title: Magnetic resonance fingerprinting based on realistic vasculature in mice.
abstract: Magnetic resonance fingerprinting (MRF) was recently proposed as a novel strategy for MR data acquisition and analysis. A variant of MRF called vascular MRF (vMRF) followed, that extracted maps of three parameters of physiological importance: cerebral oxygen saturation (SatO2), mean vessel radius and cerebral blood volume (CBV). However, this estimation was based on idealized 2-dimensional simulations of vascular networks using random cylinders and the empirical Bloch equations convolved with a diffusion kernel. Here we focus on studying the vascular MR fingerprint using real mouse angiograms and physiological values as the substrate for the MR simulations. The MR signal is calculated ab initio with a Monte Carlo approximation, by tracking the accumulated phase from a large number of protons diffusing within the angiogram. We first study the identifiability of parameters in simulations, showing that parameters are fully estimable at realistically high signal-to-noise ratios (SNR) when the same angiogram is used for dictionary generation and parameter estimation, but that large biases in the estimates persist when the angiograms are different. Despite these biases, simulations show that differences in parameters remain estimable. We then applied this methodology to data acquired using the GESFIDE sequence with SPIONs injected into 9 young wild type and 9 old atherosclerotic mice. Both the pre injection signal and the ratio of post-to-pre injection signals were modeled, using 5-dimensional dictionaries. The vMRF methodology extracted significant differences in SatO2, mean vessel radius and CBV between the two groups, consistent across brain regions and dictionaries. Further validation work is essential before vMRF can gain wider application.
authors.affiliation: Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada; Research Centre, Montreal Heart Institute, Montreal, Canada. Electronic address: ph.pouliot@gmail.com.
authors.forename: Philippe
authors.initials: P
authors.lastname: Pouliot
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, MA, United States.
authors.forename: Louis
authors.initials: L
authors.lastname: Gagnon
authors.affiliation: Department of Chemistry, McGill University, Montreal, QC, Canada.
authors.forename: Tina
authors.initials: T
authors.lastname: Lam
authors.affiliation: Research Centre, Montreal Heart Institute, Montreal, Canada.
authors.forename: Pramod K
authors.initials: PK
authors.lastname: Avti
authors.affiliation: Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Chris
authors.initials: C
authors.lastname: Bowen
authors.affiliation: Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada.
authors.forename: Michèle
authors.initials: M
authors.lastname: Desjardins
authors.affiliation: Department of Chemistry, McGill University, Montreal, QC, Canada.
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Kakkar
authors.affiliation: Dept. of Surgery, Faculty of Medicine, University of Montreal, QC, Canada; Research Centre, Montreal Heart Institute, Montreal, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Thorin
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, MA, United States.
authors.forename: Sava
authors.initials: S
authors.lastname: Sakadzic
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, MA, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Boas
authors.affiliation: Department of Electrical Engineering, Ecole Polytechnique Montreal, Montreal, QC, Canada; Research Centre, Montreal Heart Institute, Montreal, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lesage
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000000981:diagnostic imaging; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008810:Mice, Inbred C57BL
keywords: Ab initio Monte Carlo simulations of magnetic resonance signal; Gradient-echo sampling of free induction decay and echo (GESFIDE); Mouse model of atherosclerosis; Superparamagnetic iron oxide nanoparticle (SPION); Vascular magnetic resonance fingerprinting (vMRF)