Scan Plane Research Articles

Transverse anisotropy in the deformation of the muscle during dynamic contractions.

When pennate muscle fibres shorten, the transverse deformation of fibres results in an increase in pennation angle of fascicles (bundles of fibres) and transverse deformation of muscle belly. Transverse shape changes of a muscle can influence force generation. Recent modelling studies predicted asymmetrical transverse deformations in the muscle fascicles in the gastrocnemii. However, these predictions have not been tested experimentally. As muscle is a 3D entity, it is important to explore the structural changes in a 3D perspective to enhance our understanding of the underlying structural mechanisms that have functional implications. The medial and lateral gastrocnemius muscles from 12 subjects were imaged during plantarflexion movements on a dynamometer. The muscle belly was simultaneously scanned from two orthogonal directions using two ultrasound probes. Fascicle deformations were measured from the two orthogonal ultrasound scans to provide 3D information of muscle geometry. Whilst transverse deformations in the medial gastrocnemius were similar from the two directions, the data for the lateral gastrocnemius confirm that transverse anisotropy can occur in the muscle fascicles. As the lateral gastrocnemius fascicle length shortened, the pennation angle increased and the fascicles bulged transversally in one direction (closest to the typical 2D scanning plane) while thinning in the other orthogonal direction. We suggest that the transverse deformation of the muscle fascicles depends on the stiffness of the aponeuroses, properties of connective tissue structures surrounding muscle, and compressive forces both internal and external to the muscle. These results highlight that muscle fascicles do not bulge uniformly and the implications for this behaviour on muscle function remain largely unexplored.

Fast Multiple Landmark Localisation Using a Patch-based Iterative Network.

We propose a new Patch-based Iterative Network (PIN) for fast and accurate landmark localisation in 3D medical volumes. PIN utilises a Convolutional Neural Network (CNN) to learn the spatial relationship between an image patch and anatomical landmark positions. During inference, patches are repeatedly passed to the CNN until the estimated landmark position converges to the true landmark location. PIN is computationally efficient since the inference stage only selectively samples a small number of patches in an iterative fashion rather than a dense sampling at every location in the volume. Our approach adopts a multitask learning framework that combines regression and classification to improve localisation accuracy. We extend PIN to localise multiple landmarks by using principal component analysis, which models the global anatomical relationships between landmarks. We have evaluated PIN using 72 3D ultrasound images from fetal screening examinations. PIN achieves quantitatively an average landmark localisation error of 5.59mm and a runtime of 0.44s to predict 10 landmarks per volume. Qualitatively, anatomical 2D standard scan planes derived from the predicted landmark locations are visually similar to the clinical ground truth.

Translabial ultrasound: “three tracks” technique

Introduction: there are various options for the application of an ultrasound transducer in transperineal sonography procedure (TPUS), starting from percutaneous scanning of the perineum area by sector transducers and ending with the use of transalabial (TLUS), transvaginal (TVUS) and transrectal access by the intracavitary transducers. In all these cases, it is necessary to identify the relationships of pelvic organs. The ultrasonic technique of the “three tracks” (TTT) allows real-time evaluation of the spatial ratio of the urethra, vagina and rectum, as well as adjacent subjects of the pelvis, visualizing them simultaneously in the same scanning plane.Objective: to present the “three track» technique used in the conduct of translabial ultrasonography, and to study the results of revealing the pathology in lower pelvis in comparison with routine transvaginal ultrasonography (TVUS).Participants, settings, methods: the study was conducted between January 18, 2016 and November 27, 2017 in the clinic for reproductive medicine “Remedi” (Odesa). Informed consent to the investigation was obtained from all females. 70 patients of the main group underwent translabial ultrasonography in the “three track” technique (TLUS + TTT). 71 women of comparative group underwent a routine transvaginal ultrasonography.Results and discussion: visualization of three tracks: urethra, vagina and rectum in one scan plane was achieved in 65 patients of the main group (93%). In addition, in the main group, approximately twice as often as in the comparison group, a rare pathology of the lower pelvis, such as Gartner duct cysts, the Bartolin cysts, the deep endometriosis of the rectovaginal septum and unclassified cysts of the vagina, were found. However, the insufficient number of obtained results does not allow confirming their reliability.Conclusion: the using of TTT during TLUS, extends the diagnostic opportunities of the examiner in the evaluation of the relationship of adjacent organs and tissues in the pelvic floor and lower pelvis. The method requires further research and can be used as an additional bonus to improve for accuracy and safety of diagnostic and surgical gynecological practice.There is no conflict of interest to declare.

