Diffusion Tensor Imaging of the Olfactory System in Older Adults With and Without Hyposmia

Objectives: To compare gray matter microstructural characteristics of higher-order olfactory regions among older adults with and without hyposmia.Methods: Data from the Brief Smell Identification Test (BSIT) were obtained in 1998–99 for 265 dementia-free adults from the Health, Aging, and Body Composition study (age at BSIT: 74.9 ± 2.7; 62% White; 43% male) who received 3T diffusion tensor imaging in 2006–08 [Interval of time: mean (SD): 8.01 years (0.50)], Apolipoprotein (ApoEε4) genotypes, and repeated 3MS assessments until 2011–12. Cognitive status (mild cognitive impairment, dementia, normal cognition) was adjudicated in 2011–12. Hyposmia was defined as BSIT ≤ 8. Microstructural integrity was quantified by mean diffusivity (MD) in regions of the primary olfactory cortex amygdala, orbitofrontal cortex (including olfactory cortex, gyrus rectus, the orbital parts of the superior, middle, and inferior frontal gyri, medial orbital part of the superior frontal gyrus), and hippocampus. Multivariable regression models were adjusted for total brain atrophy, demographics, cognitive status, and ApoEε4 genotype.Results: Hyposmia in 1998–99 (n = 57, 21.59%) was significantly associated with greater MD in 2006–08, specifically in the orbital part of the middle frontal gyrus, and amygdala, on the right [adjusted beta (p value): 0.414 (0.01); 0.527 (0.01); respectively].Conclusion: Older adults with higher mean diffusivity in regions important for olfaction are more likely to have hyposmia up to ten years prior. Future studies should address whether hyposmia can serve as an early biomarker of brain microstructural abnormalities for older adults with a range of cognitive functions, including those with normal cognition.

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Tract Specificity of Age Effects on Diffusion Tensor Imaging Measures of White Matter Health

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.628865 ◽

2021 ◽

Vol 13 ◽

Author(s):

Stephanie Matijevic ◽

Lee Ryan

Keyword(s):

Older Adults ◽

Diffusion Tensor Imaging ◽

Individual Differences ◽

White Matter ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

White Matter Integrity ◽

White Matter Tracts ◽

Apoe Ε4 ◽

Age Related

Well-established literature indicates that older adults have poorer cerebral white matter integrity, as measured through diffusion tensor imaging (DTI). Age differences in DTI have been observed widely across white matter, although some tracts appear more sensitive to the effects of aging than others. Factors like APOE ε4 status and sex may contribute to individual differences in white matter integrity that also selectively impact certain tracts, and could influence DTI changes in aging. The present study explored the degree to which age, APOE ε4, and sex exerted global vs. tract specific effects on DTI metrics in cognitively healthy late middle-aged to older adults. Data from 49 older adults (ages 54–92) at two time-points separated by approximately 2.7 years were collected. DTI metrics, including fractional anisotropy (FA) and mean diffusivity (MD), were extracted from nine white matter tracts and global white matter. Results showed that across timepoints, FA and MD increased globally, with no tract-specific changes observed. Baseline age had a global influence on both measures, with increasing age associated with lower FA and higher MD. After controlling for global white matter FA, age additionally predicted FA for the genu, callosum body, inferior fronto-occipital fasciculus (IFOF), and both anterior and posterior cingulum. Females exhibited lower global FA on average compared to males. In contrast, MD was selectively elevated in the anterior cingulum and superior longitudinal fasciculus (SLF), for females compared to males. APOE ε4 status was not predictive of either measure. In summary, these results indicate that age and sex are associated with both global and tract-specific alterations to DTI metrics among a healthy older adult cohort. Older women have poorer white matter integrity compared to older men, perhaps related to menopause-induced metabolic changes. While age-related alterations to white matter integrity are global, there is substantial variation in the degree to which tracts are impacted, possibly as a consequence of tract anatomical variability. The present study highlights the importance of accounting for global sources of variation in DTI metrics when attempting to investigate individual differences (due to age, sex, or other factors) in specific white matter tracts.

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Multi-Dimensional Diffusion Tensor Imaging Biomarkers for Cognitive Decline From the Preclinical Stage: A Study of Post-stroke Small Vessel Disease

Frontiers in Neurology ◽

10.3389/fneur.2021.687959 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jing Du ◽

Hong Zhu ◽

Ling Yu ◽

Peiwen Lu ◽

Yage Qiu ◽

...

