2D Image Sequences Research Articles

Robust motion tracking in liver from 2D ultrasound images using supporters.

Effectiveness of image-guided radiation therapy with precise dose delivery depends highly on accurate target localization, which may involve motion during treatment due to, e.g., breathing and drift. Therefore, it is important to track the motion and adjust the radiation delivery accordingly. Tracking generally requires reliable target appearance and image features, whereas in ultrasound imaging acoustic shadowing and other artifacts may degrade the visibility of a target, leading to substantial tracking errors. To minimize such errors, we propose a method based on so-called supporters, a computer vision tracking technique. This allows us to leverage information from surrounding motion for improving robustness of motion tracking on 2D ultrasound image sequences of the liver. Image features, potentially useful for predicting the target positions, are individually tracked, and a supporter model capturing the coupling of motion between these features and the target is learned on-line. This model is then applied to predict the target position, when the target cannot be otherwise tracked reliably. The proposed method was evaluated using the Challenge on Liver Ultrasound Tracking (CLUST)-2015 dataset. Leave-one-out cross-validation was performed on the training set of 24 2D image sequences of each 1-5min. The method was then applied on the test set (24 2D sequences), where the results were evaluated by the challenge organizers, yielding 1.04mm mean and 2.26mm 95%ile tracking error for all targets. We also devised a simulation framework to emulate acoustic shadowing artifacts from the ribs, which showed effective tracking despite the shadows. Results support the feasibility and demonstrate the advantages of using supporters. The proposed method improves its baseline tracker, which uses optic flow and elliptic vessel models, and yields the state-of-the-art real-time tracking solution for the CLUST challenge.

Linear relationship found by magnetic resonance imaging between cerebrospinal fluid volume and body weight in dogs.

Despite numerous studies on cerebrospinal fluid (CSF) and its importance during hydrocephalus or myelography, no reliable values exist about its overall volume in dogs. In this study, our aim was to measure the intracranial (IC) volume of CSF in dogs and assess its possible relationship with body size and the symmetry of the lateral ventricles. We ran a 3D magnetic resonance imaging (MRI) sequence on the central nervous system of 12 healthy, male mongrel dogs between 3-5 years of age and 7.5-35.0 kg body weight. A validated semiautomatic segmentation protocol was implemented to segment the CSF and measure its volume. Values for the volume of the ventricular compartment were between 0.97 and 2.94 ml, with 62.1 ± 11.7% in the lateral ventricles, 17.6 ± 4.9% in the third ventricle, 4.9 ± 1.6% in the aqueductus mesencephali and 15.5 ± 6.6% in the fourth ventricle. In 11 cases a significant asymmetry was found between the lateral ventricles. The results suggest that it may be normal for a dog to have one of the lateral ventricles 1.5 times larger than the other. The correlation between body weight and CSF volume was linear, indicating that the current dosage protocols for myelography, based on a hypothetical proportional relationship with body weight, may have to be revised.

Bold-Independent Computational Entropy Assesses Functional Donut-Like Structures in Brain fMRI Images.

We introduce a novel method for the measurement of information level in fMRI (functional Magnetic Resonance Imaging) neural data sets, based on image subdivision in small polygons equipped with different entropic content. We show how this method, called maximal nucleus clustering (MNC), is a novel, fast and inexpensive image-analysis technique, independent from the standard blood-oxygen-level dependent signals. MNC facilitates the objective detection of hidden temporal patterns of entropy/information in zones of fMRI images generally not taken into account by the subjective standpoint of the observer. This approach befits the geometric character of fMRIs. The main purpose of this study is to provide a computable framework for fMRI that not only facilitates analyses, but also provides an easily decipherable visualization of structures. This framework commands attention because it is easily implemented using conventional software systems. In order to evaluate the potential applications of MNC, we looked for the presence of a fourth dimension's distinctive hallmarks in a temporal sequence of 2D images taken during spontaneous brain activity. Indeed, recent findings suggest that several brain activities, such as mind-wandering and memory retrieval, might take place in the functional space of a four dimensional hypersphere, which is a double donut-like structure undetectable in the usual three dimensions. We found that the Rényi entropy is higher in MNC areas than in the surrounding ones, and that these temporal patterns closely resemble the trajectories predicted by the possible presence of a hypersphere in the brain.

