The bituminous sub-ballast layer within the ballasted rail track allows some mechanical and environmental advantages. An analytical model of a ballasted rail track with sub-ballast layer has been ...proposed by considering the rail as viscous-elastic continuous beam discretely supported, at four levels of elasticity.The model was used to compare the mechanical performance of both ballasted track with and without bituminous sub-ballast layer. The results confirmed that the bituminous sub-ballast layer reduces the dynamic forces on the ground and achieves the technical objectives as reduction of ground borne vibrations and increase of the design life of the rail track.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Purpose To determine the role of gene–environmental interactions between the Class I and Class II HLA alleles and the humoral anti-Epstein–Barr Virus (EBV) responses in the development of ...brain injury and clinical disability in multiple sclerosis (MS) patients. Methods A total of 93 MS patients (62 females; 31 males) and 122 healthy controls underwent HLA typing and testing for antibodies against EBV. The MS patients underwent brain MRI and quantitative measurements of T1- and T2-lesion volumes (LVs) and brain parenchymal fraction (BPF) were obtained. There were 54 MS cases that underwent MRI and EBV-antibody assessments at the 3-year follow-up. The anti-EBV panel included measurements of the levels of anti-EBV early antigen (EA) IgG, anti-EBV nuclear antigen (EBNA) IgG and anti-EBV viral capsid antigen (VCA) IgM and anti-EBV VCA IgG. The relationships between HLA alleles, anti-EBV antibody levels, MRI and clinical parameters were assessed in regression analysis. Results The presence of HLA B7 was associated with increased T1-LV and trends indicating increased anti-EBV VCA IgG levels, higher disability (EDSS) and more destructive MRI parameters (increased T2-LV and decreased BPF). The presence of HLA A2 was associated with lower EDSS and a trend toward decreased anti-EBV VCA IgG levels; the associations with MRI variables were not significant. The HLA B7–A2 haplotype was significantly associated with higher T2-LV and T1-LV and a trend toward lower BPF was observed. Conclusions Our data suggest that gene–environment interactions between specific HLA Class I loci and EBV exposure are associated with MRI markers of lesion injury and brain atrophy in MS patients.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The aim of our work is to describe the way in which physical figures of merit such as contrast-to-noise ratio (CNR) behave when varying acquisition parameters such as emission scan duration (ESD) or ...activity at the start of acquisition
(
A
acq
)
that in clinical practice can be selected by the user, or object properties such as target dimensions or target-to-background (T/B) ratio, which depend uniquely on the intrinsic characteristics of the object being imaged. Figures of merit, used to characterize image quality and quantitative accuracy for a 3D-LSO based PET/CT scanner, were studied as a function of ESD and
A
acq
for different target sizes and T/B ratios using a multivariate approach in a wide range of conditions approaching the ones that can be encountered in clinical practice. An annular ring of water bags of
3
cm
thickness was fitted over an IEC phantom in order to obtain counting rates similar to those found in average patients. The average scatter fraction (SF) of the modified IEC phantom was similar to the mean SF measured on patients with a similar scanner. A supplemental set of micro-hollow spheres was positioned inside the phantom. The NEMA NU 2-2001 scatter phantom was positioned at the end of the IEC phantom to approximate the clinical situation of having activity that extends beyond the scanner. The phantoms were filled with a solution of water and
F
18
(
12
kBq
∕
mL
)
and the spheres with various T/B ratios of 22.5, 10.3, and 3.6. Sequential imaging was performed to acquire PET images with varying background activity concentrations of about 12, 9, 6.4, 5.3, and
3.1
kBq
∕
mL
, positioned on the linear portion of the phantom’s NECR curve, well below peak NECR of
61.2
kcps
that is reached at
31.8
kBq
∕
mL
. The ESD was set to 1, 2, 3, and
4
min
∕
bed
. With T/B ratios of 3.6, 10.3, and 22.5, the 13.0, 8.1, and
6.5
mm
spheres were detectable for the whole ranges of background activity concentration and ESD, respectively. The ESD resulted as the most significant predictor of CNR variance, followed by T/B ratio and the cross sectional area of the given sphere. Only last comes
A
acq
with a weight more than halved with respect to ESD. Thus, raising ESD seems to be much more effective than raising
A
acq
in order to obtain higher CNR, which is the physical figure of merit closely related with target detectability, at least in the simple task of the signal known exactly background known exactly model.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The clinical utility of FFRCT stratified by age Anastasius, Malcom; Maggiore, Paul; Huang, Alex ...
