Background Understanding heterogeneity of structural brain changes in aging may provide insights into susceptibility to neurodegenerative diseases. We characterize the genetics underlying brain structural heterogeneit...
Background Understanding heterogeneity of structural brain changes in aging may provide insights into susceptibility to neurodegenerative diseases. We characterize the genetics underlying brain structural heterogeneity within cognitively unimpaired (CU) individuals using data-driven machine learning applied to a diverse dataset of 27,402 individuals from 11 neuroimaging studies from the iSTAGING consortium. Method Structural brain morphologic patterns of CU individuals were independently examined in four decade-long intervals spanning ages 45 to 85. Within each interval, Smile-GAN (Yang et al., 2021) was trained on baseline anatomic and white matter hyperintensity (WMH) volumes. Smile-GAN probability scores were used as phenotypes in genome-wide association studies (GWAS). Specifically, we performed multiple linear regressions controlling for confounders (e.g., age) via Plink (Purcell et al., 2007). We observed longitudinal clustering stability across decades, so individuals from adjacent age groups were combined into broader age groups ([45,65), [65,85)) due to the large sample requirement of GWAS. Genomic loci, represented by the top leading single nucleotide polymorphisms (SNPs), were defined considering linkage disequilibrium. We investigated associations of SNPs with clinical traits and mapped them to genes using the GWAS Catalog (Buniello et al., 2019). Result Three structural brain aging patterns, relative to resilient agers (A0), consistent across decades, emerged: A1, or ‘typical’ aging with low atrophy and WMHs, and two ‘advanced’ aging patterns, one showing elevated WMHs and modest atrophy (A2) and the other displaying severe, widespread atrophy and moderate WMH load (A3) (Figure 1). GWAS discovered eight and six genomic loci in [45,65) and [65,85) age groups, respectively (Table 1, Figure 2). The lead SNPs for A1 and A2 were previously associated with several cardiometabolic risk factors, WMHs, and regional brain volumes. Interestingly, rs4843552, previo
BACKGROUNdSkull-stripping, the process of extracting brain tissue from MR images, is an important step for tumor segmentation anddownstream imaging-based analytics such as ai-powered radiomic feature extraction. Exis...
BACKGROUNd
Skull-stripping, the process of extracting brain tissue from MR images, is an important step for tumor segmentation anddownstream imaging-based analytics such as ai-powered radiomic feature extraction. Existing skull-stripping models, designed for pediatric or adult patients, show limitations in accurately segmenting tumors in sellar/suprasellar regions. This limitation hinders their reliable application across different histologies of pediatric brain tumors. We propose a deep learning approach for fully automated skull-stripping, compatible with both single- or multi-parametric MRI sequences.
Background Accumulation of amyloid (Aß) plaques is an early pathologic change of Alzheimer’s disease (Ad). However, the mechanisms and pathways by which amyloid spreads across the cerebrum are not fully understo...
Background Accumulation of amyloid (Aß) plaques is an early pathologic change of Alzheimer’s disease (Ad). However, the mechanisms and pathways by which amyloid spreads across the cerebrum are not fully understood. deriving distinct dimensions of amyloiddeposition and their associations with biomedical factors could be useful to understand how amyloid propagates. In this analysis, we identified two distinct subtypes of progression based on spatiotemporal variations using a recently developeddata-driven, deep learning clustering method called Surreal-GAN 1 . Method We useddata from 482 A+ and 801 A- subjects with 18 F-florbetapir PET from the Alzheimer’s disease Neuroimaging Initiative (AdNI; N = 832) and 11 C-PiB from the Preclinical Ad consortium (PAC; N = 451). Standardized uptake value ratio (SUVR) maps (cerebellar GM reference) were transformed to reference space. We derived amyloid status using Gaussian mixture modelling of mean total cortical SUVR for each of 4 sites. We then applied non-negative matrix factorization 2 on the SUVR maps to identify data-driven common patterns of deposition across the sample. Next, we applied Surreal-GAN on a total of 1283 subjects to determine the amyloid spatiotemporal subtypes. Correlations with clinical and cognitive variables were evaluated. Results Participants were 30%/22% female and had mean age 74.9 (±7.4)/ 67.9(±9.1) years for AdNI and PAC, respectively. We identified24 components from NMF (Fig 1A) after excluding 6 as non-target features. Surreal-GAN showed optimal agreement indices for two patterns. While both patterns shared involvement of posterior cingulate/precuneus and inferior frontal cortex, pattern r1 shows relatively more occipital deposition and pattern r2 shows more frontal deposition (Fig 1B), as seen when comparing strongly r1 vs strongly r2 participants using voxel-based morphometry (Fig 2). Both were associated with worse global cognitive function and worsening neurodegeneration (Table 1). r1 corre
Background Hypertension (HTN) is associated with gray matter (GM) atrophy and increased white matter hyperintensity (WMH) burden, increasing their susceptibility to Alzheimer’s disease and relateddementias. We devel...
