title: A modulated closed form solution for quantitative susceptibility mapping--a thorough evaluation and comparison to iterative methods based on edge prior knowledge.
abstract: The aim of this study is to perform a thorough comparison of quantitative susceptibility mapping (QSM) techniques and their dependence on the assumptions made. The compared methodologies were: two iterative single orientation methodologies minimizing the l2, l1TV norm of the prior knowledge of the edges of the object, one over-determined multiple orientation method (COSMOS) and a newly proposed modulated closed-form solution (MCF). The performance of these methods was compared using a numerical phantom and in-vivo high resolution (0.65 mm isotropic) brain data acquired at 7 T using a new coil combination method. For all QSM methods, the relevant regularization and prior-knowledge parameters were systematically changed in order to evaluate the optimal reconstruction in the presence and absence of a ground truth. Additionally, the QSM contrast was compared to conventional gradient recalled echo (GRE) magnitude and R2* maps obtained from the same dataset. The QSM reconstruction results of the single orientation methods show comparable performance. The MCF method has the highest correlation (corr MCF=0.95, r(2)MCF=0.97) with the state of the art method (COSMOS) with additional advantage of extreme fast computation time. The L-curve method gave the visually most satisfactory balance between reduction of streaking artifacts and over-regularization with the latter being overemphasized when the using the COSMOS susceptibility maps as ground-truth. R2* and susceptibility maps, when calculated from the same datasets, although based on distinct features of the data, have a comparable ability to distinguish deep gray matter structures.
authors.affiliation: Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Diana
authors.initials: D
authors.lastname: Khabipova
authors.affiliation: Institute of Sensors, Signals & Systems, Heriot-Watt University, Edinburgh, UK.
authors.forename: Yves
authors.initials: Y
authors.lastname: Wiaux
authors.affiliation: Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Department of Radiology, University of Geneva, Geneva, Switzerland; Department of Radiology, University of Lausanne, Lausanne, Switzerland.
authors.forename: Rolf
authors.initials: R
authors.lastname: Gruetter
authors.affiliation: Department of Radiology, University of Lausanne, Lausanne, Switzerland. Electronic address: jose.marques@epfl.ch.
authors.forename: José P
authors.initials: JP
authors.lastname: Marques
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001931:Brain Mapping / Q000379:methods*; D003198:Computer Simulation; D005260:Female; D066128:Gray Matter / Q000033:anatomy & histology / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019359:Knowledge; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009103:Multiple Sclerosis / Q000175:diagnosis / Q000473:pathology; D019047:Phantoms, Imaging; D066127:White Matter / Q000033:anatomy & histology / Q000473:pathology
keywords: Effective transverse relaxation; Modulated closed form solution (MCF); Phase imaging Brain Tissue susceptibility magnetic resonance imaging (MRI); Quantitative susceptibility mapping