Metal Artefact Reduction

One of the biggest challenges in the field of Computed Tomography is the presence of metal objects such as  hip implants, artificial joints, pacemaker, or orthopedic screws within a patient's body. Caused by the extremely high attenuation coefficients and the physical characteristics of x-ray photons one can obtain severe streaking artefacts in the reconstructed image. The obtained artefacts reduce the diagnostic value of the CT image up to a point where the acquisition is useless for diagnosis. The problem of metal artefact reduction (MAR) has been intensively studied for over 3 decades. A common approach for MAR is to discard the projection data influenced by metal. Therefore, an algorithm must be found that can cope with the gap within the acquired raw data (a sinogram). The majority of the high quantity of different approaches that have been published can be separated in two categories: sinogram completion-based methods and iterative methods.

Our research group at the Institute of Medical Engineering is particularly working on algorithms that incorporate criteria for consistent sinograms. An inpainting method that fills the gap in the raw data in a consistent way, regarding these criteria, allows for a reconstruction  that uses all required projections without using the corrupted projections through metal. Another project is focused on the inclusion of prior knowledge in terms of shape and composition of implants into a reconstruction algorithm. The main idea is to use the known attenuation coefficients of the metal implant in order to reduce the streaking artefacts, which are initially caused by the projections that are influenced by metal.