Combustion combined with ball milling to produce nanoscale La2O3 coated on LiMn2O4 for optimized Li-ion storage performance at high temperature

In this study, La2O3 is synthesized by combustion method and then subjected to ultrafine ball milling to obtain La2O3 nanoparticles. In neopentyl glycol, La2O3 nanoparticles are coated on the surface of spinel LiMn2O4 ultimately obtaining La2O3 coating contents of 1.5, 3, 4.5, and 6 wt%. XRD characterization reveals that the nano La2O3 exhibits a favorable crystalline intensity, without impurities and the crystalline peak of La2O3 can be observed when the coating content is of up to 6 wt%. Successful deposition of a thin layer of La2O3 on the LiMn2O4 surface is confirmed by scanning electron microscopy, transmission electron microscopy, X-ray spectrum elemental plane scanning, and line scanning. Furthermore, inductively coupled plasma emission spectrography and electrochemical impedance spectroscopy analyses show that the nano-La2O3 coating significantly relieves the dissolution of Mn in LiMn2O4 materials, and also improves the electro-conductivity. The electrochemical performances of the coated LiMn2O4 samples are also investigated in this work. Compared with the pristine LiMn2O4, the LiMn2O4 coated with 3 wt% La2O3 exhibits a higher rate capability and better reversibility, exhibiting 103.5 and 90.6 mAh g−1 at 5 and 10 °C, respectively. After 100 cycles at 60 and 1 °C, the 3 wt% nano-La2O3-coated sample still exhibits a high-capacity retention of 91.68%.

Localizing implanted fiducial markers using undersampled co-RASOR MR imaging

The goal of this work was to use an undersampled, dual-plane centre-out radial sampling acquisition pulse sequence, with off-resonance reception, to localize fiducial markers with reduced acquisition time. Two iterative reconstruction techniques, conjugate gradient CG-SENSE and the variational penalty Total Generalized Variation (TGV), were investigated to minimize the undersampling artifacts in off-resonant radial imaging. Simulations of a field perturber were performed at sub-millimeter resolution and reconstructed to display signal pileups that can be radially compressed towards the geometric centre of the perturber for high contrast visualization, but contrast is non-recoverable as the echo time increases. A cylindrical platinum fiducial marker, placed in a phantom parallel and perpendicular to the B0-field was imaged with a short-TE half-echo readout. Contrast-to-Noise (CNR) between the signal of the fiducial its adjacent surrounding shell and half-maximum area were used to compare reconstruction methods and undersampling factors. For single slice acquisitions centred about the fiducial, each slice can be performed in as little as 2.8s. The total acquisition time to localize the fiducial marker in a phantom was reduced to 73s by undersampling (R=8) 37 axial and 15 coronal slices, effectively encoding 1.4s/slice. The noise present in undersampled images, for both scan planes and fiducial orientations, decreased significantly using TGV and CG-SENSE reconstructions, with TGV displaying better spatial resolution from reduced half-maximum area.

A real-time and registration-free framework for dynamic shape instantiation.

Real-time 3D navigation during minimally invasive procedures is an essential yet challenging task, especially when considerable tissue motion is involved. To balance image acquisition speed and resolution, only 2D images or low-resolution 3D volumes can be used clinically. In this paper, a real-time and registration-free framework for dynamic shape instantiation, generalizable to multiple anatomical applications, is proposed to instantiate high-resolution 3D shapes of an organ from a single 2D image intra-operatively. Firstly, an approximate optimal scan plane was determined by analyzing the pre-operative 3D statistical shape model (SSM) of the anatomy with sparse principal component analysis (SPCA) and considering practical constraints. Secondly, kernel partial least squares regression (KPLSR) was used to learn the relationship between the pre-operative 3D SSM and a synchronized 2D SSM constructed from 2D images obtained at the approximate optimal scan plane. Finally, the derived relationship was applied to the new intra-operative 2D image obtained at the same scan plane to predict the high-resolution 3D shape intra-operatively. A major feature of the proposed framework is that no extra registration between the pre-operative 3D SSM and the synchronized 2D SSM is required. Detailed validation was performed on studies including the liver and right ventricle (RV) of the heart. The derived results (mean accuracy of 2.19mm on patients and computation speed of 1ms) demonstrate its potential clinical value for real-time, high-resolution, dynamic and 3D interventional guidance.

