Journal articles: 'Spirale de Vogel'

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Zhao, Taotao, Yanwen Hu, Shenhe Fu, Xiaonan Li, Yikun Liu, Hao Yin, Zhen Li, Juntao Li, and Zhenqiang Chen. "Aperiodic Vogel spirals for broadband optical wave focusing." Optics Letters 43, no. 24 (December 7, 2018): 5969. http://dx.doi.org/10.1364/ol.43.005969.

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Diebel, Falko, Patrick Rose, Martin Boguslawski, and Cornelia Denz. "Optical induction scheme for assembling nondiffracting aperiodic Vogel spirals." Applied Physics Letters 104, no. 19 (May 12, 2014): 191101. http://dx.doi.org/10.1063/1.4875237.

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Aubry, Geoffroy J., Luis A. Razo-López, Felipe A. Pinheiro, and Fabrice Mortessagne. "Experimental observation of electromagnetic wave localization in Vogel spirals." EPJ Web of Conferences 287 (2023): 04017. http://dx.doi.org/10.1051/epjconf/202328704017.

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We present experiments of microwave transport in planar Vogel spirals arrays of high permittivity dielectric constant. Despite the lack of disorder, wave transport in certain frequency regions is dominated by localized modes. We characterize these modes spatially, and find that in contrary to disorder induced Anderson localization, their radial decay does not only decay exponentially, but some modes are found to decay according to a power law or to a Gaussian profile. Nevertheless, by extracting experimentally the Thouless conductance, we find that the region where these Gaussian and power law modes exist are regions of low Thouless conductance, similarly to what is expected for Anderson localization. This study unveil the rich modal structure associated with these aperiodic point patterns, and pave the way toward a better understanding of wave localization in general.

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Razi, Mani, Ren Wang, Yanyan He, Robert M. Kirby, and Luca Dal Negro. "Optimization of Large-Scale Vogel Spiral Arrays of Plasmonic Nanoparticles." Plasmonics 14, no. 1 (July 7, 2018): 253–61. http://dx.doi.org/10.1007/s11468-018-0799-y.

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Manceñido, Miguel O., and Rémy Gourvennec. "A reappraisal of feeding current systems inferred for spire-bearing brachiopods." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 98, no. 3-4 (September 2007): 345–56. http://dx.doi.org/10.1017/s1755691007078462.

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ABSTRACTSpire-bearing brachiopods formally comprise four different rhynchonelliform orders. A calcified spiral brachidium (presumably supporting a spirolophe when alive) and variable median fold and sulcus (probably aiding separation of incurrent from excurrent flows) are peculiar characteristics they all share. Inferences regarding feeding current systems for these extinct taxa have long remained controversial. Two rival models (the Williams–Ager model and the Rudwick–Vogel model) have been developed, each of which has gained supporters as well as critics over the years. In this present paper they are both contrasted and reassessed on the basis of available evidence, together with a new approach that combines: (a) a morpho-functional analysis applying the plankton net as a suitable seston-collecting paradigm; (b) a review of actualistic data showing that all extant spirolophes are functionally inhalant (irrespective of water entering the valves laterally or not); (c) an evaluation of known outcomes from flume experiments yielding consistent empirical results where gaping shells are oriented transversally and dorsally upcurrent; and (d) a reappraisal of the distributions of certain epizoobionts and endosymbionts revealing compatible patterns. The evidence thus accumulated supports the main conclusion that, in most groups (with laterally tapering spiralia), the inhalant current was located medially with the exhalant currents on either side; only in atrypides (with centrally to dorsally tapering spiralia) does the reverse situation appear to have occurred.

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Trevino, Jacob, Seng Fatt Liew, Heeso Noh, Hui Cao, and Luca Dal Negro. "Geometrical structure, multifractal spectra and localized optical modes of aperiodic Vogel spirals." Optics Express 20, no. 3 (January 25, 2012): 3015. http://dx.doi.org/10.1364/oe.20.003015.

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Dal Negro, Luca, Nate Lawrence, and Jacob Trevino. "Analytical light scattering and orbital angular momentum spectra of arbitrary Vogel spirals." Optics Express 20, no. 16 (July 24, 2012): 18209. http://dx.doi.org/10.1364/oe.20.018209.

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Gorsky, Sean, Ran Zhang, Abdullah Gok, Ren Wang, Kidanemariam Kebede, Alan Lenef, Madis Raukas, and Luca Dal Negro. "Directional light emission enhancement from LED-phosphor converters using dielectric Vogel spiral arrays." APL Photonics 3, no. 12 (December 2018): 126103. http://dx.doi.org/10.1063/1.5052637.

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Lawrence, Nate, Jacob Trevino, and Luca Dal Negro. "Control of optical orbital angular momentum by Vogel spiral arrays of metallic nanoparticles." Optics Letters 37, no. 24 (December 6, 2012): 5076. http://dx.doi.org/10.1364/ol.37.005076.

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Steckmann, Sven, Michael Knaup, and Marc Kachelrieß. "High performance cone-beam spiral backprojection with voxel-specific weighting." Physics in Medicine and Biology 54, no. 12 (May 28, 2009): 3691–708. http://dx.doi.org/10.1088/0031-9155/54/12/006.

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Xu, Wenpeng, Qiuge Li, Hao Xu, Xiaoya Zhai, and Jingchao Jiang. "Voxel-based variable width continuous spiral path planning for 3D printing." Journal of Manufacturing Processes 107 (December 2023): 226–39. http://dx.doi.org/10.1016/j.jmapro.2023.10.044.

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Intonti, F., N. Caselli, N. Lawrence, J. Trevino, D. S. Wiersma, and L. Dal Negro. "Near-field distribution and propagation of scattering resonances in Vogel spiral arrays of dielectric nanopillars." New Journal of Physics 15, no. 8 (August 22, 2013): 085023. http://dx.doi.org/10.1088/1367-2630/15/8/085023.

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Trojak, Oliver J., Sean Gorsky, Connor Murray, Fabrizio Sgrignuoli, Felipe A. Pinheiro, Luca Dal Negro, and Luca Sapienza. "Cavity-enhanced light–matter interaction in Vogel-spiral devices as a platform for quantum photonics." Applied Physics Letters 118, no. 1 (January 4, 2021): 011103. http://dx.doi.org/10.1063/5.0034984.

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Anderssen-Reuster, Ulrike. "Ralf T. Vogel (2020) Existenzielle Themen in der Psychotherapie. Stuttgart: Kohlhammer Verlag. ISBN 978-3-17-036547-6; 140 Seiten; Preis Euro 29.00." Spiritual Care 10, no. 3 (June 16, 2021): 291. http://dx.doi.org/10.1515/spircare-2020-0113.

