Brain arteriovenous malformations: The long way ahead in physics, chemistry and MR-Angiography practice before fully replacing digital subtraction angiography.

Typically, only high field systems are equipped with stronger gradients and short RF pulse designs, a must for high temporal resolution that are also responsible for high SAR, high susceptibility as well as neurostimulation. Gradient induced image noise tends to be high at 3T. Often vendors try to ameliorate such increased image noise with multi-channel head arrays and aggressive filter designs allowing an appearance of high SNR and CNR quality; however, the achievable SNR and CNR in the AVM remain limited as the analyzed articles by Zhuo et al seem to have in common. A short term solution to harvest advantages of high fields with acceptable T2* loss may be to use fast 3D shimming to generate a high degree of homogeneity in the operator selected AVM tissue. In addition, to avoid susceptibility increase at high fields by the contrast pooled into neovasculature, not only for AVM but also for other vascular imaging applications, improved CM design need to accompany any such robust shimming routines. Until that and more are achieved, DSA may retain its superiority in the follow-ups of treated AVMs

Effect of Low Refocusing Angle in T1-Weighted Spin Echo and Fast Spin Echo MRI on Low-Contrast Detectability: A Comparative Phantom Study at 1.5 and 3 Tesla

MRI tissue contrast is not well preserved at high field. In this work, we used a phantom with known, intrinsic contrast (3.6%) for model tissue pairs to test the effects of low angle refocusing pulses and magnetization transfer from adjacent slices on intrinsic contrast at 1.5 and 3 Tesla. Only T1-weighted spin echo sequences were tested since for such sequences the contrast loss, tissue heating, and image quality degradation at high fields seem to present significant diagnostic and quality issues. We hypothesized that the sources of contrast loss could be attributed to low refocusing angles that do not fulfill the Hahn spin echo conditions or to magnetization transfer effects from adjacent slices in multislice imaging. At 1.5 T the measured contrast was 3.6% for 180° refocusing pulses and 2% for 120° pulses, while at 3 T, it was 4% for 180° and only 1% for 120° refocusing pulses. There was no significant difference between single slice and multislice imaging suggesting little or no role played by magnetization transfer in the phantom chosen. Hence, one may conclude that low angle refocusing pulses not fulfilling the Hahn spin echo conditions are primarily responsible for significant deterioration of T1-weighted spin echo image contrast in high-field MRI

Utilizing Fast Spin Echo MRI to Reduce Image Artifacts and Improve Implant/Tissue Interface Detection in Refractory Parkinson's Patients with Deep Brain Stimulators

Introduction:. In medically refractory Parkinson's disease (PD) deep-brain stimulation (DBS) is an effective therapeutic tool. Postimplantation MRI is important in assessing tissue damage and DBS lead placement accuracy. We wanted to identify which MRI sequence can detect DBS leads with smallest artifactual signal void, allowing better tissue/electrode edge conspicuity. Methods:. Using an IRB approved protocol 8 advanced PD patients were imaged within MR conditional safety guidelines at low RF power (SAR ≤ 0.1 W/kg) in coronal plane at 1.5T by various sequences. The image slices were subjectively evaluated for diagnostic quality and the lead contact diameters were compared to identify a sequence least affected by metallic leads. Results and Discussion. Spin echo and fast spin echo based low SAR sequences provided acceptable image quality with comparable image blooming (enlargement) of stimulator leads. The mean lead diameters were 2.2 ± 0.1 mm for 2D, 2.1 ± 0.1 mm for 3D, and 4.0 ± 0.2 mm for 3D MPRAGE sequence. Conclusion:. Low RF power spin echo and fast spin echo based 2D and 3D FSE sequences provide acceptable image quality adjacent to DBS leads. The smallest artifactual blooming of stimulator leads is present on 3D FSE while the largest signal void appears in the 3D MPRAGE sequence

