Design of proposed software system for prediction of iliosacral screw placement for iliosacral joint injuries based on X-ray and CT images

One of the crucial tasks for the planning of surgery of the iliosacral joint is placing an iliosacral screw with the goal of fixing broken parts of the pelvis. Tracking of proper screw trajectory is usually done in the preoperative phase by the acquisition of X-ray images under different angles, which guide the surgeons to perform surgery. This approach is standardly complicated due to the investigation of 2D X-ray images not showing spatial perspective. Therefore, in this pilot study, we propose complex software tools which are aimed at making a simulation model of reconstructed CT (DDR) images with a virtual iliosacral screw to guide the surgery process. This pilot study presents the testing for two clinical cases to reveal the initial performance and usability of this software in clinical conditions. This model is consequently used for a multiregional registration with reference intraoperative X-ray images to select the slide from the 3D dataset which best fits with reference X-ray. The proposed software solution utilizes input CT slices of the pelvis area to create a segmentation model of individual bone components. Consequently, a model of an iliosacral screw is inserted into this model. In the next step, we propose the software CT2DDR which makes DDR projections with the iliosacral screw. In the last step, we propose a multimodal registration procedure, which performs registration of a selected number of slices with reference X-ray, and based on the Structural Similarity Index (SSIM) and index of correlation, the procedure finds the best match of DDR with X-ray images. In this pilot study, we also provide a comparative analysis of the computational costs of the multimodal registration upon various numbers of DDR slices to show the complex software performance. The proposed complex model has versatile usage for modeling and surgery planning of the pelvis area in fractures of iliosacral joints.Web of Science126art. no. 213

Inorganic Chemistry of the Tripodal Picolinate Ligand Tpaa with Gallium(III) and Radiolabeling with Gallium-68

We report here the improved synthesis of the tripodal picolinate chelator Tpaa, with an overall yield of 41% over five steps, in comparison to the previously reported 6% yield. Tpaa was investigated for its coordination chemistry with Ga(III) and radiolabeling properties with gallium-68 (68Ga). The obtained crystal structure for [Ga(Tpaa)] shows that the three picolinate arms coordinate to the Ga(III) ion, fully occupying the octahedral coordination geometry. This is supported by 1H NMR which shows that the three arms are symmetrical when coordinated to Ga(III). Assessment of the thermodynamic stability through potentiometry gives log KGa-Tpaa = 21.32, with a single species being produced across the range of pH 3.5-7.5. Tpaa achieved >99% radiochemical conversion with 68Ga under mild conditions ([Tpaa] = 6.6 μM, pH 7.4, 37 °C) with a molar activity of 3.1 GBq μmol-1. The resulting complex, [68Ga][Ga(Tpaa)], showed improved stability over the previously reported [68Ga][Ga(Dpaa)(H2O)] in a serum challenge, with 32% of [68Ga][Ga(Tpaa)] remaining intact after 30 min of incubation with fetal bovine serum

Amino acid based gallium-68 chelators capable of radiolabeling at neutral pH

Gallium-68 ( 68 Ga) has been the subject of increasing interest for its potential in the production of radiotracers for diagnosis of diseases. In this work we report the complexation of 68 Ga by the amino acid based tripodal chelate H 3 Dpaa, and two bifunctional derivatives, H 3 Dpaa.dab and H 4 Dpaa.ga, under a range of conditions with particular emphasis on the rapid complexation of 68 Ga at pH 7.4. 100 μM H 3 Dpaa achieved a radiochemical yield of 95% at pH 7.4 in 5 minutes at 37 °C. The bifunctional derivatives H 4 Dpaa.ga and H 3 Dpaa.dab achieved 94% and 84% radiochemical yields, respectively, under the same conditions. The resulting Ga(iii) complexes show thermodynamic stabilities of logK GaDpaa = 18.53, logK GaDpaa.dab = 22.08, logK GaDpaa.ga = 18.36. Unfortunately, the resulting radiolabelled species do not present sufficient serum stability for in vivo application. Herein we show a flexible synthesis for bifunctional chelators based on amino acids that rapidly complex 68 Ga under physiological conditions

Spatial Analysis of Navigation in Virtual Geographic Environments

Human performance and navigation activity in virtual environments can be measured and assessed with the aim to draw specific conclusions about human cognition. This paper presents an original virtual geographic environment (VGE) designed and used for this purpose. The presented research is rooted in an interdisciplinary approach combining knowledge and principles from the fields of psychology, cartography, and information technologies. The VGE was embedded with user logging functionality to provide a basis from which conclusions about human cognitive processes in a VGE could be drawn. The scope of this solution is introduced, described, and discussed under a behavioral measurement framework. An exploratory research design was adopted to demonstrate the environment’s utility in proof-of-concept user testing. Twenty participants were observed in interactive, semi-interactive and non-interactive tasks, their performance and individual differences were analyzed. The behavioral measurements were supplemented by Object-Spatial Imagery and a Verbal Questionnaire to determine the participants’ cognitive styles. In this sample, significant differences in exploration strategies between men and women were detected. Differences between experienced and non-experienced users were also found in their ability to identify spatial relations in virtual scenes. Finally, areas for future research areas and development were pinpointed

