CT dose reduction using Automatic Exposure Control and iterative reconstruction: A chest paediatric phantoms study

PurposeTo evaluate the impact of Automatic Exposure Control (AEC) on radiation dose and image quality in paediatric chest scans (MDCT), with or without iterative reconstruction (IR).MethodsThree anthropomorphic phantoms representing children aged one, five and 10-year-old were explored using AEC system (CARE Dose 4D) with five modulation strength options. For each phantom, six acquisitions were carried out: one with fixed mAs (without AEC) and five each with different modulation strength. Raw data were reconstructed with Filtered Back Projection (FBP) and with two distinct levels of IR using soft and strong kernels. Dose reduction and image quality indices (Noise, SNR, CNR) were measured in lung and soft tissues. Noise Power Spectrum (NPS) was evaluated with a Catphan 600 phantom.ResultsThe use of AEC produced a significant dose reduction (p < 0.01) for all anthropomorphic sizes employed. According to the modulation strength applied, dose delivered was reduced from 43% to 91%. This pattern led to significantly increased noise (p < 0.01) and reduced SNR and CNR (p < 0.01). However, IR was able to improve these indices. The use of AEC/IR preserved image quality indices with a lower dose delivered. Doses were reduced from 39% to 58% for the one-year-old phantom, from 46% to 63% for the five-year-old phantom, and from 58% to 74% for the 10-year-old phantom. In addition, AEC/IR changed the patterns of NPS curves in amplitude and in spatial frequency.ConclusionsIn chest paediatric MDCT, the use of AEC with IR allows one to obtain a significant dose reduction while maintaining constant image quality indices.     

Spectral optimization of iodine-enhanced CT: Quantifying the effect of tube voltage on image quality and radiation exposure determined at an anthropomorphic phantom

PurposeTo provide an experimental basis for spectral optimization of iodine-enhanced CT by a quantitative analysis of image quality and radiation dose characteristics consistently measured for a large variety of scan settings at an anthropomorphic phantom.MethodsCT imaging and thermoluminescent dosimetry were performed at an anthropomorphic whole-body phantom with iodine inserts for different tube voltages (U, 70–140 kV) and current-time products (Q, 60–300 mAs). For all U-Q combinations, the iodine contrast (C), the noise level (N) and, from these, the contrast-to-noise ratio (CNR) of reconstructed CT images were determined and parameterized as a function of U, Q or the measured absorbed dose (D). Finally, two characteristic curves were derived that give the relative increase of CNR at constant D and the relative decrease of D at constant CNR when lowering U.ResultsLowering U affects the measured CNR only slightly but markedly reduces D. For example, reducing U from 120 kV to 70 kV increases the CNR at constant D by a factor of nearly 1.8 or, alternatively, reduces D at constant CNR by a factor of nearly 5.ConclusionSpectral optimization by lowering U is an effective approach to attain the necessary CNR for a specific diagnostic task at hand while at the same time reducing radiation exposure as far as practically achievable. The characteristic curves derived in this study from extensive measurements at a reference ‘person’ can support CT users in an easy-to-use manner to select an appropriate voltage for various clinical scenarios.     

Eye lens dose correlations with personal dose equivalent and patient exposure in paediatric interventional cardiology performed with a fluoroscopic biplane system

PurposeTo analyse the correlations between the eye lens dose estimates performed with dosimeters placed next to the eyes of paediatric interventional cardiologists working with a biplane system, the personal dose equivalent measured on the thorax and the patient dose.MethodsThe eye lens dose was estimated in terms of H_p(0.07) on a monthly basis, placing optically stimulated luminescence dosimeters (OSLDs) on goggles. The H_p(0.07) personal dose equivalent was measured over aprons with whole-body OSLDs. Data on patient dose as recorded by the kerma-area product (P_KA) were collected using an automatic dose management system. The 2 paediatric cardiologists working in the facility were involved in the study, and 222 interventions in a 1-year period were evaluated. The ceiling-suspended screen was often disregarded during interventions.ResultsThe annual eye lens doses estimated on goggles were 4.13 ± 0.93 and 4.98 ± 1.28 mSv. Over the aprons, the doses obtained were 10.83 ± 0.99 and 11.97 ± 1.44 mSv. The correlation between the goggles and the apron dose was R² = 0.89, with a ratio of 0.38. The correlation with the patient dose was R² = 0.40, with a ratio of 1.79 μSv Gy⁻¹ cm⁻². The dose per procedure obtained over the aprons was 102 ± 16 μSv, and on goggles 40 ± 9 μSv. The eye lens dose normalized to P_KA was 2.21 ± 0.58 μSv Gy⁻¹ cm⁻².ConclusionsMeasurements of personal dose equivalent over the paediatric cardiologist’s apron are useful to estimate eye lens dose levels if no radiation protection devices are typically used.     