Abdominal ultrasonographic imaging of laboratory animals - Current techniques

Diagnostic ultrasonography is a non-invasive imaging technique developed and applicable both in reproductive and companion animals for the diagnosis of diseases. During the last years it has also been used in laboratory animals facilitating thus the advances of biomedical research. The ultrasonographic imaging of abdominal organs in laboratory animals may take place in soft tissue organs, such as the liver, the spleen, the kidneys, the urinary bladder, but also the uterus, especially before, during and after pregnancy, as well as during parturition. It has been proved to be extremely useful both for monitoring of organ architecture during several related experimental protocols and for diagnosing possible diseases that may occur during a laboratory animal's lifetime. During the last decade technological progress has been present in scientific life leading in several advances in ultrasonographic imaging. More specifically, ultra high frequency transducers, with a potential of using sophisticated software, are now able to provide researchers with extended field of view images even of small laboratory animals, such as mice. 3D ultrasonography relies on the acquisition of images in multiple scan planes from which a 3D image is created. 4D ultrasonography provides functional data in three dimensions, whereas microbubble contrast agents have shown clinical potential for characterizing blood flow in abdominal vessels, especially with the use of ultra high frequency transducers and 3D imaging. Doppler imaging provides information on blood flow and abdominal organs blood supply. Finally, ultrasound- guided biopsy and injection of substances are important tools in biomedical research protocols.

3D image scanning microscopy with engineered excitation and detection

Scanning microscopes are important research tools for investigating 3D specimens. Modern beam shaping techniques can be combined with suitably designed data processing algorithms to improve instrument versatility and imaging performance. Here we introduce image scanning microscopy with freely programmable excitation and detection pupils and investigate point spread function (PSF) designs for parallel 3D information acquisition. The volumetric data is collected in a single 2D scan without the requirement of physical refocus. By sculpturing the excitation and detection PSFs into helical shapes of opposing handedness, we are able to capture sample information in a volume whose axial extension measures more than four times the z resolution. In a more generalized approach, jointly optimized phase masks are used in both pupils to shape the PSFs. As an exemplary case, we study the use of beam-splitting phase masks for the parallel scanning in multiple planes. The image reconstruction algorithm optimally integrates this information according to the various signal-to-noise ratios. Generalized PSF engineering scanning systems provide resolution improvement relative to confocal microscopy while accelerating data collection. We analyze the opportunities, trade-offs, and limitations of the approach.

Direct inversion algorithm for focal plane scanning optical projection tomography.

To achieve approximately parallel projection geometry, traditional optical projection tomography (OPT) requires the use of low numerical aperture (NA) objectives, which have a long depth-of-field at the expense of poor lateral resolution. Particularly promising methods to improve spatial resolution include ad-hoc post-processing filters that limit the effect of the system's MTF and focal-plane-scanning OPT (FPS-OPT), an alternative acquisition procedure that allows the use of higher NA objectives by limiting the effect of their shallow depth of field yet still assumes parallel projection rays during reconstruction. Here, we provide a detailed derivation that establishes the existence of a direct inversion formula for FPS-OPT. Based on this formula, we propose a point spread function-aware algorithm that is similar in form and complexity to traditional filtered backprojection (FBP). With simulations, we demonstrate that our point-spread-function aware FBP for FPS-OPT leads to more accurate images than both traditional OPT with deconvolution and FPS-OPT with naive FBP reconstruction. We further illustrate the technique on experimental zebrafish data, which shows that our approach reduces out-of-focus blur compared to a direct FBP reconstruction with FPS-OPT.

