title: Peak velocity and flow quantification validation for sensitivity-encoded phase-contrast MR imaging.
abstract: OBJECTIVE
  Phase-contrast (PC) magnetic resonance imaging (MRI) technique has important clinical applications in blood flow quantification and pressure gradient estimation by velocity measurement. Parallel imaging using sensitivity encoding (SENSE) may substantially reduce scan time. We demonstrate the utility of PC-MRI measurements accelerated by SENSE under clinical conditions.
  
  
  METHODS
  Accuracy and repeatability of a SENSE-PC implementation was evaluated by comparison with a commercial PC sequence with five normal volunteers. Twenty-six patients were then scanned with SENSE-PC at reduction factors (R = 1, 2, and 3). Blood flow and peak velocity were measured in the aorta and pulmonary trunk in 16 patients and peak velocity was measured at the coarctation of 10 patients. Quantitative flow, shunt ratio, and peak velocity measurements obtained with different reduction factors were compared using correlation, linear regression, and Bland-Altman statistics. All studies were approved by an Institutional Review Board, and informed consent was acquired from all subjects.
  
  
  RESULTS
  The correlation coefficients for all comparisons were >0.962 and with high statistical significance (P < .01). Linear regression slopes ranged between 0.96 and 1.11 for flow and 0.88 to 1.05 for peak velocity. For flow, the Bland-Altman statistics yielded a total mean difference ranging from -0.02 to 0.05) L/minute with 2 standard of deviation limits ranging from -0.52 to 0.75 L/minute. For peak velocity, the total mean difference ranged from -0.10 to -0.004) milliseconds with 2-SD limits ranging from -0.062 to 0.46 milliseconds. R = 3 to R = 1 comparisons had greater 2-SD limits than R = 2 to R = 1 comparisons.
  
  
  CONCLUSIONS
  SENSE PC-MRI measurements for flow and pressure gradient estimation were comparable to conventional PC-MRI.
authors.affiliation: Lucas MRS/I Center, Stanford University, 1201 Welch Road, Stanford, CA 94305. cdlew@stanford.edu
authors.forename: Calvin D
authors.initials: CD
authors.lastname: Lew
authors.forename: Marcus T
authors.initials: MT
authors.lastname: Alley
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Spielman
authors.forename: Frandics P
authors.initials: FP
authors.lastname: Chan
mesh_terms: D000328:Adult; D001011:Aorta; D001017:Aortic Coarctation / Q000175:diagnosis; D001783:Blood Flow Velocity; D003326:Coronary Circulation; D005260:Female; D006345:Heart Septal Defects, Ventricular / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008432:Mathematical Computing; D011651:Pulmonary Artery