Direct Registration Research Articles

A Kalman Filtering Perspective for Multiatlas Segmentation.

In multiatlas segmentation, one typically registers several atlases to the novel image, and their respective segmented label images are transformed and fused to form the final segmentation. In this work, we provide a new dynamical system perspective for multiatlas segmentation, inspired by the following fact: The transformation that aligns the current atlas to the novel image can be not only computed by direct registration but also inferred from the transformation that aligns the previous atlas to the image together with the transformation between the two atlases. This process is similar to the global positioning system on a vehicle, which gets position by inquiring from the satellite and by employing the previous location and velocity-neither answer in isolation being perfect. To solve this problem, a dynamical system scheme is crucial to combine the two pieces of information; for example, a Kalman filtering scheme is used. Accordingly, in this work, a Kalman multiatlas segmentation is proposed to stabilize the global/affine registration step. The contributions of this work are twofold. First, it provides a new dynamical systematic perspective for standard independent multiatlas registrations, and it is solved by Kalman filtering. Second, with very little extra computation, it can be combined with most existing multiatlas segmentation schemes for better registration/segmentation accuracy.

Optical surface plasmon resonance biosensors in molecular fishing

An optical biosensor employing surface plasmon resonance is a highly efficient instrument applicable for direct real time registration of molecular interactions without additional use of any labels or coupled processes. As an independent approach it is especially effective in analysis of various ligand receptor interactions. SPR-biosensors are used for validation of studies on intermolecular interactions in complex biological systems (affinity profiling of various groups of proteins, etc.). Recently, potential application of the SPR-biosensor for molecular fishing (direct affinity binding of target molecules from complex biological mixtures on the optical biosensor surface followed by their elution for identification by LC-MS/MS) has been demonstrated. Using SPR-biosensors in such studies it is possible to solve the following tasks: (a) SPR-based selection of immobilization conditions required for the most effective affinity separation of a particular biological sample; (b) SPR-based molecular fishing for subsequent protein identification by mass spectrometry; (c) SPR-based validation of the interaction of identified proteins with immobilized ligand. This review considers practical application of the SPR technology in the context of recent studies performed in the Institute of Biomedical Chemistry on molecular fishing of real biological objects.

Simultaneous <i>in situ</i> Detection of the Optical Fluorescence, Fluorescence Recovery Kinetics After Photobleaching & Membrane Ion Flux on the Electrophysiological Lab-on-a-Chip

The need for simultaneous data recording from multiple channels and synchronization of the correlation data processing in patch-clamp on microelectrode arrays / chips with many data capture points corresponding to single channel ionic kinetic processes of individual cells leads to the idea that adaptive variation of the local potential registration conditions in multichannel devices without signal preprocessing in real time is impossible. Moreover, the advisability of direct registration coupling with the model realization for kinetic identification of the process during patch-clamp can be realized only in case of their synchronization. We propose here such a measurement system.

Dynamic in vitro analysis of tractile forces of the anterior cruciate ligament (ACL) transplant using patellar and semitendinosus muscle tendon: a cadaver study.

The presented biomechanical study focused on the in vitro analysis of tractile forces working on the anterior cruciate ligament (ACL) and the ACL transplants, respectively, using a semitendinosus and/or patellar tendon during a passive flexion-extension movement (150-0°). Overall, 15 fresh frozen human knee joint pairs were examined. At first during arthroscopy, the tibial insertion of the ACL was drilled using a special hollow drill. Thereby, a bone cylinder was exposed at which a dynamometer was attached to enable for direct registration of tractile forces on the ACL via the connection between ACL-dynamometer and computer. The ACL transplant was fixed at the femur using a so-called endo-button, whereas the dynamometer was attached to the tibial end of the ACL transplant. The dynamic part of the examination was performed using the knee kinemator device developed by Plitz and Wirth et al. using different preload. The curves of the tractile forces of the ACL were qualitatively homogeneous with only low force values in the middle flexion position, whereas during maximum flexion and extension the forces increased reaching a maximum in the 0° position. Also, in testing the ACL transplants a force decrease between 0 and 50° flexion was recognized with even greater forces resulting at the 150° position depending on the anterior position of the femoral drill channel for implanting the ACL transplant. The amount of pre-loading showed no influence on the form of the tractile force curve. However, by enhancing the preload to 70 N, the maximal force in the ACL transplant increased significantly. The tractile forces assessed within the ACL during passive flexion movements between 10 and 90° were not greater than the forces measured in the ACL transplants. Thus, the clinical consequence is that in the early postoperative phase passive mobilization might be performed in this motion range without putting the ACL transplant at risk for damage.

