Evidence of Spin-Orbital Angular Momentum Interactions in Relativistic Heavy-Ion Collisions

The first evidence of spin alignment of vector mesons (K^{*0} and ϕ) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element ρ_{00} is measured at midrapidity (|y|<0.5) in Pb-Pb collisions at a center-of-mass energy (sqrt[s_{NN}]) of 2.76 TeV with the ALICE detector. ρ_{00} values are found to be less than 1/3 (1/3 implies no spin alignment) at low transverse momentum (p_{T}<2  GeV/c) for K^{*0} and ϕ at a level of 3σ and 2σ, respectively. No significant spin alignment is observed for the K_{S}^{0} meson (spin=0) in Pb-Pb collisions and for the vector mesons in pp collisions. The measured spin alignment is unexpectedly large but qualitatively consistent with the expectation from models which attribute it to a polarization of quarks in the presence of angular momentum in heavy-ion collisions and a subsequent hadronization by the process of recombination.

Inositols and metabolic disorders: From farm to bedside

Inositol and its derivates are catching interest in metabolism since taking part in several physiological processes, including endocrine modulation. Through several mechanisms mostly mediated by insulin signaling, these compounds regulate the activities of several hormones and are essential in oocytes maturation. It is interesting to point out the contribution of an inositol deficiency in the development of several diseases, mainly in the metabolic and endocrine setting. Inositols derive from both diet and endogenous production; among causes of inositol deficiency reduced dietary intake, increased catabolism and/or excretion, decreased biosynthesis, inhibition of gut and cellular uptake and altered microbiota could be considered. Mounting direct and indirect evidence suggests that the two main isoforms (Myo-inositol-inositol, D-chiro-inositol) are implied in glycemic and lipidic metabolism and supplementation yield a beneficial effect on these parameters without hazards for health. Moreover, they have a role in polycystic ovary syndrome, acting as insulin-sensitizing agents and free radical scavengers, helping to regulate metabolism and promoting ovulation. The aim of this narrative review is to discuss the role of inositols in metabolic function disorders paying attention to whether these compounds could be efficacious and safe as a therapeutic agent with a focus on dietary intake and the role of gut microbiota.

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Inositol deficiency is implicated in the development of metabolic and endocrine diseases.

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Inositol compounds could be safe food supplement to restore metabolic imbalance.

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Inositol compounds partly derive from microbiota phytases entering in bacterial metabolism.

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Diet inositol content has a role in shaping gut microbiota and the host metabolism.

Scattering Studies with Low-Energy Kaon-Proton Femtoscopy in Proton-Proton Collisions at the LHC

The study of the strength and behavior of the antikaon-nucleon (K[over ¯]N) interaction constitutes one of the key focuses of the strangeness sector in low-energy quantum chromodynamics (QCD). In this Letter a unique high-precision measurement of the strong interaction between kaons and protons, close and above the kinematic threshold, is presented. The femtoscopic measurements of the correlation function at low pair-frame relative momentum of (K^{+}p⊕K^{-}p[over ¯]) and (K^{-}p⊕K^{+}p[over ¯]) pairs measured in pp collisions at sqrt[s]=5, 7, and 13 TeV are reported. A structure observed around a relative momentum of 58  MeV/c in the measured correlation function of (K^{-}p⊕K^{+}p[over ¯]) with a significance of 4.4σ constitutes the first experimental evidence for the opening of the (K[over ¯]^{0}n⊕K^{0}n[over ¯]) isospin breaking channel due to the mass difference between charged and neutral kaons. The measured correlation functions have been compared to Jülich and Kyoto models in addition to the Coulomb potential. The high-precision data at low relative momenta presented in this work prove femtoscopy to be a powerful complementary tool to scattering experiments and provide new constraints above the K[over ¯]N threshold for low-energy QCD chiral models.

Risk-adjusted benchmarks in laparoscopic liver surgery in a national cohort

Background

This study aimed to assess the best achievable outcomes in laparoscopic liver resection (LLR) after risk adjustment based on surgical technical difficulty using a national registry.

