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The aim of this paper is to describe a new automatic method for compensation of metal-implant-induced segmentation errors in MR-based attenuation maps (MRMaps) and to evaluate the quantitative influence of those artifacts on the reconstructed PET activity concentration. The developed method uses a PET-based delineation of the patient contour to compensate metal-implant-caused signal voids in the MR scan that is segmented for PET attenuation correction. PET emission data of 13 patients with metal implants examined in a Philips Ingenuity PET/MR were reconstructed with the vendor-provided method for attenuation correction (MRMap(orig), PETorig) and additionally with a method for attenuation correction (MRMap(cor), PETcor) developed by our group. MRMaps produced by both methods were visually inspected for segmentation errors. The segmentation errors in MRMap(orig) were classified into four classes (L1 and L2 artifacts inside the lung and B1 and B2 artifacts inside the remaining body depending on the assigned attenuation coefficients). The average relative SUV differences (epsilon(av)(rel)) between PETorig and PETcor of all regions showing wrong attenuation coefficients in MRMap(orig) were calculated. Additionally, relative SUVmean differences (epsilon(rel)) of tracer accumulations in hot focal structures inside or in the vicinity of these regions were evaluated. MRMap(orig) showed erroneous attenuation coefficients inside the regions affected by metal artifacts and inside the patients' lung in all 13 cases. In MRMap(cor), all regions with metal artifacts, except for the sternum, were filled with the soft-tissue attenuation coefficient and the lung was correctly segmented in all patients. MRMap(cor) only showed small residual segmentation errors in eight patients. (epsilon(av)(rel)) (mean +/- standard deviation) were: (-56 +/- 3)% for B1, (-43 +/- 4)% for B2, (21+/- 18)% for L1, (120 +/- 47)% for L2 regions. epsilon(rel) (mean +/-standard deviation) of hot focal structures were: (-52 +/- 12)% in B1, (-45 +/- 13)% in B2, (19 +/- 19)% in L1, (51 +/- 31)% in L2 regions. Consequently, metal-implant-induced artifacts severely disturb MR-based attenuation correction and SUV quantification in PET/MR. The developed algorithm is able to compensate for these artifacts and improves SUV quantification accuracy distinctly.

Arterial Spin labeling (ASL) is a fully noninvasive MRI method capable to quantify cerebral perfusion. However, gray (GM) and white matter (WM) ASL perfusions are difficult to assess separately due to limited spatial resolution increasing the partial volume effects (PVE). In the present study, ASL PVE correction was implemented based on a regression algorithm in 22 healthy young men. PVE corrected perfusion of GM and WM were compared to previous studies. PVE-corrected GM perfusion was in agreement with literature values. In general, WM perfusion was higher despite the use of PVE correction.

A method for the determination of tartaric acid enantiomers using CE with contactless conductivity detection has been developed. Cu(II) as a central metal ion together with L-hydroxyproline were used as a chiral selector, the BGE was composed of 7 mM CuCl2, 14 mM trans-4-hydroxy-L-proline, and 100 mM ε-aminocaproic acid; the pH was adjusted to 5 by hydrochloric acid. Separation with a resolution of 1.9 was achieved in 9 min in a polyacrylamide-coated capillary to suppress the EOF. Various counterions of the BGE were studied, and migration order reversal was achieved when switching from ε-aminocaproic acid to L-histidine. With detection limits of about 20 μM, the method was applied to the analysis of wine and grape samples; only L-tartaric acid was found.

International audience; OBJECTIVE: The quantification of cerebral blood flow using pulsed arterial spin labeling could be erroneous with a nonoptimal inversion time (TI). We suggest that the optimal individual TI is dependent on the hemodynamic values of the supra-aortic vessels. METHODS: Twenty-two healthy volunteers (mean age, 31.8 years) underwent 7 pulsed arterial spin labeling scans at 3 T with TI ranging from 1200 to 1800 milliseconds every 100 milliseconds. The quantitative hemodynamic values of carotids were computed using a cine phase-contrast sequence. Optimal TIs were determined using visual and quantitative criteria. A correlation was sought between each optimal individual TI criterion and the hemodynamic parameter values. RESULTS: The optimal group TI was 1700 milliseconds. The individual analysis showed a significant correlation between the optimal TI of white matter signal-to-noise ratio and stroke distance, and the optimal TI of contrast-to-noise ratio with mean velocity. CONCLUSIONS: A correlation was found between optimal individual TIs and carotid hemodynamic parameters.