Journal of cardiovascular computed tomography,
March-April 2021, 2021-03-00, 20210301, Volume:
15, Issue:
2
Journal Article
Peer reviewed
CT coronary angiography (CTA) with Fractional Flow Reserve as determined by CT (FFRCT) is a safe alternative to invasive coronary angiography. A negative FFRCT has been shown to have low cardiac ...event rates compared to those with a positive FFRCT. However, the clinical utility of FFRCT according to age is not known.
Patients’ in the ADVANCE (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care) registry, were stratified into those ≥65 or <65 years of age. The impact of FFRCT on clinical decision-making, as assessed by patient age, was determined by evaluating patient management using CTA results alone, followed by site investigators submitting a report on the treatment plan based upon the newly provided FFRCT data. Outcomes at 1-year post CTA were assessed, including major adverse cardiovascular events (myocardial infarction, all-cause mortality or unplanned hospitalization for ACS leading to revascularisation) and total revascularisation. Positive FFRCT was deemed to be ≤ 0.8.
FFRCT was calculated in 1849 (40.6%) subjects aged <65 and 2704 (59.4%) ≥ 65 years of age. Subjects ≥65 years were more likely to have anatomic obstructive disease on CTA (≥50% stenosis), compared to those aged <65 (69.7% and 73.2% respectively, p = 0.008). There was a similar graded increase in recommended and actual revascularisation with either CABG or PCI, with declining FFRCT strata for subjects above and below the age of 65. MACE and revascularisation rates were not significantly different for those ≥ or <65, regardless of FFRCT positivity or stenosis severity <50% or ≥50%. With a negative FFRCT result, and anatomical stenosis ≥50%, those ≥ and <65 years of age, had similar rates of MACE (0.2% for both, p = 0.1) and revascularisation (8.7% and 10.4% respectively p = 0.4).
Logistic regression analysis, with age as a continuous variable, and adjustment for Diamond Forrester Risk, baseline FFRCT and treatment (CABG, PCI, medical therapy), indicated a statistically significant, but small increase in the odds of a MACE event with increasing age (OR 1.04, 95% CI 1.006–1.08, p = 0.02). Amongst patients with a FFRCT > 0.80, there was no effect of age on the odds of revascularisation.
The findings of this study point to a low risk of MACE events or need for revascularisation in those aged ≥ or <65 with a FFRCT>0.80, despite the higher incidence of anatomic obstructive CAD in those ≥65 years. The findings show the clinical usefulness and outcomes of FFRCT are largely constant regardless of age.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In recent studies, measures of whole brain atrophy were strongly correlated with neuropsychological testing, explaining more variance than measures of lesion burden in patients with multiple ...sclerosis. The relationship between regional lobar atrophy and cognitive impairment is yet to be examined. We endeavored to assess the clinical significance of regional lobar atrophy in multiple sclerosis.
In a cross-sectional study, we evaluated 31 patients with multiple sclerosis with brain MR imaging and neuropsychological testing. Impairment was determined by comparison with demographically matched healthy controls. MR imaging generated measures of lesion burden (fluid-attenuated inversion recovery hyperintense volume), general atrophy (brain parenchymal fraction), central atrophy (lateral ventricle volume), and lobar atrophy (regional brain parenchymal fraction of frontal, temporal, parietal, and occipital lobes in each hemisphere). Neuropsychological testing emphasized measures of processing speed and memory, because these are commonly affected in multiple sclerosis.
Patients with multiple sclerosis showed significant atrophy and impairment on all neuropsychological tests. Regional atrophy accounted for the most variance in all regression models predicting memory performance. Left temporal atrophy was the primary predictor of auditory/verbal memory (partial r's = 0.55-0.61), and both left and right temporal atrophy predicted visual/spatial memory performance (partial r's = 0.51-0.67). Models predicting learning consistency retained frontal lobe atrophy measures (partial r's = 0.44-0.68). Central and general atrophy measures were the primary predictors in modeling processing speed (partial r's = 0.42-0.64).
Regional atrophy accounts for more variance than lesion burden, whole brain atrophy, or lateral ventricle volume in predicting multiple sclerosis-associated memory dysfunction.
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