Methylnickel compounds containing 2-phosphinylethanolato ligands – Syntheses,properties, and ethene coupling reactions

Combining dimethylphosphinylethanols HO(R¹R²)CCH₂PMe₂ (1: R¹ = R² = C₆H₅; 2: R¹ = R² = 4-OMe–C₆H₄; 5: R¹ = R² = 4-NMe₂–C₆H₄) with methyl(methoxo)(trimethylphosphine)nickel gave mononuclear methyl(trimethylphosphine)nickel(chelate) compounds 7–9. Ligand 6 (R¹ = Me, R² = 4-OMe–C₆H₅) afforded a dinuclear methylnickel compound 14. By reacting (TMEDA)lithium-dimethylphosphinylmethanide with ketones OC(R¹R²), the dimethylphosphinylethanols HO(R¹R²)CCH₂PMe₂ (3: R¹R² = 9-fluorenyl; 4: R¹ = H, R² = C₆H₅) were synthesized as prechelate ligands. Under otherwise similar conditions, the fluorenyl substituted anion in 3 gave rise to a mononuclear complex 10 which was found to act as a source of trimethylphosphine forming dinuclear 11 and at the same time to act as an acceptor of trimethylphosphine forming pentacoordinate 10 · PMe₃. Ni(COD)(PMe₃)₂ was used as a scavenger of PMe₃ in converting 8 or 9 to the dinuclear methylnickel compounds 12 and 13, respectively. Modifying the P,O chelating unit of a methyl nickel compound by introducing 2-phosphinylethanolato ligands leads to novel single-component catalysts for ethene oligomerization showing moderate reactivity and thermal stability.     

Comparaison entre OSEM-3D et rétroprojection filtrée pour les images traitées par SISCOM dans l’épilepsie temporale

IntroductionWhen ictal and interictal brain SPECT are reconstructed with filtered backprojection (FBP), the noise level of subtraction images is frequently high and requires the use of thresholding methods. The aim of this study was to compare the subtraction images for cerebral SPECT reconstructed either with FBP or with a 3D iterative reconstruction method (OSEM-3D).Material and methodsAfter optimisation of the reconstruction parameters on phantom, the subtraction SPECT images, which were obtained with FBP or with OSEM-3D and coregistered with MRI images, were analyzed in 15 patients with refractory temporal epilepsy.ResultsOn phantom and with the constrain of high enough spatial resolution (full width at half of maximum for a punctual source less than or equal to 11 mm) were reached using: (i) a Butterworth filter with a cut-off frequency of 0.4 Nyquist at order 6 for FBP and (ii) five iterations, 16 subsets and a 9 mm gaussian filter for OSEM-3D. On the subtraction images, which were obtained with these optimal parameters, the temporal foci from patients were smaller with OSEM-3D than with FBP (11 ± 6 cm³ versus 17 ± 10 cm³, P = 0.02), mean voxel activities were equivalent between the two methods within temporal foci (6.30 ± 3.13 counts versus 6.34 ± 4.93 counts) but these activities were dramatically reduced by OSEM-3D within background regions (0.02 ± 0.02 counts versus 0.19 ± 0.12 counts, P < 0.001).ConclusionFor the ictal–interictal subtraction SPECT images, which are obtained in patients with refractory temporal epilepsy, the use of an optimized OSEM-3D method leads to dramatically reduce the volume of temporal foci, as well as the background noise level, two properties that are likely to facilitate the detection and localisation of epilepsy foci.     

