Sarah Eskreis-Winkler1, Dong Zhou1, Tian Liu2, Ajay Gupta1, Susan A Gauthier3, Yi Wang1, Pascal Spincemaille4. 1. Department of Radiology, Weill Cornell Medicine, 525 East 70th Street, New York, NY, USA. 2. Medimagemetric, LLC, 445 Main St, #7H, New York, NY, USA. 3. Department of Neurology, Weill Cornell Medicine, 525 East 68th Street, PO Box 117, New York, NY, USA. 4. Department of Radiology, Weill Cornell Medicine, 525 East 70th Street, New York, NY, USA. Electronic address: pas2018@med.cornell.edu.
Abstract
PURPOSE: Zero padding is a well-studied interpolation technique that improves image visualization without increasing image resolution. This interpolation is often performed as a last step before images are displayed on clinical workstations. Here, we seek to demonstrate the importance of zero padding before rather than after performing non-linear post-processing algorithms, such as Quantitative Susceptibility Mapping (QSM). To do so, we evaluate apparent spatial resolution, relative error and depiction of multiple sclerosis (MS) lesions on images that were zero padded prior to, in the middle of, and after the application of the QSM algorithm. MATERIALS AND METHODS: High resolution gradient echo (GRE) data were acquired on twenty MS patients, from which low resolution data were derived using k-space cropping. Pre-, mid-, and post-zero padded QSM images were reconstructed from these low resolution data by zero padding prior to field mapping, after field mapping, and after susceptibility mapping, respectively. Using high resolution QSM as the gold standard, apparent spatial resolution, relative error, and image quality of the pre-, mid-, and post-zero padded QSM images were measured and compared. RESULTS: Both the accuracy and apparent spatial resolution of the pre-zero padded QSM was higher than that of mid-zero padded QSM (p<0.001; p<0.001), which was higher than that of post-zero padded QSM (p<0.001; p<0.001). The image quality of pre-zero padded reconstructions was higher than that of mid- and post-zero padded reconstructions (p=0.004; p<0.001). CONCLUSION: Zero padding of the complex GRE data prior to nonlinear susceptibility mapping improves image accuracy and apparent resolution compared to zero padding afterwards. It also provides better delineation of MS lesion geometry, which may improve lesion subclassification and disease monitoring in MS patients. Copyright Â
PURPOSE: Zero padding is a well-studied interpolation technique that improves image visualization without increasing image resolution. This interpolation is often performed as a last step before images are displayed on clinical workstations. Here, we seek to demonstrate the importance of zero padding before rather than after performing non-linear post-processing algorithms, such as Quantitative Susceptibility Mapping (QSM). To do so, we evaluate apparent spatial resolution, relative error and depiction of multiple sclerosis (MS) lesions on images that were zero padded prior to, in the middle of, and after the application of the QSM algorithm. MATERIALS AND METHODS: High resolution gradient echo (GRE) data were acquired on twenty MS patients, from which low resolution data were derived using k-space cropping. Pre-, mid-, and post-zero padded QSM images were reconstructed from these low resolution data by zero padding prior to field mapping, after field mapping, and after susceptibility mapping, respectively. Using high resolution QSM as the gold standard, apparent spatial resolution, relative error, and image quality of the pre-, mid-, and post-zero padded QSM images were measured and compared. RESULTS: Both the accuracy and apparent spatial resolution of the pre-zero padded QSM was higher than that of mid-zero padded QSM (p<0.001; p<0.001), which was higher than that of post-zero padded QSM (p<0.001; p<0.001). The image quality of pre-zero padded reconstructions was higher than that of mid- and post-zero padded reconstructions (p=0.004; p<0.001). CONCLUSION: Zero padding of the complex GRE data prior to nonlinear susceptibility mapping improves image accuracy and apparent resolution compared to zero padding afterwards. It also provides better delineation of MS lesion geometry, which may improve lesion subclassification and disease monitoring in MS patients. Copyright Â
Authors: Tian Liu; Jing Liu; Ludovic de Rochefort; Pascal Spincemaille; Ildar Khalidov; James Robert Ledoux; Yi Wang Journal: Magn Reson Med Date: 2011-04-04 Impact factor: 4.668
Authors: Jing Liu; Tian Liu; Ludovic de Rochefort; James Ledoux; Ildar Khalidov; Weiwei Chen; A John Tsiouris; Cynthia Wisnieff; Pascal Spincemaille; Martin R Prince; Yi Wang Journal: Neuroimage Date: 2011-09-08 Impact factor: 6.556
Authors: Tian Liu; Ildar Khalidov; Ludovic de Rochefort; Pascal Spincemaille; Jing Liu; A John Tsiouris; Yi Wang Journal: NMR Biomed Date: 2011-03-08 Impact factor: 4.044
Authors: Ramin Jafari; Sujit Sheth; Pascal Spincemaille; Thanh D Nguyen; Martin R Prince; Yan Wen; Yihao Guo; Kofi Deh; Zhe Liu; Daniel Margolis; Gary M Brittenham; Andrea S Kierans; Yi Wang Journal: J Magn Reson Imaging Date: 2019-01-13 Impact factor: 4.813
Authors: Melanie Marcille; Sandra Hurtado Rúa; Charles Tyshkov; Abhishek Jaywant; Joseph Comunale; Ulrike W Kaunzner; Nancy Nealon; Jai S Perumal; Lily Zexter; Nicole Zinger; Olivia Bruvik; Yi Wang; Elizabeth Sweeney; Amy Kuceyeski; Thanh D Nguyen; Susan A Gauthier Journal: Sci Rep Date: 2022-03-15 Impact factor: 4.379