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Merkel, M., T. Schemme, and C. Denz. "Aperiodic biomimetic Vogel spirals as diffractive optical elements for tailored light distribution in functional polymer layers." Journal of Optics 23, no. 6 (April 29, 2021): 065401. http://dx.doi.org/10.1088/2040-8986/abf8cc.

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Wang, Nian-Mu, Huang Huang, and Chao Zhang. "Broadband second harmonic generation in aperiodic nonlinear photonic crystals: 1D projection from 2D Vogel sunflower spiral array." AIP Advances 11, no. 5 (May 1, 2021): 055219. http://dx.doi.org/10.1063/5.0052800.

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Gneist, Joachim. "Eckhard Frick, Ralf T. Vogel (Hg.) (2017) Den Abschied vom Leben verstehen. Psychoanalyse und Palliative Care. Stuttgart: Kohlhammer. ISBN: 978-3-17-029284-0; 170 Seiten; Preis: 32,00 €." Spiritual Care 8, no. 2 (April 8, 2019): 238–41. http://dx.doi.org/10.1515/spircare-2018-0067.

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Handa, Toshihiro, Miru Maebata, Takeru Murase, Shinji Fujita, Mikito Kohno, Nario Kuno, Mika Kuriki, et al. "Difference of the Gas Density Histograms in and out of spiral arms in Milky Way Galaxy." Proceedings of the International Astronomical Union 14, S345 (August 2018): 322–23. http://dx.doi.org/10.1017/s1743921319001649.

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Abstract“Gas Density Histogram (GDH)” is an observational counterpart of the probability density function (PDF) of the gas density of interstellar medium (ISM). We used 12CO data in (l, b) = (29°, 0) region from “FOREST unbiased galactic imaging survey with Nobeyama 45-m telescope (FUGIN)”, which is a large coverage survey in three CO (1-0) lines. Using the kinetic distance, we estimated the volume density of the voxel from the observed column density. The resultant GDHs of the inter-arm regions show lognormal or lognormal-like, but those in the spiral arm regions show flat-top shape.

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Xu, Chenxi, Chen Zhang, Wei Zhao, Yining Liu, Ziyu Li, Zeyu Wang, Baole Lu, Kaige Wang, and Jintao Bai. "Fabrication of Micro/Nano Dual Needle Structures with Morphological Gradient Based on Two-Photon Polymerization Laser Direct Writing with Proactive Focus Compensation." Photonics 11, no. 2 (February 18, 2024): 187. http://dx.doi.org/10.3390/photonics11020187.

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Micro/nano structures with morphological gradients possess unique physical properties and significant applications in various research domains. This study proposes a straightforward and precise method for fabricating micro/nano structures with morphological gradients utilizing single-voxel synchronous control and a nano-piezoelectric translation stage in a two-photon laser direct writing technique. To address the defocusing issue in large-scale fabrication, a methodology for laser focus dynamic proactive compensation was developed based on fluorescence image analysis, which can achieve high-precision compensation of laser focus within the entire range of the nano-piezoelectric translation stage. Subsequently, the fabrication of micro/nano dual needle structures with morphological gradients were implemented by employing different writing speeds and voxel positions. The minimum height of the tip in the dual needle structure is 80 nm, with a linewidth of 171 nm, and a dual needle total length reaching 200 μm. Based on SEM (scanning electron microscope) and AFM (atomic force microscope) characterization, the dual needle structures fabricated by the method proposed in this study exhibit high symmetry and nanoscale gradient accuracy. Additionally, the fabrication of hexagonal lattice periodic structures assembled from morphological gradient needle structures and the size gradient Archimedean spiral structures validate the capability of the single voxel-based fabrication and proactive focus compensation method for complex gradient structure fabrication.

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Jin, Craig, Amelia Gully, Michael I. Proctor, Kirrie Ballard, Sheryl Foster, Tharinda Piyadasa, and Yaoyao Yue. "Exploring the relationship between real-time midsagittal images of the vocal tract and volumetric data." Journal of the Acoustical Society of America 154, no. 4_supplement (October 1, 2023): A244. http://dx.doi.org/10.1121/10.0023428.

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3D analysis of the vocal tract using dynamic MRI remains a technically difficult challenge. Various approaches have been explored such as using parametic models of the vocal tract (Yehia et al., 1997); integrating data across parallel slices of 2D dynamic data (Zhu et al., 2012); applying stack-of-spiral MRI sampling with 3D constrained reconstruction (Zhao et al., 2020); and combining static 3D and dynamic 2D data (Douros et al., 2019). In this work, we follow a similar approach to Douros et al. and explore the relationship between 2D real-time midsagittal images and 3D volumetric scans of the vocal tract. The real-time MRI midsagittal images are recorded during vowel-consonant-vowel vocal tasks, while the 3D volumetric scans are recorded during sustained vowels. We use large deformation diffeomorphic metric mapping as the foundation for this modeling work. We explore techniques to use constraints provided by the real-time MRI midsagittal images to enable smooth deformations of the 3D volumetric data. We focus on the feasibility of the methods and report on the types of constraints explored and the resulting deformations of the 3D volumetric data.

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Maidl, Lydia. "Ralf T. Vogel (2017) Individuation und Wandlung. Der „Werdensprozess der Seele“ in der Analytischen Psychologie C.G. Jung. Stuttgart: Kohlhammer. ISBN 978-3-17-028421-0; 151 Seiten; Preis: 26,00 €, auch als E-Book-Formate erhältlich." Spiritual Care 8, no. 2 (April 8, 2019): 241–43. http://dx.doi.org/10.1515/spircare-2018-0100.

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Bezshapochny, Sergey B., Oleh G. Avrunin, Andrey V. Loburets, Valery V. Loburets, and Yuri A. Gasyuk. "Forecasting of functional results of septoplasty." OTORHINOLARYNGOLOGY, no. 4(3) 2020 (September 25, 2020): 67–72. http://dx.doi.org/10.37219/2528-8253-2020-4-67.

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Objective: to define the effectiveness of forecasting of the functional result of septoplasty. Materials and methods: forecasting based on endorhinoscopy data, spiral computed tomography, formation of a spatial segmented lofting model of nasal cavity, construction of an aerodynamic model based on a unified generalized voxel tomography of the upper respiratory tract and rhinomanometry, which were conducted in 28 patients. Results: it was found that the correction of various variants of the deviation of nasal septum in more than 80% of cases significantly reduces the aerodynamic nasal resistance. Forecasting at septoplasty allows to quantify functional results, which do not always coincide with the real ones. The introduction of more highly accurate innovative diagnostic methods in the future will improve the efficiency of forecasting in rhinosurgery

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Yazbek, Sandrine, Sanjay P. Prabhu, Pauline Connaughton, Patricia E. Grant, and Borjan Gagoski. "Comparison of accelerated 3-D spiral chemical shift imaging and single-voxel spectroscopy at 3T in the pediatric age group." Pediatric Radiology 45, no. 9 (April 1, 2015): 1417–22. http://dx.doi.org/10.1007/s00247-015-3311-2.