Task-based characterization of a deep learning image reconstruction and comparison with filtered back-projection and a partial model-based iterative reconstruction in abdominal CT: A phantom study

PurposeWe aimed to thoroughly characterize image quality of a novel deep learning image reconstruction (DLIR), and investigate its potential for dose reduction in abdominal CT in comparison with filtered back-projection (FBP) and a partial model-based iterative reconstruction (ASiR-V).MethodsWe scanned a phantom at three dose levels: regular (7 mGy), low (3 mGy) and ultra-low (1 mGy). Images were reconstructed using DLIR (low, medium and high levels) and ASiR-V (0% = FBP, 50% and 100%). Noise and contrast-dependent spatial resolution were characterized by computing noise power spectra and target transfer functions, respectively. Detectability indexes of simulated acute appendicitis or colonic diverticulitis (low contrast), and calcium-containing urinary stones (high contrast) (|ΔHU| = 50 and 500, respectively) were calculated using the nonprewhitening with eye filter model observer.ResultsAt all dose levels, increasing DLIR and ASiR-V levels both markedly decreased noise magnitude compared with FBP, with DLIR low and medium maintaining noise texture overall. For both low- and high-contrast spatial resolution, DLIR not only maintained, but even slightly enhanced spatial resolution in comparison with FBP across all dose levels. Conversely, increasing ASiR-V impaired low-contrast spatial resolution compared with FBP. Overall, DLIR outperformed ASiR-V in all simulated clinical scenarios. For both low- and high-contrast diagnostic tasks, increasing DLIR substantially enhanced detectability at any dose and contrast levels for any simulated lesion size.ConclusionsUnlike ASiR-V, DLIR substantially reduces noise while maintaining noise texture and slightly enhancing spatial resolution overall. DLIR outperforms ASiR-V by enabling higher detectability of both low- and high-contrast simulated abdominal lesions across all investigated dose levels.     

Postoperative endometrial carcinoma treated with external beam irradiation plus vaginal-cuff brachytherapy. Is there a dose relationship with G2 vaginal complications?

AimTo analyse the possible relationship between the EQD2_(α/β=3Gy) at 2 cm³ of the vagina and late toxicity in vaginal-cuff-brachytherapy (VBT) after external-beam-irradiation (EBRT) for postoperative endometrial carcinoma (EC).Materials and methodsFrom 2014 to 2016, 62 postoperative EC patients were treated with EBRT + VBT. The median EBRT dose was 45 Gy (44 Gy–50.4 Gy). VBT involved a single 7 Gy dose. Toxicity was prospectively evaluated using the RTOG score for the rectum and bladder and the objective LENT-SOMA criteria for the vagina. EQD2_{(α/β = 3Gy)} at 2 cm³ of the most exposed part of the vagina was calculated by the sum of the EBRT + VBT dose. Statistics: Boxplot, Student’s t and Chi-square tests and ROC curves.ResultsMean follow-up: 39.2 months (15–68). Late toxicity: bladder:0 patient; rectum:2 patients-G1; Vagina: 26 patients-17G1, 9G2; median EQD2_(α/β=3Gy) at 2 cm³ in G0-G1 patients was 70.4 Gy(SD2.36), being 72.5 Gy(SD2.94) for G2p. The boxplot suggested a cut-point identifying the absence of G2: 100 % of G2p received >68 Gy, ROC curves showed an area under the curve of 0.72 (sensitivity of 1 and specificity of 0.15).ConclusionsDoses >68 Gy EQD2_(α/β=3Gy) at 2 cm³ to the most exposed area of the vagina were associated with late G2 vaginal toxicity in postoperative EC patients treated with EBRT + VBT suggesting a very good dose limit to eliminate the risk of G2 late toxicity. The specificity obtained indicates the need for prospective analyses.     

Utilisation des gels de polymères MAGIC pour la dosimétrie d’une source non scellée d’yttrium 90

Polymer gels are relative chemical dosimeters. They allow to access to three-dimensional dose distribution. The aim of this study has been to investigate the preparation and the use of a polymer gel with a tissue equivalent density known as MAGIC gel from magnetic resonance imaging and x-ray computed tomography for non-sealed source dosimetry. This kind of gel is “normoxic” because it can be manufactured and used in normal room atmosphere. In the first part of this study, its accuracy and sensibility were studied using external beam irradiation by photons. Spin-spin relaxation rate (R₂) and Computed Tomography (CT) number had been used to record gel responses. Using the same manufacture process, radiolabelled gels composed of 95% MAGIC gel and 5% of ⁹⁰Y termed ⁹⁰Y-MAGIC₉₅, with varying activity ranged from 0 to 30 MBq were made. In case of photon external beam irradiation, a linear response is observed whatever the calibration method and the imaging system used (the correlation coefficient r² > 0.98 in all cases). ⁹⁰Y-MAGIC₉₅ radiolabelled gel responses were recorded after 28, 76 and 124 h. The R₂/dose curves are not linear; three phases can be described, the first being linear with a slow slope (0.14 s⁻¹ Gy⁻¹ instead of 0.41 s⁻¹ Gy⁻¹ for external beam irradiation of the same gel batch). This study shows safety of radiolabelled MAGIC gels manufacturing process and their large dosimetric feasibility. ⁹⁰Y-MAGIC₉₅ gel response appears to be reproducible and related to the absorbed dose, thus this gel is a promising tool for non-sealed source dosimetry.     

