title: Quantitative blood oxygenation level-dependent (BOLD) response of the left ventricular myocardium to hyperoxic respiratory challenge at 1.5 and 3.0 T.
abstract: The aim of this study was to quantify the response of the myocardial transverse relaxation times (ΔT2*) to hyperoxic respiratory challenge (HRC) at different field strengths in an intra-individual comparison of healthy volunteers and in a patient with coronary artery disease. Blood oxygenation level-dependent (BOLD) cardiovascular MR (CMR) data were acquired in 10 healthy volunteers (five women, five men; mean age, 29 ± 3 years; range, 22-35 years) at 1.5 and 3.0 T. Medical air (21% O2 ), pure oxygen and carbogen (95% O2 , 5% CO2 ) were administered in a block-design temporal pattern to induce normoxia, hyperoxia and hyperoxic hypercapnia, respectively. Average T2* times were derived from measurements by two independent and blind readers in 16 standard myocardial segments on three short-axis slices per patient. Inter- and intra-reader correlations of T2* measurements were good [intra-class correlation coefficient (ICC) = 0.75 and ICC = 0.79, both p < 0.001]. During normoxia, the mean T2* times were 29.9 ± 6.1 ms at 1.5 T and 27.1 ± 6.6 ms at 3.0 T. Both hyperoxic gases induced significant (all p < 0.01) T2* increases (∆T2* hyperoxia: 1.5 T, 12.7%; 3.0 T, 11.2%; hyperoxic hypercapnia: 1.5 T, 13.1%; 3.0 T, 17.7%). Analysis of variance (ANOVA) results indicated a significant (both p < 0.001) effect of the inhaled gases on the T2* times at both 1.5 T (F = 17.74) and 3.0 T (F = 39.99). With regard to the patient imaged at 1.5 T, HRC induced significant T2* increases during hyperoxia and hyperoxic hypercapnia in normal myocardial segments, whereas the T2* response was not significant in ischemic segments (p > 0.23). The myocardial ∆T2* response to HRC can reliably be imaged and quantified with BOLD CMR at both 1.5 and 3.0 T. During HRC, hyperoxia and hyperoxic hypercapnia induce a significant increase in T2*, with ∆T2* being largest at 3.0 T and during hyperoxic hypercapnia in normal myocardial segments.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland; Institute of Forensic Medicine, University of Zurich, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Winklhofer
authors.forename: Shila
authors.initials: S
authors.lastname: Pazahr
authors.forename: Robert
authors.initials: R
authors.lastname: Manka
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Andreas
authors.initials: A
authors.lastname: Boss
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzmann
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D005260:Female; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D018496:Hyperoxia / Q000097:blood* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D009206:Myocardium / Q000473:pathology*; D010100:Oxygen / Q000097:blood*; D012119:Respiration; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: BOLD; carbogen; cardiovascular MR; myocardium; respiratory challenge