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Faranna, V. "Angio-TC: Stato dell'arte e sviluppi futuri." Rivista di Neuroradiologia 10, no. 2_suppl (October 1997): 79–81. http://dx.doi.org/10.1177/19714009970100s231.

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The development of spiral acquisition techniques and the growing technology applied to both CT equipment and post-processing systems, have shown CT angiography (CTA), to be a complementary method to conventional Angiography, magnetic resonance angiography (MRA) or ultrasound, for the morphologic evaluation of vascular structures. Through the administration via intravenous injection of a contrast media and by means of a fast acquisition of the Region Of Interest, we obtain the primary information to be processed and displayed according to various imaging techniques: Axial images, Multiplanar Reformatting (MPR), volume rendering (3D) or shaded surface display (SSD), Maximum Intensity Projection (MIP), Endoscopic-CT etc. All of these processing methods, perform as a first step of the whole process, longitudinal interpolations by the data of the images. Even though few methods to improve the quality of the images exist, among these the use of overlapping sections, the precision requires of the post-processing procedures to accomplish the medical requirements for diagnosis, is affected by a common factor which is the absolute anisotropicity of the acquisition voxel (dimension along the “Z” axis different and bigger than those in the transverse plane). This represents the goal-parameter on which the various competitors will have to focus their efforts in order to obtain results with an improved diagnostic validity. At present, the systems with dual-slice acquisition, represent the first step of what will be the acquisition technology of the future: “multi-slice”. At the same time, the technologic growth of postprocessing workstations, will permit the development of new clinical applications combined with Spiral-CT acquisition which will broaden the horizons of modern medicine.

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Karimian, Reza, Mansoor Dashti Ardakani, Shahrokh Ahmadi, and Mona Zaghloul. "Human Body Specific Absorption Rate Reduction Employing a Compact Magneto-Dielectric AMC Structure for 5G Massive-MIMO Applications." Eng 2, no. 4 (November 4, 2021): 501–11. http://dx.doi.org/10.3390/eng2040032.

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A compact artificial magnetic conductor (AMC) structure for the application of specific absorption rate (SAR) reduction is presented in this paper. A magneto-dielectric (MD) structure as a host of AMC substrate is used to miniaturize the AMC size. The magneto-dielectric has been designed with a low-profile spiral loop in a way to have a high permittivity and permeability for the desired center frequency of 3.5 GHz. Simulation results confirm the zero-degree reflection phase of the proposed AMC unit cell. Moreover, a 70% reduction has been achieved in comparison to the conventional AMC. To validate the simulation results, a prototype of the board is fabricated and measured with a coplanar waveguide (CPW) antenna for the reflection coefficient. The measurement results display an excellent agreement with the simulation ones. A VOXEL model of a human body is utilized to determine the SAR value of the proposed structure. Considering the maximum SAR value for an average of 10 g human tissue, more than 70% SAR reduction is verified for the CPW antenna with the recommended MD-AMC structure compared to a conventional single CPW antenna.

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Ketten, Darlene R., Andrea M. Simmons, and James A. Simmons. "Bats to belugas: Functional anatomy of air versus water biosonar." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A94. http://dx.doi.org/10.1121/10.0018280.

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Acoustic task similarities of odontocetes (toothed whales) and microchiropterans (insectivorous bats) suggest they have common biosonar mechanisms. However, media differences; e.g., sound speeds in air versus water, may have driven variations in auditory system adaptations. We examined the peripheral auditory system of an FM bat (big brown bat Eptesicus fuscus) and two toothed whale species (harbor porpoise Phocoena phocoena; bottlenose dolphin Tursiops truncatu) using ultra high resolution (11 μm) isotropic voxel microCT. Significant differences were found among species for oval window location, cochlear length, basilar membrane gradients, cochlear spiral morphometry, cochlear curvature, and basilar membrane stiffness. High and low frequency hearing range cut-offs correlate with basilar membrane thickness/width ratios and cochlear radii of curvature. These features predict species specific high and low frequency hearing limits. Harbor porpoises, the highest frequency echolocator in the study, have large basal basilar membrane ratios and a “foveal” region with a constant membrane ratio similar to those reported for some bat species, consistent with a “stretched” frequency region. Furthermore, both the bats and harbor porpoises examined displayed unusual stapedial input locations and tightly coiled cochleae, specializations that may enhance ultrasonic frequency signal resolution and diminish low frequency cochlear propagation.

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Rigby, A. J., T. J. T. Moore, D. J. Eden, J. S. Urquhart, S. E. Ragan, N. Peretto, R. Plume, M. A. Thompson, M. J. Currie, and G. Park. "CHIMPS: physical properties of molecular clumps across the inner Galaxy." Astronomy & Astrophysics 632 (November 27, 2019): A58. http://dx.doi.org/10.1051/0004-6361/201935236.

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The latest generation of high-angular-resolution unbiased Galactic plane surveys in molecular-gas tracers are enabling the interiors of molecular clouds to be studied across a range of environments. The CO Heterodyne Inner Milky Way Plane Survey (CHIMPS) simultaneously mapped a sector of the inner Galactic plane, within 27.8° ≲ ℓ ≲ 46.2° and |b|≤ 0°.5, in 13CO (3–2) and C18O (3–2) at an angular resolution of 15 arcsec. The combination of the CHIMPS data with 12CO (3–2) data from the CO High Resolution Survey (COHRS) has enabled us to perform a voxel-by-voxel local-thermodynamic-equilibrium (LTE) analysis, determining the excitation temperature, optical depth, and column density of 13CO at each ℓ, b, v position. Distances to discrete sources identified by FELLWALKER in the 13CO (3–2) emission maps were determined, allowing the calculation of numerous physical properties of the sources, and we present the first source catalogues in this paper. We find that, in terms of size and density, the CHIMPS sources represent an intermediate population between large-scale molecular clouds identified by CO and dense clumps seen in thermal dust continuum emission, and therefore represent the bulk transition from the diffuse to the dense phase of molecular gas. We do not find any significant systematic variations in the masses, column densities, virial parameters, mean excitation temperature, or the turbulent pressure over the range of Galactocentric distance probed, but we do find a shallow increase in the mean volume density with increasing Galactocentric distance. We find that inter-arm clumps have significantly narrower linewidths, and lower virial parameters and excitation temperatures than clumps located in spiral arms. When considering the most reliable distance-limited subsamples, the largest variations occur on the clump-to-clump scale, echoing similar recent studies that suggest that the star-forming process is largely insensitive to the Galactic-scale environment, at least within the inner disc.

