SHARP edges: recovering cortical phase contrast through harmonic extension

Area of Science:

• Neuroimaging
• Biophysics
• Medical Physics

Background:

• Conventional sophisticated harmonic artifact reduction for phase data (SHARP) struggles to recover local phase contrast at brain edges.
• This limitation hinders detailed analysis of cortical regions and other peripheral brain structures.

Purpose of the Study:

• To develop an adapted SHARP method, Extended-SHARP, for recovering phase contrast at brain edges.
• To improve the coverage of magnetic field imaging in neuroimaging applications.

Main Methods:

• Utilized a three-dimensional Taylor expansion of a harmonic potential field, extending from an inner brain region to the brain edges.
• Employed an initial SHARP estimate to establish the harmonic background field.
• Assessed Extended-SHARP via numerical simulations and in vivo imaging.

Main Results:

• Extended-SHARP recovered an average of 26% more in vivo brain volume compared to conventional SHARP.
• Successfully retrieved local field contrast around previously obscured edge sources in numerical models.
• Achieved error rates comparable to conventional SHARP.

Conclusions:

• Extended-SHARP effectively recovers lost magnetic field values near brain edges.
• This adaptation offers a straightforward enhancement to conventional SHARP for improved neuroimaging.
• Facilitates better visualization and analysis of the brain periphery.