Radiobiology & Radiation Benefits in Alzheimer’s from CT: a physics assessment

This work is a review and assessment of research literature on Alzheimer’s disease (AD) today which is an irreversible neurological disorder, that continuously decreases the individual’s memory and thinking skills and, suddenly, the ability to carry out the simplest functions of daily living. Although treatment can only help manage the symptoms of AD, there is no cure for the disease. CT imaging is proven to be somewhat helpful in the detection of AD disease similar to MRI, multiple repeat CT seems to show promise in part-reversing the loss (radiation Hormesis). Invivo exposure, spatial distribution, and quantitative characterization could be essential markers in diagnosing and assessing AD progression. Phase-Contrast X-ray microcomputed tomography (micro CT) is an emerging highly sensitive imaging technique capable of high resolution and impressive soft tissue discrimination. FDG and Pittsburgh compound B PET are functional tools to map affected brain with AD. There is a potential to extend it to imaging precise 3D information about the inner structures of the entire brain in future using clinical CT machines but with phase contrast software without requiring thin sections. However, we feel clinical scanners with phase contrast modes will not provide the plaque imaging exactly for 50 μm for individual plaques but plaque tangles and high tissue contrast resolution for hippocampus structures as in highfield MRI may be possible by phase contrast CT

Quantifying Cerebellum Grey Matter and White Matter Perfusion Using Pulsed Arterial Spin Labeling

To facilitate quantification of cerebellum cerebral blood flow (CBF), studies were performed to systematically optimize arterial spin labeling (ASL) parameters for measuring cerebellum perfusion, segment cerebellum to obtain separate CBF values for grey matter (GM) and white matter (WM), and compare FAIR ASST to PICORE. Cerebellum GM and WM CBF were measured with optimized ASL parameters using FAIR ASST and PICORE in five subjects. Influence of volume averaging in voxels on cerebellar grey and white matter boundaries was minimized by high-probability threshold masks. Cerebellar CBF values determined by FAIR ASST were 43.8 ± 5.1 mL/100 g/min for GM and 27.6 ± 4.5 mL/100 g/min for WM. Quantitative perfusion studies indicated that CBF in cerebellum GM is 1.6 times greater than that in cerebellum WM. Compared to PICORE, FAIR ASST produced similar CBF estimations but less subtraction error and lower temporal, spatial, and intersubject variability. These are important advantages for detecting group and/or condition differences in CBF values

Modeling Changes in Cellular Micro-Environment in Mild to Moderate Head Trauma

Our work aims to connect and model multiple small, inter-related tissue injuries as a consequence of mild traumatic brain injuries (mTBI). It has been shown that frontal and temporal lobes are vulnerable regions for brain traumatic injury. A brain injury from a blow or high-speed impact can cause undersurface of the frontal and temporal lobes to deform against the anterior and cranial fossae. This deformation can often trigger damage to the cerebral vasculature, which is ill-understood and can result in chronic damage to larger vessels over time. These physiological injuries can be manifested psychologically; such as patients’ sleep-wake disturbances. The connection between mTBI and the cause of sleep-issues is found to be associated with vascular epithelial injuries to the pineal gland that lies directly at the anterior to the tentorial ridge. In this research, we are modeling brain trauma with two injuries tissue gliding between temporal, frontal and parietal lobes. The frontal lobe may explain the psychological problem and parietal may explain the large venous injury, while the midbrain including pineal and hypothalamus injury may explain sleep issues. Although white matter connectivity is disturbed, the literature is not enough for us to include that within our cell injury model. Learning from these devastating symptoms of mTBI, it is critical to push for more scientific researches to understand the mTBI and offer psychosocial as well as neurobiological interventions

Gender and racial disparity for hospital emergency service usage in USA: a quantitative analysis for various age groups during 2010–2017.

Background: Annually emergency department (ED) services are utilized by more than 100 million Americans making ED usage trends important determinants of healthcare quality, outcomes and cost. Previous workers have demonstrated the existence of disparity in various healthcare services in USA although a comprehensive analysis has not been undertaken. Dahlgren and Whitehead rainbow model has offered insights for multiple factors of influence on an individual’s health and focuses on the relationships among these factors. The Commission on Social Determinants of Health (CSDH; WHO initiatives) suggests that the social and environmental factors are at the root of most of the inequalities responsible for both communicable and non-communicable diseases. Methods: The objectives of this study were to quantify the existing disparity in ED usage between 2010– 2017 by age, race and gender primarily using the Federal and State databases and comparing the quantitative trends with prior works from 2006–2020 that shed lights on health disparity. Single user normalization was developed to achieve randomization to reduce the heterogeneity of the database. Results: Each age group was represented by the usage pattern of the “single” average individual revealing significantly different ED usage for different age groups. Black and white Americans as well as males and females showed large variation indicative of racial and gender disparity. Conclusions: This is the first comprehensive meta-analysis demonstrating racial and gender specific variation in the usage of emergency health care services that exist in USA and seem to be multifactorial and age specific. Using a tool of single user normalization developed in this work as a means of randomization these disparities were quantified and may help identify such disparity trends in other regions that suffer from similar disparities

