A one-dimensional velocity technique for NMR measurement of aortic distensibility.
A technique is presented for rapidly and noninvasively determining aortic distensibility, by NMR measurement of wave velocity in the aorta. A two-dimensional NMR selective-excitation pulse is used to repeatedly excite a cylinder of magnetization in the aorta, with magnetization read out along the cylinder axis each time. A toggled bipolar flow-encoding pulse is applied prior to readout, to produce a non-dimensional phase-contrast flow image. Cardiac gating and data interleaving are employed to improve the effective time resolution to 2 ms. Wave velocities are determined from the slope of the leading edge of flow measured on the resulting M-mode velocity image. The technique is sensitive over a range of distensibilities from 10(-6) to 10(-3) m s2/kg. The average value in the descending thoracic aorta in seven normal subjects was found to be 4.8 x 10(-5) m s2/kg, with a significant inverse correlation with age.
Hardy
C J
CJ
GE Corporate Research and Development Center, Schenectady, New York 12301.
Bolster
B D
BD
McVeigh
E R
ER
Adams
W J
WJ
Zerhouni
E A
EA
D000328:Adult; D000367:Age Factors; D001011:Aorta / Q000502:physiology*; D001013:Aorta, Thoracic / Q000502:physiology; D001783:Blood Flow Velocity; D002302:Cardiac Output / Q000502:physiology; D004548:Elasticity; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D009682:Magnetic Resonance Spectroscopy; D008875:Middle Aged; D008955:Models, Cardiovascular; D012039:Regional Blood Flow