Combining fMRI and DTI: A framework for exploring the limits of fMRI-guided DTI fiber tracking and for verifying DTI-based fiber tractography results

Abstract

Combining fMRI and DTI: a framework for exploring the limits of fMRI-guided DTI fiber tracking and for verifying DTI-based fiber tractography resultsStaempfli, P; Reischauer, C; Jaermann, T; Valavanis, A; Kollias, S; Boesiger, P Staempfli, P; Reischauer, C; Jaermann, T; Valavanis, A; Kollias, S; Boesiger, P (2008 Combining fMRI and DTI: a framework for exploring the limits of fMRI-guided DTI fiber tracking and for verifying DTI-based fiber tractography results AbstractA powerful, non-invasive technique for estimating and visualizing white matter tracts in the human brain in vivo is white matter fiber tractography that uses magnetic resonance diffusion tensor imaging. The success of this method depends strongly on the capability of the applied tracking algorithm and the quality of the underlying data set. However, DTI-based fiber tractography still lacks standardized validation. In the present work, a combined fMRI/DTI study was performed, both to develop a setup for verifying fiber tracking results using fMRI-derived functional connections and to explore the limitations of fMRI based DTI fiber tracking. Therefore, a minor fiber bundle that features several fiber crossings and intersections was examined: The striatum and its connections to the primary motor cortex were examined by using two approaches to derive the somatotopic organization of the striatum. First, an fMRI-based somatotopic map of the striatum was reconstructed, based on fMRI activations that were provoked by unilateral motor tasks. Second, fMRI-guided DTI fiber tracking was performed to generate DTI-based somatotopic maps, using a standard line propagation and an advanced fast marching algorithm. The results show that the fiber connections reconstructed by the advanced fast marching algorithm are in good agreement with known anatomy, and that the DTI-revealed somatotopy is similar to the fMRI somatotopy. Furthermore, the study illustrates that the combination of fMRI with DTI can supply additional information in order to choose reasonable seed regions for generating functionally relevant networks and to validate reconstructed fibers. A powerful, non-invasive technique for estimating and visualizing white matter tracts in the human brain in vivo is white matter fiber tractography that uses magnetic resonance diffusion tensor imaging. The success of this method depends strongly on the capability of the applied tracking algorithm and the quality of the underlying data set. However, DTI-based fiber tractography still lacks standardized validation. In the present work, a combined fMRI/DTI study was performed, both to develop a setup for verifying fiber tracking results using fMRI-derived functional connections and to explore the limitations of fMRI based DTI fiber tracking. Therefore, a minor fiber bundle that features several fiber crossings and intersections was examined: The striatum and its connections to the primary motor cortex were examined by using two approaches to derive the somatotopic organization of the striatum. First, an fMRI-based somat...

Tract-Specific and Region of Interest Analysis of Corticospinal Tract Integrity in Subcortical Ischemic Stroke: Reliability and Correlation with Motor Function of Affected Lower Extremity

“…An emerging method of reconstructing white matter fibers is by using functional MR imaging-guided fiber tracking technology. This technology has been performed in healthy participants 46 and in patients with brain tumors 47,48 by using DTI. This methodology has potential to be used in patients with stroke for mapping the cortical representations for upper and lower extremity motor function and guiding the placement of seeds for reconstructing CST fibers associated with upper and lower extremity motor function.…”

Diffusion tensor imaging and fiber tractography of the median nerve at 1.5T: optimization of b value

“…In-plane resolution was 1.875×1.875 mm 2 , which might be insufficient to image smaller peripheral nerves. DTI data processing is not standardized [7] and different fiber tracking software uses different fiber reconstruction algorithms [34]. In addition, we used the same parameters for fiber tracking as previous studies [1,6]; however, there are no studies which have proven that these parameters are "optimal" for DTI and fiber tracking of peripheral nerves.…”

Multimodal Approach to the Surgical Removal of Gliomas in Eloquent Brain Regions

“…These changes deform the architecture of the white matter, and, in some cases, prevent selection of the seed region of interest (ROI) from which to begin fiber tracking. To overcome this problem, some investigators have suggested posing a seed ROI in the white matter area subjacent to the maximal fMRI activity (i.e., for the pyramidal tract, in the precentral cortex) with the target ROI in the cerebral peduncle (Schomberg et al 2006;Smits et al 2007;Staempfli et al 2007). Also notable is that in language areas, DTI might emphasize the presence of white matter tracts when subcortical stimulation did not show a zone of positive response, favoring an unnecessarily conservative surgery, whereas direct stimulation would have indicated removal of the entire portion of non-eloquent tissue.…”