Methods

LLRs registered in the Italian Group of Minimally Invasive Liver Surgery registry from November 2014 to March 2018 were considered. Benchmarks were calculated according to the Achievable Benchmark of Care (ABC™). LLRs at each centre were divided into three clusters (groups I, II and III) based on the Kawaguchi classification. ABCs for overall and major morbidity were calculated in each cluster. Multivariable analysis was used to identify independent risk factors for overall and major morbidity. Significant variables were used in further risk adjustment.

Results

A total of 1752 of 2263 patients fulfilled the inclusion criteria: 1096 (62·6 per cent) in group I, 435 (24·8 per cent) in group II and 221 (12·6 per cent) in group III. The ABCs for overall morbidity (7·8, 14·2 and 26·4 per cent for grades I, II and II respectively) and major morbidity (1·4, 2·2 and 5·7 per cent) increased with the difficulty of LLR. Multivariable analysis showed an increased risk of overall morbidity associated with multiple LLRs (odds ratio (OR) 1·35), simultaneous intestinal resection (OR 3·76) and cirrhosis (OR 1·83), and an increased risk of major morbidity with intestinal resection (OR 4·61). ABCs for overall and major morbidity were 14·4 and 3·2 per cent respectively for multiple LLRs, 30 and 11·1 per cent for intestinal resection, and 14·9 and 4·8 per cent for cirrhosis.

Conclusion

Overall morbidity benchmarks for LLR ranged from 7·8 to 26·4 per cent, and those for major morbidity from 1·4 to 5·7 per cent, depending on complexity. Benchmark values should be adjusted according to multiple LLRs or simultaneous intestinal resection and cirrhosis.

Multicentre evaluation of case volume in minimally invasive hepatectomy

Background

Surgical outcomes may be associated with hospital volume and the influence of volume on minimally invasive liver surgery (MILS) is not known.

Methods

Patients entered into the prospective registry of the Italian Group of MILS from 2014 to 2018 were considered. Only centres with an accrual period of at least 12 months and stable MILS activity during the enrolment period were included. Case volume was defined by the mean number of minimally invasive liver resections performed per month (MILS/month).

Results

A total of 2225 MILS operations were undertaken by 46 centres; nine centres performed more than two MILS/month (1376 patients) and 37 centres carried out two or fewer MILS/month (849 patients). The proportion of resections of anterolateral segments decreased with case volume, whereas that of major hepatectomies increased. Left lateral sectionectomies and resections of anterolateral segments had similar outcome in the two groups. Resections of posterosuperior segments and major hepatectomies had higher overall and severe morbidity rates in centres performing two or fewer MILS/month than in those undertaking a larger number (posterosuperior segments resections: overall morbidity 30·4 versus 18·7 per cent respectively, and severe morbidity 9·9 versus 4·0 per cent; left hepatectomy: 46 versus 22 per cent, and 19 versus 5 per cent; right hepatectomy: 42 versus 34 per cent, and 25 versus 15 per cent).

Conclusion

A volume–outcome association existed for minimally invasive hepatectomy. Complex and major resections may be best managed in high-volume centres.

Measurement of ϒ(1S) Elliptic Flow at Forward Rapidity in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

The first measurement of the ϒ(1S) elliptic flow coefficient (v_{2}) is performed at forward rapidity (2.5<y<4) in Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV with the ALICE detector at the LHC. The results are obtained with the scalar product method and are reported as a function of transverse momentum (p_{T}) up to 15  GeV/c in the 5%-60% centrality interval. The measured ϒ(1S)v_{2} is consistent with 0 and with the small positive values predicted by transport models within uncertainties. The v_{2} coefficient in 2<p_{T}<15  GeV/c is lower than that of inclusive J/ψ mesons in the same p_{T} interval by 2.6 standard deviations. These results, combined with earlier suppression measurements, are in agreement with a scenario in which the ϒ(1S) production in Pb-Pb collisions at LHC energies is dominated by dissociation limited to the early stage of the collision, whereas in the J/ψ case there is substantial experimental evidence of an additional regeneration component.