Joint encryption and compression of 3D images based on tensor compressive sensing with non-autonomous 3D chaotic system

Existing techniques for the simultaneous encryption and compression of three-dimensional (3D) image sequences (e.g., video sequences, medical image sequences) may come with sufficient decryption accuracy or compression ratio, but do not inherently have both; the relationship between them is generally ignored because the images of a sequence are handled individually. To address this problem, we designed Tensor Compressive Sensing (TCS) to simultaneously encrypt and compress a 3D sequence as a tensor rather than several 2D images. To further enhance security, a non-autonomous Lorenz system is constructed to control the three measurement matrices of TCS. The proposed method preserves the intrinsic structure of tensor-based 3D image sequences and achieves a favorable balance of compression ratio, decryption accuracy, and security. Numerical simulation results verify the validity and the reliability of the TCS scheme.

Adiabatic excitation for 31P MR spectroscopy in the human heart at 7 T: A feasibility study

PurposePhosphorus magnetic resonance spectroscopy (31P‐MRS) provides a unique tool for assessing cardiac energy metabolism, often quantified using the phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio. Surface coils are typically used for excitation for 31P‐MRS, but they create an inhomogeneous excitation field across the myocardium, producing undesirable, spatially varying partial saturation. Therefore, we implemented adiabatic excitation in a 3D chemical shift imaging (CSI) sequence for cardiac 31P‐MRS at 7 Tesla (T).MethodsWe optimized an adiabatic half passage pulse with bandwidth sufficient to excite PCr and γ‐ATP together. In addition, the CSI sequence was modified to allow interleaved excitation of PCr and γ‐ATP, then 2,3‐DPG, to enable PCr/ATP determination with blood correction. Nine volunteers were scanned at 2 transmit voltages to confirm that measured PCr/ATP was independent of B1+ (i.e. over the adiabatic threshold). Six septal voxels were evaluated for each volunteer.ResultsPhantom experiments showed that adiabatic excitation can be reached at the depth of the heart using our pulse. The mean evaluated cardiac PCr/ATP ratio from all 9 volunteers corrected for blood signal was 2.14 ± 0.16. Comparing the two acquisitions with different voltages resulted in a minimal mean difference of −0.005.ConclusionAdiabatic excitation is possible in the human heart at 7 T, and gives consistent PCr/ATP ratios. Magn Reson Med 78:1667–1673, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

3D impurity inspection of cylindrical transparent containers

This paper presents a method for automatically detecting and three-dimensionally positioning particles based on sequences of 2D images of rotating cylindrical transparent containers. The method can be used in the manufacturing industry by distinguishing between particles residing inside or outside a closed container. A foreign particle on the inside is a cause of rejection, whereas a particle on the outside might represent harmless dirt. The proposed method detects, tracks and positions particles and classifies containers accordingly as either rejected or accepted. Experimental results have shown an accuracy of 85% on a test set of 20 containers and an average execution time per container of 1 s.

