Moderating Effect of Cortical Thickness on BOLD Signal Variability Age-Related Changes

The time course of neuroanatomical structural and functional measures across the lifespan is commonly reported in association with aging. Blood oxygen-level dependent signal variability, estimated using the standard deviation of the signal, or “BOLDSD,” is an emerging metric of variability in neural processing, and has been shown to be positively correlated with cognitive flexibility. Generally, BOLDSD is reported to decrease with aging, and is thought to reflect age-related cognitive decline. Additionally, it is well established that normative aging is associated with structural changes in brain regions, and that these predict functional decline in various cognitive domains. Nevertheless, the interaction between alterations in cortical morphology and BOLDSD changes has not been modeled quantitatively. The objective of the current study was to investigate the influence of cortical morphology metrics [i.e., cortical thickness (CT), gray matter (GM) volume, and cortical area (CA)] on age-related BOLDSD changes by treating these cortical morphology metrics as possible physiological confounds using linear mixed models. We studied these metrics in 28 healthy older subjects scanned twice at approximately 2.5 years interval. Results show that BOLDSD is confounded by cortical morphology metrics. Respectively, changes in CT but not GM volume nor CA, show a significant interaction with BOLDSD alterations. Our study highlights that CT changes should be considered when evaluating BOLDSD alternations in the lifespan

Semi-automatic segmentation of the fetal brain from magnetic resonance imaging

Background: Volumetric measurements of fetal brain maturation in the third trimester of pregnancy are key predictors of developmental outcomes. Improved understanding of fetal brain development trajectories may aid in identifying and clinically managing at-risk fetuses. Currently, fetal brain structures in magnetic resonance images (MRI) are often manually segmented, which requires both time and expertise. To facilitate the targeting and measurement of brain structures in the fetus, we compared the results of five segmentation methods applied to fetal brain MRI data to gold-standard manual tracings. Methods: Adult women with singleton pregnancies (n = 21), of whom five were scanned twice, approximately 3 weeks apart, were recruited [26 total datasets, median gestational age (GA) = 34.8, IQR = 30.9–36.6]. T2-weighted single-shot fast spin echo images of the fetal brain were acquired on 1.5T and 3T MRI scanners. Images were first combined into a single 3D anatomical volume. Next, a trained tracer manually segmented the thalamus, cerebellum, and total cerebral volumes. The manual segmentations were compared with five automatic methods of segmentation available within Advanced Normalization Tools (ANTs) and FMRIB’s Linear Image Registration Tool (FLIRT) toolboxes. The manual and automatic labels were compared using Dice similarity coefficients (DSCs). The DSC values were compared using Friedman’s test for repeated measures. Results: Comparing cerebellum and thalamus masks against the manually segmented masks, the median DSC values for ANTs and FLIRT were 0.72 [interquartile range (IQR) = 0.6–0.8] and 0.54 (IQR = 0.4–0.6), respectively. A Friedman’s test indicated that the ANTs registration methods, primarily nonlinear methods, performed better than FLIRT (p \u3c 0.001). Conclusion: Deformable registration methods provided the most accurate results relative to manual segmentation. Overall, this semi-automatic subcortical segmentation method provides reliable performance to segment subcortical volumes in fetal MR images. This method reduces the costs of manual segmentation, facilitating the measurement of typical and atypical fetal brain development

Implementation of Clinical Research Trials Using Web-Based and Mobile Devices: challenges and solutions.

BACKGROUND: With the increasing implementation of web-based, mobile health interventions in clinical trials, it is crucial for researchers to address the security and privacy concerns of patient information according to high ethical standards. The full process of meeting these standards is often made more complicated due to the use of internet-based technology and smartphones for treatment, telecommunication, and data collection; however, this process is not well-documented in the literature. RESULTS: The Smart Heart Trial is a single-arm feasibility study that is currently assessing the effects of a web-based, mobile lifestyle intervention for overweight and obese children and youth with congenital heart disease in Southwestern Ontario. Participants receive telephone counseling regarding nutrition and fitness; and complete goal-setting activities on a web-based application. This paper provides a detailed overview of the challenges the study faced in meeting the high standards of our Research Ethics Board, specifically regarding patient privacy. CONCLUSION: We outline our solutions, successes, limitations, and lessons learned to inform future similar studies; and model much needed transparency in ensuring high quality security and protection of patient privacy when using web-based and mobile devices for telecommunication and data collection in clinical research

GPU-Based Real-Time Beating Heart Volume Rendering Using Dynamic 3D Texture Binding

Simulation and real-time display of dynamic three-dimensional (3D) cardiac images has important applications in minimally invasive image-guided cardiac surgery and therapy. However, in practice, the high computational cost usually prohibits its application in a real-time medical environment, or else the low image quality does not satisfy the clinical requirements. Surface based models or orthogonal planes are often employed instead, but in the process important intra cardiac data are lost, and intuitive spatial anatomical relationships are eliminated. In this paper, we first take advantage of the programmability, parallelism and increased computational precision of modern graphics processing units (GPUs) to build a real-time 3D rendering engine based on ray-casting, directly running on the graphics vertex and fragment processors, in which the OpenGL Shading Language (GLSL) is utilized as a GPU programming API. This approach provides enhanced image quality similar to software-based implementations, but its rendering speed is competitive with the traditional but inferior quality slice based volume rendering approaches. Then, we propose a new dynamic volume texture binding scheme, and embedded it into our 3D rendering engine to permit real-time visualize the dynamic beating heart

