<p>Background: This study examines the relationship between delusional severity in cognitively impaired adults with automatically computed volume and texture biomarkers from the Normal Appearing Brain Matter (NABM) in FLAIR MRI. Methods: Patients with mild cognitive impairment (MCI, n = 24) and Alzheimer's Disease (AD, n = 18) with delusions of varying severities based on Neuropsychiatric Inventory-Questionnaire (NPI-Q) (1-mild, 2-moderate, 3-severe) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) were analyzed for this task. The NABM region, which is gray matter (GM) and white matter (WM) combined, was automatically segmented in FLAIR MRI volumes with intensity standardization and thresholding. Three imaging biomarkers were computed from this region, including NABM volume and two texture markers called "Integrity" and "Damage". Together, these imaging biomarkers quantify structural changes in brain volume, microstructural integrity and tissue damage. Multivariable regression was used to investigate relationships between imaging biomarkers and delusional severities (1, 2 and 3). Sex, age, education, APOE4 and baseline cerebrospinal fluid (CSF) tau were included as co-variates. Results: Biomarkers were extracted from a total of 42 participants with longitudinal time points representing 164 imaging volumes. Significant associations were found for all three NABM biomarkers between delusion level 3 and level 1. Integrity was also sensitive enough to show differences between delusion level 1 and delusion level 2. A significant specified interaction was noted with severe delusions (level 3) and CSF tau for all imaging biomarkers (p < 0.01). APOE4 homozygotes were also significantly related to the biomarkers. Conclusion: Cognitively impaired older adults with more severe delusions have greater global brain disease burden in the WM and GM combined (NABM) as measured using FLAIR MRI. Relative to patients with mild delusions, tissue degeneration in the NABM was more pronounced in subjects with higher delusional symptoms, with a significant association with CSF tau. Future studies are required to establish potential tau-associated mechanisms of increased delusional severity. </p>
Background: This study examines the relationship between delusional severity in cognitively impaired adults with automatically computed volume and texture biomarkers from the Normal Appearing Brain Matter (NABM) in FLAIR MRI. Methods: Patients with mild cognitive impairment (MCI, n = 24) and Alzheimer’s Disease (AD, n = 18) with delusions of varying severities based on Neuropsychiatric Inventory-Questionnaire (NPI-Q) (1—mild, 2—moderate, 3—severe) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) were analyzed for this task. The NABM region, which is gray matter (GM) and white matter (WM) combined, was automatically segmented in FLAIR MRI volumes with intensity standardization and thresholding. Three imaging biomarkers were computed from this region, including NABM volume and two texture markers called “Integrity” and “Damage”. Together, these imaging biomarkers quantify structural changes in brain volume, microstructural integrity and tissue damage. Multivariable regression was used to investigate relationships between imaging biomarkers and delusional severities (1, 2 and 3). Sex, age, education, APOE4 and baseline cerebrospinal fluid (CSF) tau were included as co-variates. Results: Biomarkers were extracted from a total of 42 participants with longitudinal time points representing 164 imaging volumes. Significant associations were found for all three NABM biomarkers between delusion level 3 and level 1. Integrity was also sensitive enough to show differences between delusion level 1 and delusion level 2. A significant specified interaction was noted with severe delusions (level 3) and CSF tau for all imaging biomarkers (p < 0.01). APOE4 homozygotes were also significantly related to the biomarkers. Conclusion: Cognitively impaired older adults with more severe delusions have greater global brain disease burden in the WM and GM combined (NABM) as measured using FLAIR MRI. Relative to patients with mild delusions, tissue degeneration in the NABM was more pronounced in subjects with higher delusional symptoms, with a significant association with CSF tau. Future studies are required to establish potential tau-associated mechanisms of increased delusional severity.