Determining tree height and crown diameter from high-resolution UAV imagery

ABSTRACTAdvances in computer vision and the parallel development of unmanned aerial vehicles (UAVs) allow for the extensive use of UAV in forest inventory and in indirect measurements of tree features. We used UAV-sensed high-resolution imagery through photogrammetry and Structure from Motion (SfM) to estimate tree heights and crown diameters. We reconstructed 3D structures from 2D image sequences for two study areas (25 × 25 m). Species composition for Plot 1 included Norway spruce (Picea abies L.) together with European larch (Larix decidua Mill.) and Scots pine (Pinus sylvestris L.), whereas Plot 2 was mainly Norway spruce and Scots pine together with scattered individuals of European larch and Silver birch (Betula pendula Roth.). The involved workflow used canopy height models (CHMs) for the extraction of height, the smoothing of raster images for the determination of the local maxima, and Inverse Watershed Segmentation (IWS) for the estimation of the crown diameters with the help of a geographical information system (GIS). Finally, we validated the accuracies of the two methods by comparing the UAV results with ground measurements. The results showed higher agreement between field and remote-sensed data for heights than for crown diameters based on RMSE%, which were in the range 11.42–12.62 for height and 14.29–18.56 for crown diameter. Overall, the accuracy of the results was acceptable and showed that the methods were feasible for detecting tree heights and crown diameter.

Crack healing behaviour of Cr2AlC MAX phase studied by X-ray tomography

The autonomous crack-healing capability of Cr2AlC MAX phase ceramic by surface oxidation at elevated temperatures has a huge potential for high temperature structural and protective coating applications. In this work we use time-lapse X-ray computed tomography (CT) to track the fine details of local crack filling phenomena in 3 dimensions (3D) with time. The maximum crack width that could be fully healed upon exposure to 1200°C in air is 4.8μm in 4h and 10μm after 12h. Furthermore, during healing Cr7C3 phase is observed beneath the dense Al2O3 layer (average thickness of 1μm on each crack surface) when the crack width exceeds 2μm. The 3D image sequences indicated that the rate of healing is essentially independent of position along, or across, the crack faces. The crack healing kinetics of Cr2AlC at 1200°C broadly follows a parabolic rate law with a rate constant of 4.6×10−4μm2s−1. The microstructure, composition and thickness of the oxide scale in the healed crack area are characterized via post mortem SEM-EDS measurements and confirm the formation of an initial dense alumina layer on top of which a more porous layer forms. Impurity Cr particles appear to accelerate the oxidation process locally and correlative SEM imaging of the same region suggests this is by providing Cr2O3 nucleation sites.

MitoGen: A Framework for Generating 3D Synthetic Time-Lapse Sequences of Cell Populations in Fluorescence Microscopy.

The proper analysis of biological microscopy images is an important and complex task. Therefore, it requires verification of all steps involved in the process, including image segmentation and tracking algorithms. It is generally better to verify algorithms with computer-generated ground truth datasets, which, compared to manually annotated data, nowadays have reached high quality and can be produced in large quantities even for 3D time-lapse image sequences. Here, we propose a novel framework, called MitoGen, which is capable of generating ground truth datasets with fully 3D time-lapse sequences of synthetic fluorescence-stained cell populations. MitoGen shows biologically justified cell motility, shape and texture changes as well as cell divisions. Standard fluorescence microscopy phenomena such as photobleaching, blur with real point spread function (PSF), and several types of noise, are simulated to obtain realistic images. The MitoGen framework is scalable in both space and time. MitoGen generates visually plausible data that shows good agreement with real data in terms of image descriptors and mean square displacement (MSD) trajectory analysis. Additionally, it is also shown in this paper that four publicly available segmentation and tracking algorithms exhibit similar performance on both real and MitoGen-generated data. The implementation of MitoGen is freely available.

Model reconstruction for 3d vizualization of cultural heritage sites using open data from social media: The case study of Soli, Cyprus

Given recent military conflicts, terrorism and natural disasters, many cultural heritage sites are increasingly being destroyed. As well, several of these sites are difficult to monitor due to their inaccessibility and remoteness. As aerial surveillance using drones and/or low altitude systems is more common, there is a vast amount of open data now available on social media, which are posted every day on the internet. Many of the videos posted do not include any information on the equipment that was used to acquire the video. Such media can be used to create 3D models and ortho-images of cultural heritage sites in order to monitor and document their existing status. Using open data that is available on the internet, this study used a range of imaging technique to estimate 3D landscape features from 2D image sequences subtracted from video, as well as applied image distortion correction and geo-referencing. The 3D models can be viewed using Google Earth and also be used to create ortho-image, drawings, and digital surface modeling for cultural heritage and archaeological purposes in remote or inaccessible areas. Such 3D models can be used to monitor and geo-reference cultural heritage sites. Social media can be used as a new source of information by archaeologists and cultural heritage experts to monitor and document cultural heritage sites that are in inaccessible areas, due to conflict, terrain or natural disasters.

