Sequence-phase optimal (SPO) [d̳e̳l̳t̳a̳]B₀ field control for lipid suppression and homogeneity for brain magnetic resonance spectroscopic imaging

This work develops sequence-phase optimal (SPO) [delta]B₀ shimming methods to reduce lipid contamination and improve brain metabolite spectra in proton spectroscopic imaging. A rapidly reconfigurable 32-channel, local-multi-coil-shim-array is used to enhance lipid suppression and narrow metabolite linewidth in magnetic resonance spectroscopic imaging (MRSI) of the brain. The array is optimally reconfigured dynamically during each MRSI repetition period, first during the lipid-suppression phase, by widening the spectral gap between spatially separate lipid and metabolite regions, and then to narrow metabolite linewidth during readout, by brain-only [delta]B₀ homogenization. This sequence-phase-optimal (SPO) shimming approach is demonstrated on four volunteer subjects using a commercial 3T MRI outfitted with a 32-channel integrated RF receive and local multi-coil shim array. This proposed sequence-phase-optimal shimming significantly improves brain-metabolite MRSI in vivo, as measured by lipid suppression, brain metabolite chemical shift, and line widths. The time required to compute patient specific SPO shims negligibly impacted scan time. Sequence-phase-optimal shimming reduced lipid energy in the brain volume across four subjects by 88%, improved NAA FWHM by 23%, and dramatically reduced lipid ringing artifacts in quantified NAA and Glutamate metabolites, without increasing scan time or SAR.

Name thesis:degree_name

Master

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2020

Author dc:creator

• Arango, Nicolas(Nicolas S.)

Advisor dc:contributor.advisor

• Jacob White.

• Electrical Engineering and Computer Science.

Statement dc:rights

• MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1721.1/128411

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/128411