Keyword(s):

Cognitive Impairment ◽

Diffusion Tensor Imaging ◽

White Matter ◽

Diffusion Tensor ◽

Small Vessel Disease ◽

Mean Diffusivity ◽

Cognitive Status ◽

Preclinical Stage ◽

Vessel Disease ◽

Dimensional Diffusion

Objectives: We aim to investigate whether multi-dimensional diffusion tensor imaging (DTI) measures can sensitively identify different cognitive status of cerebral small vessel disease (CSVD) and to explore the underlying pattern of white matter disruption in CSVD.Methods: Two hundred and two participants were recruited, composed of 99 CSVD patients with mild cognitive impairment (VaMCI) and 60 with no cognitive impairment (NCI) and 43 healthy subjects as normal controls (NC). Full domain neuropsychological tests and diffusion-weighted imaging were performed on each subject. DTI metrics such as fractional anisotropy (FA), mean diffusivity (MD), the skeletonized mean diffusivity (PSMD), and structural brain network measures including network strength, global efficiency (EGlobal), and local efficiency (ELocal) were calculated. Region of interest (ROI) analysis of 42 white matter tracts was performed to examine the regional anatomical white matter disruption for each group.Results: Significant differences of multiple cognitive test scores across all cognitive domains especially processing and executive function existed among the three groups. DTI measures (FA, MD, and PSMD) showed significant group difference with the cognitive status changing. FA and EGlobal showed significant correlation with processing speed, executive function, and memory. ROI analysis found that white matter integrity impairment occurred from the preclinical stage of vascular cognitive impairment (VCI) due to CSVD. These lesions in the NCI group mainly involved some longitudinal fibers such as right superior longitudinal fasciculus (SLF-R), right superior fronto-occipital fasciculus (SFO-R), and right uncinate fasciculus (UNC-R), which might be more vulnerable to the cerebrovascular aging and disease process.Conclusions: DTI measures are sensitive neuroimaging markers in detecting the early cognitive impairment and able to differentiate the different cognitive status due to CSVD. Subtle changes of some vulnerable white matter tracts may be observed from the preclinical stage of VCI and have a local to general spreading pattern during the disease progression.

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White Matter Integrity Predicts Delay Discounting Behavior in 9- to 23-Year-Olds: A Diffusion Tensor Imaging Study

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2009.21107 ◽

2009 ◽

Vol 21 (7) ◽

pp. 1406-1421 ◽

Cited By ~ 119

Author(s):

Elizabeth A. Olson ◽

Paul F. Collins ◽

Catalina J. Hooper ◽

Ryan Muetzel ◽

Kelvin O. Lim ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

White Matter ◽

Delay Discounting ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

Imaging Study ◽

Temporal Lobes ◽

Brain White Matter ◽

Independent Effects ◽

Age Range

Healthy participants (n = 79), ages 9–23, completed a delay discounting task assessing the extent to which the value of a monetary reward declines as the delay to its receipt increases. Diffusion tensor imaging (DTI) was used to evaluate how individual differences in delay discounting relate to variation in fractional anisotropy (FA) and mean diffusivity (MD) within whole-brain white matter using voxel-based regressions. Given that rapid prefrontal lobe development is occurring during this age range and that functional imaging studies have implicated the prefrontal cortex in discounting behavior, we hypothesized that differences in FA and MD would be associated with alterations in the discounting rate. The analyses revealed a number of clusters where less impulsive performance on the delay discounting task was associated with higher FA and lower MD. The clusters were located primarily in bilateral frontal and temporal lobes and were localized within white matter tracts, including portions of the inferior and superior longitudinal fasciculi, anterior thalamic radiation, uncinate fasciculus, inferior fronto-occipital fasciculus, corticospinal tract, and splenium of the corpus callosum. FA increased and MD decreased with age in the majority of these regions. Some, but not all, of the discounting/DTI associations remained significant after controlling for age. Findings are discussed in terms of both developmental and age-independent effects of white matter organization on discounting behavior.