Three‐Dimensional Brain MRI for DBS Patients within Ultra‐Low Radiofrequency Power Limits

Background: For patients with deep brain stimulators (DBS), local absorbed radiofrequency (RF) power is unknown and is much higher than what the system estimates. We developed a comprehensive, highquality brain magnetic resonance imaging (MRI) protocol for DBS patients utilizing three-dimensional (3D) magnetic resonance sequences at very low RF power. Methods: Six patients with DBS were imaged (10 sessions) using a transmit/receive head coil at 1.5 Tesla with modified 3D sequences within ultra-low specific absorption rate (SAR) limits (0.1 W/kg) using T2, fast fluid-attenuated inversion recovery (FLAIR) and T1- weighted image contrast. Tissue signal and tissue contrast from the low-SAR images were subjectively and objectively compared with routine clinical images of six age-matched controls. Results: Low-SAR images of DBS patients demonstrated tissue contrast comparable to high-SAR images and were of diagnostic quality except for slightly reduced signal. Conclusions: Although preliminary, we demonstrated diagnostic quality brain MRI with optimized, volumetric sequences in DBS patients within very conservative RF safety guidelines offering a greater safety margin

Physico-Chemical Modeling, Optical Microscopy and Near-Infrared Spectroscopic Characterization of Model Biomaterials.

Biopolymers are being developed with nanostructures which acts as a carriers for drug delivery to treat different diseases including cancers. In this project, the authors made one biopolymer PDMS with 0-0.9% of SiC filler a novel characterization was demonstrated. Characterization included optical surface microscopy (5-100X) and 2D X-ray imaging at low kVp and low mAs to ensure proper loading and uniform distribution of SiC filler content in PDMS matrix distinguishable within 0.2 vol% of SiC. MR measurements also seemed to be very promising

Standard Deviations of MR Signal Intensities Show a Consistent Trend during Imaging Follow-Ups for Glioblastoma Patients when Corrected for Non-Biological Heterogeneity Due to Hardware and Software Variation

Introduction Glioblastoma multiforme (GBM) has a poor prognosis in spite of advanced MRI guided treatments today. Routine MRI using conventional T1 or advanced permeability based MRI of GBM often does not adequately represent changing tumor phases or overall survival. In this work, region of interest (ROI) based tissue MR standard deviation (SD) is demonstrated as an important MRI variable that could be a potential biomarker of GBM heterogeneity and radioresistance. Materials and methods MRI characterization is often qualitative and lacks reproducibility. Using standardized MRI phantoms we have normalized retrospective records of 12 radioresistant GBM patients that underwent radiation therapy (RT) with concomitant and adjuvant temozolomide (TMZ) chemotherapy followed by serial MR imaging with gadolinium contrast. Results and discussion We have identified key variables like hardware, software and protocol variation and have standardized those using test phantoms at five MR systems. We suggest GBM growth during the treatment period can be linked to normalized MRI signal and its fluctuations from session to session and from magnet to magnet by using an ROI derived standard deviation that corresponds to heterogeneity of the tumor MRI signal and changes in magnetic susceptibility. The time period observed in our patient group for peak standard deviations is approximately halfway through the tumor course and may correspond to a growth of more aggressive MES subtype of cells. To model the GBM heterogeneity we performed in vitro T1 weighted inversion recovery MRI experiments at 3 T for porous media of silicate particles in 1% aq solution of Gadavist and linked SD with particle size and local gadolinium volume within porous media. Such in vitro models mimic the increased SD in radioresistant GBM and as a novel contribution suggest that finer texture with high surface area might arise approximately halfway through the overall survival duration in GBM. Conclusion Standard deviation as a measure of magnetic susceptibility may be collectively linked to the changes in texture, cell fractions (biological) and trapped contrast media (vascular as well as artifactual consequences) and should be evaluated as a potential biomarker of GBM aggressiveness than the overall MRI signal intensity from a GBM