Background Delusions in older adults correlate with white matter lesion burden [1], though the relationship with white matter texture (WMT) is unclear. White matter texture is the tissue organization in normal‐appearing brain matter (NABM) related to overall diffusion capabilities. Method Using NPI‐Q scores from the ADNI data set, a cognitively mixed sample of patients with delusions was extracted. Delusional severity was ranked from 1‐3 (1 being the lowest severity) based on the NPI‐Q scores along with downloads of FLAIR MRI volumes for each subject. Subjects and volumes were analyzed in each severity group. Normal‐appearing brain matter of FLAIR images were extracted with validated in‐house brain extraction and intensity standardization algorithms [2]. Volume texture maps representing the correlation in the NABM for each FLAIR image were generated as per Khademi et. al [3]. Result Boxplots for the NABM texture measures are shown for groups 1, 2 and 3 in Figure 1. Subjects with high delusional severity (group 3) had the most noticeable change in WMT relative to lowest delusional severity (group 1). Group 3 had a higher spatial correlation value of 6.0947 e+03 +/‐ 592.6178 than group 1 with values of 5.7630 e+03 +/‐ 832.5040. A higher value indicates more spatial correlation among pixels. This suggests that there are larger regions that are smooth in Group 3 compared to Group 1, indicating less WM “structure” in the more severe delusion group. Conclusion The severity of delusions in a cognitively diverse sample of older adults correlates with abnormalities in white matter texture, though further research is required to further validate our findings. References: [1] K. Misquitta, M. Dadar, D. L. Collins and M. C. Tartaglia and Alzheimer’s Disease Neuroimaging Initiative, White matter hyperintensities and neuropsychiatric symptoms in Alzheimer’s disease and mild cognitive impairment, bioRxiv, 2019. [2] A. Khademi, B. Reiche, G. Arezza, Method and System for Standardized Processing of MR Images, PCT Patent Application No. PCT/CA2018/051606, Filed.US. December 2018. [3] A. Khademi, D. Hosseinzadeh, A. Venetsanopoulos and A. Moody, "Nonparametric statistical tests for exploration of correlation and nonstationarity in images," 2009 16th International Conference on Digital Signal Processing, Santorini‐Hellas, 2009, pp 1‐6.
<p>A novel biomarker panel was proposed to quantify macro and microstructural biomarkers from the normal- appearing brain matter (NABM) in multicentre fluid-attenuation inversion recovery (FLAIR) MRI. The NABM is composed of the white and gray matter regions of the brain, with the lesions and cerebrospinal fluid removed. The primary hypothesis was that NABM biomarkers from FLAIR MRI are related to cognitive outcome as determined by MoCA score. There were three groups of features designed for this task based on 1) texture: microstructural integrity (MII), macrostructural damage (MAD), microstructural damage (MID), 2) intensity: median, skewness, kurtosis and 3) volume: NABM to ICV volume ratio. Biomarkers were extracted from over 1400 imaging volumes from more than 87 centres and unadjusted ANOVA analysis revealed significant differences in means of the MII, MAD, and NABM volume biomarkers across all cognitive groups. In an adjusted ANCOVA model, a significant relationship between MoCA categories was found that was dependent on subject age for MII, MAD, intensity, kurtosis and NABM volume biomarkers. These results demonstrate that structural brain changes in the NABM are related to cognitive outcome (with different relationships depending on the age of the subjects). Therefore these biomarkers have high potential for clinical translation. As a secondary hypothesis, we investigated whether texture features from FLAIR MRI can quantify microstructural changes related to how “structured” or “damaged” the tissue is. Based on correlation analysis with diffusion weighted MRI (dMRI), it was shown that FLAIR MRI texture biomarkers (MII and MAD) had strong correlations to mean diffusivity (MD) which is related to tissue degeneration in the GM and WM regions. As FLAIR MRI is routinely collected for clinical neurological examinations, novel biomarkers from FLAIR MRI could be used to supplement current clinical biomarkers and for monitoring disease progression. Biomarkers could also be used to stratify patients into homogeneous disease subgroups for clinical trials, or to learn more about mechanistic development of dementia disease.</p>
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