Objective: Evaluation of the quantitative accuracy of MR-based atten- uation correction (MRAC) in the Philips Ingenuity TF whole-body PET/MR. Materials and methods: In 13 patients, PET emission data from the PET/MR were reconstructed using two different methods for attenuation correction. In the first reconstruction the vendor-provided standard MRAC was used. In the second reconstruction, a coregistered transmission-based attenuation map from a second immediately preceding investigation with a stand-alone Siemens ECAT EXACT HR+ PET scanner was used (TRAC). The two attenuation maps were compared regarding occurrence of segmentation artifacts in the MRAC procedure. Standard uptake values (SUVs) of multiple VOIs (liver, cerebellum, hot focal structures at various locations in the trunk) were compared between both reconstructed data sets. Furthermore, a voxel-wise intensity correlation analysis of both data sets in the lung and trunk was performed. Results: VOI averaged SUV differences between MRAC and TRAC were as follows (relative differences, mean ± standard deviation): (+12 ± 6)% cerebellum, (−4 ± 9% liver, (−2 ± 11)% hot focal structures. The fitted slopes of the voxel-wise correlations in the lung and trunk were 0.87 ± 0.17 and 0.95 ± 0.10 with averaged adjusted R2 -values of 0.96 and 0.98, respectively. These figures include two instances with partially erroneous lung segmentation due to artifacts in the underlying MR images. Conclusion: The MR-based attenuation correction implemented on the Philips Ingenuity PET/MR provides reasonable quantitative accuracy. On average, deviations from TRAC-based results are small (on the order of 10% or below) across the trunk, but due to interindividual variability of the segmentation quality, deviations of more than 20% can occur. Future improvement of the segmentation quality would help to increase the quantitation accuracy further and to reduce the inter-subject variability.

Partial volume (PV) effects are caused by limited spatial resolution and significantly affect cerebral blood flow investigations with arterial spin labeling. Therefore, accurate PV correction (PVC) procedures are required. PVC is commonly based on PV maps obtained from segmented high-resolution T1 -weighted images. Segmentation of these images is error-prone, and it can be difficult to coregister these images accurately with the single-shot ASL images such as those created by echo-planar imaging (EPI). In this paper, an alternative method for PV map generation is proposed.The Look-Locker EPI (LL-EPI) acquisition is used for analyzing the T1 -recovery curve and for subsequent PV map generation. The new method was evaluated in five healthy volunteers (mean age 30 ± 3.7 years).By applying a linear regression method for PVC, a 12% decrease in regression error was reached with the new method.PV maps extraction from LL-EPI is a viable, possibly superior alternative to the standard approach based on segmentation of high-resolution T1 -weighted images.

Separation of major environmental pollutants as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) by capillary electrophoresis is reported for the first time. It is not possible to resolve the solutes in an aqueous media. However, the use of methanol and acetonitrile as the background electrolyte (BGE) solvents allowed their rapid separation in an uncoated capillary. A major effort was put into BGE optimization in respect to both separation efficiency and detection for further on-line preconcentration. 5 mmol.L⁻¹ naphthalene-1-sulfonic acid and 10 mmol.L⁻¹ triethylamine dissolved in ACN/MeOH (50:50 v/v) provided best separation and detection conditions. Next, the large-volume sample stacking and the field-amplified sample injection were applied and compared. Large-volume sample stacking improved limits of detection (LODs) with regard to the standard injection by 69 times for PFOA and 143 times for PFOS with LODs of 280 and 230 nmol.L⁻¹, respectively. Field-amplified sample injection improved LODs 624 times for PFOAand 806 times for PFOS with LODs 31 and 40 nmol.L⁻¹, respectively. Both preconcentration methods showed repeatabilities of migration times less than 1.2% RSD intraday and 6.6% RSD interday. The method was applied on PFOA and PFOS analysis in a sample of river water treated with solid-phase extraction, which further improved LOD toward 5.6 × 10⁻¹⁰ mol.L⁻¹ for PFOS and 6.4 × 10⁻¹⁰ mol.L⁻¹ for PFOA and allows the method to be used for river water contamination screening or decomposition studies.