Modelling frame losses in a parallel Alternate Frame Rendering system with a Computational Best-effort Scheme

Virtual reality (VR) surgical training and presurgical planning require the creation of 3D virtual models of patient anatomy from medical scans (e.g. CT or MRI). Real-time head tracking in VR applications allows users to navigate in the virtual anatomy from any 3D position and orientation. The process of interactively rendering highly detailed 3D volumetric data of anatomical models from a dynamically changing observer׳s perspective is extremely demanding for computational resources. We propose a parallel computing solution to this problem, involving a distributed volume graphics rendering system composed of multiple nodes concurrently working on different frames of the output stream, which are later integrated to form the final animation. In this scenario, it is important to consider frame losses generated by their out-of-order arrivals in the output sequence of 2D images. This paper presents a study of frame losses for a distributed graphics rendering system consisting of multiple GPU-based heterogeneous nodes running in a best-effort rendering scheme and applying an Alternate Frame Rendering technique. We describe a mathematical model of frame losses, as well as a performance evaluation comparing model predictions with experimental results.

Subject-specific and respiration-corrected 4D liver model from real-time ultrasound image sequences

Respiratory liver motion is one of the major issues affecting the liver interventions, such as biopsy and ablation, in the clinical practice. Traditional 4D liver model methods using magnetic resonance imaging (MRI) or computed tomography (CT) data sets for motion compensation to solve this problem have proved time-consuming and costly. In addition, the widely used freehand 3D ultrasound techniques, which lack respiratory corrections, cannot effectively track breathing-induced liver motion. On the other hand, clinical solutions are straightforward but present restrictions for patients. Motivated by both the technical and clinical needs, we propose a novel method for creating a sequence of subject-specific and respiration-corrected 3D ultrasound (US) images, from multiple robotic-assisted-swept 2D US image sequences. Moreover, we also observed the motion difference between subjects on the generated 4D model. The results of quantitative evaluation on the accuracy of the models show that the overlap ratio of the liver boundary between the generated model and ground truth at end of exhale and end of inhale phases were 0.90 and 0.89, respectively. The overall distance error of pinpointed landmarks was 2.44 mm, which is within the acceptance range of clinical applications. Therefore, we conclude that the reconstructed 3D image sequence can capture the moving liver during a half respiratory cycle, and the proposed method is feasible to visualise the 3D liver motion. The clinicians who worked with us in this study also suggest that this preoperative subject-specific motion information could help them to diagnose the existence, or determine the possible position, of a tumour.

Computation and Display of 3D Movie From a Single Integral Photography

Integral photography is an auto-stereoscopic technique that allows, among other interesting applications, the display of 3D images with full parallax and avoids the painful effects of the accommodation-convergence conflict. Currently, one of the main drawbacks of this technology is the need of a huge amount of data, which have to be stored and transmitted. This is due to the fact that behind every visual resolution unit, i.e. behind any microlens of an integral-photography monitor, between 100 and 300 pixels should appear. In this paper, we make use of an updated version of our algorithm, SPOC 2.0, to alleviate this situation. We propose the application of SPOC 2.0 for the calculation of complete 3D traveling sequences from a single integral photograph. Specifically, our method permits to generate a sequence of 3D images that simulate the travelling 3D frames captured by a non-static cameraman. In the traveling sequence, we can fix at will, for every frame, the size and position of the field of view, and the parts of the scene that are displayed in front or behind the monitor. Our research is illustrated with experiments in which we generate and display a full traveling sequence.