How much will linked deformable registrations decrease the quality of multi-atlas segmentation fusions?

Background and purposeMulti-atlas segmentation can yield better results than single atlas segmentation, but practical applications are limited by long calculation times for deformable registration. To shorten the calculation time pre-calculated registrations of atlases could be linked via a single atlas registered in runtime to the current patient. The primary purpose of this work is to investigate and quantify segmentation quality changes introduced by such linked registrations. We also determine the optimal parameters for fusing linked multi-atlas labels using probabilistic weighted fusion.Material and methodsComputed tomography images of 10 head and neck cancer patients were used as atlases, with parotid glands, submandibular glands, the mandible and lymph node levels II-IV segmented by an experienced radiation oncologist following published consensus guidelines. The change in segmentation quality scored by Dice similarity coefficient (DSC) for linking free-form deformable registrations, modeled by B-splines, was investigated for both single- and multi-atlas label fusion by using a leave-one-out approach.ResultsThe median decrease of the DSC was in the range 2.8% to 8.4% compared to direct registrations for all structures while reducing the computer calculation time to that of a single deformable registration. Linking several registrations showed a DSC decrease almost linear to the number of links, suggesting that extrapolation to zero links provides an observer independent measure of the inherent precision with which the segmentation guidelines can be applied.ConclusionsLinking pre-made registrations of multiple atlases via a runtime registration of a single atlas provides a feasible method for reducing computation time in multi-atlas registration.

A method for quantitative analysis of regional lung ventilation using deformable image registration of CT and hybrid hyperpolarized gas/1H MRI

Hyperpolarized gas magnetic resonance imaging (MRI) generates highly detailed maps of lung ventilation and physiological function while CT provides corresponding anatomical and structural information. Fusion of such complementary images enables quantitative analysis of pulmonary structure-function. However, direct image registration of hyperpolarized gas MRI to CT is problematic, particularly in lungs whose boundaries are difficult to delineate due to ventilation heterogeneity. This study presents a novel indirect method of registering hyperpolarized gas MRI to CT utilizing 1H-structural MR images that are acquired in the same breath-hold as the gas MRI. The feasibility of using this technique for regional quantification of ventilation of specific pulmonary structures is demonstrated for the lobes.The direct and indirect methods of hyperpolarized gas MRI to CT image registration were compared using lung images from 15 asthma patients. Both affine and diffeomorphic image transformations were implemented. Registration accuracy was evaluated using the target registration error (TRE) of anatomical landmarks identified on 1H MRI and CT. The Wilcoxon signed-rank test was used to test statistical significance.For the affine transformation, the indirect method of image registration was significantly more accurate than the direct method (TRE = 14.7 ± 3.2 versus 19.6 ± 12.7 mm, p = 0.036). Using a deformable transformation, the indirect method was also more accurate than the direct method (TRE = 13.5 ± 3.3 versus 20.4 ± 12.8 mm, p = 0.006).Accurate image registration is critical for quantification of regional lung ventilation with hyperpolarized gas MRI within the anatomy delineated by CT. Automatic deformable image registration of hyperpolarized gas MRI to CT via same breath-hold 1H MRI is more accurate than direct registration. Potential applications include improved multi-modality image fusion, functionally weighted radiotherapy planning, and quantification of lobar ventilation in obstructive airways disease.

Deformable registration of preoperative MR, pre-resection ultrasound, and post-resection ultrasound images of neurosurgery.