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Orhan, Ayse I., and Esra C. Tatli. "Evaluation of Root Canal Obturation Quality in Deciduous Molars with Different Obturation Materials: An In Vitro Micro-Computed Tomography Study." BioMed Research International 2021 (July 2, 2021): 1–6. http://dx.doi.org/10.1155/2021/6567161.

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Objective. To evaluate the voids in root canal treatment of deciduous molar canals using three obturating materials and two obturation systems using micro-CT. Study Design. Thirty freshly extracted deciduous molars were used in this study. The specimens were instrumented using a ProTaper Universal rotary instrument and randomly assigned into six groups ( n = 5 ). Mesiobuccal root canals were obturated using Ca(OH)2 and iodoform-Ca(OH)2 and ZOE cement. The materials were applied straight from the syringe up to the 2 mm coronal level of the apex. Subsequently, the Lentulo spiral and ultrasonic activation with endoactivator were used for obturation. All samples were scanned by micro-CT with 9.1 μm isotropic voxel resolution. The voids in cross-sectional images and 3D volumes of voids were measured. Differences among materials were statically evaluated ( p < 0.05 ). Results. All study groups showed voids. Ca(OH)2 and iodoform-Ca(OH)2 with ultrasonic activation produced fewer voids whereas the ZOE groups showed higher voids with statistical significance ( p < 0.05 ). Conclusions. Ca(OH)2 and iodoform-Ca(OH)2 with ultrasonic activation decrease void formation. Further studies should be done with other obturation techniques and materials for deciduous tooth root canal management.

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IYER, LAXMI R., KIRUTHIKA RAMANATHAN, and SHENG-UEI GUAN. "MULTI-LEARNER BASED RECURSIVE SUPERVISED TRAINING." International Journal of Computational Intelligence and Applications 06, no. 03 (September 2006): 429–49. http://dx.doi.org/10.1142/s1469026806001861.

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In this paper, we propose the multi-learner based recursive supervised training (MLRT) algorithm, which uses the existing framework of recursive task decomposition, by training the entire dataset, picking out the best learnt patterns, and then repeating the process with the remaining patterns. Instead of having a single learner to classify all datasets during each recursion, an appropriate learner is chosen from a set of three learners, based on the subset of data being trained, thereby avoiding the time overhead associated with the genetic algorithm learner utilized in previous approaches. In this way MLRT seeks to identify the inherent characteristics of the dataset, and utilize it to train the data accurately and efficiently. We observed that empirically MLRT performs considerably well as compared with RPHP and other systems on benchmark data with 11% improvement in accuracy on the SPAM dataset and comparable performances on the VOWEL and the TWO-SPIRAL problems. In addition, for most datasets, the time taken by MLRT is considerably lower than that of the other systems with comparable accuracy. Two heuristic versions, MLRT-2 and MLRT-3, are also introduced to improve the efficiency in the system, and to make it more scalable for future updates. The performance in these versions is similar to the original MLRT system.

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Naveiro, José M., Luis Gracia, Jorge Roces, Jorge Albareda, and Sergio Puértolas. "Three-Dimensional Computational Model Simulating the Initial Callus Growth during Fracture Healing in Long Bones: Application to Different Fracture Types." Bioengineering 10, no. 2 (February 2, 2023): 190. http://dx.doi.org/10.3390/bioengineering10020190.

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Bone fractures are among the most common and potentially serious injuries to the skeleton, femoral shaft fractures being especially severe. Thanks to recent advances in the area of in silico analysis, several approximations of the bone healing process have been achieved. In this context, the objective of this work was to simulate the initial phase of callus formation in long bones, without a pre-meshed domain in the 3D space. A finite element approach was computationally implemented to obtain the values of the cell concentrations along the whole domain and evaluate the areas where the biological quantities reached the thresholds necessary to trigger callus growth. A voxel model was used to obtain the 3D domain of the bone fragments and callus. A mesh growth algorithm controlled the addition of new elements to the domain at each step of the iterative procedure until complete callus formation. The implemented approach is able to reproduce the generation of the primary callus, which corresponds to the initial phase of fracture healing, independently of the fracture type and complexity, even in the case of several bone fragments. The proposed approach can be applied to the most complex bone fractures such as oblique, severely comminuted or spiral-type fractures, whose simulation remains hardly possible by means of the different existing approaches available to date.

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Warnert, E. A. H., F. Incekara, A. J. P. E. Vincent, J. W. Schouten, M. J. van den Bent, P. J. French, H. J. Dubbink, J. M. Kros, J. A. Hernandez-Tamames, and M. Smits. "P04.11 Voxelwise correlation between vascular MRI parameters obtained with ASL and DSC is decreased in IDH-wt non-enhancing glioma." Neuro-Oncology 21, Supplement_3 (August 2019): iii31. http://dx.doi.org/10.1093/neuonc/noz126.106.

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Abstract BACKGROUND Comparative studies of dynamic susceptibility contrast (DSC) based measurement of cerebral blood volume (CBV) or cerebral blood flow (CBF) and arterial spin labelling (ASL) based measurement of CBF have previously shown good correlation of these parameters in human glioma. However, these studies were mostly done before inclusion of the mutation status of the isocitrate dehydrogenase (IDH) encoding gene in brain tumour classification. In light of the call for gadolinium-free imaging, here we investigate the effect of IDH-mutation status on the correlation between ASL and DSC-based perfusion measurements in non-enhancing glioma. MATERIAL AND METHODS Twenty-two patients with non-enhancing glioma and confirmed IDH-mutation status (next generation sequencing, 6 IDH-wildtype and 16 IDH-mutated) underwent 3T MRI scanning (GE, Milwaukee, WI, USA). Image acquisition included a 3D spiral pseudocontinuous ASL with time-encoded labelling (7 effective label delays from 0.8 to 2 s, reconstruction matrix 128x128x42, resolution 1.9x1.9x3.5 mm3), and 2D DSC imaging (122 TRs, TR/TE 1500m/18.6ms, 15 slices, voxel size: 1.88x1.88x4 mm3) in which a bolus of 7.5ml of gadolinium-based contrast agent (Gadovist, Bayer, Leverkussen, GE) was injected. A pre-load bolus of equal size was given 5 minutes prior to DSC imaging. DSC and ASL images were motion corrected and linearly registered to high resolution FLAIR images (FSL, version 5.0.9, Oxford, UK). DSC-relative CBV (rCBV), DSC-relative CBF (rCBF), and ASL-CBF maps were calculated via previously described methods. The glioma region of interest (ROI) was determined via manual segmentation on the FLAIR images. Voxel-wise Pearson’s linear correlation coefficients (ρ) within this ROI were calculated between ASL-CBF and DSC-rCBV, and between ASL-CBF and DSC-rCBF. RESULTS Normalised histograms indicate that IDH-wt glioma has higher values for ASL-CBF, DSC-rCBV, and DSC-rCBF than IDH-mutated glioma. IDH-wildtype glioma has a significantly lower ρ ASL-CBF vs DSC-rCBV and ρ ASL-CBF vs DSC-rCBF than IDH-mutated glioma (two-sample t-tests p < 0.05). CONCLUSION IDH-mutation status of non-enhancing glioma potentially affects the correlation between ASL-CBF and DSC-rCBF/rCBV and should be taken into account when moving towards ASL-only imaging. The decreased correlation between ASL and DSC-based vascular parameters in IDH-wt gliomas may be due to more aggressive vasculature in subtypes of IDH-wt tumours. Future work includes expansion of the current patient cohort (part of the ongoing iGENE study).

