scholarly journals Bundle-specific fornix reconstruction for dual-tracer PET-tractometry

2018 ◽  
Author(s):  
Francois Rheault ◽  
Maggie Roy ◽  
Stephen Cunnane ◽  
Maxime Descoteaux
Keyword(s):  
State Of The Art ◽  
Emission Tomography ◽  
Hippocampal Atrophy ◽  
Current State ◽  
Positron Emission ◽  
Spatial Coverage ◽  
Before And After ◽  
Position And Orientation ◽  
First Time ◽  
Dual Tracer

AbstractTractography is known to have problems reconstructing white matter bundles that are narrow, have high curvature, or go through partial volume voxels contaminated by CSF or gray matter. One such bundle is the fornix, the major output tract of the hippocampus, which is especially problematic with aging. Hippocampal atrophy and ventricular expansion make the fornix even harder (often impossible) to track with current state-of-the-art techniques. In this work, a bundle-specific tractography algorithm is proposed to fully reconstruct the fornix. By injecting shape, position, and orientation priors, fornix reconstruction is markedly is improved. We report an increase in spatial coverage and better reproducibility across test-retest. These improvements over classical tractography algorithms also enable tractometry of the fornix to be combined with dual-tracer positron emission tomography (PET) data in participants with mild cognitive impairment (MCI). MCI participants underwent a multi-modal brain imaging before and after a 6-month daily ketogenic supplement. We report, for the first time, significant diffusion measures and 18F-fluorodeoxyglucose (FDG) uptake differences in specific sub-sections of the fornix after the ketogenic supplement.

scholarly journals Optimal transport- and kernel-based early detection of mild cognitive impairment patients based on magnetic resonance and positron emission tomography images

2022 ◽  
Vol 14 (1) ◽  
Author(s):  
Ziyu Liu ◽  
Travis S. Johnson ◽  
Wei Shao ◽  
Min Zhang ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Transfer Learning ◽  
Optimal Transport ◽  
State Of The Art ◽  
Emission Tomography ◽  
Brain Scans ◽  
Current State ◽  
Positron Emission

Abstract Background To help clinicians provide timely treatment and delay disease progression, it is crucial to identify dementia patients during the mild cognitive impairment (MCI) stage and stratify these MCI patients into early and late MCI stages before they progress to Alzheimer’s disease (AD). In the process of diagnosing MCI and AD in living patients, brain scans are collected using neuroimaging technologies such as computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET). These brain scans measure the volume and molecular activity within the brain resulting in a very promising avenue to diagnose patients early in a minimally invasive manner. Methods We have developed an optimal transport based transfer learning model to discriminate between early and late MCI. Combing this transfer learning model with bootstrap aggregation strategy, we overcome the overfitting problem and improve model stability and prediction accuracy. Results With the transfer learning methods that we have developed, we outperform the current state of the art MCI stage classification frameworks and show that it is crucial to leverage Alzheimer’s disease and normal control subjects to accurately predict early and late stage cognitive impairment. Conclusions Our method is the current state of the art based on benchmark comparisons. This method is a necessary technological stepping stone to widespread clinical usage of MRI-based early detection of AD.

scholarly journals Hybrid positron emission tomography–magnetic resonance of the heart: current state of the art and future applications

2018 ◽  
Vol 19 (9) ◽  
pp. 962-974 ◽  
Author(s):  
Muhummad Sohaib Nazir ◽  
Tevfik F Ismail ◽  
Eliana Reyes ◽  
Amedeo Chiribiri ◽  
Philipp A Kaufmann ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Magnetic Resonance ◽  
State Of The Art ◽  
Emission Tomography ◽  
Current State ◽  
Positron Emission

scholarly journals Electro-Quasistatic Animal Body Communication for Untethered Rodent Biopotential Recording

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shreeya Sriram ◽  
Shitij Avlani ◽  
Matthew P. Ward ◽  
Shreyas Sen
Keyword(s):  
Lower Energy ◽  
Sensor Node ◽  
State Of The Art ◽  
The Body ◽  
Animal Body ◽  
Current State ◽  
Communication Modalities ◽  
First Time ◽  
Biopotential Recording