Dissociation kinetics of Mn2+ complexes of NOTA and DOTA

International audienceThe kinetics of transmetallation of [Mn(nota)](-) and [Mn(dota)](2-) was investigated in the presence of Zn(2+) (5-50-fold excess) at variable pH (3.5-5.6) by (1)H relaxometry. The dissociation is much faster for [Mn(nota)](-) than for [Mn(dota)](2-) under both experimental and physiologically relevant conditions (t(½) = 74 h and 1037 h for [Mn(nota)](-) and [Mn(dota)](2-), respectively, at pH 7.4, c(Zn(2+)) = 10(-5) M, 25 °C). The dissociation of the complexes proceeds mainly via spontaneous ([Mn(nota)](-)k(0) = (2.6 ± 0.5) × 10(-6) s(-1); [Mn(dota)](2-)k(0) = (1.8 ± 0.6) × 10(-7) s(-1)) and proton-assisted pathways ([Mn(nota)](-)k(1) = (7.8 ± 0.1) × 10(-1) M(-1) s(-1); [Mn(dota)](2-)k(1) = (4.0 ± 0.6) × 10(-2) M(-1) s(-1), k(2) = (1.6 ± 0.1) × 10(3) M(-2) s(-1)). The observed suppression of the reaction rates with increasing Zn(2+) concentration is explained by the formation of a dinuclear Mn(2+)-L-Zn(2+) complex which is about 20-times more stable for [Mn(dota)](2-) than for [Mn(nota)](-) (K(MnLZn) = 68 and 3.6, respectively), and which dissociates very slowly (k(3)∼10(-5) M(-1) s(-1)). These data provide the first experimental proof that not all Mn(2+) complexes are kinetically labile. The absence of coordinated water makes both [Mn(nota)](-) and [Mn(dota)](2-) complexes inefficient for MRI applications. Nevertheless, the higher kinetic inertness of [Mn(dota)](2-) indicates a promising direction in designing ligands for Mn(2+) complexation

Chemical, radiochemical and biological studies of Sm and Ho complexes of H4dota analogues containing one methylphosphonic/phosphinic acid pendant arm

International audienceThis work intends to investigate samarium and holmium complexes with a set of H4dota-analogues bearing methylphosphonate/methylphosphinic acid pendant arms (H5do3ap, H5do3apPrA and H4do3apABn) as new bifunctional ligands for radiolanthanide targeted therapy. Radiolanthanide complexes of these ligands were prepared and evaluated and thermodynamic solution studies were also performed to get a better insight on the radiochemical results. The radiocomplexes were quantitatively prepared, are hydrophilic and negatively charged. They present a high in vitro and in vivo stability, a low plasma protein binding and a rapid clearance from the main organs with a high rate of whole body radioactivity excretion. Stability constants with Sm(III) and Ho(III) were determined by potentiometry and the values found are very high for all the ligands. Actually, they are similar to those of H4dota for the phosphinate analogues and even higher for the phosphonate ligand, being the constants similar to those with other lanthanide(III) ions. The effect of methylphosphorus acid pendant arms functionalization and the use of these ligands as bifunctional chelate agents are discussed. Copyright © 2009 John Wiley & Sons, Ltd

Isovists compactness and stairs as predictors of evacuation route choice

AbstractThe building design is a crucial factor that can be actively adjusted and optimized to prevent human and property threats in emergency scenarios. Previous research suggests that specific building layouts may significantly influence human behaviour during evacuation. However, detailed empirical data about human behaviour in various types of buildings with different layouts are still missing and only marginal recommendations from this field are reflected in actual construction practice. In this study, desktop VR technologies were employed to study human decision-making in problematic T-intersections in the context of an emergency evacuation. More specifically, we studied fundamental attributes of buildings such as the width and length of the corridors and the presence of stairs to explore how they influence the choice of the evacuation route. The space-syntax isovist method was used to describe spatial parameters of corridors, which makes the results applicable to all buildings. Behavioural data from 208 respondents were analysed using multilevel regression models. Our results support previous claims concerning the importance of specific spatial layouts of evacuation corridors because respondents systematically chose wider and shorter corridors with visible staircases as the preferred evacuation route. The present findings further promote the ongoing discussion on the design of marked evacuation routes and building design that takes human factors into consideration.</jats:p