International audience; PURPOSE: To compare 12-channel and 32-channel phased-array coils and to determine the optimal parallel imaging (PI) technique and factor for brain perfusion imaging using Pulsed Arterial Spin labeling (PASL) at 3 Tesla (T). MATERIALS AND METHODS: Twenty-seven healthy volunteers underwent 10 different PASL perfusion PICORE Q2TIPS scans at 3T using 12-channel and 32-channel coils without PI and with GRAPPA or mSENSE using factor 2. PI with factor 3 and 4 were used only with the 32-channel coil. Visual quality was assessed using four parameters. Quantitative analyses were performed using temporal noise, contrast-to-noise and signal-to-noise ratios (CNR, SNR). RESULTS: Compared with 12-channel acquisition, the scores for 32-channel acquisition were significantly higher for overall visual quality, lower for noise and higher for SNR and CNR. With the 32-channel coil, artifact compromise achieved the best score with PI factor 2. Noise increased, SNR and CNR decreased with PI factor. However mSENSE 2 scores were not always significantly different from acquisition without PI. CONCLUSION: For PASL at 3T, the 32-channel coil at 3T provided better quality than the 12-channel coil. With the 32-channel coil, mSENSE 2 seemed to offer the best compromise for decreasing artifacts without significantly reducing SNR, CNR.

The objective of my work is to refer to huge influence of oil and petroleum products in our EU economy. Although we hold only 0,4 % of world's oil proved reserves, our economy is planned on oil.Oil participates in energy mix with 38 % and is the most considirable and useful primamry energy. To satisfy our needs we have to import a lot of tons of oil. Our economy is dependent on oil imports of 85 % from abroad. In addition our economy is dependent on foreign countries. My objective and desire is to improve our situation in European Union in my future life.

International audience; PURPOSE: To determine the minimal optimal functional arterial spin labeling (fASL) sequence duration allowing steady and reproducible motor activation mapping. MATERIALS AND METHODS: Three magnetic resonance imaging (MRI) sessions including fASL and blood oxygenation level-dependent (BOLD) functional MRI (fMRI) sequences were performed on 12 healthy subjects at 3T with a 32-channel coil. The raw 7-minute fASL sequence was truncated to obtain six fASL sequences with durations ranging from 1-6 minutes. All the resulting fASL activations were compared between themselves and with both the 7-minute fASL and BOLD activations. Quantitative parameters assessed activation location (activated volume, barycenter, and distance between barycenters), activation quantification (activation-related cerebral blood flow), and intraindividual reproducibility across fMRI sessions. The statistical analysis was based on analysis of variance (ANOVA) and Tukey's multiple comparisons. RESULTS: Four-minute fASL achieved steady location and quantification of activation with the activated volume corresponding to 81% of the 7-minute fASL volume and a barycenter located 1.2 mm from the 7-minute fASL barycenter and 3.0 mm from the BOLD fMRI barycenter. Four-minute fASL reproducibility was high and statistically equivalent to 7-minute values. CONCLUSION: A 4-minute fASL sequence is thus a reliable tool for motor activation mapping and suitable for use in clinical practice.

Background As is well known, limited spatial resolution leads to partial volume effects (PVE) and consequently to limited signal recovery. Determination of the mean activity concentration of a target structure is thus compromised even at target sizes much larger than the reconstructed spatial resolution. This leads to serious size-dependent underestimates of true signal intensity in hot spot imaging. For quantitative PET in general and in the context of therapy assessment in particular it is, therefore, mandatory to perform an adequate partial volume correction (PVC). The goal of our work was to develop and to validate a model-free PVC algorithm for hot spot imaging. Methods The algorithm proceeds in two automated steps. Step 1: estimation of the actual object boundary with a threshold based method and determination of the total activity A measured within the enclosed volume V. Step 2: determination of the activity fraction B, which is measured outside the object due to the partial volume effect (spill-out). The PVE corrected mean value is then given by Cmean = (A+B)/V. For validation simulated tumours were used which were derived from real patient data (liver metastases of a colorectal carcinoma and head and neck cancer, respectively). The simulated tumours have characteristics (regarding tumour shape, contrast, noise, etc.) which are very similar to those of the underlying patient data, but the boundaries and tracer accumulation are exactly known. The PVE corrected mean values of 37 simulated tumours were determined and compared with the true mean values. Results For the investigated simulated data the proposed approach yields PVE corrected mean values which agree very well with the true values (mean deviation (± s.d.): .(-0.8 ± 2.5)%). Conclusions The described method enables accurate quantitative partial volume correction in oncological hot spot imaging.

