipper-like lines that appear across the image. These artifacts can significantly degrade image quality and obscure anatomical details. Causes • Radiofrequency (RF) Interference: External RF signals infiltrate the MRI scanner's RF shielding. • Gradient Malfunctions: Issues with the MRI scanner’s gradient system can introduce periodic noise. • Improper Shielding: Compromises in the MRI room’s Faraday cage, which is designed to block external RF interference. • Loose Connections: Poor connections in the RF coil or cables. MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 12
- 13. Remedies: • Ensure ProperRF Shielding • Check and Secure Connections • Minimize External RF Sources • Regular Maintenance of Equipment • Use of RF Filters MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 13
- 14. References • 1. Haacke,E. M., Brown, R. W., Thompson, M. R., & Venkatesan, R. (1999). Magnetic Resonance Imaging: Physical Principles and Sequence Design. Wiley-Liss. • 2. McRobbie, D. W., Moore, E. A., Graves, M. J., & Prince, M. R. (2017). MRI from Picture to Proton (3rd ed.). Cambridge University Press. • 3. Zhuo, J., & Gullapalli, R. P. (2006). AAPM/RSNA physics tutorial for residents: MR artifacts, safety, and quality control. Radiographics, 26(1), 275-297. https://doi.org/10.1148/rg.261055138 • 4. Westbrook, C., Roth, C. K., & Talbot, J. (2011). MRI in Practice (4th ed.). Wiley-Blackwell. • 5. Elster, A. D., & Burdette, J. H. (2001). Questions and Answers in Magnetic Resonance Imaging (2nd ed.). Mosby. MRI Image Artifacts and Their Remedies By- Dheeraj Kumar 14
- 15. Thank You MRI ImageArtifacts and Their Remedies By- Dheeraj Kumar 15