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Structural brain changes after 4 wk of unilateral strength training of the lower limb

Journal of Applied Physiology ◽

10.1152/japplphysiol.00277.2012 ◽

2013 ◽

Vol 115 (2) ◽

pp. 167-175 ◽

Cited By ~ 23

Author(s):

H. S. Palmer ◽

A. K. Håberg ◽

M. S. Fimland ◽

G. M. Solstad ◽

V. Moe Iversen ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Strength Training ◽

Isometric Contraction ◽

Healthy Adult ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

Cortical Activation ◽

Maximum Voluntary Isometric Contraction ◽

The Right ◽

Unilateral Strength Training

Strength training enhances muscular strength and neural drive, but the underlying neuronal mechanisms remain unclear. This study used magnetic resonance imaging (MRI) to identify possible changes in corticospinal tract (CST) microstructure, cortical activation, and subcortical structure volumes following unilateral strength training of the plantar flexors. Mechanisms underlying cross-education of strength in the untrained leg were also investigated. Young, healthy adult volunteers were assigned to training ( n = 12) or control ( n = 9) groups. The 4 wk of training consisted of 16 sessions of 36 unilateral isometric plantar flexions. Maximum voluntary isometric contraction torque was tested pre- and posttraining. MRI investigation included a T1-weighted scan, diffusion tensor imaging and functional MRI. Probabilistic fiber tracking of the CST was performed on the diffusion tensor imaging images using a two-regions-of-interest approach. Fractional anisotropy and mean diffusivity were calculated for the left and right CST in each individual before and after training. Standard functional MRI analyses and volumetric analyses of subcortical structures were also performed. Maximum voluntary isometric contraction significantly increased in both the trained and untrained legs of the training group, but not the control group. A significant decrease in mean diffusivity was found in the left CST following strength training of the right leg. No significant changes were detected in the right CST. No significant changes in cortical activation were observed following training. A significant reduction in left putamen volume was found after training. This study provides the first evidence for strength training-related changes in white matter and putamen in the healthy adult brain.

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Abstract P59: Peak Width of Skeletonized Mean Diffusivity Outperforms Other Diffusion Tensor Imaging Metrics as Biomarker for Cognition in Memory-Clinic Subjects With Cerebral Amyloid Angiopathy

Stroke ◽

10.1161/str.52.suppl_1.p59 ◽

2021 ◽

Vol 52 (Suppl_1) ◽

Author(s):

Maria Clara Zanon Zotin ◽

Dorothee Schoemaker ◽

Valentina Perosa ◽

Martin Bretzner ◽

Lukas Sveikata ◽

...

Keyword(s):

Executive Function ◽

Diffusion Tensor Imaging ◽

Linear Regression ◽

Processing Speed ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

Amyloid Angiopathy ◽

Peak Width ◽

Memory Clinic ◽

Cerebral Amyloid

Introduction: Peak width of skeletonized mean diffusivity (PSMD) is a novel fully automated diffusion tensor imaging (DTI) marker that has been consistently associated with cognition in cerebral small vessel disease (SVD) cohorts, including cerebral amyloid angiopathy (CAA). We hypothesized that PSMD would be more strongly associated with cognitive performance compared to other conventional DTI metrics in our CAA sample. Methods: We recruited non-demented subjects with probable-CAA from a single-center memory-clinic cohort. We analyzed structural MRIs to compute a validated CAA burden score (0-6 points scale, based on the following MRI features: lobar microbleeds, superficial siderosis, perivascular spaces in centrum semiovale, and white matter hyperintensities). PSMD was obtained using a freely available script ( www.psmd-marker.com ). We used the same skeleton-mask to compute: mean of skeletonized mean diffusivity (mean MD) and mean of skeletonized fractional anisotropy (mean FA). We used linear regression analyses to explore relationships with CAA burden score and cognitive composite scores (processing speed, executive function, memory, and language - z-scores adjusted for age, sex and education level). Results: We included 43 subjects (mean age 74.4 ± 5.9 years; 48.8% female; PSMD median [IQR]: 4.05 [3.58 - 4.80] x 10 -4 mm 2 /s). In linear regression models adjusting for age, DTI metrics were significantly associated with CAA burden score (mean FA: β = -0.563, Adj. R 2 : 0.27; p < 0.001; mean MD: β = 0.581; Adj. R 2 : 0.32; p < 0.001; PSMD: β = 0.364, Adj. R 2 : 0.12; p = 0.018). PSMD was significantly associated with cognitive performance, specifically in the domains of executive function ( β = -0.568; Adj. R 2 : 0.25; p < 0.001) and processing speed ( β = -0.447; Adj. R 2 : 0.19; p = 0.004). Other DTI metrics were not significantly associated with cognitive scores. Conclusion: In this CAA sample, all DTI metrics were associated with CAA burden scores, however, only PSMD was significantly associated with cognition, in domains that are commonly affected in vascular cognitive impairment. Our results warrant confirmation in larger samples, but support PSMD as biomarker for cognition in CAA, outperforming other conventional DTI metrics.