Investigations of Anisotropic Flow Using Multiparticle Azimuthal Correlations in pp, p-Pb, Xe-Xe, and Pb-Pb Collisions at the LHC

Measurements of anisotropic flow coefficients (v_{n}) and their cross-correlations using two- and multiparticle cumulant methods are reported in collisions of pp at sqrt[s]=13  TeV, p-Pb at a center-of-mass energy per nucleon pair sqrt[s_{NN}]=5.02  TeV, Xe-Xe at sqrt[s_{NN}]=5.44  TeV, and Pb-Pb at sqrt[s_{NN}]=5.02  TeV recorded with the ALICE detector. The multiplicity dependence of v_{n} is studied in a very wide range from 20 to 3000 particles produced in the midrapidity region |η|<0.8 for the transverse momentum range 0.2<p_{T}<3.0  GeV/c. An ordering of the coefficients v_{2}>v_{3}>v_{4} is found in pp and p-Pb collisions, similar to that seen in large collision systems, while a weak v_{2} multiplicity dependence is observed relative to nucleus-nucleus collisions in the same multiplicity range. Using a novel subevent method, v_{2} measured with four-particle cumulants is found to be compatible with that from six-particle cumulants in pp and p-Pb collisions. The magnitude of the correlation between v_{n}^{2} and v_{m}^{2}, evaluated with the symmetric cumulants SC(m,n) is observed to be positive at all multiplicities for v_{2} and v_{4}, while for v_{2} and v_{3} it is negative and changes sign for multiplicities below 100, which may indicate a different v_{n} fluctuation pattern in this multiplicity range. The observed long-range multiparticle azimuthal correlations in high multiplicity pp and p-Pb collisions can neither be described by pythia 8 nor by impact-parameter-Glasma, music, and ultrarelativistic quantum molecular dynamics model calculations, and hence, provide new insights into the understanding of collective effects in small collision systems.

P6174On-site CT-derived FFR predicts the need for revascularization

Background and purpose

Coronary computed tomography angiography (CTA) in combination with CT-derived fractional flow reserve (CT-FFR) is a solid tool for assessing both the anatomical and functional impact of coronary atherosclerotic disease (CAD) in a single study. The development of new software for on-site CT-FFR quantification may reduce costs and increase availability. The aim of this study was to analyze the incremental value of CT-FFR over CTA alone and its ability to predict the need for revascularization.

Methods

Patients referred for invasive coronary angiography (ICA) who accepted to undergo a CTA/CT-FFR study were prospectively included. Patients with any contraindication for CT, atrial fibrillation, chronic total occlusions, severe ventricular hypertrophy or previous coronary revascularization were excluded. On-site CT-FFR was calculated for each coronary vessel. Invasive FFR was quantified during ICA, considering ≤0.8 as a surrogate for the need for revascularization.

Results

33 patients (90 vessels) were included. Mean age was 65±10 years, 88% were males, 60% had hypertension, 77% dyslipidaemia and 40% diabetes. The average analysis time of CT-FFR was 16±4 minutes. There was a good correlation between CT-FFR and FFR in all three main epicardial vessels as well as in proximal segments or in moderate to severe stenosis (see Table). 83% of vessels with FFR≤0.8 were predicted by CT-FFR study (89% of LAD lesions, 86% of LCX and 66% of RCA). CT-FFR added incremental diagnostic value over CTA alone to predict FFR≤0.8 (ΔAUC 0.0336 with a net reclassification index 1.4±0.23; p<0.001) (see Image).