Rapid judgment of distal inward or outward rotation during closed reduction and intramedullary nailing for complex tibial fractures

Objective To explore how to make a rapid judgment of distal inward or outward rotation during closed reduction and intramedullary nailing for complex tibial fractures so as to avoid bad reduction of the distal rotation. Methods Twenty-one patients with complex tibial fracture underwent closed reduction and intramedullary nailing from January 2014 to January 2016. They were 16 males and 5 females, aged from 22 to 53 years (average, 34.6 years). By AO/OTA classification, 6 cases were type 42-C1, 2 type 42-C2, and 13 type 42-C3. During surgery, the relationship between the connecting rod of the front pressure lever of intramedullary nail in the tibia and the second metatarsal bone was used to judge the rotation. After surgery CT plane scanning was used to assess reliability of the intraoperative judgment of the rotation. Validity of the rotation judgment was finally evaluated by comparing Functional Index Questionnaire (FIQ) scores, Olerud Molander ankle scores (OMAS) and Health Status Questionnaire (SF-36) scores between pre-injury and final follow-up. Results The 21 patients were followed up for 12 to 24 months (average, 18.3 months). Bony union was achieved from 3 to 7 months after surgery (average, 4.5 months) without nonunion or refracture. There was no significant difference in the tangent angle between the proximal and distal tibiae on CT scan between the healthy side (47.1°±2.9°) and the affected side (44.8°±5.6°) (P >0.05). There were no significant differences either in FIQ scores, OMAS or SF-36 scores between pre-injury and final follow-up (P >0.05). Conclusion In the course of closed reduction and intramedullary nailing for complex tibial fractures, it is simple and effective to judge the distal inward or outward rotation by pointing the connecting rod of the front pressure lever of intramedullary nail in the tibia to the second metatarsal bone. Key words: Tibial farctures; Fracture fixation, intramedullary; Feasibility studies; Judgment

Experimental Validation of a Wideband Metasurface for Wide-Angle Scanning Leaky-Wave Antennas

Beam scanning arrays typically suffer from scan loss; an increasing degradation in gain as the beam is scanned from broadside toward the horizon in any given scan plane. Here, a metasurface is presented that reduces the effects of scan loss for a leaky-wave antenna (LWA). The metasurface is simple, being composed of an ultrathin sheet of subwavelength split-ring resonators. The leaky-wave structure is balanced, scanning from the forward region, through broadside, and into the backward region, and designed to scan in the magnetic plane. The metasurface is effectively invisible at broadside, where balanced LWAs are most sensitive to external loading. It is shown that the introduction of the metasurface results in increased directivity, and hence, gain, as the beam is scanned off broadside, having an increasing effect as the beam is scanned to the horizon. Simulations show that the metasurface improves the effective aperture distribution at higher scan angles, resulting in a more directive main beam, while having a negligible impact on cross-polarization gain. Experimental validation results show that the scan range of the antenna is increased from $-39 {^{\circ }} \leq \theta \leq +32 {^{\circ }}$ to $-64 {^{\circ }} \leq \theta \leq +70 {^{\circ }}$ , when loaded with the metasurface, demonstrating a flattened gain profile over a 135° range centered about broadside. Moreover, this scan range occurs over a frequency band spanning from 9 to 15.5 GHz, demonstrating a relative bandwidth of 53% for the metasurface.

Development and Validation of MRI Sacroiliac Joint Scoring Methods for the Semiaxial Scan Plane Corresponding to the Berlin and SPARCC MRI Scoring Methods, and of a New Global MRI Sacroiliac Joint Method.

To develop semiaxial magnetic resonance imaging (MRI) scoring methods for assessment of sacroiliac joint (SIJ) bone marrow edema (BME) in patients with axial spondyloarthritis, and to compare the reliability with equivalent semicoronal scoring methods. Two semiaxial SIJ MRI scoring methods were developed based on the principles of the semicoronal Berlin and Spondyloarthritis Research Consortium of Canada (SPARCC) methods. A global quadrant-based method was also developed. Baseline and 12-week MRI of the SIJ from 51 patients participating in a randomized double-blind placebo-controlled trial of adalimumab 40 mg every other week versus placebo were scored by the semiaxial and the corresponding semicoronal methods. Results were compared by linear regression analysis. The reproducibility and sensitivity were evaluated by intraclass correlation coefficients (ICC) and smallest detectable change [SDC, absolute values and percentage of the highest observed score (SDC-HOS)]. Interreader and intrareader ICC were moderate to very high for semiaxial scoring methods (baseline 0.83-0.88 and 0.85-0.97; change 0.33-0.78), while high to very high for semicoronal scoring methods (baseline 0.90-0.92 and 0.93-0.97; change 0.77-0.89). Association between semiaxial and semicoronal scores were high for both the Berlin and SPARCC method (baseline: R2 = 0.93 and 0.88; change: R2 = 0.82 and 0.87, respectively), while lower for the global method (baseline: R2 = 0.79; change: R2 = 0.54). The SDC-HOS were 9.8-18.6% and 5.9-10.7% for the semiaxial and semicoronal methods, respectively. Detection of SIJ BME in the semiaxial scan plane is feasible and reproducible. However, a slightly lower reliability of all 3 semiaxial methods supports the general practice of using the coronal scan-plane in therapeutic studies.