Trispyrazolylmethane piano stool complexes of iron(II) and cobalt(II)

A series of cationic trispyrazolylmethane complexes of the general form [Tm^RM(CH₃CN)₃]²⁺ (Tm = tris(pyrazolyl)methane, 1, R = 3,5-Me₂, M = Fe(II); 2, R = 3-Ph, M = Fe(II); 3, R = 3,5-Me₂, M = Co(II); 4, R = 3-Ph, M = Co(II)) with ‘piano-stool’ structures was prepared by the reaction of the N₃tripodal ligands (Tm^R)with [(CH₃CN)₆M](BF₄)₂ in a 1:1 stoichiometric ratio. Magnetic susceptibility measurements indicate that all four complexes with BF₄⁻ counter anions are paramagnetic, high-spin systems in the solid state with μ_eff at high temperatures of 5.2 (1, S = 2), 5.4 (2, S = 2), 4.9 (3, S = 3/2) and 4.6 (4, S = 3/2) BM, respectively. Comparisons of bond lengths from the metal centre to the Tm^R nitrogen donors, and from the metal centre to the acetonitrile nitrogen donors indicate that the neutral tripodal ligands appear to be more weakly coordinated to the metal centre than are the acetonitrile ligands. Reactions of these tripodal complexes with bidentate phosphine ligands, such as 1,2-diphosphinoethane or 1,2-bis(diallylphosphino)ethane leads to displacement of the tripodal ligand, or to the formation of more thermally stable bis-ligand complexes M(Tm^R)₂ (R = 3,5-dimethyl).     

Confrontation des données de la TEP/TDM au 18FDG initiale aux statuts p16 (INK4a) et HPV des cancers des VADS localement avancés traités par radiochimiothérapie

PurposeThe overexpression of p16 and HPV status are now well established as independent prognostic factors in head and neck squamous cell carcinoma (HNSCC). It was suggested that some parameters derived from initial 18F-FDG PET are also independent prognostic factors. Our purpose was to study the correlation between virology and pretreatment PET/CT in locally advanced HNSCC treated by radio-chemotherapy.MethodsForty HNSCC patients with tumor volumes > 3 cm³ were prospectively recruited. All patients underwent initial 18F-FDG PET/CT, from which metabolic volume, intensity (SUV), overall activity, heterogeneity and shape parameters were extracted. The correlation of these parameters with virological data extracted from pre treatment biopsy, including p16 expression, DNA HPV 16 and HPV status (p16 + DNA HPV 16) was subsequently studied.ResultsP16 + tumors exhibited higher SUV_max (P = 0.028) and SUV_mean (P = 0.02). P16+ tumors were also more heterogeneous, albeit with a lower correlation (P = 0.004 for local heterogeneity). In addition, P16+ and HPV+ tumors were characterized by less complex shapes (P = 0.03).ConclusionLocally advanced HNSCC show specific PET characteristics in case of P16+ tumors. The relationship between those different biological characterization approaches and overall patient outcome needs to be investigated.     

