title: Estimation of aortic pulse pressure using Fourier velocity encoded M-mode MR.
abstract: OBJECTIVE
  To use a simplified hemodynamic model and Fourier-encoded velocity data to measure pulse pressure (PP) in the descending aorta.
  
  
  METHODS
  A one-dimensional, cylindrically localized pulse sequence with Fourier velocity encoding (FVE) was used to obtain time-dependent velocity distributions along the descending aorta. Numerical evaluation of a simplified hemodynamic model, based on a cross-sectionally averaged form of the mass conservation equation, allowed estimation of the average pressure waveform and PP along 6-cm-long segments located within the descending aorta. Magnetic resonance (MR)-derived pressures were compared against applanation tonometry (AT) performed in healthy subjects (n = 18) and intravascular pressure measurements (IVPM) obtained in patients (n = 4) undergoing diagnostic cardiac angiography and then found to be either normal or with clinically insignificant coronary artery disease.
  
  
  RESULTS
  The root mean square (RMS) error between MR- and AP-derived pressure waveforms was 11.7 ± 5.8%. With respect to IVPM, the RMS error ranged from 4.2% to 14.7%. In terms of pulse pressures, there was good agreement with both AT (bias = 0.99 mmHg; 95% limits of agreement (LOA) = [-5.0 to 7.0 mmHg]; range = 12.0 mmHg) and IVPM (bias = -1.82 mmHg; 95% LOA = [-7.2 to 3.5 mmHg]; range = 10.7 mmHg).
  
  
  CONCLUSIONS
  FVE M-mode and numerical evaluation of a simplified flow model can be used to estimate central pulse pressures noninvasively and accurately with respect to well-established gold standards.
authors: Department of Radiology, University of Cambridge, Cambridge, UK.
authors: Valentina
authors: V
authors: Taviani
authors: Stacey S
authors: SS
authors: Hickson
authors: Christopher J
authors: CJ
authors: Hardy
authors: Andrew J
authors: AJ
authors: Patterson
authors: Victoria E
authors: VE
authors: Young
authors: Carmel M
authors: CM
authors: McEniery
authors: Ian B
authors: IB
authors: Wilkinson
authors: Jonathan H
authors: JH
authors: Gillard
authors: Martin J
authors: MJ
authors: Graves
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D062186:Arterial Pressure; D006328:Cardiac Catheterization; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000473:pathology; D005583:Fourier Analysis; D064368:Healthy Volunteers; D006439:Hemodynamics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008365:Manometry; D008875:Middle Aged; D011312:Pressure
keywords: Fourier velocity encoding; aortic pulse pressure; cylindrical excitation; distensibility