MR method and apparatus employing magnetization transfer contrast inducing fat-selective RF pulse

US5270652A · kind A · utility

Assignee

• North American Philips Corporation · US

Inventors

• William Dixon · Clifton Park, US
• Xiaole Hong · Acton, US

Key dates

• Filing date: May 20, 1992
• Grant date: Dec 14, 1993
• Expiry date: May 20, 2012

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/5617
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A magnetic resonance and apparatus in which an examination zone is exposed, preferably repeatedly, with a sequence in which the same RF pulse is both selective to fat, for acting in a fat suppression scheme within the sequence and is configured for inducing substantial magnetization transfer contrast. Design parameters are given for a 1-2-1 binomial RF pulse and a 1-2-1-1-2-1double binomial RF pulse having a 0.degree. net flip angle at the Larmor frequency of water protons and a nominal 180.degree. net flip angle at the Larmor frequency of fat bound protons. The partial derivatives of the latter nominal flip angle with respect to chemical shift and with respect to RF amplitude are each zero. Each of these RF pulse designs is implemented by a pulse which is substantially rectangular in amplitude, but which has alternations of phase between 0.degree. and 180.degree. during its duration to form the sub-pulses. An illustrative imaging sequence incorporates this RF pulse for preparing the spin system n the examination zone prior to an at least partial tipping of longitudinal magnetization into the transverse plane by an RF excitation pulse.