n Mean difference from Bland-Altman Pearson's r coefficient p value All-vessels 90 0.037±0.1 0.8 <0.001 Lesions in LAD 40 0.005±0.11 0.81 <0.001 Lesions in LCX 32 0.061±0.094 0.85 <0.001 Lesions in RCA 18 0.06±0.11 0.83 <0.001 Moderate lesions (50–69% QCA stenosis) 24 0.02±0.06 0.88 <0.001 Severe lesions (70–99% QCA stenosis) 25 0.034±0.18 0.4 <0.001 Proximal lesions 42 0.012±0.11 0.84 <0.001 Non-proximal lesions 48 0.061±0.1 0.78 <0.001

Conclusions

On-site CT-FFR is a good predictor of the need for revascularization in all three main coronary vessels and adds incremental diagnostic value over CTA alone. There is higher dispersion of the values in severe stenosis, lesions in LCX or RCA although this do not result in misclassification.

P6185Impact of coronary atherosclerotic plaque metrics on the correlation between on-site CT-FFR and invasive FFR

Background

Developed in the last years, coronary computed tomography-derived fractional flow reserve (CT-FFR) has shown good correlation with invasive fractional flow reserve (FFR). However, little is known about the interaction of coronary atherosclerotic plaque characteristics in the correlation between CT-FFR and FFR.

Purpose

This study sought to determine the effect of main coronary atherosclerotic plaque metrics (APM) on the correlation between on-site CT-FFR and invasive FFR.

Methods

Patients referred for invasive coronary angiography (ICA) who accepted to undergo a CT-FFR study were prospectively included. We excluded patients with atrial fibrillation, chronic total occlusions, severe ventricular hypertrophy or previous coronary revascularization, and those with any contraindication for CT. On-site CT-FFR and APM were calculated for each coronary vessel. Continuous variables of APM were dichotomized as above and below the median and their interaction on the correlation between on-site CT-FFR and invasive FFR was assessed by multiple linear regression model.

Results

33 patients (90 vessels) were included. Mean age was 65±10 years, 88% were males, 60% had hypertension, 77% dyslipidaemia and 40% diabetes. The mean delay time between CTA and ICA of 21 days. The average analysis time of CT-FFR was 16±4 minutes. Overall, correlation between FFR and CT-FFR showed a Pearson's r coefficient of 0.77±0.06 and a standardized beta coefficient of 0.8 (p<0.001). The beta coefficients between CT-FFR and FFR did not change significantly after the interaction with different APM (p>0.05 for all) (see Table).

Standardized Beta coefficients for on-site CT-FFR with invasive FFR as a gold standard Below the median Above the median p value for interaction Total atheroma volume (TAV) (mm3) 0.66 0.93 0.071 Percent atheroma volume (PAV) (%) 1.00 0.69 0.063 Calcified atheroma plaque volume (%) 0.89 0.68 0.175 Remodeling index 0.94 0.71 0.129 Lesion length (LL) (mm) 0.67 0.89 0.158 Minimal lumen area (mm2) 0.73 0.71 0.955

Conclusions

There is a good correlation between on-site CT-FFR and invasive FFR, which is not affected by main atherosclerotic plaque characteristics.

First Observation of an Attractive Interaction between a Proton and a Cascade Baryon

This Letter presents the first experimental observation of the attractive strong interaction between a proton and a multistrange baryon (hyperon) Ξ^{-}. The result is extracted from two-particle correlations of combined p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+} pairs measured in p-Pb collisions at sqrt[s_{NN}]=5.02  TeV at the LHC with ALICE. The measured correlation function is compared with the prediction obtained assuming only an attractive Coulomb interaction and a standard deviation in the range [3.6, 5.3] is found. Since the measured p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+} correlation is significantly enhanced with respect to the Coulomb prediction, the presence of an additional, strong, attractive interaction is evident. The data are compatible with recent lattice calculations by the HAL-QCD Collaboration, with a standard deviation in the range [1.8, 3.7]. The lattice potential predicts a shallow repulsive Ξ^{-} interaction within pure neutron matter and this implies stiffer equations of state for neutron-rich matter including hyperons. Implications of the strong interaction for the modeling of neutron stars are discussed.