Publications

2018[ to top ]
  • Ziemann, C., Stille, M., Cremers, F., Buzug, T. M. and Rades, D.: Improvement of dose calculation in radiation therapy due to metal artifact correction using the augmented likelihood image reconstruction, Journal of Applied Clinical Medical Physics, 19(3), 227–233, 2018, DOI: 10.1002/acm2.12325.
2017[ to top ]
  • Ziemann, C., Stille, M., Cremers, F., Rades, D. and Buzug, T. M.: The effects of metal artifact reduction on the retrieval of attenuation values, Journal of applied clinical medical physics, 18(1), 243–250, 2017, DOI: 10.1002/acm2.12002.
2016[ to top ]
  • Stille, M. and Buzug, T. M.: Augmented likelihood image reconstruction with non-local prior image regularization, 145–8, 2016.
  • Stille, M., Kleine, M., Hagele, J., Barkhausen, J. and Buzug, T.: Augmented Likelihood Image Reconstruction, IEEE Transactions on Medical Imaging, 35(1), 158–173, 2016, DOI: 10.1109/TMI.2015.2459764.
2013[ to top ]
  • Stille, M., Kratz, B., Müller, J., Maaß, N., Schasiepen, I., Elter, M., Weyers, I. and Buzug, T. M.: Influence of metal segmentation on the quality of metal artifact reduction methods, 86683C, 2013, DOI: 10.1117/12.2006810.
2012[ to top ]
  • Hamer, J., Kratz, B., Müller, J. and Buzug, T. M.: Modified Eulers Elastica Inpainting for Metal Artifact Reduction in CT, 310–315, 2012, DOI: 10.1007/978-3-642-28502-8_54.
  • Kleine, M., Müller, J. and Buzug, T. M.: L1-Regularisierung für die Computertomographie mit begrenztem Aufnahmewinkel, 147–152, 2012, DOI: 10.1007/978-3-642-28502-8_27.
  • Duschka, R., Bischoff, P., May, K., Levakhina, Y., Buzug, T., Kovacs, A., Hunold, P., Barkhausen, J. and Vogt, F.: Digitale Tomosynthese - Ein neues Verfahren zur Beurteilung degenerativer Gelenkveränderungen im Vergleich zum konventionellen Röntgen, VO216_4, 2012, DOI: 10.1055/s-0032-1311150.
  • Kratz, B., Weyers, I. and Buzug, T. M.: A fully 3D approach for metal artifact reduction in computed tomography, Medical Physics, 39(11), 7042–7054, 2012, DOI: 10.1118/1.4762289.
  • Kratz, B., Ens, S., Kaethner, C., Müller, J. and Buzug, T. M.: Quality evaluation for metal influenced CT data, 83143Y, 2012, DOI: 10.1117/12.911349.
  • Kleine, M. and Buzug, T. M.: Curvelet-based Inpainting for Metal Artifact Reduction in Computed Tomography, 242–245, 2012.
2011[ to top ]
  • Kleine, M., Hamer, J. and Buzug, T. M.: Sparse recovery for SPECT imaging of inflammation at implants, 64, 2011.
  • Kratz, B., Ens, S., Müller, J. and Buzug, T. M.: Reference-free ground truth metric for metal artifact evaluation in CT images, Medical Physics, 38(7), 4321–4328, 2011, DOI: 10.1118/1.3603198.
2010[ to top ]
  • Levakhina, Y., Kratz, B. and Buzug, T.: Two-Step Metal Artifact Reduction Using 2D-NFFT and Spherically Symmetric Basis Functions, 3343–3345, 2010, DOI: 10.1109/NSSMIC.2010.5874424.
  • Buzug, T. M.: Computed Tomography: From Photon Statistics to Modern Cone-Beam CT, Springer, Berlin, 2010, DOI: 10.1007/978-3-540-39408-2.
2009[ to top ]
  • Müller, J. and Buzug, T. M.: Spurious Structures Created by Interpolation-Based CT Metal Artifact Reduction, 72581Y, 2009, DOI: 10.1117/12.813515.
  • Kratz, B. and Buzug, T. M.: Metallartefakte in der Computertomographie. Softwarebasierte Ansätze zur Artefaktreduktion, 1213–1222, 2009.
  • Yu, L., Li, H., Mueller, J., Kofler, J. M., Liu, X., Primak, A. N., Fletcher, J. G., Guimaraes, L. S., Macedo, T. and McCollough, C. H.: Metal Artifact Reduction From Reformatted Projections for Hip Prostheses in Multislice Helical Computed Tomography, Investigative Radiology, 44(11), 691–696, 2009, DOI: 10.1097/rli.0b013e3181b0a2f9.
  • Kratz, B. and Buzug, T.: Metal artifact reduction in computed tomography using nonequispaced fourier transform, 2720–2723, 2009, DOI: 10.1109/NSSMIC.2009.5401974.
2008[ to top ]
  • Oehler, M., Kratz, B., Knopp, T., Müller, J. and Buzug, T. M.: Evaluation of surrogate data quality in sinogram-based CT metal-artifact reduction, 1–10, 2008, DOI: 10.1117/12.793622.
  • Kratz, B., Knopp, T., Müller, J., Oehler, M. and Buzug, T.: Comparison of Nonequispaced Fourier Transform and Polynomial based Metal Artifact Reduction Methods in Computed Tomography, 21–25, 2008, DOI: 10.1007/978-3-540-78640-5_5.
  • Müller, J. and Buzug, T.: Intersection Line Length Normalization in CT Projection Data, 77–81, 2008, DOI: 10.1007/978-3-540-78640-5_16.
  • Oehler, M. and Buzug, T. M.: Sinogram Inpainting for Metal Artifact Reduction in CT Images, 651–654, 2008, DOI: 10.1007/978-3-540-89208-3_155.
  • Kratz, B., Knopp, T., Oehler, M., Ens, S. and Buzug, T.: CT-MAR Reconstruction Using Non-Uniform Fourier Transform, 861–865, 2008, DOI: 10.1007/978-3-540-89208-3_206.
2007[ to top ]
  • Oehler, M. and Buzug, T. M.: Two Step MLEM Algorithm for Artefact Reduction in CT Images, Computer Assisted Radiology and Surgery, 2(1:1), 38–41, 2007, DOI: 10.1007/s11548-007-0082-8.
  • Oehler, M. and Buzug, T. M.: A Sinogram-Based Metal Artifact Suppression Strategy for Transmission Computed Tomography, 255–262, 2007.
  • Oehler, M. and Buzug, T.: The λ-MLEM Algorithm: An Iterative Reconstruction Technique for Metal Artifact Reduction in CT Images, 42–47, 2007, DOI: 10.1007/978-3-540-68764-1_6.
  • Buzug, T. and Oehler, M.: Statistical Image Reconstruction for Inconsistent CT Projection Data, Methods of Information in Medicine, 46(3), 261–269, 2007, DOI: 10.1160/me9041.
2006[ to top ]
  • Oehler, M. and Buzug, T. M.: Gewichtete MLEM-Rekonstruktion zur Artefaktreduktion in der Transmissions-Computertomographie, 345–346, 2006.
  • Oehler, M. and Buzug, T.: Modified MLEM Algorithm for Artifact Suppression in CT, 3511–3518, 2006, DOI: 10.1109/NSSMIC.2006.353757.
  • Oehler, M. and Buzug, T.: Maximum-Likelihood-Ansatz zur Metallartefaktreduktion bei der Computertomographie, 36–40, 2006, DOI: 10.1007/3-540-32137-3_8.
  • Oehler, M. and Buzug, T. M.: Statistische Bildrekonstruktion zur Behandlung inkonsistenter Projektionsdaten der Computertomographie, 2006.
2005[ to top ]
  • Oehler, M., Pfaffmann, L. and Buzug, T.: Reduction of Metal Artifacts in Computed Tomography, Computer Assisted Radiology and Surgery, 1281, 1310, 2005, DOI: 10.1016/j.ics.2005.03.024.
  • Oehler, M., Pfaffmann, L. and Buzug, T. M.: Artefact Suppression in Computed Tomography using Iterative Reconstruction Methods, 1130–1131, 2005.
  • Oehler, M. and Buzug, T. M.: CT Artifact Reduction with an Iterative Maximum Likelihood Approach, 44, 2005.