Catalyzing the transient response in steady-state MRI sequences

US6452387B1 · kind B1 · utility

Assignee

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

Inventors

• Brain A. Hargreaves · Stanford, US
• Shreyas S. Vasanawala · Stanford, US
• John M. Pauly · Stanford, US
• Dwight G. Nishimura · Palo Alto, US

Key dates

• Filing date: Mar 7, 2001
• Grant date: Sep 17, 2002
• Expiry date: Mar 15, 2021

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/5613
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A steady-state condition for tipped nuclear spins is accelerated or catalyzed by first determining magnetization magnitude of the steady state and the scaling magnetization along one axis (Mz) to at least approximate the determined magnetization magnitude. Then the scaled magnetization is rotated to coincide with a real-valued eigenvector extension of the tipped steady-state magnetization. Any error vector will then decay to the steady-state condition without oscillation. In one embodiment, the magnetic resonance imaging utilizes steady-state free precession (SSFP). The scaling and rotating steps are followed by the steps of applying read-out magnetic gradients and detecting magnetic resonance signals from the tipped nuclear spins. The magnetization magnitude is determined by eigenvector analysis, and the eigenvector extension is a real-valued eigenvector determined in the analysis.