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Discrimination of epileptogenic lesions and perilesional white matter using diffusion tensor magnetic resonance imaging

The Neuroradiology Journal ◽

10.1177/1971400918813991 ◽

2018 ◽

Vol 32 (1) ◽

pp. 10-16

Author(s):

Alexander Rau ◽

Elias Kellner ◽

Niels A Foit ◽

Niklas Lützen ◽

Dieter H Heiland ◽

...

Keyword(s):

White Matter ◽

Fractional Anisotropy ◽

Diffusion Tensor ◽

Focal Cortical Dysplasia ◽

Mean Diffusivity ◽

Area Under The Curve ◽

P Value ◽

Radial Diffusivity ◽

Normal Appearing White Matter ◽

Diffusion Parameters

The aim of this study was to evaluate whether ganglioglioma (GGL), dysembryoplastic neuroepithelial tumour (DNET) and FCD (focal cortical dysplasia) are distinguishable through diffusion tensor imaging. Additionally, it was investigated whether the diffusion measures differed in the perilesional (pNAWM) and in the contralateral normal appearing white matter (cNAWM). Six GGLs, eight DNETs and seven FCDs were included in this study. Quantitative diffusion measures, that is, axial, radial and mean diffusivity and fractional anisotropy, were determined in the lesion identified on isotropic T2 or FLAIR-weighted images and in pNAWM and cNAWM, respectively. DNET differed from FCD in mean diffusivity, and GGL from FCD in radial diffusivity. Both types of glioneuronal tumours were different from pNAWM in fractional anisotropy and radial diffusivity. For identifying the tumour edges, threshold values for tumour-free tissue were investigated with receiver operating characteristic analyses: tumour could be separated from pNAWM at a threshold ≤ 0.32 (fractional anisotropy) or ≥ 0.56 (radial diffusivity) *10–3 mm2/s (area under the curve 0.995 and 0.990 respectively). While diffusion parameters of FCDs differed from cNAWM (radial diffusivity (*10–3 mm/s2): 0.74 ± 0.19 vs. 0.43 ± 0.05; corrected p-value < 0.001), the pNAWM could not be differentiated from the FCD.

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Diffusion tensor imaging of cerebral white matter in patients with myotonic dystrophy

Acta Radiologica ◽

10.1080/02841850510015974 ◽

2005 ◽

Vol 46 (1) ◽

pp. 104-109 ◽

Cited By ~ 23

Author(s):

H. Fukuda ◽

J. Horiguchi ◽

C. Ono ◽

T. Ohshita ◽

J. Takaba ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

White Matter ◽

Myotonic Dystrophy ◽

Normal Control ◽

Diffusion Tensor ◽

Age At Onset ◽

Mean Diffusivity ◽

Magnetic Resonance Images ◽

Microstructural Changes ◽

Control Subjects

Purpose: To determine whether myotonic dystrophy (MyD) patients have diffusion tensor abnormalities suggestive of microstructural changes in normal‐appearing white matter (NAWM). Material and Methods: Conventional and diffusion tensor magnetic resonance images of the brain were obtained in 19 MyD patients and 19 age‐matched normal control subjects. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated in white matter lesions (WMLs) and NAWM in MyD patients and in the white matter of normal control subjects. Differences between WML and NAWM values and between MyD patient and control subject values were analyzed statistically. Results: Significantly lower FA and higher MD values were found in all regions of interest in the NAWM of MyD patients than in the white matter of control subjects ( P<0.01), as well as significantly lower FA and higher MD values in WMLs than in NAWM of MyD patients ( P<0.05). There was no significant correlation of mean FA or MD values in NAWM with patient age, age at onset, or duration of illness ( P>0.1). Conclusion: Diffusion tensor imaging analysis suggests the presence of diffuse microstructural changes in NAWM of MyD patients that may play an important role in the development of disability.