Regulating effects of climate,net primary productivity,and nitrogen on carbon sequestration rates in temperate wetlands,Northeast China

Temperate wetlands in the Northern Hemisphere have high long-term carbon sequestration rates, and play critical roles in mitigating regional and global atmospheric CO₂ increases at the century timescale. We measured soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) from 11 typical freshwater wetlands (Heilongjiang Province) and one saline wetland (Jilin Province) in Northeast China, and estimated carbon sequestration rates using ²¹⁰Pb and ¹³⁷Cs dating technology. Effects of climate, net primary productivity, and nutrient availability on carbon sequestration rates (R_carbon) were also evaluated. Chronological results showed that surface soil within the 0–40 cm depth formed during the past 70–205 years. Soil accretion rates ranged from 2.20 to 5.83 mm yr⁻¹, with an average of 3.84 ± 1.25 mm yr⁻¹ (mean ± SD). R_carbon ranged from 61.60 to 318.5 gC m⁻² yr⁻¹ and was significantly different among wetland types. Average R_carbon was 202.7 gC m⁻² yr⁻¹ in the freshwater wetlands and 61.6 gC m⁻² yr⁻¹ in the saline marsh. About 1.04 × 10⁸ tons of carbon was estimated to be captured by temperate wetland soils annually in Heilongjiang Province (in the scope of 45.381–51.085°N, 125.132–132.324°E). Correlation analysis showed little impact of net primary productivity (NPP) and soil nutrient contents on R_carbon, whereas climate, specifically the combined dynamics of temperature and precipitation, was the predominant factor affecting R_carbon. The negative relationship observed between R_carbon and annual mean temperature (T) indicates that warming in Northeast China could reduce R_carbon. Significant positive relationships were observed between annual precipitation (P), the hydrothermal coefficient (defined as P/AT, where AT was accumulative temperature ≥10 °C), and R_carbon, indicating that a cold, humid climate would enhance R_carbon. Current climate change in Northeast China, characterized by warming and drought, may form positive feedbacks with R_carbon in temperate wetlands and accelerate carbon loss from wetland soils.     

Correlation between VEGFR-2 receptor kinase domain-containing receptor (KDR) mRNA and angiotensin II receptor type 1 (AT1-R) mRNA in endometrial cancer

PurposeAngiogenesis, a multistep process that results in new blood vessel formation from preexisting vasculature is essential for both the growth of solid tumour and for metastasis. Stimulation of vascular endothelial growth factor receptor (VEGFR), a transmembrane glycoprotein, results in mitogenesis. Within this family of receptors, VEGFR 2/kinase-insert-domain containing receptor appears to be principally upregulated during tumorigenesis. The aim of this study was to determine the expression of VEGFR-2/kinase-insert-domain containing receptor (KDR) and its correlation with angiotensin receptor type 1 (AT1-R) and clinical factors in endometrial carcinoma.MethodsThe expression of KDR and AT1-R was studied in endometrial carcinoma and normal endometrium by Real-time RT-PCR and Western blot analysis in 136 samples. The expression profile was correlated with the clinicopathological characteristics of endometrial adenocarcinoma.ResultsWe noted a significant correlation between the expression of KDR and AT1-R in tumour grade G1, G2 and G3 (R_s = 0.50; p = 0.002, R_s = 0.69; p = 0.0001, R_s = 0.52; p = 0.005, respectively). In stage I and stage II carcinoma, a significant correlation was also found between the expression of KDR and AT1-R (R_s = 0.70, p = 0.0001, R_s = 0.67; p = 0.001, respectively). Moreover significant correlation was observed between both KDR and AT1-R in tissue with different myometrial invasion (R_s = 0.54, p = 0.0001, R_s = 0.68; p = 0.0001; respectively for tumours with invasion into the inner half and invasion into the outer half).ConclusionsBasing on received correlation between AT1-R and KDR expression and previous results we speculate that angiotensin through AT1-R modulates KDR expression and thus have influence on local VEGF level. However, further studies are required to clarify the biological interaction between KDR, AT1-R and other hormonal regulators in endometrial carcinoma.     

Object shape dependency of in-plane resolution for iterative reconstruction of computed tomography

The present study aimed to investigate whether the in-plane resolution property of iterative reconstruction (IR) of computed tomography (CT) data is object shape-dependent by testing columnar shapes with diameters of 3, 7, and 10 cm (circular edge method) and a cubic shape with 5-cm side lengths (linear edge method). For each shape, objects were constructed of acrylic (contrast in Hounsfield units [ΔHU] = 120) as well as a soft tissue equivalent material (ΔHU = 50). For each shape, we measured the modulation transfer functions (MTFs) of IR and filtered back projection (FBP) using two multi-slice CT scanners at scan doses of 5 and 10 mGy. In addition, we evaluated a thin metal wire using the conventional method at 10 mGy. For FBP images, the MTF results of the tested objects and the wire method showed substantial agreement, thus demonstrating the validity of our analysis technique. For IR images, the MTF results of different shapes were nearly identical for each object contrast and dose combination, and we did not observe shape-dependent effects of the resolution properties of either tested IR. We conclude that both the circular edge method and linear edge method are equally useful for evaluating the resolution properties of IRs.     