Gynecological brachytherapy with Elekta microSelectron V3 afterloading system

Abstract Objective: For commissioning of source path mo-dels for ring tubes of Nucletron (now Elekta) CT/MR ring applicators, a method was established using a source position simulator (SPS) and a CT scanner. Methods: An acrylic glass support for ring tubes was constructed serving as defined coordinate system. With SPS, 40 positions were set in the ring in steps of 2.5mm from proximal to distal direction. In each position a CT-series was taken with ring plane inside scan plane using a GE Optima 580 scanner (slice width 0.625mm). Evaluation was done in multiplanar recon-struction mode under display settings revealing dummy source shape. With a 3D-cursor dwell position coordinate (center of Ir-192 core) was determined. Measurements were validated by film autoradiography in selected positions. Four rings were investigated: 60° Φ26, 45° Φ26, 60° Φ30, and 45° Φ30 with figures denoting angle between ring plane and stem and ring diameter in mm. Results: The method is feasible to reconstruct source dwell positions with an overall accuracy of ±0.3mm. Detected coordinates are consistent and in excel-lent agreement with those obtained by autoradiography. Comparison with Elekta’s source path models, however, re-vealed mean deviations of up to 3.5mm. Discussion: It is advisable to measure individual source paths and have them added to the data base of the treatment planning system.

Generation of realistic virtual nodules based on three-dimensional spatial resolution in lung computed tomography: A pilot phantom study.

The aim of this feasibility study using phantoms was to propose a novel method for obtaining computer-generated realistic virtual nodules in lung computed tomography (CT). In the proposed methodology, pulmonary nodule images obtained with a CT scanner are deconvolved with the point spread function (PSF) in the scan plane and slice sensitivity profile (SSP) measured for the scanner; the resultant images are referred to as nodule-like object functions. Next, by convolving the nodule-like object function with the PSF and SSP of another (target) scanner, the virtual nodule can be generated so that it has the characteristics of the spatial resolution of the target scanner. To validate the methodology, the authors applied physical nodules of 5-, 7- and 10-mm-diameter (uniform spheres) included in a commercial CT test phantom. The nodule-like object functions were calculated from the sphere images obtained with two scanners (Scanner A and Scanner B); these functions were referred to as nodule-like object functions A and B, respectively. From these, virtual nodules were generated based on the spatial resolution of another scanner (Scanner C). By investigating the agreement of the virtual nodules generated from the nodule-like object functions A and B, the equivalence of the nodule-like object functions obtained from different scanners could be assessed. In addition, these virtual nodules were compared with the real (true) sphere images obtained with Scanner C. As a practical validation, five types of laboratory-made physical nodules with various complicated shapes and heterogeneous densities, similar to real lesions, were used. The nodule-like object functions were calculated from the images of these laboratory-made nodules obtained with Scanner A. From them, virtual nodules were generated based on the spatial resolution of Scanner C and compared with the real images of laboratory-made nodules obtained with Scanner C. Good agreement of the virtual nodules generated from the nodule-like object functions A and B of the phantom spheres was found, suggesting the validity of the nodule-like object functions. The virtual nodules generated from the nodule-like object function A of the phantom spheres were similar to the real images obtained with Scanner C; the root mean square errors (RMSEs) between them were 10.8, 11.1, and 12.5 Hounsfield units (HU) for 5-, 7-, and 10-mm-diameter spheres, respectively. The equivalent results (RMSEs) using the nodule-like object function B were 15.9, 16.8, and 16.5 HU, respectively. These RMSEs were small considering the high contrast between the sphere density and background density (approximately 674 HU). The virtual nodules generated from the nodule-like object functions of the five laboratory-made nodules were similar to the real images obtained with Scanner C; the RMSEs between them ranged from 6.2 to 8.6 HU in five cases. The nodule-like object functions calculated from real nodule images would be effective to generate realistic virtual nodules. The proposed method would be feasible for generating virtual nodules that have the characteristics of the spatial resolution of the CT system used in each institution, allowing for site-specific nodule generation.