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Diffusion Tensor Imaging of the Kidneys: Influence of b-Value and Number of Encoding Directions on Image Quality and Diffusion Tensor Parameters

Journal of Clinical Imaging Science ◽

10.4103/2156-7514.122323 ◽

2013 ◽

Vol 3 ◽

pp. 53 ◽

Cited By ~ 14

Author(s):

Natalie C. Chuck ◽

Günther Steidle ◽

Iris Blume ◽

Michael A. Fischer ◽

Daniel Nanz ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Image Quality ◽

Fractional Anisotropy ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

Renal Medulla ◽

Whole Body ◽

Acquisition Time ◽

Data Sets ◽

B Values

Objectives: The purpose of this study was to evaluate to which degree investment of acquisition time in more encoding directions leads to better image quality (IQ) and what influence the number of encoding directions and the choice of b-values have on renal diffusion tensor imaging (DTI) parameters. Material and Methods: Eight healthy volunteers (32.3 y ± 5.1 y) consented to an examination in a 1.5T whole-body MR scanner. Coronal DTI data sets of the kidneys were acquired with systematic variation of b-values (50, 150, 300, 500, and 700 s/mm2) and number of diffusion-encoding directions (6, 15, and 32) using a respiratory-triggered echo-planar sequence (TR/TE 1500 ms/67 ms, matrix size 128 × 128). Additionally, two data sets with more than two b-values were acquired (0, 150, and 300 s/mm2 and all six b-values). Parametrical maps were calculated on a pixel-by-pixel basis. Image quality was determined with a reader score. Results: Best IQ was visually assessed for images acquired with 15 and 32 encoding directions, whereas images acquired with six directions had significantly lower IQ ratings. Image quality, fractional anisotropy, and mean diffusivity only varied insignificantly for b-values between 300 and 500 s/mm2. In the renal medulla fractional anisotropy (FA) values between 0.43 and 0.46 and mean diffusivity (MD) values between 1.8-2.1 × 10-3 mm2/s were observed. In the renal cortex, the corresponding ranges were 0.24-0.25 (FA) and 2.2-2.8 × 10-3 mm2/s (MD). Including b-values below 300 s/mm2, notably higher MD values were observed, while FA remained constant. Susceptibility artifacts were more prominent in FA maps than in MD maps. Conclusion: In DTI of the kidneys at 1.5T, the best compromise between acquisition time and resulting image quality seems the application of 15 encoding directions with b-values between 300 and 500 s/mm2. Including lower b-values allows for assessment of fast diffusing spin components.

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Re: Prospective Associations between Diffusion Tensor Imaging Parameters and Frailty in Older Adults

Journal of the American Geriatrics Society ◽

10.1111/jgs.16456 ◽

2020 ◽

Cited By ~ 2

Author(s):

Mathieu Maltais ◽

Philipe Souto Barreto ◽

Lisa Perus ◽

Jean‐François Mangin ◽

Antoine Grigis ◽

...

Keyword(s):

Older Adults ◽

Diffusion Tensor Imaging ◽

Diffusion Tensor ◽

Imaging Parameters

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Diffusion Tensor Imaging Evaluation of Corticospinal Tract Hyperintensity in Upper Motor Neuron-Predominant ALS Patients

Journal of Aging Research ◽

10.4061/2011/481745 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

Venkateswaran Rajagopalan ◽

Didier Allexandre ◽

Guang H. Yue ◽

Erik P. Pioro

Keyword(s):

Diffusion Tensor Imaging ◽

Motor Neuron ◽

Corticospinal Tract ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

Internal Capsule ◽

Proton Density ◽

Imaging Evaluation ◽

Axonal Pathology ◽

Als Patients

Amyotrophic lateral sclerosis (ALS) patients with predominant upper motor neuron (UMN) signs occasionally have hyperintensity of corticospinal tract (CST) on T2- and proton-density-(PD-) weighted brain images. Diffusion tensor imaging (DTI) was used to assess whether diffusion parameters along intracranial CST differ in presence or absence of hyperintensity and correspond to UMN dysfunction. DTI brain scans were acquired in 47 UMN-predominant ALS patients with (n=21) or without (n=26) CST hyperintensity and in 10 control subjects. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured in four regions of interests (ROIs) along CST. Abnormalities (P<0.05) were observed in FA, AD, or RD in CST primarily at internal capsule (IC) level in ALS patients, especially those with CST hyperintensity. Clinical measures corresponded well with DTI changes at IC level. The IC abnormalities suggest a prominent axonopathy in UMN-predominant ALS and that tissue changes underlying CST hyperintensity have specific DTI changes, suggestive of unique axonal pathology.

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