Evaluation of (Z)-2-((1-benzyl-1H-indol-3-yl)methylene)-quinuclidin-3-one analogues as novel,high affinity ligands for CB1 and CB2 cannabinoid receptors

A small library of N-benzyl indolequinuclidinone (IQD) analogs has been identified as a novel class of cannabinoid ligands. The affinity and selectivity of these IQDs for the two established cannabinoid receptor subtypes, CB1 and CB2, was evaluated. Compounds 8 (R = R² = H, R¹ = F) and 13 (R = COOCH₃, R¹ = R² = H) exhibited high affinity for CB2 receptors with K_i values of 1.33 and 2.50 nM, respectively, and had lower affinities for the CB1 receptor (K_i values of 9.23 and 85.7 nM, respectively). Compound 13 had the highest selectivity of all the compounds examined, and represents a potent cannabinoid ligand with 34-times greater selectivity for CB2R over CB1R. These findings are significant for future drug development, given recent reports demonstrating beneficial use of cannabinoid ligands in a wide variety of human disease states including drug abuse, depression, schizophrenia, inflammation, chronic pain, obesity, osteoporosis and cancer.     

Effect of diagnostic cone-beam computed tomography protocols on image quality,patient dose,and lesion detection

ObjectiveTo evaluate the effect of cone-beam computed tomography (CBCT) image acquisition protocols on image quality, lesion detection, delineation, and patient dose.Methods100-patients and a CTDI phantom combined with an electron density phantom were examined using four different CBCT-image acquisition protocols during image-guided transarterial chemoembolization (TACE). Protocol-1 (time: 6 s, tube rotation: 360°), protocol-2 (5 s, 300°), protocol-3 (4 s, 240°) and protocol-4 (3 s, 180°) were used. The protocols were first investigated using a phantom. The protocols that were found to be clinically appropriate in terms of image quality and radiation dose were then assessed on patients. A higher radiation dose and/or a poor image quality were inappropriate for the patient imaging. Patient dose (patient-entrance dose and dose-area product), image quality (Hounsfield Unit, noise, signal-to-noise ratio and contrast-to-noise ratio), and lesion delineation (tumor-liver contrast) were assessed and compared using appropriate statistical tests. Lesion detectability, sensitivity, and predictive values were estimated for CBCT-image data using pre-treatment patient magnetic resonance imaging.ResultsThe estimated patient dose showed no statistical significance (p > 0.05) between protocols-2 and -3; the assessed image quality between these protocols manifested insignificant difference (p > 0.05). Two other phantom protocols were not considered for patient imaging due to significantly higher dose (protocols-1) and poor image quality (protocol-4). Lesion delineation and detection were insignificant (p > 0.05) between protocols-2 and -3. Lesion sensitivities generated were 81–89% (protocol-2) and 81–85% (protocol-3) for different lesion types.ConclusionData acquisition using protocols-2 and -3 provided good image quality, lesion detection and delineation with acceptable patient dose during CBCT-imaging mainly due to similar frame numbers acquired.     

Validation of a free software for unsupervised assessment of abdominal fat in MRI

PurposeTo demonstrate the accuracy of an unsupervised (fully automated) software for fat segmentation in magnetic resonance imaging. The proposed software is a freeware solution developed in ImageJ that enables the quantification of metabolically different adipose tissues in large cohort studies.MethodsThe lumbar part of the abdomen (19 cm in craniocaudal direction, centered in L3) of eleven healthy volunteers (age range: 21–46 years, BMI range: 21.7–31.6 kg/m²) was examined in a breath hold on expiration with a GE T1 Dixon sequence. Single-slice and volumetric data were considered for each subject. The results of the visceral and subcutaneous adipose tissue assessments obtained by the unsupervised software were compared to supervised segmentations of reference. The associated statistical analysis included Pearson correlations, Bland-Altman plots and volumetric differences (VD_%).ResultsValues calculated by the unsupervised software significantly correlated with corresponding supervised segmentations of reference for both subcutaneous adipose tissue – SAT (R = 0.9996, p < 0.001) and visceral adipose tissue – VAT (R = 0.995, p < 0.001). Bland-Altman plots showed the absence of systematic errors and a limited spread of the differences. In the single-slice analysis, VD_% were (1.6 ± 2.9)% for SAT and (4.9 ± 6.9)% for VAT. In the volumetric analysis, VD_% were (1.3 ± 0.9)% for SAT and (2.9 ± 2.7)% for VAT.ConclusionsThe developed software is capable of segmenting the metabolically different adipose tissues with a high degree of accuracy. This free add-on software for ImageJ can easily have a widespread and enable large-scale population studies regarding the adipose tissue and its related diseases.     

