کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6268338 | 1614628 | 2015 | 9 صفحه PDF | دانلود رایگان |
- 4D magnetic susceptibility (Ï) tomography provides a 4D Ï data space.
- A reconstructed Ï map represents an intrinsic magnetic state.
- A Ï activation map reveals the co-occurrence of bidirectional BOLD responses.
- There are two different approaches to achieve Ï-based functional mapping.
BackgroundBy solving an inverse problem of T2*-weighted magnetic resonance imaging for a dynamic fMRI study, we reconstruct a 4D magnetic susceptibility source (Ï) data space for intrinsic functional mapping.New methodsA 4D phase dataset is calculated from a 4D complex fMRI dataset. The background field and phase wrapping effect are removed by a Laplacian technique. A 3D Ï source map is reconstructed from a 3D phase image by a computed inverse MRI (CIMRI) scheme. A 4D Ï data space is reconstructed by repeating the 3D Ï source reconstruction for each time point. A functional map is calculated by a temporal correlation between voxel signals in the 4D Ï space and the timecourse of the task paradigm.ResultsWith a finger-tapping experiment, we obtain two 3D functional mappings in the 4D magnitude data space and in the reconstructed 4D Ï data space. We find that the Ï-based functional mapping reveals co-occurrence of bidirectional responses in a 3D activation map that is different from the conventional magnitude-based mapping.Comparison with existing methodsThe Ï-based functional mapping can also be achieved by a 3D deconvolution of a phase activation map. Based on a subject experimental comparison, we show that the 4D Ï tomography method could produce a similar Ï activation map as obtained by the 3D deconvolution method.ConclusionBy removing the dipole effect and other fMRI technological contaminations, 4D Ï tomography provides a 4D Ï data space that allows a more direct and truthful functional mapping of a brain activity.
Journal: Journal of Neuroscience Methods - Volume 241, 15 February 2015, Pages 85-93