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Staartjes, Victor E., Peter R. Seevinck, W. Peter Vandertop, Marijn van Stralen, and Marc L. Schröder. "Magnetic resonance imaging–based synthetic computed tomography of the lumbar spine for surgical planning: a clinical proof-of-concept." Neurosurgical Focus 50, no. 1 (January 2021): E13. http://dx.doi.org/10.3171/2020.10.focus20801.

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OBJECTIVEComputed tomography scanning of the lumbar spine incurs a radiation dose ranging from 3.5 mSv to 19.5 mSv as well as relevant costs and is commonly necessary for spinal neuronavigation. Mitigation of the need for treatment-planning CT scans in the presence of MRI facilitated by MRI-based synthetic CT (sCT) would revolutionize navigated lumbar spine surgery. The authors aim to demonstrate, as a proof of concept, the capability of deep learning–based generation of sCT scans from MRI of the lumbar spine in 3 cases and to evaluate the potential of sCT for surgical planning.METHODSSynthetic CT reconstructions were made using a prototype version of the “BoneMRI” software. This deep learning–based image synthesis method relies on a convolutional neural network trained on paired MRI-CT data. A specific but generally available 4-minute 3D radiofrequency-spoiled T1-weighted multiple gradient echo MRI sequence was supplemented to a 1.5T lumbar spine MRI acquisition protocol.RESULTSIn the 3 presented cases, the prototype sCT method allowed voxel-wise radiodensity estimation from MRI, resulting in qualitatively adequate CT images of the lumbar spine based on visual inspection. Normal as well as pathological structures were reliably visualized. In the first case, in which a spiral CT scan was available as a control, a volume CT dose index (CTDIvol) of 12.9 mGy could thus have been avoided. Pedicle screw trajectories and screw thickness were estimable based on sCT findings.CONCLUSIONSThe evaluated prototype BoneMRI method enables generation of sCT scans from MRI images with only minor changes in the acquisition protocol, with a potential to reduce workflow complexity, radiation exposure, and costs. The quality of the generated CT scans was adequate based on visual inspection and could potentially be used for surgical planning, intraoperative neuronavigation, or for diagnostic purposes in an adjunctive manner.

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Sgrignuoli, F., R. Wang, F. A. Pinheiro, and L. Dal Negro. "Localization of scattering resonances in aperiodic Vogel spirals." Physical Review B 99, no. 10 (March 15, 2019). http://dx.doi.org/10.1103/physrevb.99.104202.

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Prado, M., F. Sgrignuoli, Y. Chen, L. Dal Negro, and F. A. Pinheiro. "Structural entropy and spatial decay of quasimodes in Vogel spirals." Physical Review B 104, no. 18 (November 29, 2021). http://dx.doi.org/10.1103/physrevb.104.184204.

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Razo-López, Luis A., Geoffroy J. Aubry, Felipe A. Pinheiro, and Fabrice Mortessagne. "Strong localization of microwaves beyond two dimensions in aperiodic Vogel spirals." Physical Review B 109, no. 1 (January 8, 2024). http://dx.doi.org/10.1103/physrevb.109.014205.

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Pfeiffer, Walter, Martin Aeschlimann, Felix Fenner, Tobias Brixner, Benjamin Frisch, Patrick Folge, Michael Hartelt, et al. "Direct Imaging of Photonic Band Edge States in Golden Vogel Spirals using Photoemission Electron Microscopy." Journal of the Optical Society of America B, January 10, 2023. http://dx.doi.org/10.1364/josab.479667.

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Adanyeguh, Isaac M., Nutandev Bikkamane Jayadev, Pierre‐Gilles Henry, and Dinesh K. Deelchand. "Fast high‐resolution prospective motion correction for single‐voxel spectroscopy." Magnetic Resonance in Medicine, December 12, 2023. http://dx.doi.org/10.1002/mrm.29950.

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AbstractPurposeTo develop a fast high‐resolution image‐based motion correction method using spiral navigators with multislice‐to‐volume registration.MethodsA semi‐LASER sequence was modified to include a multislice spiral navigator for prospective motion correction (∼305 ms including acquisition, processing, and feedback) as well as shim and frequency navigators for prospective shim and frequency correction (∼100 ms for each). MR spectra were obtained in the prefrontal cortex in five healthy subjects at 3 T with and without prospective motion and shim correction. The effect of key navigator parameters (number of slices, image resolution, and excitation flip angle) on registration accuracy was assessed using simulations.ResultsWithout prospective motion and shim correction, spectral quality degraded significantly in the presence of voluntary motion. In contrast, with prospective motion and shim correction, spectral quality was improved (metabolite linewidth = 6.7 ± 0.6 Hz, SNR= 67 ± 9) and in good agreement with baseline data without motion (metabolite linewidth = 6.9 ± 0.9 Hz, SNR = 73 ± 9). In addition, there was no significant difference in metabolites concentrations measured without motion and with prospective motion and shim correction in the presence of motion. Simulations showed that the registration precision was comparable when using three navigator slices with 3 mm resolution and when using the entire volume (all slices) with 8 mm resolution.ConclusionThe proposed motion correction scheme allows fast and precise prospective motion and shim correction for single‐voxel spectroscopy at 3 T. With 3 mm resolution, only a few navigator slices are necessary to achieve excellent motion correction performance.

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Lim, Yongwan, Prakash Kumar, and Krishna S. Nayak. "Speech production real‐time MRI at 0.55 T." Magnetic Resonance in Medicine, October 5, 2023. http://dx.doi.org/10.1002/mrm.29843.

