Variable density fourier velocity encoding MR imaging

US6650115B2 · kind B2 · utility

Assignee

• The Board of Trustees of the Leland Stanford Junior University · US

Inventors

• Julie Camille DiCarlo · Stanford, US
• Dwight G. Nishimura · Palo Alto, US

Key dates

• Filing date: Oct 12, 2001
• Grant date: Nov 18, 2003
• Expiry date: Dec 14, 2021

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/563
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Real time spatially localized velocity distribution is measured using magnetic resonance techniques by first exciting a column-shaped region using a 2D RF excitation pulse. A cyclical readout gradient is then played along the excited column's axis while the magnetic resonance signal is continuously sampled to create a 2D sample set of velocity frequency vs. spatial frequencies in the same direction. If the cyclical readout gradient, for example a sawtooth-shaped gradient, has lobes of increasing area, the spacing between samples in the velocity-frequency direction is increased to emphasize sampling at low velocity-frequency and to more coarsely sample high velocity-frequencies. The sequence can be repeated to collect a time series of velocity-position images, which can then be sampled to create a velocity-time image at a single location.