The first application of boromycin as a chiral selector in capillary electrophoresis is described. Given boromycin's insolubility in water, a non-aqueous background electrolyte based on methanol was used for enantiomeric discrimination of selected chiral primary amines (α-methylbenzylamine, R,S-tryptophanol, R,S-norepinephrine, R,S-octopamine, R,S-p-hydroxynorephedrine and R,S-2-amino-1-phenylethanol). A basic study of experimental conditions including the influence of boromycin concentration, the composition and concentration of background electrolyte and also the influence of different organic solvents was performed. The best separation condition was 75 mM Tris/50 mM boric acid in methanol, pH w s 9.0, with a positive separation voltage. The enantiomeric separation of the primary amines was achieved within 14 min with resolution values greater than 1.5 for the majority of the studied analytes.

International audience; Functional arterial spin labeling (fASL) is an innovative biomarker of neuronal activation that allows direct and absolute quantification of activation-related CBF and is less sensitive to venous contamination than BOLD fMRI. This study evaluated fASL for motor activation mapping in comparison with BOLD fMRI in terms of involved anatomical area localization, intra-individual reproducibility of location, quantification of neuronal activation, and spatial accuracy. Imaging was performed at 3T with a 32-channel coil and dedicated post-processing tools were used. Twelve healthy right-handed subjects underwent fASL and BOLD fMRI while performing a right hand motor activation task. Three sessions were performed 7days apart in similar physiological conditions. Our results showed an activation in the left primary hand motor area for all 36 sessions in both fASL and BOLD fMRI. The individual functional maps for fASL demonstrated activation in ipsilateral secondary motor areas more often than the BOLD fMRI maps. This finding was corroborated by the group maps. In terms of activation location, fASL reproducibility was comparable to BOLD fMRI, with a distance between activated volumes of 2.1mm and an overlap ratio for activated volumes of 0.76, over the 3 sessions. In terms of activation quantification, fASL reproducibility was higher, although not significantly, with a CVintra of 11.6% and an ICC value of 0.75. Functional ASL detected smaller activation volumes than BOLD fMRI but the areas had a high degree of co-localization. In terms of spatial accuracy in detecting activation in the hand motor area, fASL had a higher specificity (43.5%) and a higher positive predictive value (69.8%) than BOLD fMRI while maintaining high sensitivity (90.7%). The high intra-individual reproducibility and spatial accuracy of fASL revealed in the present study will subsequently be applied to pathological subjects.

International audience; Arterial spin labeling (ASL) allows non-invasive imaging and quantification of brain perfusion by magnetically labeling blood in the brain-feeding arteries. ASL has been used to study cerebrovascular diseases, brain tumors and neurodegenerative disorders as well as for functional imaging. The use of a perfusion template could be of great interest to study inter-subject regional variation of perfusion and to perform automatic detection of individual perfusion abnormalities. However, low spatial resolution and partial volume effects (PVE) issues inherent to ASL acquisitions remain to be solved. The purpose of this study is to enhance the template quality by using DARTEL non-rigid registration and by correcting for PVE. PICORE-Q2TIPS ASL datasets were acquired on 25 healthy volunteers at 3T. Four methods of creating the template were evaluated using leave-one-out cross correlation. Subsequently, these methods were applied to hyper-perfusion detection on functional ASL data of 8 healthy volunteers and compared with the standard generalized linear model (GLM) activation detection.

In this paper, we demonstrate the possibility to use magnetic nanoparticles as immunosupports for allergy diagnosis. Most immunoassays used for immunosupports and clinical diagnosis are based on a heterogeneous solid-phase system and suffer from mass-transfer limitation. The nanoparticles’ colloidal behavior and magnetic properties bring the advantages of homogeneous immunoassay, i.e., species diffusion, and of heterogeneous immunoassay, i.e., easy separation of the immunocomplex and free forms, as well as analyte preconcentration. We thus developed a colloidal, non-competitive, indirect immunoassay using magnetic core–shell nanoparticles (MCSNP) as immunosupports. The feasibility of such an immunoassay was first demonstrated with a model antibody and described by comparing the immunocapture kinetics using macro (standard microtiter plate), micro (microparticles) and nanosupports (MCSNP). The influence of the nanosupport properties (surface chemistry, antigen density) and of the medium (ionic strength, counter ion nature) on the immunocapture efficiency and specificity was then investigated. The performances of this original MCSNP-based immunoassay were compared with a gold standard enzyme-linked immunosorbent assay (ELISA) using a microtiter plate. The capture rate of target IgG was accelerated 200-fold and a tenfold lower limit of detection was achieved. Finally, the MCSNP-based immunoassay was successfully applied to the detection of specific IgE from milk-allergic patient’s sera with a lower LOD and a good agreement (CV < 6%) with the microtiter plate, confirming the great potential of this analytical platform in the field of immunodiagnosis.

