BME Seminar: Silu Han
Monday, September 26th, 2022, 12:00 p.m.
Silu Han
Ph.D. Candidate, Nan-Kuei Chen Lab
The University of Arizona
"Reconstruction of Accelerated and Multi-contrast Echo-planar Imaging"
Keating 103 | Zoom link. Passcode: BearDown
(Instructor permission required for enrolled students to attend via Zoom)
Hosts: Dr. Beth Hutchinson and Dr. Shang Song
Persons with a disability may request a reasonable accommodation by contacting the Disability Resource Center at 621-3268 (V/TTY).
ABSTRACT: Echo-planar imaging (EPI) is a fast MRI pulse sequence commonly used in functional MRI (fMRI) and other studies requiring a high temporal resolution. Single-shot EPI has a limited spatial resolution due to signal decay and contains geometric distortion due to a relatively long echo spacing. These limitations can be addressed by incorporating multi-shot and/or parallel MRI schemes and the temporal resolution can be further improved by the multi-band (MB)/simultaneous multi-slice (SMS) technique. EPI with these various schemes are all susceptible to Nyquist artifact, resulting from inconsistency between positive- and negative-readout ky lines, which reduces signal-to-noise ratio (SNR) and image quality.
Multi-contrast imaging can be applied to quantitative MRI, detecting microstructural processes related to tissue remodeling in aging and neurological diseases. Most quantitative MRI require a series of images obtained with different scan parameters such as different echo or inversion times, allowing for parametric fitting of signals to generate a quantitative mapping of different parameters, such as T1, T2* and magnetic susceptibility. However, the resulting acquisition times of quantitative MRI can be relatively long. With its intrinsic high temporal resolution, EPI can be applied to multi-contrast imaging to shorten the acquisition time.
In this presentation, Han will introduce a novel inherent coil-signature-based phase correction for Nyquist artifact removal, which does not rely on time-consuming 2D phase calibration scans and can effectively remove 2D Nyquist artifacts in EPI data obtained with different schemes.
In addition, Han will introduce a functional connectivity network and default mode network activation mapping using EPI data obtained with our proposed method. Finally, Han will introduce a customized MRI pulse sequence, double-echo steady state EPI (DESS-EPI) and inverse double-echo steady state EPI (iDESS-EPI), for multi-contrast imaging.