Aad van der Lugt

Carotid artery segmentation and plaque quantification in CTA

A novel, slice-based, semi-automatic method for plaque segmentation and quantification in CTA of carotid arteries is introduced. The method starts with semi-automatic, levelset based, lumen segmentation initialized with three points. Pixel based GentleBoost classification is used to segment the inner and outer vessel wall region using distance from the lumen, intensity and Gaussian derivatives as features. 3D calcified regions located within the vessel wall are segmented using a similar set of features and the same classification method. Subsequently, an ellipse-shaped deformable model is fitted using the inner-outer vessel wall and calcium classification, and plaque components within the wall are characterized using HU ranges. The method is quantitatively evaluated on 5 carotid arteries. Vessel and plaque segmentation are compared to the interobserver variability. Furthermore, correlation of slice-based plaque component quantification with the ground truth values is determined. The accuracy of our method is comparable to the interobserver variability.

Tracking Brain Development and Dimensional Psychiatric Symptoms in Children: A Longitudinal Population-Based Neuroimaging Study

OBJECTIVEnPsychiatric symptomatology during childhood predicts persistent mental illness later in life. While neuroimaging methodologies are routinely applied cross-sectionally to the study of child and adolescent psychopathology, the nature of the relationship between childhood symptoms and the underlying neurodevelopmental processes remains unclear. The authors used a prospective population-based cohort to delineate the longitudinal relationship between childhood psychiatric problems and brain development.nnnMETHODnA total of 845 children participated in the study. Psychiatric symptoms were measured with the parent-rated Child Behavior Checklist at ages 6 and 10. MRI data were collected at ages 8 and 10. Cross-lagged panel models and linear mixed-effects models were used to determine the associations between psychiatric symptom ratings and quantitative anatomic and white matter microstructural measures over time.nnnRESULTSnHigher ratings for externalizing and internalizing symptoms at baseline predicted smaller increases in both subcortical gray matter volume and global fractional anisotropy over time. The reverse relationship did not hold; thus, baseline measures of gray matter and white matter were not significantly related to changes in symptom ratings over time.nnnCONCLUSIONSnChildren presenting with behavioral problems at an early age show differential subcortical and white matter development. Most neuroimaging models tend to explain brain differences observed in psychopathology as an underlying (causal) neurobiological substrate. However, the present work suggests that future neuroimaging studies showing effects that are pathogenic in nature should additionally explore the possibility of the downstream effects of psychopathology on the brain.

Association of Coffee Consumption with MRI Markers and Cognitive Function: A Population-Based Study

BACKGROUNDnCoffee is one of the most widely consumed beverages worldwide and has been of considerable interest in research on cognition and dementia.nnnOBJECTIVEnTo investigate the effect of coffee on preclinical brain MRI markers of dementia and cognitive performance.nnnMETHODSnIn 2,914 participants from the population-based Rotterdam Study (mean age: 59.3±7.2 years, 55% females), we assessed coffee consumption, performed brain MRI, and assessed cognition at baseline. To study cognitive change, cognitive assessment was repeated after 5 years of follow-up. Coffee consumption was analyzed continuously (per cup increase) and in categories (0-1,u200a>1-3,u200a>3 cups/day). Using logistic and linear regression, associations of coffee consumption with lacunar infarcts and brain tissue volumes on MRI, and cognitive performance (cross-sectional and longitudinal) were investigated, adjusting for relevant confounders.nnnRESULTSnWe found that higher coffee consumption was associated with a lower prevalence of lacunar infarcts [odds ratio per cup increase: 0.88 (95% CI:0.79;0.98)], and smaller hippocampal volume [difference: -0.01 (95% CI:-0.02;0.00)]. Also, we found that the highest category of coffee consumption was associated with better performance on the Letter Digit Substitution Task [difference: 1.13(95% CI:0.39;1.88)], Word Fluency test [0.74(95% CI:0.04,1.45)], Stroop interference task [1.82(95% CI:0.23;3.41)], and worse performance on the 15-Word Learning test delayed recall [-0.38(95% CI:-0.74;-0.02)]. These associations were not found when cognition was analyzed longitudinally.nnnCONCLUSIONnWe found complex associations between coffee consumption, brain structure, and cognition. Higher coffee consumption was cross-sectionally associated with a lower occurrence of lacunar infarcts and better executive function, but also with smaller hippocampal volume and worse memory function.

MRI Based Quantification of Outflow Boundary Conditions for Computational Fluid Dynamics of Stenosed Human Carotid Arteries

Many studies have been performed to investigate the contribution of wall shear stress (WSS) to pathophysiological processes related to atherosclerosis (Groen, et al., 2007; Kaazempur-Mofrad, et al., 2004; Ku, et al., 1985). To investigate these relationships in stenosed human carotid arteries, accurate assessment of WSS is required. WSS can be calculated in vivo by coupling medical imaging and computational fluid dynamics (CFD). However, often patient specific in- and outflow information is unavailable. Therefore flow through the common (CCA), internal (ICA) and external (ECA) carotid artery needs to be estimated. Murray’s law (Murray, 1926) is often used for that purpose, but it is unclear whether this law holds for stenosed arteries. The goal of this study was to determine outflow boundary conditions for WSS calculations in stenosed carotid bifurcations. Therefore we first quantified the flow (Q) in carotid arteries with different degrees of area stenosis using phase-contrast MRI and determined an empirical relation between outflow-ratios and degree of area stenosis. Secondly we compared the estimated flow ratio based on Murray’s law to the ones measured by MRI. Finally we analyzed the influence of the outflow conditions on the calculated WSS using CFD.Copyright