ASL allows non-invasive imaging and quantification of brain perfusion by magnetically labeling blood in the brain-feeding arteries. In this study, a template created from perfusion images of 25 resting healthy subjects was used to automatically detect hyper perfusion patterns of 8 other subjects. DARTEL registration was used to improve the precision of the template and partial volume correction to prevent interpolation artifacts. MR imaging was performed on a 3T MR scanner with a 32-channel head coil and consisted in a 1x1x1mm3 3D T1 and a PICORE Q2TIPS ASL with 3x3x7mm3 pixel size, TR/TE=3000/25ms, TI=1700ms and Q2TIPS saturation [3] at 700ms. ASL images were acquired in 25 healthy subjects (mean age 31.6). Additionally, 8 healthy right-handed subjects underwent fASL study following a bloc-design experiment with seven interleaved 30s-phases of rest and motor task of the dominant hand. The following processing was applied: a) Perfusion was quantified [2]; b) ASL images were co-registered with their T1 images; c) T1 images were segmented to GM/WM regions; d) Partial volume effects in ASL images were corrected for using high-resolution segmentation [4]; e) T1 images were aligned to the ICBM-152 template [5]; f) T1 images were aligned using DARTEL registration [1]; g) ASL images were spatially normalized using the transformations from e,f); h) The perfusion template was created as the mean and variance of the spatially normalized ASL images of the 25 resting subjects. For each of the 8 fASL subjects, the activated image was created by averaging the images acquired during activity phases. Hyperperfused areas were identified by comparison with the template (p

International audience; Arterial spin labeling (ASL) is a noninvasive MRI method that uses magnetically labeled blood to measure cerebral perfusion. Spatial resolution of ASL is relatively small and as a consequence perfusion from different tissue types is mixed in each pixel. An average ratio of gray matter (GM) to white matter (WM) blood flow is 3 to 1. Disregarding the partial volume effects (PVE) can thus cause serious errors of perfusion quantification. PVE also complicates spatial filtering of ASL images as apart from noise there is a spatial signal variation due to tissue partial volume. Recently, an algorithm for correcting PVE has been published by Asllani et al. It represents the measured magnetization as a sum of different tissue magnetizations weighted by their fractional volume in a pixel. With the knowledge of the partial volume obtained from a high-resolution MRI image, it is possible to separate the individual tissue contributions by linear regression on a neighborhood of each pixel. We propose an extension of this algorithm by minimizing the total-variation of the tissue specific magnetization. This makes the algorithm more flexible to local changes in perfusion. We show that this method can be used to denoise ASL images without mixing the WM and GM signal.

International audience; Arterial spin labeling (ASL) is an MRI method for imaging brain perfusion by magnetically labeling blood in brain feeding arteries. The perfusion is obtained from the difference between images with and without prior labeling. Image noise is one of the main problems of ASL as the difference is around 0.5-2% of the image magnitude. Usually, 20-40 pairs of images need to be acquired and averaged to reach a satisfactory quality. The images are acquired shortly after the labeling to allow the labeled blood to reach the imaged slice. A sequence of images with multiple delays is more suitable for quantification of the cerebral blood flow as it gives more information about the blood arrival and relaxation. Although the quantification methods are sensitive to noise, no filtering or only Gaussian filtering is used to denoise the data in the temporal domain prior to quantification. In this article, we propose an efficient way to use the redundancy of information in the time sequence of each pixel to suppress noise. For this purpose, the vectorial NL-means method is adapted to work in the temporal domain. The proposed method is tested on simulated and real 3T MRI data. We demonstrate a clear improvement of the image quality as well as a better performance compared to Gaussian and normal spatial NL-means filtering.