Sites that use ultrasound (US) in image-guided neurosurgery (IGNS) of brain tumors generally have three sets of imaging data: preoperative magnetic resonance (MR) image, pre-resection US, and post-resection US. The MR image is usually acquired days before the surgery, the pre-resection US is obtained after the craniotomy but before the resection, and finally, the post-resection US scan is performed after the resection of the tumor. The craniotomy and tumor resection both cause brain deformation, which significantly reduces the accuracy of the MR-US alignment. Three unknown transformations exist between the three sets of imaging data: MR to pre-resection US, pre- to post-resection US, and MR to post-resection US. We use two algorithms that we have recently developed to perform the first two registrations (i.e., MR to pre-resection US and pre- to post-resection US). Regarding the third registration (MR to post-resection US), we evaluate three strategies. The first method performs a registration between the MR and pre-resection US, and another registration between the pre- and post-resection US. It then composes the two transformations to register MR and post-resection US; we call this method compositional registration. The second method ignores the pre-resection US and directly registers the MR and post-resection US; we refer to this method as direct registration. The third method is a combination of the first and second: it uses the solution of the compositional registration as an initial solution for the direct registration method. We call this method group-wise registration. We use data from 13 patients provided in the MNI BITE database for all of our analysis. Registration of MR and pre-resection US reduces the average of the mean target registration error (mTRE) from 4.1 to 2.4 mm. Registration of pre- and post-resection US reduces the average mTRE from 3.7 to 1.5 mm. Regarding the registration of MR and post-resection US, all three strategies reduce the mTRE. The initial average mTRE is 5.9 mm, which reduces to 3.3 mm with the compositional method, 2.9 mm with the direct technique, and 2.8 mm with the group-wise method. Deformable registration of MR and pre- and post-resection US images significantly improves their alignment. Among the three methods proposed for registering the MR to post-resection US, the group-wise method gives the lowest TRE values. Since the running time of all registration algorithms is less than 2 min on one core of a CPU, they can be integrated into IGNS systems for interactive use during surgery.

Onboard instrumentation of the Yak-42D “Roshydromet” new-generation research aircraft for measuring and registering flight parameters and atmospheric thermodynamic parameters

Given is a brief description and technical characteristics of onboard hardware-and-software complex for measuring flight parameters and atmospheric thermodynamic characteristics; also, described is the complex for registering these parameters from the Yak-42D “Roshydromet” new-generation research aircraft measurement system. Described are the basic principles of the construction of the onboard system for the registration of heterogeneous measurement data recorded with different frequency and following different protocols of data transmission. Presented are the results of flight tests of aircraft systems for the measurement and registration of navigation parameters, air temperature, wind speed, wind direction, and turbulence. Noted is the reliable operation of hardware and software packages which enable carrying out the acquisition and registration of data. Described is the method for taking account of airflow aerodynamic disturbances caused by the aircraft. Presented are the values of error corrections for the readings of pressure and temperature sensors depending on the construction of sensors and their placing at the research aircraft. Given are the results of the comparison of air temperature and wind speed measured by aircraft instruments and radio sounding method. Demonstrated is the reliability of the obtained data.

Mathematical modeling and simulations for machine directional register in hybrid roll-to-roll printing systems

Roll-to-roll (R2R) solution printing method has been attracting as a promising technology for a mass production of flexible functionalities, such as radio-frequency identification (RFID), photovoltaic, flexible batteries, etc. High resolution of register control is mandatory to prevent electrical leakages, and short circuitries in the multilayered flexible printed circuitries through R2R mass production. In this paper, a mathematical modeling of the register was derived for the hybrid printing systems, which consisted of contact printing and non-contact printing such as gravure and inkjet printing. Parameter sensitivity analysis was carried out in various operation conditions. And linear quadratic (LQ) regulator was proposed to control both the tension and register. The performance of the LQ regulation of the register was trade-off considering the permitted variation of tension and resolution of register. The proposed mathematical model will be used for the development of hybrid register controller.

Quick Steps, Incremental Reform—Shenzhen Social Organization Registration Management System Reform

This case study describes the process of Shenzhen’s social organizations registration and management system reform in the past ten years. Shenzhen has taken three modest reform measures, including the disconnection of trade associations from administrative departments, direct registration of trade associations and expanded range of direct registration, which has lowered the threshold for the registration of social organizations and kindled the vigor of social organizations. In line with the reform and devolution of city-level departments of civil affairs, different districts have made efforts to experiment and innovate with new policies, issuing reform plans regarding the filing of community social organizations, the incubation of social organizations, etc.

