title: Quantification of microcirculatory parameters by joint analysis of flow-compensated and non-flow-compensated intravoxel incoherent motion (IVIM) data.
abstract: The aim of this study was to improve the accuracy and precision of perfusion fraction and blood velocity dispersion estimates in intravoxel incoherent motion (IVIM) imaging, using joint analysis of flow-compensated and non-flow-compensated motion-encoded MRI data. A double diffusion encoding sequence capable of switching between flow-compensated and non-flow-compensated encoding modes was implemented. In vivo brain data were collected in eight healthy volunteers and processed using the joint analysis. Simulations were used to compare the performance of the proposed analysis method with conventional IVIM analysis. With flow compensation, strong rephasing was observed for the in vivo data, approximately cancelling the IVIM effect. The joint analysis yielded physiologically reasonable perfusion fraction maps. Estimated perfusion fractions were 2.43 ± 0.81% in gray matter, 1.81 ± 0.90% in deep gray matter, and 1.64 ± 0.72% in white matter (mean ± SD, n = 8). Simulations showed improved accuracy and precision when using joint analysis of flow-compensated and non-flow-compensated data, compared with conventional IVIM analysis. Double diffusion encoding with flow compensation was feasible for in vivo imaging of the perfusion fraction in the brain. The strong rephasing implied that blood flowing through the cerebral microvascular system was closer to the ballistic limit than the diffusive limit.
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund, Sweden.
authors.forename: André
authors.initials: A
authors.lastname: Ahlgren
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund, Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Knutsson
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund, Sweden.
authors.forename: Ronnie
authors.initials: R
authors.lastname: Wirestam
authors.affiliation: Lund University Bioimaging Center, Lund University, Lund, Sweden.
authors.forename: Markus
authors.initials: M
authors.lastname: Nilsson
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund, Sweden.|Lund University Bioimaging Center, Lund University, Lund, Sweden.|Department of Diagnostic Radiology, Lund University, Lund, Sweden.
authors.forename: Freddy
authors.initials: F
authors.lastname: Ståhlberg
authors.affiliation: Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Topgaard
authors.affiliation: CR Development AB, Lund, Sweden.
authors.forename: Samo
authors.initials: S
authors.lastname: Lasič
mesh_terms: D003198:Computer Simulation; D004058:Diffusion; D066128:Gray Matter / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008833:Microcirculation; D009038:Motion; D010477:Perfusion; D019047:Phantoms, Imaging; D013223:Statistics as Topic; D066127:White Matter / Q000033:anatomy & histology
keywords: IVIM; blood flow; flow compensation; motion encoding; perfusion fraction; velocity dispersion