Alexander Seiler1, Ralf Deichmann2, Ulrike Nöth2, Waltraud Pfeilschifter2, Joachim Berkefeld2, Oliver C Singer2, Johannes C Klein2, Marlies Wagner2. 1. From the Department of Neurology (A.S., W.P., O.C.S.), Brain Imaging Center and Institute of Neuroradiology (R.D., U.N.), and Institute of Neuroradiology (J.B., M.W.), Goethe University Frankfurt, Germany; Nuffield Department of Clinical Neurosciences, Oxford University, United Kingdom (J.C.K.); and Department of Neurology, Oxford University Hospitals NHS Trust, United Kingdom (J.C.K.). alexander.seiler@kgu.de. 2. From the Department of Neurology (A.S., W.P., O.C.S.), Brain Imaging Center and Institute of Neuroradiology (R.D., U.N.), and Institute of Neuroradiology (J.B., M.W.), Goethe University Frankfurt, Germany; Nuffield Department of Clinical Neurosciences, Oxford University, United Kingdom (J.C.K.); and Department of Neurology, Oxford University Hospitals NHS Trust, United Kingdom (J.C.K.).
Abstract
BACKGROUND AND PURPOSE: Quantitative T2'/R2' mapping detect locally increased concentrations of deoxygenated hemoglobin-causing a decrease of T2' and increase of R2'-and might reflect increased cerebral oxygen extraction fraction. Because increases of (relative) cerebral blood volume (rCBV) may influence T2' and R2' through accumulation of deoxygenated hemoglobin, we aimed to investigate the impact of rCBV on T2'/R2' in patients with ischemic stroke. METHODS: Data from patients with acute internal carotid artery and middle cerebral artery occlusion were analyzed. T2', R2', and rCBV were measured within the ischemic core, slightly and severely hypoperfused areas, and their relationship was examined. RESULTS: A strong negative correlation with rCBV was found for R2' (r=-0.544; P=0.002), and T2' correlated positively with rCBV (r=0.546; P=0.001) in time-to-peak-delayed areas. T2'/R2' within hypoperfused tissue remained unchanged at normal or elevated rCBV levels. CONCLUSIONS: T2' decrease/R2' increase within hypoperfused areas in ischemic stroke is not caused by local elevations of rCBV but most probably only by increased cerebral oxygen extraction fraction. However, considering rCBV is crucial to assess extent of oxygen extraction fraction changes by means of T2'/R2'.
BACKGROUND AND PURPOSE: Quantitative T2'/R2' mapping detect locally increased concentrations of deoxygenated hemoglobin-causing a decrease of T2' and increase of R2'-and might reflect increased cerebral oxygen extraction fraction. Because increases of (relative) cerebral blood volume (rCBV) may influence T2' and R2' through accumulation of deoxygenated hemoglobin, we aimed to investigate the impact of rCBV on T2'/R2' in patients with ischemic stroke. METHODS: Data from patients with acute internal carotid artery and middle cerebral artery occlusion were analyzed. T2', R2', and rCBV were measured within the ischemic core, slightly and severely hypoperfused areas, and their relationship was examined. RESULTS: A strong negative correlation with rCBV was found for R2' (r=-0.544; P=0.002), and T2' correlated positively with rCBV (r=0.546; P=0.001) in time-to-peak-delayed areas. T2'/R2' within hypoperfused tissue remained unchanged at normal or elevated rCBV levels. CONCLUSIONS: T2' decrease/R2' increase within hypoperfused areas in ischemic stroke is not caused by local elevations of rCBV but most probably only by increased cerebral oxygen extraction fraction. However, considering rCBV is crucial to assess extent of oxygen extraction fraction changes by means of T2'/R2'.
Authors: Alexander Seiler; Nicholas P Blockley; Ralf Deichmann; Ulrike Nöth; Oliver C Singer; Michael A Chappell; Johannes C Klein; Marlies Wagner Journal: J Cereb Blood Flow Metab Date: 2017-09-20 Impact factor: 6.200
Authors: Alan J Stone; George W J Harston; Davide Carone; Thomas W Okell; James Kennedy; Nicholas P Blockley Journal: Hum Brain Mapp Date: 2019-03-12 Impact factor: 5.038