Dense Omnidirectional RGB‐D Mapping of Large‐scale Outdoor Environments for Real‐time Localization and Autonomous Navigation

This paper presents a novel method and innovative apparatus for building three‐dimensional (3D) dense visual maps of large‐scale unstructured environments for autonomous navigation and real‐time localization. The main contribution of the paper is focused on proposing an efficient and accurate 3D world representation that allows us to extend the boundaries of state‐of‐the‐art dense visual mapping to large scales. This is achieved via an omnidirectional key‐frame representation of the environment, which is able to synthesize photorealistic views of captured environments at arbitrary locations. Locally, the representation is image‐based (egocentric) and is composed of accurate augmented spherical panoramas combining photometric information (RGB), depth information (D), and saliency for all viewing directions at a particular point in space (i.e., a point in the light field). The spheres are related by a graph of six degree of freedom (DOF) poses (3 DOF translation and 3 DOF rotation) that are estimated through multiview spherical registration. It is shown that this world representation can be used to perform robust real‐time localization (in 6 DOF) of any configuration of visual sensors within their environment, whether they be monocular, stereo, or multiview. Contrary to feature‐based approaches, an efficient direct image registration technique is formulated. This approach directly exploits the advantages of the spherical representation by minimizing a photometric error between a current image and a reference sphere. Two novel multicamera acquisition systems have been developed and calibrated to acquire this information, and this paper reports for the first time the second system. Given the robustness and efficiency of this representation, field experiments demonstrating autonomous navigation and large‐scale mapping will be reported in detail for challenging unstructured environments, containing vegetation, pedestrians, varying illumination conditions, trams, and dense traffic.

Assessment of regional non-linear tissue deformation and air volume change of human lungs via image registration

We evaluate the non-linear characteristics of the human lung via image registration-derived local variables based on volumetric multi-detector-row computed tomographic (MDCT) lung image data of six normal human subjects acquired at three inflation levels: 20% of vital capacity (VC), 60% VC and 80% VC. Local variables include Jacobian (ratio of volume change) and maximum shear strain for assessment of lung deformation, and air volume change for assessment of air distribution. First, the variables linearly interpolated between 20% and 80% VC images to reflect deformation from 20% to 60% VC are compared with those of direct registration of 20% and 60% VC images. The result shows that the linearly-interpolated variables agree only qualitatively with those of registration (P<0.05). Then, a quadratic (or linear) interpolation is introduced to link local variables to global air volumes of three images (or 20% and 80% VC images). A sinusoidal breathing waveform is assumed for assessing the time rate of change of these variables. The results show significant differences between two-image and three-image results (P<0.05). The three-image results for the whole lung indicate that the peak of the maximum shear rate occurs at about 37% of the maximum volume difference between 20% and 80% VC, while the peaks for the Jacobian and flow rate occur at 50%. This is in agreement with accepted physiology whereby lung tissues deform more at lower lung volumes due to lower elasticity and greater compliance. Furthermore, the three-image results show that the upper and middle lobes, even in the recumbent, supine posture, reach full expansion earlier than the lower lobes.

Shareholding in EU: is “indirect holding” approach appropriate in achieving financial integration?

Purpose – The purpose of this paper is to focus on the specific “shareholder's” concept of transparency. Design/methodology/approach – It considers that indirect securities holding systems limit the degree of “post-trading” transparency. The main concern is that an adverse effect of globalized capital markets is that the actual shareholders are not registered in the official registries and registrations are effected in the name of intermediaries acting on their behalf. It further considers that new EU legislative action should be taken to address the legal issues of securities holdings as a key parameter for EU integration. Findings – A new architecture of the securities holding system is proposed in this paper to be adopted at the EU level on the basis of the analyzed direct registration, i.e. registration of all the actual shareholders in the registries. It is considered that this architecture will promote securities holdings transparency for all systems, either direct or indirect, and hence enhance investors' protection and financial confidence in the markets. Focusing on the financial crisis of the recent years, it is worthy of note that a key parameter in solving this crisis problem could be considered not only the imposition of more possible regulatory requirements on all financial players but also the improvement credibility of the markets by making their operation more transparent. Direct registration could be defined as a method of making the markets more transparent in this regard. Originality/value – In the light of the financial crisis of 2007-2009, this is one of the first studies, which clearly argues that direct registration could be considered the appropriate method of making the financial markets more transparent. Therefore, it calls for the EU legal intervention should therefore be accelerated. By delaying improvement in the efficiency of the available infrastructures mainly by utilizing all the advantages that technology offers, the markets accept the additional cost of higher risk coverage.