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AbstractPurposeTo demonstrate speech‐production real‐time MRI (RT‐MRI) using a contemporary 0.55T system, and to identify opportunities for improved performance compared with conventional field strengths.MethodsExperiments were performed on healthy adult volunteers using a 0.55T MRI system with high‐performance gradients and a custom 8‐channel upper airway coil. Imaging was performed using spiral‐based balanced SSFP and gradient‐recalled echo (GRE) pulse sequences using a temporal finite‐difference constrained reconstruction. Speech‐production RT‐MRI was performed with three spiral readout durations (8.90, 5.58, and 3.48 ms) to determine trade‐offs with respect to articulator contrast, blurring, banding artifacts, and overall image quality.ResultsBoth spiral GRE and bSSFP captured tongue boundary dynamics during rapid consonant‐vowel syllables. Although bSSFP provided substantially higher SNR in all vocal tract articulators than GRE, it suffered from banding artifacts at TR > 10.9 ms. Spiral bSSFP with the shortest readout duration (3.48 ms, TR = 5.30 ms) had the best image quality, with a 1.54‐times boost in SNR compared with an equivalent GRE sequence. Longer readout durations led to increased SNR efficiency and blurring in both bSSFP and GRE.ConclusionHigh‐performance 0.55T MRI systems can be used for speech‐production RT‐MRI. Spiral bSSFP can be used without suffering from banding artifacts in vocal tract articulators, provide better SNR efficiency, and have better image quality than what is typically achieved at 1.5 T or 3 T.

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Adanyeguh, Isaac M., Young Woo Park, Pierre‐Gilles Henry, and Dinesh K. Deelchand. "B₀‐insensitive image navigators for prospective motion‐corrected MRS with localized second‐order shimming." Magnetic Resonance in Medicine, May 5, 2024. http://dx.doi.org/10.1002/mrm.30151.

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AbstractPurposeLocalized shimming in single‐voxel MRS often results in large B0 inhomogeneity outside the volume‐of‐interest. This causes unacceptable degradation in motion navigator images. Switching back and forth between whole‐brain shim and localized shim is possible for linear shims, but not for higher‐order shims. Here we propose motion navigators largely insensitive to B0 inhomogeneity for prospective motion‐corrected MRS with localized higher‐order shimming.MethodsA recent fast high‐resolution motion navigator based on spiral‐in/out k‐space trajectories and multislice‐to‐volume registration was modified by splitting the readout into multiple shot interleaves which shortened the echo time and reduced the effect of B0 inhomogeneity. The performance of motion correction was assessed in healthy subjects in the prefrontal cortex using a sLASER sequence at 3T (N = 5) and 7T (N = 5).ResultsWith multiple spatial interleaves, excellent quality navigator images were acquired in the whole brain in spite of large B0 inhomogeneity outside the MRS voxel. The total duration of the navigator in sLASER remained relatively short even with multiple shots (3T: 10 spatial interleaves 94 ms per slice; 7T: 15 spatial interleaves 103 ms per slice). Prospective motion correction using the multi‐shot navigators yielded comparable spectral quality (water linewidth and metabolite SNR) with and without subject motion.ConclusionB0‐insensitive motion navigators enable prospective motion correction for MRS with all first‐ and second‐order shims adjusted in the MRS voxel, providing optimal spectral linewidth.

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Mächler, Ruth. "Ralf T. Vogel (2023) Das Geheimnis der Seele: Grundlagen einer zeitgemäßen Psychotherapiewissenschaft. Stuttgart: Kohlhammer. ISBN-10:‎ 3170440039; 136 Seiten; Preis: D 37,00 €; E-Book 32,99 € The secret of the soul: Foundations of a contemporary psychotherapy science." Spiritual Care, May 18, 2024. http://dx.doi.org/10.1515/spircare-2024-0010.

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Merton, Renske, Daan Bosshardt, Gustav J. Strijkers, Aart J. Nederveen, Eric M. Schrauben, and Pim van Ooij. "Reproducibility of 3D thoracic aortic displacement from 3D cine balanced SSFP at 3 T without contrast enhancement." Magnetic Resonance in Medicine, October 13, 2023. http://dx.doi.org/10.1002/mrm.29856.

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AbstractPurposeAortic motion has direct impact on the mechanical stresses acting on the aorta. In aortic disease, increased stiffness of the aorta may lead to decreased aortic motion over time, which could be a predictor for aortic dissection or rupture. This study investigates the reproducibility of obtaining 3D displacement and diameter maps quantified using accelerated 3D cine MRI at 3 T.MethodsA noncontrast‐enhanced, free‐breathing 3D cine sequence based on balanced SSFP and pseudo‐spiral undersampling with high spatial isotropic resolution was developed (spatial/temporal resolution [1.6 mm]3/67 ms). The thoracic aorta of 14 healthy volunteers was prospectively scanned three times at 3 T: twice on the same day and a third time 2 weeks later. Aortic displacement was calculated using iterative closest point nonrigid registration of manual segmentations of the 3D aorta at end‐systole and mid‐diastole. Interexamination and interobserver regional analysis of mean displacement for five regions of interest was performed using Bland–Altman analysis. Additionally, a complementary voxel‐by‐voxel analysis was done, allowing a more local inspection of the method.ResultsNo significant differences were found in mean and maximum displacement for any of the regions of interest for the interexamination and interobserver analysis. The maximum displacement measured in the lower half of the ascending aorta was 11.0 ± 3.4 mm (range: 3.0–17.5 mm) for the first scan. The smallest detectable change in mean displacement in the lower half of the ascending aorta was 3 mm.ConclusionDetailed 3D cine balanced SSFP at 3 T allows for reproducible quantification of systolic–diastolic mean aortic displacement within acceptable limits.

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Bom Braga, Gabriela O., Annapaola Parrilli, Robert Zboray, Milica Bulatović, and Franca Wagner. "Quantitative Evaluation of the 3D Anatomy of the Human Osseous Spiral Lamina Using MicroCT." Journal of the Association for Research in Otolaryngology, July 5, 2023. http://dx.doi.org/10.1007/s10162-023-00904-3.

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Abstract Purpose The osseous spiral lamina (OSL) is an inner cochlear bony structure that projects from the modiolus from base to apex, separating the cochlear canal into the scala vestibuli and scala tympani. The porosity of the OSL has recently attracted the attention of scientists due to its potential impact on the overall sound transduction. The bony pillars between the vestibular and tympanic plates of the OSL are not always visible in conventional histopathological studies, so imaging of such structures is usually lacking or incomplete. With this pilot study, we aimed, for the first time, to anatomically demonstrate the OSL in great detail and in 3D. Methods We measured width, thickness, and porosity of the human OSL by microCT using increasing nominal resolutions up to 2.5-µm voxel size. Additionally, 3D models of the individual plates at the basal and middle turns and the apex were created from the CT datasets. Results We found a constant presence of porosity in both tympanic plate and vestibular plate from basal turn to the apex. The tympanic plate appears to be more porous than vestibular plate in the basal and middle turns, while it is less porous in the apex. Furthermore, the 3D reconstruction allowed the bony pillars that lie between the OSL plates to be observed in great detail. Conclusion By enhancing our comprehension of the OSL, we can advance our comprehension of hearing mechanisms and enhance the accuracy and effectiveness of cochlear models.

