Carlos Milovic1,2,3, Cristian Tejos1,2,3, Julio Acosta-Cabronero4, Pinar Senay Özbay5, Ferdinand Schwesser6,7, Jose Pedro Marques8, Pablo Irarrazaval1,3,9, Berkin Bilgic10, Christian Langkammer11. 1. Department of Electrical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile. 2. Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, Chile. 3. Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile. 4. Tenoke Ltd., Cambridge, United Kingdom. 5. Laboratory of Functional and Molecular Imaging, National Institutes of Health, Bethesda, Maryland. 6. Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, The State University of New York, Buffalo, New York. 7. Center for Biomedical Imaging, Clinical and Translational Science Institute, University at Buffalo, The State University of New York, Buffalo, New York. 8. Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands. 9. Institute for Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile. 10. Martinos Center for Biomedical Imaging, Harvard Medical School, MA, USA. 11. Department of Neurology, Medical University of Graz, Graz, Austria.
Abstract
PURPOSE: The 4th International Workshop on MRI Phase Contrast and QSM (2016, Graz, Austria) hosted the first QSM Challenge. A single-orientation gradient recalled echo acquisition was provided, along with COSMOS and the χ33 STI component as ground truths. The submitted solutions differed more than expected depending on the error metric used for optimization and were generally over-regularized. This raised (unanswered) questions about the ground truths and the metrics utilized. METHODS: We investigated the influence of background field remnants by applying additional filters. We also estimated the anisotropic contributions from the STI tensor to the apparent susceptibility to amend the χ33 ground truth and to investigate the impact on the reconstructions. Lastly, we used forward simulations from the COSMOS reconstruction to investigate the impact noise had on the metric scores. RESULTS: Reconstructions compared against the amended STI ground truth returned lower errors. We show that the background field remnants had a minor impact in the errors. In the absence of inconsistencies, all metrics converged to the same regularization weights, whereas structural similarity index metric was more insensitive to such inconsistencies. CONCLUSION: There was a mismatch between the provided data and the ground truths due to the presence of unaccounted anisotropic susceptibility contributions and noise. Given the lack of reliable ground truths when using in vivo acquisitions, simulations are suggested for future QSM Challenges.
PURPOSE: The 4th International Workshop on MRI Phase Contrast and QSM (2016, Graz, Austria) hosted the first QSM Challenge. A single-orientation gradient recalled echo acquisition was provided, along with COSMOS and the χ33 STI component as ground truths. The submitted solutions differed more than expected depending on the error metric used for optimization and were generally over-regularized. This raised (unanswered) questions about the ground truths and the metrics utilized. METHODS: We investigated the influence of background field remnants by applying additional filters. We also estimated the anisotropic contributions from the STI tensor to the apparent susceptibility to amend the χ33 ground truth and to investigate the impact on the reconstructions. Lastly, we used forward simulations from the COSMOS reconstruction to investigate the impact noise had on the metric scores. RESULTS: Reconstructions compared against the amended STI ground truth returned lower errors. We show that the background field remnants had a minor impact in the errors. In the absence of inconsistencies, all metrics converged to the same regularization weights, whereas structural similarity index metric was more insensitive to such inconsistencies. CONCLUSION: There was a mismatch between the provided data and the ground truths due to the presence of unaccounted anisotropic susceptibility contributions and noise. Given the lack of reliable ground truths when using in vivo acquisitions, simulations are suggested for future QSM Challenges.
Authors: Ferdinand Schweser; Simon Daniel Robinson; Ludovic de Rochefort; Wei Li; Kristian Bredies Journal: NMR Biomed Date: 2016-10-07 Impact factor: 4.044
Authors: Itthi Chatnuntawech; Patrick McDaniel; Stephen F Cauley; Borjan A Gagoski; Christian Langkammer; Adrian Martin; P Ellen Grant; Lawrence L Wald; Kawin Setsompop; Elfar Adalsteinsson; Berkin Bilgic Journal: NMR Biomed Date: 2016-06-22 Impact factor: 4.044
Authors: José P Marques; Jakob Meineke; Carlos Milovic; Berkin Bilgic; Kwok-Shing Chan; Renaud Hedouin; Wietske van der Zwaag; Christian Langkammer; Ferdinand Schweser Journal: Magn Reson Med Date: 2021-02-26 Impact factor: 4.668