Automatic 3D Intersubject Registration of MR Volumetric Data in Standardized Talairach Space
ABSTRACT In both diagnostic and research applications, the interpretation of MR images of the human brain is facilitated when different data sets can be compared by visual inspection of equivalent anatomical planes. Quantitative analysis with predefined atlas templates often requires the initial alignment of atlas and image planes. Unfortunately, the axial planes acquired during separate scanning sessions are often different in their relative position and orientation, and these slices are not coplanar with those in the atlas. We have developed a completely automatic method to register a given volumetric data set with Talairach stereotaxic coordinate system.
The registration method is based on multi-scale, three-dimensional (3D) cross-correlation with an average (n > 300) MR brain image volume aligned with the Talariach stereotaxic space. Once the data set is re-sampled by the transformation recovered by the algorithm, atlas slices can be directly superimposed on the corresponding slices of the re-sampled volume. the use of such a standardized space also allows the direct comparison, voxel to voxel, of two or more data sets brought into stereotaxic space.
With use of a two-tailed Student t test for paired samples, there was no significant difference in the transformation parameters recovered by the automatic algorithm when compared with two manual landmark-based methods (p > 0.1 for all parameters except y-scale, where p > 0.05). Using root-mean-square difference between normalized voxel intensities as an unbiased measure of registration, we show that when estimated and averaged over 60 volumetric MR images in standard space, this measure was 30% lower for the automatic technique than the manual method, indicating better registrations. Likewise, the automatic method showed a 57% reduction in standard deviation, implying a more stable technique. The algorithm is able to recover the transformation even when data are missing from the top or bottom of the volume.
We present a fully automatic registration method to map volumetric data into stereotaxic space that yields results comparable with those of manually based techniques. The method requires no manual identification of points or contours and therefore does not suffer the drawbacks involved in user intervention such as reproducibility and interobserver variability.
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- "The native T1 - weighted images were corrected for non - uniform intensity resulting from inhomogeneities in the magnetic field ( Sled et al . , 1998 ) and normalized into a standardized stereotaxic space using affine transformation ( Collins et al . , 1994 ) . The corrected and normalized volumes were classified as WM , GM , CSF , or background using an advanced neural network classifier ( Zijdenbos et al . , 2002 ) . The partial volume effect classification was performed using the trimmed minimum covariance determinant method ( Tohka et al . , 2004 ) . The partial volume fractions of eac"
ABSTRACT: The mean diffusivity (MD) value has been used to describe microstructural properties in Diffusion Tensor Imaging (DTI) in cortical gray matter (GM). Recently, researchers have applied a cortical surface generated from the T1-weighted volume. When the DTI data are analyzed using the cortical surface, it is important to assign an accurate MD value from the volume space to the vertex of the cortical surface, considering the anatomical correspondence between the DTI and the T1-weighted image. Previous studies usually sampled the MD value using the nearest-neighbor (NN) method or Linear method, even though there are geometric distortions in diffusion-weighted volumes. Here we introduce a Surface Guided Diffusion Mapping (SGDM) method to compensate for such geometric distortions. We compared our SGDM method with results using NN and Linear methods by investigating differences in the sampled MD value. We also projected the tissue classification results of non-diffusion-weighted volumes to the cortical midsurface. The CSF probability values provided by the SGDM method were lower than those produced by the NN and Linear methods. The MD values provided by the NN and Linear methods were significantly greater than those of the SGDM method in regions suffering from geometric distortion. These results indicate that the NN and Linear methods assigned the MD value in the CSF region to the cortical midsurface (GM region). Our results suggest that the SGDM method is an effective way to correct such mapping errors.Frontiers in Neuroscience 07/2015; 9:236. DOI:10.3389/fnins.2015.00236 · 3.70 Impact Factor
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- "Based on a data-driven whole-brain approach for meta-analysis. Studies based on selected ROIs were excluded, 7. Were reported in standard stereotaxic spaces such as Montreal Neurological Institute (MNI) [Collins et al., 1994] or Talairach and Tournoux space [Talairach and Tornoux, 1988] 8. Were driven by categorical contrasts rather than correlation analyses, and 9. Reported a t-value 3 or a Z-score 2.33 to ensure comparable specificity [Friebel et al., 2011]. "
ABSTRACT: Previous positron emission tomography (PET) studies have shown that various cortical areas are activated to process speech signal in cochlear implant (CI) users. Nonetheless, differences in task dimension among studies and low statistical power preclude from understanding sound processing mechanism in CI users. Hence, we performed activation likelihood estimation meta-analysis of PET studies in CI users and normal hearing (NH) controls to compare the two groups. Eight studies (58 CI subjects/92 peak coordinates; 45 NH subjects/40 peak coordinates) were included and analyzed, retrieving areas significantly activated by lexical and nonlexical stimuli. For lexical and nonlexical stimuli, both groups showed activations in the components of the dual-stream model such as bilateral superior temporal gyrus/sulcus, middle temporal gyrus, left posterior inferior frontal gyrus, and left insula. However, CI users displayed additional unique activation patterns by lexical and nonlexical stimuli. That is, for the lexical stimuli, significant activations were observed in areas comprising salience network (SN), also known as the intrinsic alertness network, such as the left dorsal anterior cingulate cortex (dACC), left insula, and right supplementary motor area in the CI user group. Also, for the nonlexical stimuli, CI users activated areas comprising SN such as the right insula and left dACC. Previous episodic observations on lexical stimuli processing using the dual auditory stream in CI users were reconfirmed in this study. However, this study also suggests that dual-stream auditory processing in CI users may need supports from the SN. In other words, CI users need to pay extra attention to cope with degraded auditory signal provided by the implant. Hum Brain Mapp, 2015. © 2014 Wiley Periodicals, Inc.Human Brain Mapping 05/2015; 36(5):1982-94. DOI:10.1002/hbm.22750 · 6.92 Impact Factor
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- "Scores are means (SD); rating scale (1 — very low, 10 — perfect). by first normalizing individual data through linear registration to the MNI template using an in-house algorithm (Collins et al., 1994 "
ABSTRACT: We used fMRI to investigate neural activation in reading aloud in bilinguals differing in age of acquisition. Three groups were compared: French-English bilinguals who acquired two languages from birth (simultaneous), French-English bilinguals who learned their L2 after the age of 5 years (sequential), and English-speaking monolinguals. While the bilingual groups contrasted in age of acquisition, they were matched for language proficiency, although sequential bilinguals produced speech with a less native-like accent in their L2 than in their L1. Simultaneous bilinguals activated similar brain regions to an equivalent degree when reading in their two languages. In contrast, sequential bilinguals more strongly activated areas related to speech-motor control and orthographic to phonological mapping, the left inferior frontal gyrus, left premotor cortex, and left fusiform gyrus, when reading aloud in L2 compared to L1. In addition, the activity in these regions showed a significant positive correlation with age of acquisition. The results provide evidence for the engagement of overlapping neural substrates for processing two languages when acquired in native context from birth. However, it appears that the maturation of certain brain regions for both speech production and phonological encoding are limited by a sensitive period for L2 acquisition regardless of language proficiency. Copyright © 2015 Elsevier Inc. All rights reserved.NeuroImage 03/2015; 112. DOI:10.1016/j.neuroimage.2015.03.016 · 6.36 Impact Factor