Comparison of Modern 3D and 2D MR Imaging Sequences of the Wrist at 3 Tesla

To compare the image quality of modern 3 D and 2 D sequences for dedicated wrist imaging at 3 Tesla (T) MRI. At 3 T MRI, 18 patients (mean age: 36.2 years) with wrist pain and 16healthy volunteers (mean age: 26.4 years) were examined using 2 D proton density-weighted fat-saturated (PDfs), isotropic 3 D TrueFISP, 3 D MEDIC, and 3 D PDfs SPACE sequences. Image quality was rated on a five-point scale (0 - 4) including overall image quality (OIQ), visibility of important structures (cartilage, ligaments, TFCC) and degree of artifacts. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) of cartilage/bone/muscle/fluid as well as the mean overall SNR/CNR were calculated using region-of-interest analysis. ANOVA, paired t-, and Wilcoxon-signed-rank tests were applied. The image quality of all tested sequences was superior to 3 D PDfs SPACE (p < 0.01). 3 D TrueFISP had the highest combined cartilage score (mean: 3.4) and performed better in cartilage comparisons against 3 D PDfs SPACE in both groups and 2 D PDfs in volunteers (p < 0.05). 3 D MEDIC performed better in 7 of 8 comparisons (p < 0.05) regarding ligaments and TFCC. 2 D PDfs provided constantly high scores. The mean overall SNR/CNR for 2 D PDfs, 3 D PDfs SPACE, 3 D TrueFISP, and 3 D MEDIC were 68/65, 32/27, 45/47, and 57/45, respectively. 2 D PDfs performed best in most SNR/CNR comparisons (p < 0.05) and 3 D MEDIC performed best within the 3 D sequences (p < 0.05). Except 3 D PDfs SPACE, all tested 3 D and 2 D sequences provided high image quality. 3 D TrueFISP was best for cartilage imaging, 3 D MEDIC for ligaments and TFCC and 2 D PDfs for general wrist imaging. • 3 D TrueFISP is recommended for cartilage imaging of the wrist at 3 T.• 3 D MEDIC is recommended for ligaments and TFCC.• Robust 2 D PDfs should be used in routine protocols. 3 D sequences may be added depending on the clinical question.• 3 D PDfs SPACE is currently inferior. Citation Format: • Rehnitz C, Klaan B, von Stillfried F et al. Comparison of Modern 3D and 2D MR Imaging Sequences of the Wrist at 3 Tesla. Fortschr Röntgenstr 2016; 188: 753 - 762.

Depth-Resolved Full-Field Measurement of Corneal Deformation by Optical Coherence Tomography and Digital Volume Correlation

The study of vertebrate eye cornea is an interdisciplinary subject and the research on its mechanical properties has significant importance in ophthalmology. The measurement of depth-resolved 3D full-field deformation behaviour of cornea under changing intraocular pressure is a useful method to study the local corneal mechanical properties. In this work, optical coherence tomography was adopted to reconstruct the internal structure of a porcine cornea inflated from 15 to 18.75 mmHg (close to the physical porcine intraocular pressure) in the form of 3D image sequences. An effective method has been developed to correct the commonly seen refraction induced distortions in the optical coherence tomography reconstructions, based on Fermat’s principle. The 3D deformation field was then determined by performing digital volume correlation on these corrected 3D reconstructions. A simple finite element model of the inflation test was developed and the predicted values were compared against digital volume correlation results, showing good overall agreement.

Single shot three-dimensional pulse sequence for hyperpolarized 13 C MRI.

