Registration Step Research Articles

Latent Space Representations for Marker-Less Realtime Hand-Eye Calibration.

Marker-less hand-eye calibration permits the acquisition of an accurate transformation between an optical sensor and a robot in unstructured environments. Single monocular cameras, despite their low cost and modest computation requirements, present difficulties for this purpose due to their incomplete correspondence of projected coordinates. In this work, we introduce a hand-eye calibration procedure based on the rotation representations inferred by an augmented autoencoder neural network. Learning-based models that attempt to directly regress the spatial transform of objects such as the links of robotic manipulators perform poorly in the orientation domain, but this can be overcome through the analysis of the latent space vectors constructed in the autoencoding process. This technique is computationally inexpensive and can be run in real time in markedly varied lighting and occlusion conditions. To evaluate the procedure, we use a color-depth camera and perform a registration step between the predicted and the captured point clouds to measure translation and orientation errors and compare the results to a baseline based on traditional checkerboard markers.

Influence of multiple risk factor control level on cardiovascular outcomes in hypertensive patients.

The relationship between the level of baseline risk factor control and cardiovascular outcomes in hypertensive patients with blood pressure intervention is not well understood. It is also unclear whether the level of baseline risk factor control is persuasively associated with cardiovascular outcomes in hypertensive patients with blood pressure lowering strategy. We performed an analysis of the Strategy of Blood Pressure Intervention in the Elderly Hypertensive Patients (STEP) trial. Participants without complete baseline risk factor data were excluded. The primary outcome was a composite of cardiovascular events and all-cause mortality. Cox proportional hazard models were used to calculate the hazard ratio (HR) and estimate association between risk factor control levels (≥6, 5, 4, and≤3) and cardiovascular outcomes. A total of 8337 participants were involved in the analysis and the median follow-up period was 3.19 years. Each additional risk factor uncontrolled was associated with a 24% higher cardiovascular risk (HR 1.24, 95% CI 1.11-1.37). Compared with participants with optimal risk factor control, those with≤3 factors control exhibited 95% higher cardiovascular risk (HR 1.95, 95% CI 1.37-2.77). The corresponding protective effects of multiple risk factor modification were not influenced by intensive or standard antihypertensive treatment (P for interaction=0.71). A stepwise association was observed between cardiovascular risk and the number of risk factor control in hypertensive patients. The more risk factor was modified, the less cardiovascular risk was observed, irrespective of different blood pressure lowering strategies. Comprehensive risk factor control strategies are warranted to reduce cardiovascular disease risk in hypertensive patients. Trial registration STEP ClinicalTrials.gov number, NCT03015311. Registered 2 January 2017.

Quantification of Resection Margin following Sublobar Resection in Lung Cancer Patients through Pre- and Post-Operative CT Image Comparison: Utilizing a CT-Based 3D Reconstruction Algorithm.

Sublobar resection has emerged as a standard treatment option for early-stage peripheral non-small cell lung cancer. Achieving an adequate resection margin is crucial to prevent local tumor recurrence. However, gross measurement of the resection margin may lack accuracy due to the elasticity of lung tissue and interobserver variability. Therefore, this study aimed to develop an objective measurement method, the CT-based 3D reconstruction algorithm, to quantify the resection margin following sublobar resection in lung cancer patients through pre- and post-operative CT image comparison. An automated subvascular matching technique was first developed to ensure accuracy and reproducibility in the matching process. Following the extraction of matched feature points, another key technique involves calculating the displacement field within the image. This is particularly important for mapping discontinuous deformation fields around the surgical resection area. A transformation based on thin-plate spline is used for medical image registration. Upon completing the final step of image registration, the distance at the resection margin was measured. After developing the CT-based 3D reconstruction algorithm, we included 12 cases for resection margin distance measurement, comprising 4 right middle lobectomies, 6 segmentectomies, and 2 wedge resections. The outcomes obtained with our method revealed that the target registration error for all cases was less than 2.5 mm. Our method demonstrated the feasibility of measuring the resection margin following sublobar resection in lung cancer patients through pre- and post-operative CT image comparison. Further validation with a multicenter, large cohort, and analysis of clinical outcome correlation is necessary in future studies.

Studi Komparasi Hukum atas Perlindungan Hukum Hak Cipta pada Media Elektronik dalam Common Law dan Civil Law

This article aims to compare the legal protection of copyright in electronic media in common law and civil law. This research adopts normative legal research methods. This method is used to understand, explain, and evaluate normative aspects of the legal system. The research results show that the Common Law system relies on precedents and previous court decisions as the main source of law. Copyright laws may be more general and may evolve through court interpretation. Copyright is automatically granted when a creative work is created without formal registration requirements. Meanwhile, the Civil Law system has more detailed and codified coverage of the law. Copyright law is often regulated in specific and detailed copyright statutes. In some Civil Law systems, copyright registration is an important requirement to obtain legal protection. Copyright may not be granted automatically and requires registration steps. Similarities in Copyright Protection The Common Law and Civil Law legal systems lie in the legal system generally recognizing copyright as the exclusive right of the owner of a work to control the use and distribution of his work. In the context of international protection, both Common Law and Civil Law generally follow international agreements such as the Berne Convention to protect copyright across borders.