Background Hypertension (HTN) is associated with gray matter (GM) atrophy and increased white matter hyperintensity (WMH) burden, increasing their susceptibility to Alzheimer’s disease and relateddementias. We developed a machine learning based model to quantify spatial patterns of abnormality recognizing HTN-related brain changes (SPARE-HTN) from structural magnetic resonance images (sMRI). We performed a genome wide association study (GWAS) to identify the genetic variants and associated biological traits that underlie the “expression” of HTN-related brain changes, i.e., the individualized SPARE-HTN index. Method SPARE-HTN model was trained on the large multi-study iSTAGING dataset, with regional GM volumes from T1-weighted images and lobar WMH volumes from T2-weighted FLaiR images used as imaging features. GWAS was carried out in a subset of N = 7490 (46% Female, Age = 65.5±7 years) hypertensive participants from UK-Biobank. A GWAS of SPARE-HTN scores was run using linear regression with Plink, correcting for the top 40 genetic principal components, age, sex, and intracranial volume. Significant SNPs were identified and mapped to functional genes using the Functional Mapping and Annotation (FUMA) platform; and candidate SNPs were mapped to the GWAS catalog. Result SPARE-HTN was associated with regional atrophy most prominent in perisylvian and temporal cortex and increased WMH volumes, particularly in frontal white matter. SPARE-HTN scores showed better discriminative power between normal and stage 1 participants (Cohen’s-d effect size, d = 0.2) and stage 2 (d = 0.71) hypertensive participants when compared to total WMH volume (d = 0.04 and 0.38, respectively). GWAS identified N = 321 independently significant SNPs, of which a subset N = 46 candidate SNPs were mapped to 6 genes (ICA1L, CARF, WdR12, NBEAL1, KRT8P15, CYP20A1) in Chromosome 2 (Figure 2). These genes were previously reported to be associated with several cardiovascular conditions including coronary
Multi-organ biological aging clocks across different organ systems have been shown to predict human disease and mortality. Here, we extend this multi-organ framework to plasma metabolomics, developing five organ-speci...
Background We sought to validate two structural MRI-based brain health models: Spatial Pattern of Atrophy for REcognition of Alzheimer’s disease (SPARE-Ad) and SPARE-Brain Age Gap (SPARE-BAG), which estimates the dis...
Background We sought to validate two structural MRI-based brain health models: Spatial Pattern of Atrophy for REcognition of Alzheimer’s disease (SPARE-Ad) and SPARE-Brain Age Gap (SPARE-BAG), which estimates the discrepancy between biological brain age and chronological age. These models' generalization to non-amnestic Ad (naAd) syndromes and associations with positron emission tomography (PET) and plasma biomarkers remain underinvestigated. We hypothesized that SPARE-Ad scores in naAd would be lower (less abnormal) than in amnestic Ad (aAd) but elevated (more abnormal) relative to controls; and that SPARE-Ad but not SPARE-BAG scores would be associated with PET and plasma biomarkers of Ad. Method SPARE-Ad and SPARE-BAG scores were estimated for each of 1607 MRI scans from 277 cognitively normal adults (62.8% female; mean age = 69.5 years) and 902 clinical participants (54.2% female; mean age = 73.1 years), including 585 with amnestic mild cognitive impairment (aMCI) or aAd; 56 with naAd syndromes; 28 with vascular disease; 28 with Lewy body disorders (LBd); 18 with suspected frontotemporal lobar degeneration (FTLd); 56 with non-amnestic MCI of uncertain etiology; and 131 with other clinical diagnoses. We used mixed effects models adjusting for age, sex, and global cognition to test group differences in SPARE-Ad and SPARE-BAG. Additionally, we assessed associations with tau (n = 122) and amyloid-beta (n = 199) PET imaging and plasma-based phosphorylated tau-181 (p-tau181) and glial fibrillary acidic protein (GFAP) (n = 358). Result SPARE-Ad scores were elevated vs. controls in aMCI/aAd, naAd, vascular disease, FTLd, and naMCI (all p<0.003) but not in LBd or other diagnoses (p>0.1). NaAd patients had lower SPARE-Ad (p<0.02) but higher SPARE-BAG scores (p<0.02) than aMCI/aAd patients. SPARE-Ad scores were positively associated with mean cortical tau PET uptake, amyloid PET positivity, and plasma p-tau181 and GFAP (all p<0.001). In contrast, SPARE-BAG scores were not
暂无评论