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Landsmann, Anna, Carlotta Ruppert, Jann Wieler, Patryk Hejduk, Alexander Ciritsis, Karol Borkowski, Moritz C. Wurnig, Cristina Rossi, and Andreas Boss. "Radiomics in photon-counting dedicated breast CT: potential of texture analysis for breast density classification." European Radiology Experimental 6, no. 1 (July 20, 2022). http://dx.doi.org/10.1186/s41747-022-00285-x.

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Abstract Background We investigated whether features derived from texture analysis (TA) can distinguish breast density (BD) in spiral photon-counting breast computed tomography (PC-BCT). Methods In this retrospective single-centre study, we analysed 10,000 images from 400 PC-BCT examinations of 200 patients. Images were categorised into four-level density scale (a–d) using Breast Imaging Reporting and Data System (BI-RADS)-like criteria. After manual definition of representative regions of interest, 19 texture features (TFs) were calculated to analyse the voxel grey-level distribution in the included image area. ANOVA, cluster analysis, and multinomial logistic regression statistics were used. A human readout then was performed on a subset of 60 images to evaluate the reliability of the proposed feature set. Results Of the 19 TFs, 4 first-order features and 7 second-order features showed significant correlation with BD and were selected for further analysis. Multinomial logistic regression revealed an overall accuracy of 80% for BD assessment. The majority of TFs systematically increased or decreased with BD. Skewness (rho -0.81), as a first-order feature, and grey-level nonuniformity (GLN, -0.59), as a second-order feature, showed the strongest correlation with BD, independently of other TFs. Mean skewness and GLN decreased linearly from density a to d. Run-length nonuniformity (RLN), as a second-order feature, showed moderate correlation with BD, but resulted in redundant being correlated with GLN. All other TFs showed only weak correlation with BD (range -0.49 to 0.49, p < 0.001) and were neglected. Conclusion TA of PC-BCT images might be a useful approach to assess BD and may serve as an observer-independent tool.

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Ketten, Darlene R., James A. Simmons, Hiroshi Riquimaroux, and Andrea Megela Simmons. "Functional Analyses of Peripheral Auditory System Adaptations for Echolocation in Air vs. Water." Frontiers in Ecology and Evolution 9 (September 6, 2021). http://dx.doi.org/10.3389/fevo.2021.661216.

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The similarity of acoustic tasks performed by odontocete (toothed whale) and microchiropteran (insectivorous bat) biosonar suggests they may have common ultrasonic signal reception and processing mechanisms. However, there are also significant media and prey dependent differences, notably speed of sound and wavelengths in air vs. water, that may be reflected in adaptations in their auditory systems and peak spectra of out-going signals for similarly sized prey. We examined the anatomy of the peripheral auditory system of two species of FM bat (big brown bat Eptesicus fuscus; Japanese house bat Pipistrellus abramus) and two toothed whales (harbor porpoise Phocoena phocoena; bottlenose dolphin Tursiops truncatus) using ultra high resolution (11–100 micron) isotropic voxel computed tomography (helical and microCT). Significant differences were found for oval and round window location, cochlear length, basilar membrane gradients, neural distributions, cochlear spiral morphometry and curvature, and basilar membrane suspension distributions. Length correlates with body mass, not hearing ranges. High and low frequency hearing range cut-offs correlate with basilar membrane thickness/width ratios and the cochlear radius of curvature. These features are predictive of high and low frequency hearing limits in all ears examined. The ears of the harbor porpoise, the highest frequency echolocator in the study, had significantly greater stiffness, higher basal basilar membrane ratios, and bilateral bony support for 60% of the basilar membrane length. The porpoise’s basilar membrane includes a “foveal” region with “stretched” frequency representation and relatively constant membrane thickness/width ratio values similar to those reported for some bat species. Both species of bats and the harbor porpoise displayed unusual stapedial input locations and low ratios of cochlear radii, specializations that may enhance higher ultrasonic frequency signal resolution and deter low frequency cochlear propagation.

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Zhou, Liangdong, Yi Li, Elizabeth M. Sweeney, Xiuyuan H. Wang, Amy Kuceyeski, Gloria C. Chiang, Jana Ivanidze, et al. "Association of brain tissue cerebrospinal fluid fraction with age in healthy cognitively normal adults." Frontiers in Aging Neuroscience 15 (June 16, 2023). http://dx.doi.org/10.3389/fnagi.2023.1162001.

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Background and purposeOur objective was to apply multi-compartment T2 relaxometry in cognitively normal individuals aged 20–80 years to study the effect of aging on the parenchymal CSF fraction (CSFF), a potential measure of the subvoxel CSF space.Materials and methodsA total of 60 volunteers (age range, 22–80 years) were enrolled. Voxel-wise maps of short-T2 myelin water fraction (MWF), intermediate-T2 intra/extra-cellular water fraction (IEWF), and long-T2 CSFF were obtained using fast acquisition with spiral trajectory and adiabatic T2prep (FAST-T2) sequence and three-pool non-linear least squares fitting. Multiple linear regression analyses were performed to study the association between age and regional MWF, IEWF, and CSFF measurements, adjusting for sex and region of interest (ROI) volume. ROIs include the cerebral white matter (WM), cerebral cortex, and subcortical deep gray matter (GM). In each model, a quadratic term for age was tested using an ANOVA test. A Spearman’s correlation between the normalized lateral ventricle volume, a measure of organ-level CSF space, and the regional CSFF, a measure of tissue-level CSF space, was computed.ResultsRegression analyses showed that there was a statistically significant quadratic relationship with age for CSFF in the cortex (p = 0.018), MWF in the cerebral WM (p = 0.033), deep GM (p = 0.017) and cortex (p = 0.029); and IEWF in the deep GM (p = 0.033). There was a statistically highly significant positive linear relationship between age and regional CSFF in the cerebral WM (p < 0.001) and deep GM (p < 0.001). In addition, there was a statistically significant negative linear association between IEWF and age in the cerebral WM (p = 0.017) and cortex (p < 0.001). In the univariate correlation analysis, the normalized lateral ventricle volume correlated with the regional CSFF measurement in the cerebral WM (ρ = 0.64, p < 0.001), cortex (ρ = 0.62, p < 0.001), and deep GM (ρ = 0.66, p < 0.001).ConclusionOur cross-sectional data demonstrate that brain tissue water in different compartments shows complex age-dependent patterns. Parenchymal CSFF, a measure of subvoxel CSF-like water in the brain tissue, is quadratically associated with age in the cerebral cortex and linearly associated with age in the cerebral deep GM and WM.