The Procedures for Documenting Organizational Knowledge and Experiences: A Scoping Review.

The present study was motivated by issues with earlier studies on documenting knowledge and experiences. This scoping review investigates and maps the procedures for documenting organizational knowledge and experiences. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) extension for Scoping Reviews (PRISMA-ScR) guidelines, a scoping review was conducted. Data were obtained by searching PubMed, Web of Science, Scopus, ProQuest, Embase, and Emerald Insight databases and Persian databases, such as Magiran, Noormags, and Ensani. The selected terms were searched using the Boolean AND/OR operators, phrases, parentheses, and truncations in the title, abstract, keywords, and text word fields. The inclusion criteria were resources relevant to the research question, studies in English and Persian, original research articles, and resources published between 2011 and 2022. Finally, 8 related papers were selected as the research population after screening records. The review of the selected studies indicates that there have been different steps for documenting knowledge and experiences according to the subject's scope and the goals of the studies. The included articles revealed numerous steps for documentation-including planning, acquisition, registration, evaluation, submission, maintenance, publication, application, payment, and compensation. Although a systematic mechanism for documenting knowledge and experience is essential, many processes and phases are offered for documentation. Therefore, a complete review that synthesizes and integrates past study findings must still be included. Several shortcomings in past research on documenting knowledge and expertise prompted the present study. The results of the present study can be of great use to managers and employees of various organizations in topics such as the creation of standards for documenting knowledge and experiences, organizational-structural planning in this field, and training on different documentation methods.

Impact of image registration errors on the quality of hyperspectral images in imaging static Fourier transform spectrometry

Imaging static Fourier transform spectrometry (isFTS) is used for pushbroom airborne or spaceborne hyperspectral remote sensing. In isFTS, a static two-wave interferometer imprints linear interference fringes over the image of the scene, so that the spectral information is multiplexed over several instantaneous images, and numerical reconstruction is needed to recover the full spectrum for each pixel. The image registration step is crucial since insufficient accuracy leads to artefacts on the images and the estimated spectra. In order to investigate these artifacts, we performed a theoretical study and designed a simulation program. We established that registration errors create crenellated spatial patterns, the magnitude of which depends on the radiance gradient of the scene, the amplitude of the registration error, and the wavelength. In the case of sinusoidal perturbations, which may correspond for instance to mechanical vibrations of the carrier, we established that spurious peaks appear on the spectrum, similarly to what happens in dynamic FTS, but with spatial patterns specific to static interferometers.

Implementation of thyroid eye disease registry in Iran: rationale and research protocol.

To describe the implementation of a registry system for patients with thyroid eye disease (TED) in Iran to obtain more information about its nature, prevalence, and annual incidence, as well as extend insight into the etiology, pathogenesis, and eventually make an accurate prognosis of different medical or surgical treatment methods. After receiving approval from the Disease Registry Committee of Iran University of Medical Sciences (IUMS) in 2019 and the Ministry of Health and Medical Education (MOHME) in 2020, the protocol was introduced in three consecutive phases at regional, provincial and national levels. The establishment of a registry committee in Rassoul Akram Hospital, one of the medical centers affiliated to IUMS, was the first step to organizing the registry project's main core. The steering committee included six subgroups of required subject fields. The members are experts in developing a guideline, providing a new dataset, drawing an outline for the next steps, and structuring user-friendly software through several panel discussion meetings. The data is collected from clinical and para-clinical/imaging findings, laboratory evaluations, and their selected treatment strategy, retrospectively and prospectively. The purpose is to broaden our knowledge about the profile of TED; accordingly, data related to patients' demographics, thyroid gland disease (status, duration, treatments, and function tests), general medical and ocular history, along with visual/ocular exams resulting TED status are collected and recorded in a 2- language software. The web-based software system is accessible at https://orc.iums.ac.ir . To maintain data security, prioritized user access was defined for different members. Furthermore, diverse methods, such as employing trained staff and utilizing software validation rules, were implemented to control data quality in every step of data collection, entry, and registration. Medical records of retrospective subjects were also evaluated and entered after accuracy verification. Iran's TED registry provides practitioners with comprehensive data on natural history and phenotype variations in clinical features and outcomes. It facilitates patient recruitment and, consequently, earlier diagnosis on a large scale which helps improve treatment and quality of life for patients.

Automated Point Cloud Registration Approach Optimized for a Stop-and-Go Scanning System.

The latest advances in mobile platforms, such as robots, have enabled the automatic acquisition of full coverage point cloud data from large areas with terrestrial laser scanning. Despite this progress, the crucial post-processing step of registration, which aligns raw point cloud data from separate local coordinate systems into a unified coordinate system, still relies on manual intervention. To address this practical issue, this study presents an automated point cloud registration approach optimized for a stop-and-go scanning system based on a quadruped walking robot. The proposed approach comprises three main phases: perpendicular constrained wall-plane extraction; coarse registration with plane matching using point-to-point displacement calculation; and fine registration with horizontality constrained iterative closest point (ICP). Experimental results indicate that the proposed method successfully achieved automated registration with an accuracy of 0.044 m and a successful scan rate (SSR) of 100% within a time frame of 424.2 s with 18 sets of scan data acquired from the stop-and-go scanning system in a real-world indoor environment. Furthermore, it surpasses conventional approaches, ensuring reliable registration for point cloud pairs with low overlap in specific indoor environmental conditions.