Characterization of radiation dose from tube current modulated CT examinations with considerations of both patient size and variable tube current.

The volume CT dose index (CTDIvol ) and the size-specific dose estimate (SSDE) are widely used for monitoring patient dose from CT examinations. Both metrics may represent the average dose over the central scan plane of the CTDI phantom or the patient under constant tube current (mA), but they are not intended for the tube current modulation (TCM)-enabled CT examinations, in which the peak dose across the scanned range may not be at the scan range center. To overcome the limitation, this paper illustrates an alternative approach, its implementation, and the relationship between longitudinal dose distribution DL (z) in water cylinder and mA line shape, scan length, as well as phantom diameter. A dose calculation algorithm and the published data by Li etal. [Med. Phys. 40, 031903 (10pp.) (2013); 41, 111910 (5pp.) (2014)] were used to calculate DL (z) for the central and peripheral axes of 10- to 50-cm diameter water phantoms undergoing CT scans of one constant and three variable mA distributions, each of which in three scan lengths of 10, 28.6, and 50cm. All scans had an identical average tube current over the scan ranges. The results in the scanned ranges were used to assess the DL (z) to mA(z) ratios, and their coefficients of variation (CV=stdev/mean) were used to compare the line shapes of DL (z) and mA(z) for congruence: identical line shapes would result in CV=0, but largely different line shapes would result in high CV. In 30-cm diameter water phantom, the line shape of DL (z) was largely different from that of mA(z). CV was higher in a variable mA scan than in a constant mA scan. As the scan length of variable mA scan increased, CV mostly decreased, and the line shape of DL (z) more closely resembled that of mA(z). When two phantom axes were compared, CV was smaller and the line shape of DL (z) more closely resembled that of mA(z) on the peripheral axis than on the central axis. In 41 water phantoms included in this study, CV mostly increased with phantom diameter, and approached the limiting levels on the peripheral axes of large phantoms. In constant mA scans, CV ranged from 5.5% to 14.0% on the phantom central axes and from 4.6% to 6.4% on the phantom peripheral axes. However, in variable tube current scans, CV ranged from 7.4% to 70.0% on the phantom central axes and from 5.1% to 35.9% on the phantom peripheral axes. DL (z) (water) may be advantageous over current CT dose metrics in characterizing the dose dependences on both patient size and mA line shape from tube current modulated examinations. Evaluating DL (z) (water) with the water equivalent diameter and tube current curve from clinical examinations has a potential to improve CT dose monitoring program.

A hall microscope for measuring magnetic properties of films

A magnetic measuring microscope with a spatial resolution of 3 μm in the determination of current dipole coordinates is described. For the primary transducer, a film Hall transducer with sensitive-zone dimensions of 250 × 400 μm is used. The transducer is positioned at a distance of 3 mm from the plane of scanning. Superresolution as compared to the sensor dimensions and distance from the object was reached by using a priori information about the scanned object. A means of calibration of the magnetic microscope and measurement of its metrological characteristics is proposed. The effectiveness and consistency of the obtained estimate of coordinates is shown by comparison of the random error in measurements of current dipole coordinates with the Cramer–Rao bound. The measuring microscope can be applied in studying elements of functional electronics.

