Retrospective correction of B 0-field-induced geometric distortions in multislice echo-planar images: A 3D solution

Roderick W. McColl, Edward A. Coburn

Research output: Chapter in Book/Report/Conference proceedingConference contribution


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 languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Number of pages11
StatePublished - 2000
EventMedical Imaging 2000: Physics of Medical Imaging - San Diego, CA, USA
Duration: Feb 13 2000Feb 15 2000


OtherMedical Imaging 2000: Physics of Medical Imaging
CitySan Diego, CA, USA

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


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