AbstractContinuous multi-channel monitoring of biopotential signals is vital in understanding the body as a whole, facilitating accurate models and predictions in neural research. The current state of the art in wireless technologies for untethered biopotential recordings rely on radiative electromagnetic (EM) fields. In such transmissions, only a small fraction of this energy is received since the EM fields are widely radiated resulting in lossy inefficient systems. Using the body as a communication medium (similar to a ’wire’) allows for the containment of the energy within the body, yielding order(s) of magnitude lower energy than radiative EM communication. In this work, we introduce Animal Body Communication (ABC), which utilizes the concept of using the body as a medium into the domain of untethered animal biopotential recording. This work, for the first time, develops the theory and models for animal body communication circuitry and channel loss. Using this theoretical model, a sub-inch$$^3$$ 3 [1″ × 1″ × 0.4″], custom-designed sensor node is built using off the shelf components which is capable of sensing and transmitting biopotential signals, through the body of the rat at significantly lower powers compared to traditional wireless transmissions. In-vivo experimental analysis proves that ABC successfully transmits acquired electrocardiogram (EKG) signals through the body with correlation $$>99\%$$ > 99 % when compared to traditional wireless communication modalities, with a 50$$\times$$ × reduction in power consumption.

Positron Emission Tomography with 11C-Methionine and Computed Tomography of Intracranial Tumours Compared with Histopathologic Examination of Multiple Biopsies

1987 ◽  
Vol 28 (6) ◽  
pp. 673-681 ◽  
Author(s):  
M. Mosskin ◽  
H. von Holst ◽  
M. Bergström ◽  
V. P. Collins ◽  
L. Eriksson ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
Contrast Medium ◽  
Mass Effect ◽  
Tumour Cells ◽  
Emission Tomography ◽  
Normal Brain ◽  
Positron Emission ◽  
Multiple Biopsies ◽  
Before And After

A selected group of 36 patients with suspected supratentorial gliomas were investigated with positron emission tomography (PET) using 11C-methionine and transmission computed tomography (CT) before and after intravenous injection of contrast medium. Every examination was performed with the head fixed in a plastic helmet and a baseplate to guarantee that the slice orientation was the same at examinations with the two modalities and over time. Guided by the examinations, multiple stereotactic biopsies were performed with the biopsy instrument mounted on the baseplate. Regional accumulation of methionine was compared with histology of the corresponding samples and with attenuation before and after injection of contrast medium as well as mass effect on CT. Typically, there was a low attenuating lesion with a slight mass effect on CT. There was an increased accumulation compared with normal brain tissue in 31 cases of tumours and ordinary or decreased accumulation in 3 cases of tumours. In 22 cases with increased accumulation of methionine the extension of the tumour judged by PET corresponded with that of histology. In 4 cases tumour cells were found outside the area with pathologic methionine uptake. In 5 patients there were areas with increased methionine accumulation where no tumour cells were found. In 22 cases PET using methionine was more accurate than CT in defining the tumour boundaries as determined from the histologic findings. Four groups of biopsy specimens with different amounts of methionine accumulation are described. The uptake in a single biopsy gives good but not exact information about the histology of the specimen.

scholarly journals A Step by Step Methodology for Building Sustainable Cementitious Matrices

2020 ◽  
Vol 10 (8) ◽  
pp. 2955 ◽  
Author(s):  
Styliani Papatzani ◽  
Kevin Paine
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Silica Fume ◽  
Carbon Footprint ◽  
State Of The Art ◽  
Cost Effective ◽  
Strength Development ◽  
Low Carbon ◽  
Current State ◽  
First Time

In an effort to produce cost-effective and environmentally friendly cementitious binders. mainly ternary (Portland cement + limestone + pozzolanas) formulations have been investigated so far. Various proportions of constituents have been suggested, all, however, employing typical Portland cement (PC) substitution rates, as prescribed by the current codes. With the current paper a step by step methodology on developing low carbon footprint binary, ternary and quaternary cementitious binders is presented (PC replacement up to 57%). Best performing binary (60% PC and 40% LS (limestone)) and ternary formulations (60% PC, 20% LS, 20% FA (fly ash) or 43% PC, 20% LS 37% FA) were selected on the grounds of sustainability and strength development and were further optimized with the addition of silica fume. For the first time a protocol for successfully selecting and testing binders was discussed and the combined effect of highly pozzolanic constituents in low PC content formulations was assessed and a number of successful matrices were recommended. The present paper enriched the current state of the art in composite low carbon footprint cementitious binders and can serve as a basis for further enhancements by other researchers in the field.

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