title: Reliable estimation of capillary transit time distributions using DSC-MRI.
abstract: The regional availability of oxygen in brain tissue is traditionally inferred from the magnitude of cerebral blood flow (CBF) and the concentration of oxygen in arterial blood. Measurements of CBF are therefore widely used in the localization of neuronal response to stimulation and in the evaluation of patients suspected of acute ischemic stroke or flow-limiting carotid stenosis. It was recently demonstrated that capillary transit time heterogeneity (CTH) limits maximum oxygen extraction fraction (OEF(max)) that can be achieved for a given CBF. Here we present a statistical approach for determining CTH, mean transit time (MTT), and CBF using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Using numerical simulations, we demonstrate that CTH, MTT, and OEF(max) can be estimated with low bias and variance across a wide range of microvascular flow patterns, even at modest signal-to-noise ratios. Mean transit time estimated by singular value decomposition (SVD) deconvolution, however, is confounded by CTH. The proposed technique readily identifies malperfused tissue in acute stroke patients and appears to highlight information not detected by the standard SVD technique. We speculate that this technique permits the non-invasive detection of tissue with impaired oxygen delivery in neurologic disorders such as acute ischemic stroke and Alzheimer's disease during routine diagnostic imaging.
authors.affiliation: Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: Kim
authors.initials: K
authors.lastname: Mouridsen
authors.affiliation: Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: Mikkel Bo
authors.initials: MB
authors.lastname: Hansen
authors.affiliation: 1] Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark [2] Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Leif
authors.initials: L
authors.lastname: Østergaard
authors.affiliation: 1] Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark [2] Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
authors.forename: Sune Nørhøj
authors.initials: SN
authors.lastname: Jespersen
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology; D002196:Capillaries / Q000000981:diagnostic imaging / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D018810:Magnetic Resonance Angiography; D008833:Microcirculation / Q000502:physiology*; D008955:Models, Cardiovascular; D010100:Oxygen / Q000378:metabolism; D011859:Radiography
chemical_list: D010100:Oxygen