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Repetitive mild traumatic brain injury in American football players has garnered increasing public attention following reports of chronic traumatic encephalopathy, a progressive tauopathy. While the mechanisms underlying repetitive mild traumatic brain injury-induced neurodegeneration are unknown and antemortem diagnostic tests are not available, neuropathology studies suggest a pathogenic role for microvascular injury, specifically blood-brain barrier dysfunction. Thus, our main objective was to demonstrate the effectiveness of a modified dynamic contrast-enhanced MRI approach we have developed to detect impairments in brain microvascular function. To this end, we scanned 42 adult male amateur American football players and a control group comprising 27 athletes practicing a non-contact sport and 26 non-athletes. MRI scans were also performed in 51 patients with brain pathologies involving the blood-brain barrier, namely malignant brain tumours, ischaemic stroke and haemorrhagic traumatic contusion. Based on data from prolonged scans, we generated maps that visualized the permeability value for each brain voxel. Our permeability maps revealed an increase in slow blood-to-brain transport in a subset of amateur American football players, but not in sex- and age-matched controls. The increase in permeability was region specific (white matter, midbrain peduncles, red nucleus, temporal cortex) and correlated with changes in white matter, which were confirmed by diffusion tensor imaging. Additionally, increased permeability persisted for months, as seen in players who were scanned both on- and off-season. Examination of patients with brain pathologies revealed that slow tracer accumulation characterizes areas surrounding the core of injury, which frequently shows fast blood-to-brain transport. Next, we verified our method in two rodent models: rats and mice subjected to repeated mild closed-head impact injury, and rats with vascular injury inflicted by photothrombosis. In

Repetitive mild traumatic brain injury in American football players has garnered increasing public attention following reports of chronic traumatic encephalopathy, a progressive tauopathy. While the mechanisms underlying repetitive mild traumatic brain injury-induced neurodegeneration are unknown and antemortem diagnostic tests are not available, neuropathology studies suggest a pathogenic role for microvascular injury, specifically blood-brain barrier dysfunction. Thus, our main objective was to demonstrate the effectiveness of a modified dynamic contrast-enhanced MRI approach we have developed to detect impairments in brain microvascular function. To this end, we scanned 42 adult male amateur American football players and a control group comprising 27 athletes practicing a non-contact sport and 26 non-athletes. MRI scans were also performed in 51 patients with brain pathologies involving the blood-brain barrier, namely malignant brain tumours, ischaemic stroke and haemorrhagic traumatic contusion. Based on data from prolonged scans, we generated maps that visualized the permeability value for each brain voxel. Our permeability maps revealed an increase in slow blood-to-brain transport in a subset of amateur American football players, but not in sex- and age-matched controls. The increase in permeability was region specific (white matter, midbrain peduncles, red nucleus, temporal cortex) and correlated with changes in white matter, which were confirmed by diffusion tensor imaging. Additionally, increased permeability persisted for months, as seen in players who were scanned both on- and off-season. Examination of patients with brain pathologies revealed that slow tracer accumulation characterizes areas surrounding the core of injury, which frequently shows fast blood-to-brain transport. Next, we verified our method in two rodent models: rats and mice subjected to repeated mild closed-head impact injury, and rats with vascular injury inflicted by photothrombosis. In

Gabriel Katz, 1, 2,* Fidaa el Zhalka, 3,* Ronel Veksler, 1 Anfisa Ayalon, 3 Elad Moisseiev 2, 3 1Department of Ophthalmology, Sheba Medical Center, Ramat Gan, Israel; 2Sackler School of Medicine, TelAviv University, TelAviv, Israel; 3Department of Ophthalmology, Meir Medical Center, Kfar Saba, Israel*These authors contributed equally to this workCorrespondence: Elad MoisseievDepartment of Ophthalmology, Meir Medical Center, 59 Tshernichovsky St., Kfar Saba, 4428164, IsraelTel +97297471527Fax +97297472427Email elad_moi@netvision.net.ilPurpose: To investigate the effect of phacovitrectomy on the post-operative anterior chamber depth (ACD) and refractive outcomes, and to analyze the potential differences between vitreous filling with BSS, air and gas.Methods: Patients who underwent phacovitrectomy were included in this study and invited for repeated post-operative examination including refraction and biometry at least 3 months after the surgery. Data retrieved included demographic information, indication for phacovitrectomy, surgical details, type of vitreous filling (BSS, air or gas), pre-operative and post-operative biometric data including K-readings, axial length (AL), and ACD, as well as spherical equivalent (SE) values of the target and final refraction.Results: Forty-three eyes of 43 patients were included in this study, including 10 eyes filled with BSS, 18 with air and 15 with gas. The mean difference between the final measured spherical equivalent (SE) and the SE of the intended target refraction was 0.61± 0.68 D (p = 0.019). Only 58.1% of eyes had a final SE within ± 0.5D of the target refraction. Following surgery, AL remained unchanged, while mean pre-operative ACD increased significantly from 3.11± 0.34 mm to 4.77± 0.47 mm (p < 0.001). There was no difference in refractive error between the vitreous fillings and no correlation with AL or ACD.Conclusions: Phacovitrectomy is associated with lower accuracy o

Gabriel Katz,1,2 Fidaa el Zhalka,3 Ronel Veksler,1 Anfisa Ayalon,3 Elad Moisseiev2,3 1Department of Ophthalmology, Sheba Medical Center, Ramat Gan, Israel; 2Sackler School of Medicine, TelAviv University, TelAviv, Israel; 3Department of Ophthalmology, Meir Medical Center, Kfar Saba, IsraelCorrespondence: Elad MoisseievDepartment of Ophthalmology, Meir Medical Center, 59 Tshernichovsky St, Kfar Saba 4428164, IsraelEmail elad_moi@netvision.net.il View the original paper by Dr Katz and colleagues This is in response to the Letter to the Editor

We present the concept of fiber-flux density for locally quantifying white matter (WM) fiber bundles. By combining scalar diffusivity measures (e.g., fractional anisotropy) with fiber-flux measurements, we define new local descriptors called Fiber-Flux Diffusion Density (FFDD) vectors. Applying each descriptor throughout fiber bundles allows along-tract coupling of a specific diffusion measure with geometrical properties, such as fiber orientation and coherence. A key step in the proposed framework is the construction of an FFDD dissimilarity measure for sub-voxel alignment of fiber bundles, based on the fast marching method (FMM). The obtained aligned WM tract-profiles enable meaningful inter-subject comparisons and group-wise statistical analysis. We demonstrate our method using two different datasets of contact sports players. Along-tract pairwise comparison as well as group-wise analysis, with respect to non-player healthy controls, reveal significant and spatially-consistent FFDD anomalies. Comparing our method with along-tract FA analysis shows improved sensitivity to subtle structural anomalies in football players over standard FA measurements.