Abstract
A method has been developed to utilize a 3D B 0 fieldmap, with a multi-volume-of-interest segmentation map, to quantify and correct geometric distortions in echo-planar images. The purpose is to provide accurate co-registration of anatomical MRI to functional MRI time course sequences. A data structure capable of extracting and reporting the necessary information forms a central part of the solution. Images were obtained from a 1.5 Tesla scanner with an experimental y-gradient insert coil. Two 3D-gradient echo sequences supply the data needed to calculate the B 0 map across the volume. Segmentation of the volume into brain/background produces the data needed for the phase unwrapping and volume(s) of interest generation, from which the global B 0 variation map is obtained. Subsequent EPI acquisition yields the fMRI time-course information. Tests were carried out on a phantom and a human volunteer engaged in a motor task (finger-tapping). Strong distortions were measured, and subsequently corrected, particularly near the petrous bone/mastoid air cells and in the frontal and maxillary sinuses. Additionally, a strong eddy current resulting from the unshielded y-gradient was detected. The method facilitates geometric distortion correction through an imaging volume, containing multiple regions of interest within a slice, starting from a single starting point.
Original language | English (US) |
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Title of host publication | Proceedings of SPIE - The International Society for Optical Engineering |
Publisher | Society of Photo-Optical Instrumentation Engineers |
Pages | 559-569 |
Number of pages | 11 |
Volume | 3977 |
State | Published - 2000 |
Event | Medical Imaging 2000: Physics of Medical Imaging - San Diego, CA, USA Duration: Feb 13 2000 → Feb 15 2000 |
Other
Other | Medical Imaging 2000: Physics of Medical Imaging |
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City | San Diego, CA, USA |
Period | 2/13/00 → 2/15/00 |
ASJC Scopus subject areas
- Electrical and Electronic Engineering
- Condensed Matter Physics