title: Accuracy and precision of MR velocity mapping in measurement of stenotic cross-sectional area, flow rate, and pressure gradient.
abstract: Reliability of magnetic resonance (MR) velocity mapping to assess severity of stenosis was assessed in vitro. Steady flow at different flow rates through five stenoses with a central orifice area ranging from 17 to 176 mm2 was measured with velocity mapping performed perpendicular to the stenotic jet. Besides determination of the stenotic cross-sectional area and flow rate, the pressure gradient was calculated with the modified Bernoulli equation and compared with manometer measurements. Cross-sectional areas were measured with an accuracy of > or = 76%, a precision of > or = 91%, and an error of < or = 19 mm2. Flow rates had an accuracy of > or = 72%, a precision of > or = 94%, and an error of < or = 1.4 L/min. The modification of the Bernoulli equation limited its reliability to stenoses with areas of 35-113 mm2. Pressure gradients were calculated with an accuracy of > or = 80%, a precision of > or = 88%, and an error of < or = 15 mm Hg. The method was applied in a single patient with aortic stenosis and gave estimates that agreed with those obtained by heart catheterization.
authors.affiliation: Danish Research Center of Magnetic Resonance, Hvidovre Hospital.
authors.forename: L
authors.initials: L
authors.lastname: Søndergaard
authors.forename: F
authors.initials: F
authors.lastname: Ståhlberg
authors.forename: C
authors.initials: C
authors.lastname: Thomsen
authors.forename: A
authors.initials: A
authors.lastname: Stensgaard
authors.forename: K
authors.initials: K
authors.lastname: Lindvig
authors.forename: O
authors.initials: O
authors.lastname: Henriksen
mesh_terms: D001021:Aortic Valve / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000175:diagnosis / Q000503:physiopathology*; D001783:Blood Flow Velocity; D006801:Humans; D008279:Magnetic Resonance Imaging; D008961:Models, Structural; D011312:Pressure