title: Comparison of 4D flow and 2D velocity-encoded phase contrast MRI sequences for the evaluation of aortic hemodynamics.
abstract: The purpose of this study was to compare aortic flow and velocity quantification using 4D flow MRI and 2D CINE phase-contrast (PC)-MRI with either one-directional (2D-1dir) or three-directional (2D-3dir) velocity encoding. 15 healthy volunteers (51 ± 19 years) underwent MRI including (1) breath-holding 2D-1dir and (2) free breathing 2D-3dir PC-MRI in planes orthogonal to the ascending (AA) and descending (DA) aorta, as well as (3) free breathing 4D flow MRI with full thoracic aorta coverage. Flow quantification included the co-registration of the 2D PC acquisition planes with 4D flow MRI data, AA and DA segmentation, and calculation of AA and DA peak systolic velocity, peak flow and net flow volume for all sequences. Additionally, the 2D-3dir velocity taking into account the through-plane component only was used to obtain results analogous to a free breathing 2D-1dir acquisition. Good agreement was found between 4D flow and 2D-3dir peak velocity (differences = -3 to 6 %), peak flow (-7 %) and net volume (-14 to -9 %). In contrast, breath-holding 2D-1dir measurements exhibited indices significantly lower than free breathing 2D-3dir and 2D-1dir (differences = -35 to -7 %, p < 0.05). Finally, high correlations (r ≥ 0.97) were obtained for indices estimated with or without eddy current correction, with the lowest correlation observed for net volume. 4D flow and 2D-3dir aortic hemodynamic indices were in concordance. However, differences between respiration state and 2D-1dir and 2D-3dir measurements indicate that reference values should be established according to the PC-MRI sequence, especially for the widely used net flow (e.g. stroke volume in the AA).
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan ave-Suite 1600, Chicago, IL, 60611, USA. emilie.bollache@northwestern.edu.
authors.forename: Emilie
authors.initials: E
authors.lastname: Bollache
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan ave-Suite 1600, Chicago, IL, 60611, USA.
authors.forename: Pim
authors.initials: P
authors.lastname: van Ooij
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan ave-Suite 1600, Chicago, IL, 60611, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Powell
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan ave-Suite 1600, Chicago, IL, 60611, USA.
authors.forename: James
authors.initials: J
authors.lastname: Carr
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan ave-Suite 1600, Chicago, IL, 60611, USA.|Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Markl
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan ave-Suite 1600, Chicago, IL, 60611, USA.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Barker
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging* / Q000502:physiology*; D001783:Blood Flow Velocity; D005260:Female; D064368:Healthy Volunteers; D006439:Hemodynamics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D055815:Young Adult
keywords: 4D flow MRI; Aortic hemodynamics; MRI; Phase-contrast