727 research outputs found
Cerebral microbleeds: Spatial distribution implications
Cerebral microbleeds are considered an imaging marker of cerebral small vessel disease. The location of microbleeds is thought to reflect the underlying pathology. Microbleeds in the deep and infratentorial region are thought to reflect hypertensive arteriopathy whereas lobar microbleeds are associated clinically with cerebral amyloid angiopathy (CAA). Aside from patient populations, microbleeds are frequently observed in seemingly asymptomatic populations. Moreover, many elderly, both in clinical and preclinical populations, have multiple coexisting pathologies in their brains, which complicates the interpretation of cerebral microbleeds, especially early in the clinical course. In this commentary, we discuss the influence of the strongest genetic risk factor for CAA, Apolipoprotein E (APOE), in the spatial distribution of microbleeds, and we additionally address issues in interpretation and implication of the location of microbleeds in clinical and asymptomatic populations
Increased gravitational force reveals the mechanical, resonant nature of physiological tremor
Human physiological hand tremor has a resonant component. Proof of this is that its frequency can be modified by adding mass. However, adding mass also increases the load which must be supported. The necessary force requires muscular contraction which will change motor output and is likely to increase limb stiffness. The increased stiffness will partly offset the effect of the increased mass and this can lead to the erroneous conclusion that factors other than resonance are involved in determining tremor frequency. Using a human centrifuge to increase head-to-foot gravitational field strength, we were able to control for the increased effort by increasing force without changing mass. This revealed that the peak frequency of human hand tremor is 99% predictable on the basis of a resonant mechanism. We ask what, if anything, the peak frequency of physiological tremor can reveal about the operation of the nervous system.This work was funded by a BBSRC Industry Interchange Award
to J.P.R.S. and R.F.R. C.J.O. was funded by BBSRC grant
BB/I00579X/1. C.A.V. was funded by A∗Midex (Aix-Marseille
Initiative of Excellence
Progression of arterial calcifications:what, where, and in whom?
Objectives: There is a lack of information on the development of arteriosclerosis over time. This study aims to assess long-term sex-specific changes in arterial calcifications in five arteries, and the influence of cardiovascular risk factors hereon. Methods: From a population-based cohort, 807 participants (mean baseline age, 65.8; SD, 4.2) underwent a non-contrast computed tomography (CT) examination between 2003 and 2006, and after a median follow-up of 14 years. We assessed incidences and changes in volumes of coronary artery calcification (CAC), aortic arch calcification (AAC), extracranial (ECAC) and intracranial carotid artery calcification (ICAC), and vertebrobasilar artery calcification (VBAC). We investigated the simultaneous presence of severe progression (upper quartile of percentual change volumes). Associations of cardiovascular risk factors with changes in calcification volumes were assessed using multivariate linear regression models. Results: The difference in AAC was most substantial; the median volume (mm3) increased from of 129 to 916 in men and from 93 to 839 in women. For VBAC, no change in volumes was observed though more than a quarter of participants without baseline VBAC developed VBAC during follow-up. Severe progression was most often observed in only one artery at the same time. Hypertension was most consistently associated with increase in calcifications. Associations of diabetes, hypercholesterolemia, and smoking with changes in calcifications varied across arteries and sex. Conclusions: We found a considerable incidence and increase in volumes of calcifications in different arteries, over a 14-year time interval. Cardiovascular risk factors were associated with increase of calcifications with sex-specific differential effects across arteries. Clinical relevance statement: There is a considerable incidence and increase in volumes of calcifications in different arteries, over a 14-year time interval. Cardiovascular risk factors are associated with increase of calcifications with sex-specific differential effects across arteries; thus, assessing changes in only one artery may thus not provide a good reflection of the systemic development of arteriosclerosis. Key Points: • Assessing change in arterial calcification in only one artery does not reflect the systemic development of arterial calcification. • Cardiovascular risk factors are associated with progression of arterial calcifications. • Progression of arterial calcification is sex and artery-specific. Graphical Abstract: [Figure not available: see fulltext.].</p
Progression of arterial calcifications:what, where, and in whom?