Definition of a measurement scale of graininess from reflectance and visual measurements

Effect pigments in coatings produce eye-catching colour and texture effects and are widely used in automotive, cosmetics, coatings, inks, flooring, textile or decoration. One of these texture effects is graininess, which is the perceived texture exhibited when the effect coating is observed under diffuse illumination. To date there is not a standard procedure to measure graininess from reflectance measurements. The objective of this work is to propose a methodology for traceable graininess measurements, similarly as it was proposed for colour in 1931. In this article, the relevant reflectance-based quantities are clearly defined, and a formal relation with data from visual experiments is given. This methodology would allow a measurement scale of graininess and a difference formula to be agreed once conclusive visual data become available.

Impact of primary cancer features on behaviour of colorectal liver metastases and survival after hepatectomy

Background

Markers of tumour biology may be valuable prognostic indicators after hepatic resection of colorectal cancer liver metastases (CRLMs). Identification of the aggressiveness of these metastases might inform the appropriateness of hepatic surgery.

Methods

Patients undergoing liver resection for CRLMs between January 2001 and July 2013 in four tertiary hospitals were reviewed. A mathematical model to estimate CRLM doubling times was constructed for patients with metachronous metastases. Tumour doubling time was investigated in relation to the features of colorectal cancer, including KRAS status. The hazard rate for recurrence and death following hepatectomy was explored through the Kernel‐smoothed estimator.

Results

Of 1063 patients undergoing liver resection for CRLMs, 361 with metachronous metastases undergoing single‐stage hepatectomy were analysed. The mean doubling time in patients not receiving chemotherapy between surgery for colorectal cancer and CRLM was 71·4 days. Tumour doubling time was shorter in patients with more advanced primary tumour stages, with mutant KRAS and in those who did not receive chemotherapy. For fast‐growing CRLMs (doubling time less than 48 days), the risk of recurrence was highest within the first postoperative year, and was about 7 per cent per month.

Conclusion

Primary features of colorectal cancer were linked to aggressiveness of CRLMs as measured by doubling time.

Index for the evaluation of the general photometric performance of photometers

The General V(λ) Mismatch Index, f1 ^', was defined for a general description of the photometric performance of photometers. This index is widely-used in photometry, and it is very relevant for selecting photometers for low-uncertainty photometric measurements. It quantifies the spectral mismatch between the relative spectral responsivity of a photometer and the luminous efficiency function for photopic vision, V(λ). The linear correlation between the real general photometric measurement error and f1 ^' of 77 photometers was studied for four sets of light sources: R, G and B LEDs (narrowband spectral power distributions, SPDs), blackbodies at different colour temperatures (broadband SPDs), phosphor-based LEDs at different correlated color temperatures (SPDs with narrow- and broad-band features), and a mixture of blackbodies and phosphor-based LED sources. This article shows that it can be defined an alternative index which is notably better correlated with the real general photometric measurement error of the photometers under light sources with broadband features in their SPDs, adequate for general lighting. This index is based on filtering the high spectral frequencies variations between the relative spectral responsivity of the photometer and V(λ). The use of this new index for the assessment of the general photometric performance of photometers would improve the selection of high quality photometers and, consequently, would contribute to the general improvement of photometric measurements.

First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process

The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190  GeV/c π^{-} beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3  GeV/c^{2} and 8.5  GeV/c^{2}. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.

Diagnostic accuracy and cost-effectiveness of different strategies to triage women with adnexal masses: a prospective study

OBJECTIVE

Transvaginal sonography (TVS) and serum biomarkers are used widely in clinical practice to triage women with adnexal masses, but the effectiveness of current biomarkers is weak. The aim of this study was to determine the best method of diagnosing patients with adnexal masses, in terms of diagnostic accuracy and economic costs, among four triage strategies: (1) the International Ovarian Tumor Analysis group's simple rules (SR) for interpretation of TVS with subjective assessment (SA) by an experienced ultrasound operator when TVS results are inconclusive (referred to hereafter as SR ± SA), (2) SR ± SA and cancer antigen 125 (CA 125), (3) SR ± SA and human epididymis protein 4 (HE4) and (4) SR ± SA and the risk of malignancy algorithm (ROMA). Our main hypothesis was that the addition of the biomarkers to SR ± SA could improve triaging of these patients in terms of diagnostic accuracy (i.e. malignant vs benign). As secondary analyses, we estimated the cost effectiveness of the four strategies and the diagnostic accuracy of SR ± SA at the study hospitals.

