US 7,078,900 B2 · Method and system of determining parameters for MR data acquisition with real-time B1 optimization

Abstract

The present invention provides a system and method of MR scan prescription to achieve in a fast, simple, and effective manner the optimal peak excitation field strength for a given pulse shape and flip angle such that the minimum TR for the MR scan can be optimized and based on SAR constraints. The present invention provides a technique to obtain optimal B1 parameters for an arbitrary shape and flip angle of an excitation pulse in real-time while satisfying SAR and/or RF hardware limits to determine the minimum achievable repetition time for a pulse sequence. The present invention is particularly applicable with breath-hold and cardiac imaging techniques that are carried out at relatively high field strengths.

Claims29

Dependent claims

An MRI apparatus comprising:

a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images;
and
a computer programmed to:
(A) model a SAR constrained minimum TR for a given pulse sequence;
(B) adjust strength of a B1 pulse of the pulse sequence based on the model;
(C) determine if the strength of the B1 pulse is inside a range of acceptable B1 field strength values;
and if so, commence imaging, and if not,
(D) repeat (A)–(C) until strength of the B1 pulse is adjusted to a value minimally inside the range of acceptable B1 field strength values;
wherein the computer is further programmed to decrement the strength of the B1 pulse if the SAR constrained minimum TR exceeds a non-SAR constrained minimum TR and increment the strength of the B1 pulse if the SAR constrained minimum TR is less than the non-SAR constrained minimum TR.

6 more elements

A computer readable storage medium having a computer program stored thereon and representing a set of instructions that when executed by a computer causes the computer to:

determine one of excitation pulse magnitude and excitation pulse duration of an MR pulse sequence;
determine a first minimum TR for the MR pulse sequence based on a least one of the excitation pulse magnitude and excitation pulse duration such that SAR during the first minimum TR does not exceed a given prescribed SAR level;
determine a second minimum TR for the MR pulse sequence based on other parameters of the MR pulse sequence, wherein the second minimum TR is independent of SAR constraints;
determine a minimum TR target range from the second minimum TR;
compare the first minimum TR to the minimum TR target range;
and
adjust one of excitation pulse magnitude and excitation pulse duration of an excitation pulse of the MR pulse sequence from the comparison.

4 more elements

Dependencies are inferred from the claim text.

Method and system of determining parameters for MR data acquisition with real-time B1 optimization

Life of this patent

Method and system of determining parameters for MR data acquisition with real-time B1 optimization

Life of this patent

Abstract

Claims29