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Related Experiment Videos

Designing optimal universal pulses using second-order, large-scale, non-linear optimization.

Christopher Kumar Anand¹, Alex D Bain, Andrew Thomas Curtis

¹Department of Computing and Software, McMaster University, Hamilton, ON, Canada L8S 4K1.

Journal of Magnetic Resonance (San Diego, Calif. : 1997)

|May 24, 2012

Summary

We developed a full second-order radiofrequency (RF) pulse design method that accounts for relaxation and magnetic field inhomogeneities. This advanced technique improves existing pulse designs and enables accurate R(2) measurements in Carr-Purcell-Meiboom-Gill (CPMG) experiments.

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Area of Science:

Magnetic Resonance Imaging
Pulse Sequence Design
Quantum Control

Background:

First-order and quasi-second-order RF pulse design methods are actively researched.
Existing methods have limitations in incorporating complex physical parameters.

Purpose of the Study:

To present a full second-order RF pulse design method.
To incorporate relaxation, B(0), and B(1) inhomogeneities.
To enable reliable R(2) measurements in CPMG experiments.

Main Methods:

Formulated pulse design as a generic optimization problem.
Developed efficient calculation of second derivatives.
Utilized symbolic solutions of Bloch equations for acceleration.
Designed a universal refocusing pulse for CPMG.

Main Results:

Demonstrated visible improvements over existing optimized pulses.
Showcased the method's ability to handle diverse pulse sequence features.
Achieved reliable R(2) measurements for offsets within ±γB(1).
Compared the designed pulse with published refocusing pulses in CPMG experiments.

Conclusions:

The full second-order design method offers superior performance and flexibility.
The designed universal refocusing pulse enhances R(2) measurement accuracy in CPMG.
This approach advances RF pulse design for magnetic resonance applications.