Prevalencia de hiperandrogenismo y síndrome de ovario poliquístico en transexuales de mujer a hombre

IntroductionPrevalence of hyperandrogenism (HA), including the polycystic ovary syndrome (PCOS), in female-to-male transsexuals (FMT) is high. This has been related to metabolic syndrome (MS), which appears to increase cardiovascular morbidity and mortality throughout cross-sex hormone (CSH) therapy.ObjectivesTo assess the prevalence of HA and PCOS in FMT patients before the start of CSH therapy, and their association to MS and its components, insulin resistance (IR) and other cardiovascular risk (CVR) factors.Materials and methodsSeventy-seven FMTs underwent clinical and biochemical assessment for HA before the start of CSH therapy. CVR, IR, and other MS parameters were also assessed.ResultsPrevalence of HA was 49.4% (73.7% were cases of PCOS [Rotterdam criteria]), and prevalence of PCOS in the overall sample was 36.4%. Prevalence of MS was 38.4% and 51.7% according to ATP-III and IDF criteria respectively). MS (according to ATP-III and IDF criteria respectively) was found in 36.8% and 57.9% as compared to 25.6% and 41% of patients with and without HA respectively (p < 0.0001 and P < 0.01 respectively). Of total patients, 54.5% had normal weight (body mass index [BMI] 18.5-24.9 kg.m^-2), 26% were overweight (BMI 25-29.9 kg.m^-2), and 19.5% were obese (BMI ≥ 30 kg.m^-2). After adjusting for BMI, the comparison of hormonal, metabolic, and anthropometric parameters showed statistically significant differences in plasma glucose, HOMA-IR, and abdominal circumference (P < 0.001 for all), as well as HDL cholesterol (HDL) (P = 0.033), but not in total testosterone or calculated free testosterone levels. In the total sample, 27.3% had HDL levels less than 50 mg/dL.ConclusionsOverall HA, and PCOS in particular, are highly prevalent in FMTs. HA and PCOS are related to early development of SM, IR, and other CVR factors with unknown consequences in adulthood.     

Imaging performance of phase-contrast breast computed tomography with synchrotron radiation and a CdTe photon-counting detector

PurposeWithin the SYRMA-CT collaboration based at the ELETTRA synchrotron radiation (SR) facility the authors investigated the imaging performance of the phase-contrast computed tomography (CT) system dedicated to monochromatic in vivo 3D imaging of the female breast, for breast cancer diagnosis.MethodsTest objects were imaged at 38 keV using monochromatic SR and a high-resolution CdTe photon-counting detector. Signal and noise performance were evaluated using modulation transfer function (MTF) and noise power spectrum. The analysis was performed on the images obtained with the application of a phase retrieval algorithm as well as on those obtained without phase retrieval. The contrast to noise ratio (CNR) and the capability of detecting test microcalcification clusters and soft masses were investigated.ResultsFor a voxel size of (60 μm)³, images without phase retrieval showed higher spatial resolution (6.7 mm⁻¹ at 10% MTF) than corresponding images with phase retrieval (2.5 mm⁻¹). Phase retrieval produced a reduction of the noise level and an increase of the CNR by more than one order of magnitude, compared to raw phase-contrast images. Microcalcifications with a diameter down to 130 μm could be detected in both types of images.ConclusionsThe investigation on test objects indicates that breast CT with a monochromatic SR source is technically feasible in terms of spatial resolution, image noise and contrast, for in vivo 3D imaging with a dose comparable to that of two-view mammography. Images obtained with the phase retrieval algorithm showed the best performance in the trade-off between spatial resolution and image noise.