Objectives: There is a lack of information on the development of arteriosclerosis over time. This study aims to assess long-term sex-specific changes in arterial calcifications in five arteries, and the influence of cardiovascular risk factors hereon. Methods: From a population-based cohort, 807 participants (mean baseline age, 65.8; SD, 4.2) underwent a non-contrast computed tomography (CT) examination between 2003 and 2006, and after a median follow-up of 14 years. We assessed incidences and changes in volumes of coronary artery calcification (CAC), aortic arch calcification (AAC), extracranial (ECAC) and intracranial carotid artery calcification (ICAC), and vertebrobasilar artery calcification (VBAC). We investigated the simultaneous presence of severe progression (upper quartile of percentual change volumes). Associations of cardiovascular risk factors with changes in calcification volumes were assessed using multivariate linear regression models. Results: The difference in AAC was most substantial; the median volume (mm3) increased from of 129 to 916 in men and from 93 to 839 in women. For VBAC, no change in volumes was observed though more than a quarter of participants without baseline VBAC developed VBAC during follow-up. Severe progression was most often observed in only one artery at the same time. Hypertension was most consistently associated with increase in calcifications. Associations of diabetes, hypercholesterolemia, and smoking with changes in calcifications varied across arteries and sex. Conclusions: We found a considerable incidence and increase in volumes of calcifications in different arteries, over a 14-year time interval. Cardiovascular risk factors were associated with increase of calcifications with sex-specific differential effects across arteries. Clinical relevance statement: There is a considerable incidence and increase in volumes of calcifications in different arteries, over a 14-year time interval. Cardiovascular risk factors are associated with increase of calcifications with sex-specific differential effects across arteries; thus, assessing changes in only one artery may thus not provide a good reflection of the systemic development of arteriosclerosis. Key Points: • Assessing change in arterial calcification in only one artery does not reflect the systemic development of arterial calcification. • Cardiovascular risk factors are associated with progression of arterial calcifications. • Progression of arterial calcification is sex and artery-specific. Graphical Abstract: [Figure not available: see fulltext.].</p
AI-based association analysis for medical imaging using latent-space geometric confounder correction
AI has greatly enhanced medical image analysis, yet its use in
epidemiological population imaging studies remains limited due to visualization
challenges in non-linear models and lack of confounder control. Addressing
this, we introduce an AI method emphasizing semantic feature interpretation and
resilience against multiple confounders. Our approach's merits are tested in
three scenarios: extracting confounder-free features from a 2D synthetic
dataset; examining the association between prenatal alcohol exposure and
children's facial shapes using 3D mesh data; exploring the relationship between
global cognition and brain images with a 3D MRI dataset. Results confirm our
method effectively reduces confounder influences, establishing less confounded
associations. Additionally, it provides a unique visual representation,
highlighting specific image alterations due to identified correlations.Comment: 18 pages; 7 figure
Learning unbiased group-wise registration (LUGR) and joint segmentation: evaluation on longitudinal diffusion MRI
Analysis of longitudinal changes in imaging studies often involves both
segmentation of structures of interest and registration of multiple timeframes.
The accuracy of such analysis could benefit from a tailored framework that
jointly optimizes both tasks to fully exploit the information available in the
longitudinal data. Most learning-based registration algorithms, including joint
optimization approaches, currently suffer from bias due to selection of a fixed
reference frame and only support pairwise transformations. We here propose an
analytical framework based on an unbiased learning strategy for group-wise
registration that simultaneously registers images to the mean space of a group
to obtain consistent segmentations. We evaluate the proposed method on
longitudinal analysis of a white matter tract in a brain MRI dataset with 2-3
time-points for 3249 individuals, i.e., 8045 images in total. The
reproducibility of the method is evaluated on test-retest data from 97
individuals. The results confirm that the implicit reference image is an
average of the input image. In addition, the proposed framework leads to
consistent segmentations and significantly lower processing bias than that of a
pair-wise fixed-reference approach. This processing bias is even smaller than
those obtained when translating segmentations by only one voxel, which can be
attributed to subtle numerical instabilities and interpolation. Therefore, we
postulate that the proposed mean-space learning strategy could be widely
applied to learning-based registration tasks. In addition, this group-wise
framework introduces a novel way for learning-based longitudinal studies by
direct construction of an unbiased within-subject template and allowing
reliable and efficient analysis of spatio-temporal imaging biomarkers.Comment: SPIE Medical Imaging 2021 (oral
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