Abstract
Magnetic susceptibility differences exist near the interface of air/tissue in the ventral brain in fMRI (functional magnetic resonance imaging). These susceptibility differences will not only cause field inhomogeneity and its gradients which will result in image artifacts, but also cause shifts in the echo time for gradients echo acquisitions. The echo time shifts are caused by shifts in the effective k-space trajectory due to the gradients of the field inhomogeneity. Previous work has shown and validated methods for estimating the echo time shift based on the effective k-space trajectory. In this work, we demonstrate that accurate estimation of the R2* decay map (R2*=1/T2*) not only need to account for the field map and its gradients, but also needs to include the echo time shift. These changes in T2* sensitivity are directly related to changes in sensitivity in BOLD (blood oxygenation level dependent) fMRI studies.
| Original language | English (US) |
|---|---|
| Title of host publication | Proceedings - 2009 IEEE International Symposium on Biomedical Imaging |
| Subtitle of host publication | From Nano to Macro, ISBI 2009 |
| Pages | 710-713 |
| Number of pages | 4 |
| DOIs | |
| State | Published - 2009 |
| Event | 2009 IEEE International Symposium on Biomedical Imaging: From Nano to Macro, ISBI 2009 - Boston, MA, United States Duration: Jun 28 2009 → Jul 1 2009 |
Other
| Other | 2009 IEEE International Symposium on Biomedical Imaging: From Nano to Macro, ISBI 2009 |
|---|---|
| Country | United States |
| City | Boston, MA |
| Period | 6/28/09 → 7/1/09 |
Keywords
- BOLD fMRI
- Echo time shift
- Field inhomogeneity
- Magnetic susceptibility
ASJC Scopus subject areas
- Biomedical Engineering
- Radiology Nuclear Medicine and imaging