Method and processor and magnetic resonance apparatus for designing RF pulses to mitigate off-resonance effects

US8866478B2 · kind B2 · utility

Assignees

• Siemens Aktiengesellschaft · DE
• The General Hospital Corporation · US
• Massachusetts Institute of Technology · US

Inventors

• Elfar Adalsteinsson · Belmont, US
• Hans-Peter Fautz · Forchheim, DE
• Kawin Setsompop · Boston, US
• Lawrence L. Wald · Cambridge, US

Key dates

• Filing date: Jul 13, 2011
• Grant date: Oct 21, 2014
• Expiry date: Jan 10, 2033

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/5614
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In a magnetic resonance apparatus and operating method therefor, and in a processor that is programmed to design RF pulses for operating such a magnetic resonance apparatus, the RF pulses are designed to mitigate off-resonance effects caused by inhomogeneity of the basic (B0) magnetic field in the magnetic resonance apparatus. The RF pulses of a parallel transmit array are designed with different spatial phase distributions, that deviate from a constant phase from pulse-to-pulse, with the absolute value of the difference between respective spatial phase distributions of any two successively radiated RF pulses corresponding to the off-resonance that is caused by B0-inhomogeneity during the time between the radiation of the successive pulses. Additionally, or separately, currents supplied to the shim coils can be taken into account in the design of the RF pulses as an additional degree of freedom, with the shimming of the basic magnetic field produced by the shim currents deviating from shim currents designed to ideally produce a homogenous B0 field.