METHODS

Between February 2013 and January 2015, 447 consecutive patients who were scheduled for surgery for an adnexal mass at the S. Anna and Mauriziano Hospitals in Turin were enrolled in this multicenter prospective cohort study. Preoperative TVS was performed and preoperative CA 125 and HE4 levels were measured. Pathology reports were used to assess the diagnostic accuracy of the four triage strategies and the cost of each strategy was calculated.

RESULTS

A total of 391 patients were included in the analysis: 57% (n = 221) were premenopausal and 43% (n = 170) were postmenopausal. The overall prevalence of malignancy was 21%. SR were conclusive in 89% of patients and thus did not require SA; the overall performance of SR ± SA showed a sensitivity of 82%, specificity of 92% and positive and negative predictive values and positive and negative likelihood ratios of 74%, 95%, 10.5 and 0.19, respectively. In premenopausal women, mean cost among the four triage strategies varied from €36.41 for SR ± SA to €70.12 for SR ± SA + ROMA. The addition of biomarkers to SR ± SA showed no diagnostic advantage compared with SR ± SA alone and was more costly. Among postmenopausal women, mean cost among the four triage strategies varied from €39.52 for SR ± SA to €73.23 for SR ± SA + ROMA. Among these women, SR ± SA + CA 125 and SR ± SA + ROMA had a higher sensitivity (both 92% (95% CI, 85-99%)) than SR ± SA (81% (95% CI, 71-91%)), but SR ± SA had a higher specificity (84% (95% CI, 77-91%)). SR ± SA + CA 125 and SR ± SA + ROMA improved diagnostic accuracy, each diagnosing a third more malignant adnexal masses. In postmenopausal women, compared with SR ± SA alone, SR ± SA + CA 125 showed a net reclassification improvement (NRI) of 28.8% at an extra cost of €13.00, while the extra cost for SR ± SA + ROMA was €33.71, with a comparable gain, in terms of NRI, as that of SR ± SA + CA 125.

CONCLUSIONS

In our study sample, SR ± SA seems to be the best strategy to triage women with adnexal masses for surgical management. Among postmenopausal women, SR ± SA + CA 125 increased the NRI at a reasonable extra cost. Our data do not justify the use of HE4 and ROMA in the initial triage of women with adnexal masses. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Ultra-High Spatial Resolution, Multi-Energy CT using Photon Counting Detector Technology

Two ultra-high-resolution (UHR) imaging modes, each with two energy thresholds, were implemented on a research, whole-body photon-counting-detector (PCD) CT scanner, referred to as sharp and UHR, respectively. The UHR mode has a pixel size of 0.25 mm at iso-center for both energy thresholds, with a collimation of 32 × 0.25 mm. The sharp mode has a 0.25 mm pixel for the low-energy threshold and 0.5 mm for the high-energy threshold, with a collimation of 48 × 0.25 mm. Kidney stones with mixed mineral composition and lung nodules with different shapes were scanned using both modes, and with the standard imaging mode, referred to as macro mode (0.5 mm pixel and 32 × 0.5 mm collimation). Evaluation and comparison of the three modes focused on the ability to accurately delineate anatomic structures using the high-spatial resolution capability and the ability to quantify stone composition using the multi-energy capability. The low-energy threshold images of the sharp and UHR modes showed better shape and texture information due to the achieved higher spatial resolution, although noise was also higher. No noticeable benefit was shown in multi-energy analysis using UHR compared to standard resolution (macro mode) when standard doses were used. This was due to excessive noise in the higher resolution images. However, UHR scans at higher dose showed improvement in multi-energy analysis over macro mode with regular dose. To fully take advantage of the higher spatial resolution in multi-energy analysis, either increased radiation dose, or application of noise reduction techniques, is needed.

