Shengwei Zhang

Development of a high angular resolution diffusion imaging human brain template.

Brain diffusion templates contain rich information about the microstructure of the brain, and are used as references in spatial normalization or in the development of brain atlases. The accuracy of diffusion templates constructed based on the diffusion tensor (DT) model is limited in regions with complex neuronal micro-architecture. High angular resolution diffusion imaging (HARDI) overcomes limitations of the DT model and is capable of resolving intravoxel heterogeneity. However, when HARDI is combined with multiple-shot sequences to minimize image artifacts, the scan time becomes inappropriate for human brain imaging. In this work, an artifact-free HARDI template of the human brain was developed from low angular resolution multiple-shot diffusion data. The resulting HARDI template was produced in ICBM-152 space based on Turboprop diffusion data, was shown to resolve complex neuronal micro-architecture in regions with intravoxel heterogeneity, and contained fiber orientation information consistent with known human brain anatomy.

Development of a human brain diffusion tensor template.

The development of a brain template for diffusion tensor imaging (DTI) is crucial for comparisons of neuronal structural integrity and brain connectivity across populations, as well as for the development of a white matter atlas. Previous efforts to produce a DTI brain template have been compromised by factors related to image quality, the effectiveness of the image registration approach, the appropriateness of subject inclusion criteria, and the completeness and accuracy of the information summarized in the final template. The purpose of this work was to develop a DTI human brain template using techniques that address the shortcomings of previous efforts. Therefore, data containing minimal artifacts were first obtained on 67 healthy human subjects selected from an age-group with relatively similar diffusion characteristics (20-40 years of age), using an appropriate DTI acquisition protocol. Non-linear image registration based on mean diffusion-weighted and fractional anisotropy images was employed. DTI brain templates containing median and mean tensors were produced in ICBM-152 space and made publicly available. The resulting set of DTI templates is characterized by higher image sharpness, provides the ability to distinguish smaller white matter fiber structures, contains fewer image artifacts, than previously developed templates, and to our knowledge, is one of only two templates produced based on a relatively large number of subjects. Furthermore, median tensors were shown to better preserve the diffusion characteristics at the group level than mean tensors. Finally, white matter fiber tractography was applied on the template and several fiber-bundles were traced.

Role of standardized and study-specific human brain diffusion tensor templates in inter-subject spatial normalization

To investigate the effect of standardized and study‐specific human brain diffusion tensor templates on the accuracy of spatial normalization, without ignoring the important roles of data quality and registration algorithm effectiveness.

White matter segmentation based on a skeletonized atlas: Effects on diffusion tensor imaging studies of regions of interest

To compare the influence of conventional and skeletonized atlas‐based white matter (WM) segmentation on diffusion tensor imaging (DTI) region‐of‐interest (ROI) investigations.

Corrigendum to “Development of a human brain diffusion tensor template” [NeuroImage 46 (2009) 967–980]

This study 67 20–40 3 Turboprop 94 12 10.5 No Non-linear, (FA and mean DW) M: 27 F: 40 Jones et al. 2002 11 25–39 1.5 EPI 107 64 15.6 No Affine, (FA) M: 11 F: 0 Mori et al. 2008 81 18–59 1.5 EPI, Parallel imaging N/A 30 15.6 No Affine, (mean DW) M: 42 F: 39 Muller et al. 2007 13 53.1±15.3 1.5 EPI 93 12 4.95 No Affine, (b=0 s/mm) M: 10 F: 3 Goodlett et al. 2006 5 1 3 EPI 73 6 8 No Non-linear, (FA) Zhang et al. 2006 9 19–30 3 EPI 99 12 8.88 Yes Non-linear, (tensors) Park et al. 2003 16 30–51 1.5 Line–Scan 64 6 8.77 Yes Non-linear, (multi-channel) Chiang et al. 2008 34 73.6±9 1.5 EPI 106 44 7.92 Yes Non-linear, (tensors) M: 20 F: 14 Xu et al. 2003 9 N/A 1.5 EPI, segmented N/A 6 11.4 No Non-linear, (T1-weighted) Ardekani et al. 2006 10 31±3 3 EPI, Parallel imaging 91 6 3.4 No Non-linear, (trace and FA) M: 8 F: 2 Van Hecke et al. 2008 20 25±3 1.5 EPI 100 60 8 N/A Non-linear, (tensors) M: 8 F: 12

Evaluation of standardized and study-specific diffusion tensor imaging templates of the adult human brain: Template characteristics, spatial normalization accuracy, and detection of small inter-group FA differences

&NA; Digital diffusion tensor imaging (DTI) templates of the adult human brain are commonly used in neuroimaging research, and their characteristics influence the accuracy of the application. However, a systematic evaluation of the characteristics and performance of standardized and study‐specific DTI templates has not been conducted. The purpose of this work was to compare eight available standardized DTI templates to each other (ICBM81, ENIGMA, FMRIB58, SRI24, IIT2, NTU‐DSI‐122‐DTI, IIT v.3.0, Eve), as well as to study‐specific templates, in terms of template characteristics (image sharpness, ability to identify small brain structures, artifacts, mean values, noise properties) and performance in spatial normalization and detection of small inter‐group FA differences. The IIT v.3.0 template was shown to combine a number of desirable characteristics: includes full‐tensor information, is population‐based, has high image sharpness, shows no visible artifacts, has low noise levels, has diffusion tensor properties and spatial features representative of data from the average individual adult brain. Furthermore, the IIT v.3.0 template was shown to allow higher inter‐subject DTI spatial normalization accuracy, and detection of smaller inter‐group FA differences, compared to all other templates, including study‐specific templates. These findings were consistent when evaluating the templates in younger as well as older adult cohorts. Graphical abstract Figure. No caption available.

WHITE MATTER CORRELATES OF SUSCEPTIBILITY TO SCAM IN COMMUNITY-DWELLING OLDER ADULTS

utilization was measured by using the Resource Utilization in Dementia questionnaire and health related quality of life using the Short Form 12. Quality adjusted life years were calculated using the area under the curve and the subject based approach. Healthcare costs were assessed from the payer perspective as well as from societal perspective. Results:There were no significant differences in resource utilization/costs or health-related quality of life between intervention and control group at baseline. The Incremental-Cost-Effectiveness-Ratio (ICER) after two years of intervention will be presented at the conference by using a cost-effectiveness-plane and a cost-effectiveness-acceptability curve. Differences in quality adjusted life years, hospitalization and institutionalization between intervention and control group will be analyzed and presented in more detail. Conclusions:This analysis can add evidence to the existing inconclusive results of cost-effectiveness analyses of dementia care management programs.

Late-life cognitive activity and brain diffusion characteristics in nondemented elderly

Association between age and diffusion properties for different white matter tractsICV indicates intra cranial volume, WML white matter lesion, FA fractional anisotropy, MD mean diffusivity, ATR anterior thalamic radiation, IFO inferior fronto-occipital fasciculus, ILF inferior longitudinal fasciculus, PTR posterior thalamic radiation, SLF superior longitudinal fasciculus, UNC uncinate fasciculus, FMA forceps major, FMI forceps minor, CGC cingulate gyrus part of cingulum, CGH parahippocampal part of cingulum, CST corticospinal tract, MCP middle cerebellar peduncle, ML medial lemniscus, STR superior thalamic radiation.Values represent normalized regression coefficients for change in FA or MD per year increase in age, adjusted for sex and ICV (and additionally for tract volume and WML load in other models). Significant associations (at Bonferroni corrected threshold p1⁄40.0004) are printed in bold Tracts are ordered by functional role.