PurposeMetabolic imaging with hyperpolarized 13C‐labeled cell substrates is a promising technique for imaging tissue metabolism in vivo. However, the transient nature of the hyperpolarization, and its depletion following excitation, limits the imaging time and the number of excitation pulses that can be used. We describe here a single‐shot three‐dimensional (3D) imaging sequence and demonstrate its capability to generate 13C MR images in tumor‐bearing mice injected with hyperpolarized [1‐13C]pyruvate.MethodsThe pulse sequence acquires a stack‐of‐spirals at two spin echoes after a single excitation pulse and encodes the kz‐dimension in an interleaved manner to enhance robustness to B0 inhomogeneity. Spectral‐spatial pulses are used to acquire dynamic 3D images from selected hyperpolarized 13C‐labeled metabolites.ResultsA nominal spatial/temporal resolution of 1.25 × 1.25 × 2.5 mm3 × 2 s was achieved in tumor images of hyperpolarized [1‐13C]pyruvate and [1‐13C]lactate acquired in vivo. Higher resolution in the z‐direction, with a different k‐space trajectory, was demonstrated in measurements on a thermally polarized [1‐13C]lactate phantom.ConclusionThe pulse sequence is capable of imaging hyperpolarized 13C‐labeled substrates at relatively high spatial and temporal resolutions and is robust to moderate system imperfections. Magn Reson Med 77:740–752, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Transrectal ultrasound for image-guided adaptive brachytherapy in cervix cancer – An alternative to MRI for target definition?

PurposeTo compare the maximum high risk clinical target volume (CTVHR) dimensions and image quality between magnetic resonance imaging (MRI), transrectal ultrasound (TRUS) and computed tomography (CT) in image guided adaptive brachytherapy (IGABT) of locally advanced cervical cancer. Material and methodsAll patients with locally advanced cervical cancer treated with radiochemotherapy and IGABT between 09/2012-05/2013 were included in this study. T2-weighted MRI (1.5 tesla), TRUS and CT were performed before (MRIpreBT, TRUSpreBT) and/or after (MRIBT, TRUSBT and CTBT) insertion of the applicator. 3D TRUS image acquisition was done with a customized US stepper device and software. The HR CTV was defined on 3D image sequences acquired with different imaging modalities by one blinded observer, in accordance to the GEC-ESTRO recommendations for MRI-based target volume delineation, as the complete cervical mass including the tumour, any suspicious areas of parametrial involvement and the normal cervical stroma. Maximum HR CTV width and thickness were measured on transversal planes. Image quality was classified using the following scoring system: Grade 0: not depicted, Grade 1: inability to discriminate, margin not recognizable, Grade 2: fair discrimination, margin indistinct, Grade 3: excellent discrimination, margin distinct. Descriptive statistics, mean differences between the groups, with MRIBT as reference, and a paired t-test were calculated. ResultsImages from 19 patients (FIGO IB: 3, IIB: 9, IIIB: 5, IVB: 2) were available for analysis. The mean difference in maximum HR CTV width of TRUSBT, TRUSpreBT, MRIpreBT, CTBT to MRIBT was 0.0mm±4.7 (n.s.), −1.1mm±5.6 (n.s.), 0.7mm±6.4 (n.s.) and 13.8mm±6.7 (p<0.001). The mean difference in maximum HR CTV thickness of TRUSBT, TRUSpreBT, MRIpreBT, CTBT to MRIBT was -3.4mm±5.9 (p=0.037), −3.4mm±4.2 (p<0.001), 2.0mm±6.1 (n.s.) and 13.9mm±6.3 (p<0.001). Mean scores of image quality of the target volume was 2.9 for TRUSpreBT, 2.3 for TRUSBT, 2.9 for MRIpreBT, 2.7 for MRIBT and 2.1 for CTBT. ConclusionFor the assessment of the HR CTV in IGABT of cervical cancer, TRUS is within the intraobserver variability of MRI. TRUS is superior to CT as it yields systematically smaller deviations from MRI, with good to excellent image quality. Small differences of TRUS HR CTV thickness are likely related to differences in image slice orientation and compression of the cervix by the TRUS probe before insertion of the brachytherapy applicator.

