title: Impact of physiological noise correction on detecting blood oxygenation level-dependent contrast in the breast.
abstract: Physiological fluctuations are expected to be a dominant source of noise in blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) experiments to assess tumour oxygenation and angiogenesis. This work investigates the impact of various physiological noise regressors: retrospective image correction (RETROICOR), heart rate (HR) and respiratory volume per unit time (RVT), on signal variance and the detection of BOLD contrast in the breast in response to a modulated respiratory stimulus. BOLD MRI was performed at 3 T in ten volunteers at rest and during cycles of oxygen and carbogen gas breathing. RETROICOR was optimized using F-tests to determine which cardiac and respiratory phase terms accounted for a significant amount of signal variance. A nested regression analysis was performed to assess the effect of RETROICOR, HR and RVT on the model fit residuals, temporal signal-to-noise ratio, and BOLD activation parameters. The optimized RETROICOR model accounted for the largest amount of signal variance ([Formula: see text]  =  3.3  ±  2.1%) and improved the detection of BOLD activation (P  =  0.002). Inclusion of HR and RVT regressors explained additional signal variance, but had a negative impact on activation parameter estimation (P  <  0.001). Fluctuations in HR and RVT appeared to be correlated with the stimulus and may contribute to apparent BOLD signal reactivity.
authors.affiliation: Department of Radiology, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK. NIHR Cambridge Biomedical Research Centre, Cambridge Biomedical Campus, Cambridge, UK.
authors.forename: Tess E
authors.initials: TE
authors.lastname: Wallace
authors.forename: Roido
authors.initials: R
authors.lastname: Manavaki
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Graves
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Patterson
authors.forename: Fiona J
authors.initials: FJ
authors.lastname: Gilbert
mesh_terms: D000328:Adult; D016477:Artifacts; D001940:Breast / Q000000981:diagnostic imaging*; D005260:Female; D006339:Heart Rate; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood*; D012044:Regression Analysis; D012119:Respiration; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D055815:Young Adult
chemical_list: D010100:Oxygen