Multilateral spectral radiance factor scale comparison

The field of spectral radiance factor (SRF) measurements has seen growing interest in recent years. Scale conformity has so far only been established between the national metrology institutes (NMIs) of Germany and the USA. This study aims at a bigger, multilateral scale comparison. For this purpose, a total of six NMIs participated in a scale comparison of goniospectrophotometers based on neutral and colored diffusely reflecting ceramics samples. In addition, two universities, providing a home-built gonioreflectometer and two widely used commercially available color measurement instruments, respectively, were involved. The wavelength range of the scale comparison covers the visible wavelength range from 380 nm to 780 nm. Results indicate systematic issues and that the uncertainty evaluation of the NMIs requires further work; although for the greatest part of the covered spectral range the agreement is good.

Renal Stone Characterization using High Resolution Imaging Mode on a Photon Counting Detector CT System

In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm × 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same sub-elements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

Lung Nodule Volume Quantification and Shape Differentiation with an Ultra-High Resolution Technique on a Photon Counting Detector CT System

A new ultra high-resolution (UHR) mode has been implemented on a whole body photon counting-detector (PCD) CT system. The UHR mode has a pixel size of 0.25 mm by 0.25 mm at the iso-center, while the conventional (macro) mode is limited to 0.5 mm by 0.5 mm. A set of synthetic lung nodules (two shapes, five sizes, and two radio-densities) was scanned using both the UHR and macro modes and reconstructed with 2 reconstruction kernels (4 sets of images in total). Linear regression analysis was performed to compare measured nodule volumes from CT images to reference volumes. Surface curvature was calculated for each nodule and the full width half maximum (FWHM) of the curvature histogram was used as a shape index to differentiate sphere and star shape nodules. Receiver operating characteristic (ROC) analysis was performed and area under the ROC curve (AUC) was used as a figure of merit for the differentiation task. Results showed strong linear relationship between measured nodule volume and reference standard for both UHR and macro mode. For all nodules, volume estimation was more accurate using UHR mode with sharp kernel (S80f), with lower mean absolute percent error (MAPE) (6.5%) compared with macro mode (11.1% to 12.9%). The improvement of volume measurement from UHR mode was more evident particularly for small nodule size (3mm, 5mm), or star-shape nodules. Images from UHR mode with sharp kernel (S80f) consistently demonstrated the best performance (AUC = 0.85) when separating star from sphere shape nodules among all acquisition and reconstruction modes. Our results showed the advantages of UHR mode on a PCD CT scanner in lung nodule characterization. Various clinical applications, including quantitative imaging, can benefit substantially from this high resolution mode.

Customizing plasmonic diffraction patterns by laser interference

This work reports a versatile and efficient production of periodic microstructures surrounded by metallic alloy nanoparticles supported on glass with customized visible diffraction patterns by using the technique of phase mask laser interference.

Color characterization of coatings with diffraction pigments

Coatings with diffraction pigments present high iridescence, which needs to be characterized in order to describe their appearance. The spectral bidirectional reflectance distribution functions (BRDFs) of six coatings with SpectraFlair diffraction pigments were measured using the robot-arm-based goniospectrophotometer GEFE, designed and developed at CSIC. Principal component analysis has been applied to study the coatings of BRDF data. From data evaluation and based on theoretical considerations, we propose a relevant geometric factor to study the spectral reflectance and color gamut variation of coatings with diffraction pigments. At fixed values of this geometric factor, the spectral BRDF component due to diffraction is almost constant. Commercially available portable goniospectrophotometers, extensively used in several industries (automotive and others), should be provided with more aspecular measurement angles to characterize the complex reflectance of goniochromatic coatings based on diffraction pigments, but they would not require either more than one irradiation angle or additional out-of-plane geometries.