MRI method and apparatus for selective image suppression of material based on T1 and T2 relation times

US5655531A · kind A · utility

Assignee

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

Inventors

• Dwight G. Nishimura · Palo Alto, US
• Jean H. Brittain · Pewaukee, US

Key dates

• Filing date: May 15, 1995
• Grant date: Aug 12, 1997
• Expiry date: May 15, 2015

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61B5/055
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The selective imaging of an object having two materials with different relaxation times (T1 or T2) is provided by using a driven equilibrium sequence (T2 weighted preparation sequence) followed by an inversion recovery sequence. In the driven equilibrium sequence the object is placed in a static magnetic field along a longitudinal axis, an excitation pulse is applied to tip nuclei spins into a transverse plane, and at least one refocusing pulse is applied to produce a spin echo having a magnetization component as a function of relaxation time. At least one pulse is then applied to the object to drive the spin echo to an inverted position along the longitudinal axis. A readout excitation is then applied at a later time when the longitudinal magnetization of one material is substantially reduced. In one embodiment, an inversion pulse is applied prior to the T2 weighted preparation sequence.