Sheet-Like Remodeling of the T-System of Ventricular Cardiomyocytes in Heart Failure

The transverse tubular system (t-system) is a membrane specialization of striated myocytes crucial for excitation-contraction coupling. Various studies demonstrated remodeling of t-system in heart disease in species including rodent, canine and human. Commonly, disease was associated with heterogeneous t-system depletion. Here, we test the hypothesis that t-system remodeling underlies inefficient excitation-contraction coupling in human heart failure.We investigated the t-system in left-ventricular myocardium samples from 5 patients undergoing cardiac surgery. The tissues were labeled for ryanodine receptors (RyRs), and the extracellular space including the t-system. We acquired 3D images with a Leica SP8 confocal microscope using a 63x oil immersion lens. After image deconvolution, we segmented individual cardiomyocytes. We reconstructed the t-system and quantified the RyR intensity and distance of RyR clusters to the t-system. Furthermore, isolated myocytes were labeled with di-8-ANEPPS and Fluo-4 to acquire 2D image sequences of calcium transients using a Zeiss Live 5 Duo confocal microscope.Our studies revealed a novel type of t-system remodeling, characterized by flat sheets rather than tubular structures. Three-dimensional reconstructions indicated that sheet cavities were connected with the extracellular space. Principal component analysis showed that sheets were aligned with the longitudinal myocyte axis. One sample did not show sheets and served as control. Comparing 5 cells with sheets to 5 control cells, we found significantly increased distances between RyR clusters and the t-system (0.82±0.12µm and 0.5±0.06µm, respectively) and a significantly higher fraction of RyRs present >1µm from the sarcolemma (49±6.9% and 21±5.5%, respectively). Cardiomyocytes with sheets exhibited spatial heterogeneity and asynchrony of calcium transients.Our studies present a novel phenotype of remodeled t-system, with a strikingly increased number of non-junctional RyR clusters. We suggest that the associated spatially heterogeneous and asynchronous calcium release contributes to reduced contractility in heart failure.

AR技術を用いた３次元足部挙動の計測評価システムの開発

Running form with pronation characteristic is an important key to choose suitable footwear and running gear. This paper describes development of a three-dimensional foot behavior measurement system with low-cost and small-footprint, and formulation of an evaluation parameter to identify runner's pronation characteristic accurately. The measurement system has SngleCamera3D (Photron Co., Ltd.) based on AR technology. In this system, subjects run on a treadmill with four AR markers attached on their heels and calves, while their running forms are recorded from behind by a single video camera. From a sequence of 2D images, three-dimensional orientation matrices of the heel and the calf during running are obtained by modified OpenCV image processing. We also proposed “pronation score” which took into account subtalar joint, heel inclination and tibial rotation angles during stance phase. As a result, the score showed good agreement with runner's pronation type evaluated by specialists. By using the proposed system, we evaluated 216 recreational runners in a major marathon event in Japan, and found that 22%, 40% and 38% of runners were underpronators, neutral pronators and overpronators, respectively.

Rotation update on manifold in probabilistic NRSFM for robust 3D face modeling

This paper focuses on recovering the 3D structure and motion of human faces from a sequence of 2D images. Based on a probabilistic model, we extensively studied the rotation constraints of the problem. Instead of imposing numerical optimizations, the inherent geometric properties of the rotation matrices are taken into account. The conventional Newton’s method for optimization problems was generalized on the rotation manifold, which ultimately resolves the constraints into unconstrained optimization on the manifold. Furthermore, we also extended the algorithm to model within-individual and between-individual shape variances separately. Evaluation results give evidence to the improvement over the state-of-the-art algorithms on the Mocap-Face dataset with additive noise, as well as on the Binghamton University A 3D Facial Expression (BU-3DFE) dataset. Robustness in handling noisy data and modeling multiple subjects shows the capability of our system to deal with real-world image tracks.