A novel fuzzy-logic based method for determination of individual bubble velocity and size from dual-plane ultrafast X-ray tomography data of two-phase flow

Ultrafast X-ray tomography enables non-invasive imaging of gas-liquid flows with high spatial and temporal resolution. While it is relatively straightforward to extract e.g. gas fraction profiles from cross-sectional tomographic images, the extraction of bubble and gas-liquid interface information requires advanced image processing techniques. Thereby it is an important necessity to transform the temporal scale in the scanned sequences into a corresponding length scale for obtaining correct volumetric information. For bubbly flows this means that the velocity of the dispersed phase, e.g. the gas bubbles, has to be determined from dual-plane scans. A common and widely applied method to obtain gas phase velocities is cross-correlating the image sequences of the two scanning planes. This gives an averaged velocity for each position in the cross-section. In the present work, a new method is introduced, which determines the velocity of individual gas bubbles. This new method is termed as “bubble twinning method”, because it tries to identify twin-bubbles in both scanning planes. The developed algorithm compares essential bubble parameters, that is, volume, position and residence time in the slice, by applying a fuzzy-logic based membership function approach. The algorithm was tested for bubbly flow as well as slug flow conditions. Results are compared with established theoretical predictions as well as the cross-correlation method.

SonoNet: Real-Time Detection and Localisation of Fetal Standard Scan Planes in Freehand Ultrasound.

Identifying and interpreting fetal standard scan planes during 2-D ultrasound mid-pregnancy examinations are highly complex tasks, which require years of training. Apart from guiding the probe to the correct location, it can be equally difficult for a non-expert to identify relevant structures within the image. Automatic image processing can provide tools to help experienced as well as inexperienced operators with these tasks. In this paper, we propose a novel method based on convolutional neural networks, which can automatically detect 13 fetal standard views in freehand 2-D ultrasound data as well as provide a localization of the fetal structures via a bounding box. An important contribution is that the network learns to localize the target anatomy using weak supervision based on image-level labels only. The network architecture is designed to operate in real-time while providing optimal output for the localization task. We present results for real-time annotation, retrospective frame retrieval from saved videos, and localization on a very large and challenging dataset consisting of images and video recordings of full clinical anomaly screenings. We found that the proposed method achieved an average F1-score of 0.798 in a realistic classification experiment modeling real-time detection, and obtained a 90.09% accuracy for retrospective frame retrieval. Moreover, an accuracy of 77.8% was achieved on the localization task.

Design of circular antenna arrays of circular subarrays exploiting rotational symmetry

This paper presents a design of fractal antenna arrays based on circular arrays of circular subarrays for scannable pattern using rotational symmetry properties of the complex feeding excitations for a maximum performance in terms of side lobe level (SLL) and directivity (DIR). This fractal array design considers the optimization of the amplitude and phase excitations exploiting the fractal characteristics of the geometry (rotational symmetry) in order to generate a scannable pattern. The synthesis process is carried out by the method of Differential Evolution (DE). The main advantages of using rotational symmetry are that the optimal excitations for a particular beam steering angle could be applied to other beam steering angles remaining in the same array factor characteristics (SLL and directivity) for every beam steering angle. This design of fractal antenna arrays provides a complete scanning of the azimuth plane with optimal characteristics of the radiation pattern using just one optimal design vector of amplitude and phase excitations. Furthermore, the performance of the fractal antenna array optimized with DE is compared with respect to the cases of Genetic Algorithms (GA), Particle Swarm Optimization (PSO), and the conventional progressive phase for the same array geometry.

The value of midbrain morphology in predicting prognosis in chronic disorders of consciousness: A preliminary ultrasound study

Transcranial sonography (TCS) of the brainstem is currently used to support the clinical diagnosis of movement disorders. The aim of the study was to assess the usefulness of midbrain TCS in assessing outcome in patients with Chronic Disorders of Consciousness (DOC). Eleven patients with Minimally Conscious State (MCS) and Unresponsive Wakefulness Syndrome (UWS) were included in the study. We measured the area and echogenicity of the midbrain by encoding and digitally analyzing the corresponding images from the orbitomeatal plane, the morphology of brain parenchyma from the thalamic and cella media plane, and the intracranial circulation. All the patients showed an increase of pulsatility index and numerous morphological alterations on all the scan planes. In particular, we found a loss of the characteristic butterfly-shape of the midbrain, which appeared hypoechoic in the UWS but not in the MCS patients. After six months, the patients were clinically assessed by using Glasgow Outcome Scale Extended (GOSE). We found that a higher increase in GOSE scoring at follow-up was correlated with larger area and higher echogenicity of the midbrain at baseline. The present study suggests that TCS data of the midbrain may support clinical assessment of patients with chronic DOC to estimate their outcome.