Direct electrophysiological registration of phonological and semantic perception in the human subthalamic nucleus

Direct electrophysiological registration of phonological and semantic perception in the human subthalamic nucleus

3D–2D registration for surgical guidance: effect of projection view angles on registration accuracy

An algorithm for intensity-based 3D–2D registration of CT and x-ray projections is evaluated, specifically using single- or dual-projection views to provide 3D localization. The registration framework employs the gradient information similarity metric and covariance matrix adaptation evolution strategy to solve for the patient pose in six degrees of freedom. Registration performance was evaluated in an anthropomorphic phantom and cadaver, using C-arm projection views acquired at angular separation, Δθ, ranging from ∼0°–180° at variable C-arm magnification. Registration accuracy was assessed in terms of 2D projection distance error and 3D target registration error (TRE) and compared to that of an electromagnetic (EM) tracker. The results indicate that angular separation as small as Δθ ∼10°–20° achieved TRE <2 mm with 95% confidence, comparable or superior to that of the EM tracker. The method allows direct registration of preoperative CT and planning data to intraoperative fluoroscopy, providing 3D localization free from conventional limitations associated with external fiducial markers, stereotactic frames, trackers and manual registration.

Multi-modal registration for correlative microscopy using image analogies

Correlative microscopy is a methodology combining the functionality of light microscopy with the high resolution of electron microscopy and other microscopy technologies for the same biological specimen. In this paper, we propose an image registration method for correlative microscopy, which is challenging due to the distinct appearance of biological structures when imaged with different modalities. Our method is based on image analogies and allows to transform images of a given modality into the appearance-space of another modality. Hence, the registration between two different types of microscopy images can be transformed to a mono-modality image registration. We use a sparse representation model to obtain image analogies. The method makes use of corresponding image training patches of two different imaging modalities to learn a dictionary capturing appearance relations. We test our approach on backscattered electron (BSE) scanning electron microscopy (SEM)/confocal and transmission electron microscopy (TEM)/confocal images. We perform rigid, affine, and deformable registration via B-splines and show improvements over direct registration using both mutual information and sum of squared differences similarity measures to account for differences in image appearance.

Thunderstorm ground enhancements—Model and relation to lightning flashes

In the beginning of last century C.T.R. Wilson proposed that strong electric field of the thunderclouds might accelerate electrons to very high energies. However, this and many other electromagnetic processes in our atmosphere are poorly understood till now; the key questions about the thundercloud electrification and lightning initiation remain unanswered. During recent decades several observations of gamma ray, electron and neutron fluxes correlated with thunderstorms were reported. Nonetheless, the origin of these fluxes is under debate till now. The direct registration of the particle showers initiated by the runaway electrons (the most popular theory) was missing. We present the experimental evidence of the microsecond duration electron bursts originated from runaway electrons accelerated in thunderclouds. The electron acceleration downward becomes possible after creation of the Lower Positive Charged Region below the main negative charged layer in the middle of the thundercloud. Our analysis is based on the vast thunderstorm data from the Aragats Mountain in Armenia, 3200m above sea level. Varieties of particle detectors located at Aragats Space Environmental Center are registering neutral and charged particle fluxes correlated with thunderstorms, so-called Thunderstorm Ground Enhancements. Simultaneously the electric mills and lightning detectors are monitoring the near-surface electric field and lightning flashes. In the paper we present the model of TGE initiation. We demonstrate the necessity of the Lower positive charge region development for the lower dipole operation and TGE initiation. Our observations establish direct relationship of the negative electric field strength and rain rate with TGE.