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Collins, Aaron, Søren Foghsgaard, Edgar Druce, Valerio Margani, Olivia Mejia, and Stephen O’Leary. "The Effect of Electrode Position on Behavioral and Electrophysiologic Measurements in Perimodiolar Cochlear Implants." Otology & Neurotology, January 18, 2024. http://dx.doi.org/10.1097/mao.0000000000004080.

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Background The shape and position of cochlear implant electrodes could potentially influence speech perception, as this determines the proximity of implant electrodes to the spiral ganglion. However, the literature to date reveals no consistent association between speech perception and either the proximity of electrode to the medial cochlear wall or the depth of insertion. These relationships were explored in a group of implant recipients receiving the same precurved electrode. Methods This was a retrospective study of adults who underwent cochlear implantation with Cochlear Ltd.’s Slim Perimodiolar electrode at the Royal Victorian Eye and Ear Hospital between 2015 and 2018 (n = 52). Postoperative images were obtained using cone beam computed tomography (CBCT) and analyzed by multi-planar reconstruction to identify the position of the electrode contacts within the cochlea, including estimates of the proximity of the electrodes to the medial cochlear wall or modiolus and the angular depth of insertion. Consonant-vowel-consonant (CVC) monosyllabic phonemes were determined preoperatively, and at 3 and 12 months postoperatively. Electrically evoked compound action potential (ECAP) thresholds and impedance were measured from the implant array immediately after implantation. The relationships between electrode position and speech perception, electrode impedance, and ECAP threshold were an analyzed by Pearson correlation. Results Age had a negative impact on speech perception at 3 months but not 12 months. None of the electrode-wide measures of proximity between electrode contacts and the modiolus, nor measures of proximity to the medial cochlear wall, nor the angular depth of insertion of the most apical electrode correlated with speech perception. However, there was a moderate correlation between speech perception and the position of the most basal electrode contacts; poorer speech perception was associated with a greater distance to the modiolus. ECAP thresholds were inversely related to the distance between electrode contacts and the modiolus, but there was no clear association between this distance and impedance. Conclusions Speech perception was significantly affected by the proximity of the most basal electrodes to the modiolus, suggesting that positioning of these electrodes may be important for optimizing speech perception. ECAP thresholds might provide an indication of this proximity, allowing for its optimization during surgery.

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Marzo, Vincenzo De, Sara Seitun, Umberto Viglino, Joao Gavina Matos, Maria Pigati, Matteo Vercellino, Gabriele Crimi, Manrico Balbi, and Italo Porto. "579 Pre-operative computed tomography evaluation of suprarenal aortic burden predicts post-procedural acute kidney injury after transcatheter aortic valve replacement: the spread-AKI study." European Heart Journal Supplements 23, Supplement_G (December 1, 2021). http://dx.doi.org/10.1093/eurheartj/suab134.013.

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Abstract Aims Acute kidney injury (AKI) is a potential complication of transcatheter aortic valve replacement (TAVR). Athero-embolization linked to catheter manipulation in the supra-renal aorta is a possible pathogenetic mechanism of AKI after TAVR. We sought to determine the impact of supra-renal aortic atheroma burden (AB) on AKI, and the potential role of pre-operative multislice computed tomography (PO-MSCT) in evaluating the supra-renal aortic atherosclerosis and the pre-operative risk of AKI. Methods and results We collected PO-MSCT, as well as baseline, procedural, and post-procedural characteristics of 222 consecutive patients who underwent TAVR from January 2018 to December 2020 at a single, high-volume, Italian centre. PO-MSCT was performed using a dedicated TAVR protocol with an ECG-triggered high-pitch spiral acquisition. The non-contrast aortic valve calcium score (AV-CS) was calculated by a dedicated software. Angiographic data were analysed on a dedicated 3D workstation. Bidimensional measurements, total renal volume (TRV), and presence of significant (≥50%) renal artery stenosis (RAS) were recorded. The supra-renal AB was quantified using a ‘plaque analysis’ module that automatically segments the entire aortic root, from the sino-tubular junction to the renal arteries, by drawing a centreline across the aortic lumen and delineating the inner and outer vessel walls (including the plaque). Manual correction was applied. A set of Hounsfield unit (HU) intensity ranges were defined and mapped to a color overlay to visualize the various elements of atherosclerotic lesion by using the plaque density classification of the Society of Cardiovascular Computed Tomography (necrotic core, fibro-fatty, fibrous, and calcified plaque); calcified plaque were subcategorized on a voxel-level basis into three strata: low- (351–700 HU), mid- (701–1000 HU), and high-calcium (>1000 HU, termed 1K plaque). Post-procedural complications were defined according to Valve Academic Research Consortium (VARC-3) criteria. Mean age was 83.3 ± 5.7 years, and 95 (42.8%) patients were males. AKI occurred in 67/222 (30.2%). Patients who developed AKI had higher supra-renal AB (17.6 ± 5.1% vs. 13.9 ± 4.3%, P < 0.001), TRV indexed for body surface area (TRVBSA; 153.7 ± 43.1 vs. 134.9 ± 38.7, P = 0.002), mid-calcium plaque (2.2 ± 1.5% vs. 1.3 ± 1.1%, P < 0.001), 1K plaque (5.4 ± 3.7% vs. 2.4 ± 2.4%, P < 0.001) and suffered more post-procedural major/life-threatening (severe) bleedings [9/67 (13.4%) vs. 5/155 (3.2%), P = 0.004], whereas there was no difference in AV-CS (P = 0.691) and RAS (P = 0.077). Multivariate logistic regression analysis adjusted for other univariate predictors (male sex, baseline eGFR, baseline ejection fraction, baseline mean aortic gradient, and RAS) showed percent supra-renal AB (HR: 1.15, 95% CI: 1.06–1.26, P = 0.002), mid-to-high calcium plaque (HR: 5.67, 95% CI: 2.49–13.77, P < 0.001), severe bleedings (HR: 4.93, 95% CI: 1.09–24.69, P = 0.043), and TRVBSA (HR: 1.015, 95% CI: 1.01–1.02, P = 0.021) as independent predictors of AKI. Finally, a 3-knots spline curve analysis identified percent of supra-renal AB > 15.0% as the optimal threshold to predict an increased risk of AKI. Conclusions Suprarenal AB is associated with the occurrence of AKI, and this association is strengthened as the percentage of calcified plaque increases. Quantitative and qualitative pre-operative MSCT assessment of aortic atherosclerosis may help in early identification of patients at high-risk for AKI who could benefit from higher peri-operative surveillance.

Journal articles on the topic 'Spirale de Vogel'

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