I.: A novel tetraazamacrocycle bearing a thiol pendant arm for labeling biomolecules with radiolanthanides. Dalton Trans

The novel tetraazamacrocycle 10-(2-sulfanylethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H 4 DO3ASH) was synthesized and characterized by multinuclear NMR spectroscopy, 2D NMR techniques and mass spectrometry. The protonation constants of H 4 DO3ASH were determined by potentiometry at 25 • C in 0.1 M KCl ionic strength, and the protonation sequence was assigned based 153 Sm, logD = -2.1; 166 Ho, logD = -1.6) has been studied in different buffers, in human serum and in the presence of excess of cysteine and glutathione. 153 Sm-DO3ASH has shown a high stability under these conditions and a relatively low protein binding (2.1%), while 166 Ho-DO3ASH was less stable, including in the presence of cysteine and glutathione, and had a slightly higher protein binding (6.7%). In vivo studies have been performed only for the more stable 153 Sm-DO3ASH complex and its biological profile and in vivo stability has been compared to that of 153 Sm-DO3A in the same animal model. The biodistribution profile presents a similar trend with rapid total excretion from the whole animal body, mainly via the urinary pathway. The most striking difference found is related to a slightly slower clearance of 153 Sm-DO3ASH from organs like blood, bone and muscle as compared to 153 Sm-DO3A. Additionally, the fraction of 153 Sm-DO3ASH taken by the hepatobiliar tract is also modestly higher than that of 153 Sm-DO3A

Scandium(III) complexes of monophosphorus acid DOTA analogues: a thermodynamic and radiolabelling study with 44 Sc from cyclotron and from a 44 Ti/ 44 Sc generator †

International audienceThe complexation ability of DOTA analogs bearing one methylenephosphonic (DO3AP) or methylene-phosphinic (DO3AP PrA and DO3AP ABn) acid pendant arm toward scandium was evaluated. Stability constants of their scandium(III) complexes were determined by potentiometry combined with 45 Sc NMR spectroscopy. The stability constants of the monophosphinate analogues are somewhat lower than that of the Sc–DOTA complex. The phosphorus acid moiety interacts with trivalent scandium even in very acidic solutions forming out-of-cage complexes; the strong affinity of the phosphonate group to Sc(III) precludes stability constant determination of the Sc–DO3AP complex. These results were compared with those obtained by the free-ion selective radiotracer extraction (FISRE) method which is suitable for trace concentrations. FISRE underestimated the stability constants but their relative order was preserved. Nonetheless , as this method is experimentally simple, it is suitable for a quick relative comparison of stability constant values under trace concentrations. Radiolabelling of the ligands with 44 Sc was performed using the radioisotope from two sources, a 44 Ti/ 44 Sc generator and 44m Sc/ 44 Sc from a cyclotron. The best radio-labelling conditions for the ligands were pH = 4, 70 °C and 20 min which were, however, not superior to those of the parent DOTA. Nonetheless, in vitro behaviour of the Sc(III) complexes in the presence of hydroxyapatite and rat serum showed sufficient stability of 44 Sc complexes of these ligands for in vivo applications. PET images and ex vivo biodistribution of the 44 Sc–DO3AP complex performed on healthy Wistar male rats showed no specific bone uptake and rapid clearance through urine

The 3D hype: Evaluating the potential of real 3D visualization in geo-related applications.

The use of 3D visualization technologies has increased rapidly in many applied fields, including geovisualization, and has been researched from many different perspectives. However, the findings for the benefits of 3D visualization, especially in stereoscopic 3D forms, remain inconclusive and disputed. Stereoscopic "real" 3D visualization was proposed as encouraging the visual perception of shapes and volume of displayed content yet criticised as problematic and limited in a number of ways, particularly in visual discomfort and increased response time in tasks. In order to assess the potential of real 3D visualization for geo-applications, 91 participants were engaged in this study to work with digital terrain models in different 3D settings. The researchers examined the effectivity of stereoscopic real 3D visualization compared to monoscopic 3D (or pseudo 3D) visualization under static and interactive conditions and applied three tasks with experimental stimuli representing different geo-related phenomena, i.e. objects in the terrain, flat areas marked in the terrain and terrain elevation profiles. The authors explored the significant effects of real 3D visualization and interactivity factors in terms of response time and correctness. Researchers observed that the option to interact (t = -10.849, p < 0.001) with a virtual terrain and its depiction with real 3D visualization (t = 4.64, p < 0.001) extended the participants' response times. Counterintuitively, the data demonstrated that the static condition increased response correctness (z = 5.38, p < 0.001). Regarding detailed analysis of data, an interactivity factor was proposed as a potential substitute for real 3D visualization in 3D geographical tasks