Central Aortic Blood Pressure and Management of Hypertension

See related article, pp 1138–1145 Hypertension, a condition of elevated arterial blood pressure (BP) conventionally diagnosed by brachial cuff sphygmomanometry, is associated with increased risk of cardiovascular mortality and morbidity and end-organ damage. However, the marked differences in pulse pressure between the central aorta and peripheral limbs1 suggest that effects of peak values of arterial BP (eg, systolic BP) on centrally located organs (heart, brain, kidney) may not be accurately assessed using peripheral measurements. Our early studies2 showed substantial difference in the effects of sublingual nitroglycerin on peripheral and central (carotid) pulse pressures: in some cases, central systolic BP decreasing ≤20 mm Hg with little or no effect on brachial or radial systolic BP. There were, however, marked changes in the pulse wave form.2 The relationship between central aortic and radial pressure waves, quantified in terms of a mathematical transfer function, has been validated to be applicable across a large range of physiological pressures.3 The use of this noninvasive technique (and other variations, including other forms of analysis of the radial pulse or direct registration of the carotid pulse) has facilitated a large number of studies highlighting the differential effects of antihypertensive therapy on central aortic systolic BP for similar values of brachial cuff systolic BP.4 A seminal study by McEniery et al5 in >10 000 subjects demonstrated a substantial overlap of central and brachial BP between categories of hypertension. Approximately 32% of men and 10% of women who would be considered to have normal brachial systolic BP (and therefore, not treated) would be classified as having stage 1 hypertension based on equivalent central aortic systolic BP. Indeed, the implications of these findings suggested a possible sign of a paradigm shift in the management and treatment of hypertension as a significant cardiovascular risk.6 Subsequent studies …

Methods of local interstellar medium investigation

The question of the Sun's motion relative to the local interstellar medium (LISM) is examined. Results from Russian, US, and French satellites and space probes observing scattered solar radiation in hydrogen Lyman-alpha and helium lines are presented. Data are briefly discussed on the direct registration inside the Solar System of neutral helium atoms, picked-up helium ions, and fast neutral hydrogen atoms entering from the LISM. The fast neutral hydrogen atoms arise in the region of solar wind–LISM interaction.

SU‐E‐J‐79: Characterizing Accuracy in 4DCT Deformable Registration Using the POPI M odel

Purpose: Deformable image registration can aid in fully utilizing 4DCT data without significantly increasing workload. In this study, we characterize the accuracy of a commercially available free‐form intensity‐based DIR algorithm on 4DCT using both successive registration through intermediate phases (SERIAL) and direct registration between the phases of interest (DIRECT). Methods: Two real‐patient 4DCT phantom datasets from the POPI model were used to test the SERIAL and DIRECT registration methods. One POPI model (patient1) displayed typical respiratory motion, 6.3mm +/− 3.0mm while the other (patient2) displayed significant respiratory motion, 14.0mm +/− 7.2mm, between end‐expiration and end‐inspiration. The phantoms were also used to study the relationship between initial rigid registration error and residual registration error after deformation. Results: For patient1, the residual errors after DIRECT and SERIAL deformation were 0.8mm +/− 0.4mm and 1.8mm +/− 1.4mm, respectively. For patient2, the errors after DIRECT and SERIAL were 5.1mm +/− 7.5mm and 1.6mm +/− 1.6mm, respectively. The correlation between initial and residual error was significant for both DIRECT (r = 0.72: linear, r = 0.80: second order polynomial) and SERIAL (r = 0.32: linear). The mean residual errors for points of interest with &lt;5mm, 5–10mm, 10–15mm, 15–20mm, 20–25mm, and 25+mm initial error were 0.9mm, 0.9mm, 1.4mm, 4.7mm, 9.7mm, and 20.2mm after DIRECT and 1.3mm, 1.4mm, 2.1mm, 2.3mm, 1.9mm, and 3.1mm after SERIAL, respectively. Conclusion: DIRECT was more accurate for typical respiratory motion while SERIAL was more accurate when significant respiratory motion was present. There was flat correlation between residual and initial error for SERIAL as compared to a very steep correlation for DIRECT. Results show that the DIRECT approach delivers excellent results when the movement is limited to 15mm but when the movement increases, the SERIAL approach is favorable. Aaron Nelson and Jon Piper are both employees and owners of MIM Software Inc.