Identification of microbial contamination by CE has interested many researchers mainly because of the high speed of CE analysis. However, the CE separation of such big structures brings a lot of questions mainly about the behavior of microorganisms and about the mechanism of separation. In this work, we constructed a simple apparatus where a microscope was used as one detector and a UV detector was used as the second one and we made the comparison of three typical setups for CE of microorganisms. Saccharomyces cerevisiae was chosen as a model microorganism and was analyzed in bare fused-silica capillaries, covalently modified capillaries and dynamically modified capillaries by poly(ethylene oxide) or CTAB. Results showed that the use of CE instrument directly connected with a microscope could be advantageous for the study of separation mechanisms and/or migration behavior.

The assessment of capillary electrophoresis for separation and identification of microorganisms is described in this article. The work brings a comparison of the application of uncoated capillaries modified with poly(ethylene oxide) and coated capillaries for the separation of model microorganisms Saccharomyces cerevisiae and Escherichia coli with Tris-borate-EDTA and Tris-citrate-fructose as electrolytes. The best separation was achieved in the coated capillary using 1 mM Tris-citrate-fructose buffer, pH 6.9. A simple identification based on the migration time and UV spectrum was found unsatisfactory and thus a method based on a post-separation cultivation and sequential analysis was developed. Off-line combination with mass spectrometric analysis with the use of desorption electrospray was shown to be an interesting alternative in a study of microorganisms. Mass spectra allowed distinguishing among analyzed cells.

A new on-line preconcentration technique was developed that makes possible to determine nanomolar concentrations of weak acidic analytes in CE. The method consists of long-running electrokinetic sample injection and stacking (electrokinetic immobilization) of the analytes at a boundary of two electrolytes with different pH values (pH 9.5 and 2.5) and consequent mobilization of the stacked uncharged analytes in a micellar system (containing SDS micelles). Several factors including buffer concentration, pH, applied voltage, time of preconcentration, and SDS concentration were tested to optimize the analysis method. An about 4600-fold increase of the sample concentration (in comparison with the standard CZE) can be achieved during the preconcentration step. Two preservatives applied in food industry -- benzoic acid and sorbic acid were used as model samples. The applicability of the proposed method in food analysis was demonstrated by determination of nanomolar concentrations of benzoic acid in sunflower oil. An extended version of the computer program Simul was used for modeling both the preconcentration and mobilization processes taking place in the capillary.

A review of some fundamental aspects of ITP from the student point of view, imaginations of some basic facts and laws, use of ITP, and the recent trends are presented. The results of theoretical computations of ITP separation processes are added for comparison of imaginations with the exact mathematical description.

Online combination of transient ITP and CZE is employed for the determination of Cd(II), Pb(II), Cu(II), Ni(II), and Zn(II). Acetic acid is used for creating the transient isotachophoretic state. alpha-Hydroxyisobutyric acid and 4-aminopyridine are used as BGEs for the separation and indirect UV detection. At optimum conditions, the method allows to determine the metals at levels of 40-120 microg/L, about 50 times more sensitive than conventional CZE. In combination with a 20-fold evaporative concentration, the method is suitable for environmental monitoring of the heavy metals in snow samples.

An on-line preconcentration capillary electrophoresis (CE) technique, which combines a large volume sample stacking with a dynamic pH junction technique, is introduced in this paper. This dynamic pH junction with co-electroosmotic migration is formed between sodium borate pH 9.5 and sodium phosphate pH 2.5 with 150 mM sodium dodecylsulfate (SDS). A full capillary based injection allows determination of weak acidic compounds at ppb concentration levels (achieved LOD for benzoic acid was 11 nmol L−1). The proposed preconcentration method was compared with ITP/ITP (LOD 120 nmol L−1), ITP/CZE (LOD 740 nmol L−1) and a simple CZE method (LOD 23,330 nmol L−1). The analytical potential of this method was assessed with juice test samples.

Parallel MRI (pMRI) is a way to increase the speed of the MRI acquisition by combining data obtained simultaneously from several receiver coils with distinct spatial sensitivities. The measured data contains additional information about the position of the signal with respect to data obtained by a standard, uniform sensitivity coil. The idea is to speed up the acquisition by sampling more sparsely in the k -space and to compensate the data loss using the additional information obtained by a higher number of receiver coils. Most parallel reconstruction methods work in image domain and estimate the reconstruction transformation independently in each pixel. We propose an algorithm that uses B-spline functions to approximate the reconstruction map which reduces the number of parameters to estimate and makes the reconstruction faster and less sensitive to noise. The proposed method is tested on both phantom and in vivo images. The results are compared with commercial implementation of GRAPPA and SENSE algorithms in terms of time complexity and quality of the reconstruction.

