Measurement of the aortic pulse wave velocity in MRI: Comparison of transit time estimators

The efficiency of a new transit time (Δt) estimator (MSeg) for Pulse Wave Velocity (PWV) estimation is compared with three previously described methods (MUpslope, MFoot, MPoint), in terms of correlation with aging and reproducibility. SSFP and PC acquisitions from 40 subjects (42±15 year), recorded at the level of the aortic arch were studied. Δt was defined as the time shift between the flow curves in the ascending (CA) and descending (CD) aorta and calculated with: 1) MSeg, by minimizing the area delimited by two sigmoid curves fitted to the systolic up-slope of CA and CD, 2) MUpslope, by minimizing the area between the systolic up-slope of CA and the CD curve, 3) MFoot using CA and CD feet, 4) MPoin,t using the half maximum of CA and CD. The MSeg estimator resulted in a higher reproducibility (6%), better correlation of pulse wave velocity with aging (r=0.85), and less overlap between the <;40 and ≥40 years groups.