Fetal Response to a Maternal Internal Auditory Stimulus

Background: Functional MRI (fMRI) is a noninvasive method to investigate the neural correlates of brain development. Insight into the rapidly developing brain in utero is limited, and fetal fMRI can be used to gain a greater understanding of the developmental process. Fetal brain fMRI is typically limited to resting-state fMRI due to the difficulty to instruct or provide a stimulus to the fetus. Previous studies have employed auditory task fMRI with an external sound stimulus directly on the abdomen of the mother; however, this practice has since been deemed unsafe for the developing fetus. Purpose: To investigate a reliable and safe paradigm to study the development of fetal brain networks, we postulated that an internal task, such as the mother\u27s singing, as the auditory stimulus would result in activation in the fetal primary auditory cortex. Study type: Cohort. Population: Pregnant women with singleton pregnancies (n = 9; 33–38 weeks gestational age). Field Strength/Sequence: All subjects underwent two task-based block design blood oxygen level-dependent (BOLD) at 1.5T or 3T. Assessment: Each volume was assessed for fetal motion and manually reoriented and realigned to correct for fetal motion. Once the motion was corrected, a gestational age-matched parcellated atlas with regions of interest overlaid onto the activation map was used to determine which regions in the brain had activation during task phases. Statistical Tests: First Level Analysis. MRI data were analyzed using SPM 12 as a task fMRI. Results: Eight subjects had activation on the right Heschl\u27s gyrus; six fetuses demonstrated activation on the left when exposed to the internal acoustic stimulus. Additionally, activation was found on the right and left middle cingulate cortex (MCC) and the left putamen. Data Conclusion: Maternal singing can be used as an internal stimulus to activate the auditory network and Heschl\u27s gyrus during fetal fMRI. Level of Evidence 2. Technical Efficacy Stage 2. J. Magn. Reson. Imaging 2020;52:139–145

Video Context Improves Performance in Identifying Operative Planes on Static Surgical Images

BACKGROUND: Correct identification of the surgical tissue planes of dissection is paramount at the operating room, and the needed skills seem to be improved with realistic dynamic models rather than mere still images. The objective is to assess the role of adding video prequels to still images taken from operations on the precision and accuracy of tissue plane identification using a validated simulation model, considering various levels of surgeons’ experience. METHODS: A prospective observational study was conducted involving 15 surgeons distributed to three equal groups, including a consultant group [C], a senior group [S], and a junior group [J]. Subjects were asked to identify and draw ideal tissue planes in 20 images selected at suitable operative moments of identification before and after showing a 10- second videoclip preceding the still image. A validated comparative metric (using a modified Hausdorff distance [%Hdu] for object matching) was used to measure the distance between lines. A precision analysis was carried out based on the difference in %Hdu between lines drawn before and after watching the videos, and between-group comparisons were analyzed using a one-way analysis of variance (ANOVA). The analysis of accuracy was done on the difference in %Hdu between lines drawn by the subjects and the ideal lines provided by an expert panel. The impact of videos on accuracy was assessed using a repeated-measures ANOVA. RESULTS: The C group showed the highest preciseness as compared to the S and J groups (mean Hdu 9.17±11.86 versus 12.1±15.5 and 20.0±18.32, respectively, p \u3c0.001) and significant differences between groups were found in 14 images (70%). Considering the expert panel as a reference, the interaction between time and experience level was significant ( F (2, 597) = 4.52, p \u3c0.001). Although the subjects of the J group were significantly less accurate than other surgeons, only this group showed significant improvements in mean %Hdu values after watching the lead-in videos ( F (1, 597) = 6.04, p = 0.014). CONCLUSIONS: Adding video context improved the ability of junior trainees to identify tissue planes of dissection. A realistic model is recommended considering experience-based differences in precision in training programs

Does ventricular volume affect the neurodevelopmental outcome in infants with intraventricular hemorrhage?

OBJECTIVE: The aim of this study is to investigate whether ventricular volume in posthemorrhagic ventricle dilatation impacts neurodevelopmental outcome. Infants were scanned with 3D cranial ultrasound in the first few months of life, and their neurodevelopmental outcome at 4, 8, 12, and 24 months corrected age (CA) was examined. METHODS: Forty-nine infants who suffered an intraventricular hemorrhage (IVH) were enrolled in the study. Subjects were scanned multiple times during their stay in the neonatal intensive care unit. Images were manually segmented to measure total volume of the lateral ventricles, and the highest volume was taken. Infants with a volume ≤ 20 cc were considered low-volume (n = 33), and infants with a volume ≥ 40 cc were considered high-volume (n = 12). Developmental outcome was assessed at 4, 8, and 12 months CA with the Alberta Infant Motor Scale (AIMS) and Infant Neurological International Battery (Infanib), and at 24 months CA with the Bayley Scales of Infant Development 3e (BSID III). RESULTS: Infants in the low-volume group had higher scores on the Infanib at 4 months CA, and on both the AIMS and Infanib at 8 and 12 months CA, even after controlling for gestational age, birth weight, and worst grade of IVH. We observed a trend where low-volume infants also scored higher on the cognitive and gross-motor subtests of the BSID III at 24 months CA. CONCLUSION: Our results show that ventricular volume affects neurodevelopmental outcome in infants with IVH. This finding could guide the timing of future interventions, as earlier intervention may decrease the likelihood of adverse neurodevelopmental outcome