We synthesised and used new type of quaternary ammonium salt [S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate] as effective additive to acidic background electrolytes. We used this quaternary ammonium salt as effective agent for capillary zone electrophoresis separation of model mixture of five tricyclic antidepressants (amitriptyline, nortriptyline, imipramine, desipramine and clomipramine) as model analytes. We observed that addition of S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate ([HMDP](+) [BF(4)](-)) to acidic background electrolytes leads to suppression of magnitude of electroosmotic flow (EOF) and gradually change the direction of the EOF. Baseline separation of five TAs was achieved by using of 91.1 mmol L(-1) (20 gL(-1)) of [HMDP](+) [BF(4)](-) in 25 mmol L(-1) sodium phosphate pH 2.5, where electroosmotic mobility was -11.3 x 10(-9) m(2) V(-1) s(-1). We achieved baseline separation of five TAs with using of [HMDP](+) [BF(4)](-) as water solution too. We observed that [HMDP](+) [BF(4)](-) can be used as buffer additive, which offers relatively smaller anodic electroosmotic flow instead of cationic surfactants that are mostly used for genarating of anodic electroosmotic flow in capillary electrophoresis.

Enantiomers of (±) 5-[2 ( R , S )-{[2-( o -ethoxyphenoxy) ethyl] amino} propyl]-2-methoxy-benzenesulfonamide (tamsulosin, drug frequently used in the treatment of prostate diseases) were separated by capillary electrophoresis (CE). An acidic background electrolyte (BGE) with sulfated-β-cyclodextrin (S-β-CD) was used to create a chiral separation environment. Baseline separation of the isomers was achieved during 5 min using cathodic electro-osmotic flow (EOF) (countercurrent mode). The quantification limits were 5.3 × 10 −6 mol l −1 for R -isomer and 5.7 × 10 −6 mol l −1 for S -isomer. The R.S.D. values of peak area were 0.54% for R -isomer and 0.75% for S -isomer. The results achieved enable determination of 0.5% of optical impurity.

Purpose: Accurate volumetric tumor delineation is of increasing importance in radiation treatment planning. Many tumors exhibit only moderate tracer uptake heterogeneity and delineation methods using an adaptive threshold lead to robust results. These methods use a tumor reference valueR (e.g., ROI maximum) and the tumor background Bg to compute the volume reproducing threshold. This threshold corresponds to an isocontour which defines the tumor boundary. However, the boundaries of strongly heterogeneous tumors can not be described by an isocontour anymore and therefore conventional threshold methods are not suitable for accurate delineation. The aim of this work is the development and validation of a delineation method for heterogeneous tumors. Methods: The new method (voxel-specific threshold method, VTM) can be considered as an extension of an adaptive threshold method (lesion-specific threshold method, LTM), where instead of a lesion-specific threshold for the whole ROI, a voxel-specific threshold is computed by determining for each voxelBg and R in the close vicinity of the voxel. The absolute threshold for the considered voxel is then given by T abs = T × (R − Bg) + Bg, where T = 0.39 was determined with phantom measurements. Validation: 30 clinical datasets from patients with non-small-cell lung cancer were used to generate 30 realistic anthropomorphic software phantoms of tumors with different heterogeneities and well-known volumes and boundaries. Volume delineation was performed with VTM and LTM and compared with the known lesion volumes and boundaries. Results: In contrast to LTM, VTM was able to reproduce the true tumor boundaries accurately, independent of the heterogeneity. The deviation of the determined volume from the true volume was (0.8 ± 4.2)% for VTM and (11.0 ± 16.4)% for LTM. Conclusions: In anthropomorphic software phantoms, the new method leads to promising results and to a clear improvement of volume delineation in comparison to conventional background-corrected thresholding. In the next step, the suitability for clinical routine will be further investigated.

Fluorescent core–shell nanohybrids with the shells derived from carbon dots and cores differing in the chemical nature and morphology were synthesized. Hybrid nanoparticles combine fluorescence with other functionalities such as magnetic response on a single platform. These hybrids can be used in various bioapplications as demonstrated with labeling of stem cells.