In vivo strain measurements in the human buttock during sitting using MR-based digital volume correlation

Advancements in systems for prevention and management of pressure ulcers require a more detailed understanding of the complex response of soft tissues to compressive loads. This study aimed at quantifying the progressive deformation of the buttock based on 3D measurements of soft tissue displacements from MR scans of 10 healthy subjects in a semi-recumbent position. Measurements were obtained using digital volume correlation (DVC) and released as a public dataset. A first parametric optimisation of the global registration step aimed at aligning skeletal elements showed acceptable values of Dice coefficient (around 80%). A second parametric optimisation on the deformable registration method showed errors of 0.99mm and 1.78mm against two simulated fields with magnitude 7.30±3.15mm and 19.37±9.58mm, respectively, generated with a finite element model of the buttock under sitting loads. Measurements allowed the quantification of the slide of the gluteus maximus away from the ischial tuberosity (IT, average 13.74 mm) that was only qualitatively identified in the literature, highlighting the importance of the ischial bursa in allowing sliding. Spatial evolution of the maximus shear strain on a path from the IT to the seating interface showed a peak of compression in the fat, close to the interface with the muscle. Obtained peak values were above the proposed damage threshold in the literature. Results in the study showed the complexity of the deformation of the soft tissues in the buttock and the need for further investigations aimed at isolating factors such as tissue geometry, duration and extent of load, sitting posture and tissue properties.

Coarse-to-fine registration and time-intensity curves constraint for liver DCE-MRI synthesis

Image registration plays a crucial role in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), used as a fundamental step for the subsequent diagnosis of benign and malignant tumors. However, the registration process encounters significant challenges due to the substantial intensity changes observed among different time points, resulting from the injection of contrast agents. Furthermore, previous studies have often overlooked the alignment of small structures, such as tumors and vessels. In this work, we propose a novel DCE-MRI registration framework that can effectively align the DCE-MRI time series. Specifically, our DCE-MRI registration framework consists of two steps, i.e., a de-enhancement synthesis step and a coarse-to-fine registration step. In the de-enhancement synthesis step, a disentanglement network separates DCE-MRI images into a content component representing the anatomical structures and a style component indicating the presence or absence of contrast agents. This step generates synthetic images where the contrast agents are removed from the original images, alleviating the negative effects of intensity changes on the subsequent registration process. In the registration step, we utilize a coarse registration network followed by a refined registration network. These two networks facilitate the estimation of both the coarse and refined displacement vector fields (DVFs) in a pairwise and groupwise registration manner, respectively. In addition, to enhance the alignment accuracy for small structures, a voxel-wise constraint is further conducted by assessing the smoothness of the time-intensity curves (TICs). Experimental results on liver DCE-MRI demonstrate that our proposed method outperforms state-of-the-art approaches, offering more robust and accurate alignment results.

Co-Designing an Initiative to Increase Shared Access to Older Adults' Patient Portals: Stakeholder Engagement.

The patient portal is a widely available secure digital platform offered by care delivery organizations that enables patients to communicate electronically with clinicians and manage their care. Many organizations allow patients to authorize family members or friends-"care partners"-to share access to patient portal accounts, thus enabling care partners to receive their own identity credentials. Shared access facilitates trilateral information exchange among patients, clinicians, and care partners; however, uptake and awareness of this functionality are limited. We partnered with 3 health care organizations to co-design an initiative that aimed to increase shared access registration and use and that can be implemented using existing patient portals. In 2020, we undertook a rigorous selection process to identify 3 geographically diverse health care organizations that had engaged medical informatics teams and clinical champions within service delivery lines caring for older adults. We prioritized selecting organizations that serve racially and socioeconomically diverse populations and possess sophisticated reporting capabilities, a stable patient portal platform, a sufficient volume of older adult patients, and active patient and family advisory councils. Along with patients and care partners, clinicians, staff, and other stakeholders, the study team co-designed an initiative to increase the uptake of shared access guided by either an iterative, human-centered design process or rapid assessment procedures of stakeholders' inputs. Between February 2020 and April 2022, 73 stakeholder engagements were conducted with patients and care partners, clinicians and clinic staff, medical informatics teams, marketing and communications staff, and administrators, as well as with funders and thought leaders. We collected insights regarding (1) barriers to awareness, registration, and use of shared access; (2) features of consumer-facing educational materials to address identified barriers; (3) features of clinician- and staff-facing materials to address identified barriers; and (4) approaches to fit the initiative into current workflows. Using these inputs iteratively via a human-centered design process, we produced brochures and posters, co-designed organization-specific web pages detailing shared access registration processes, and developed clinician and staff talking points about shared access and staff tip sheets that outline shared access registration steps. Educational materials emphasized the slogan "People remember less than half of what their doctors say," which was selected from 9 candidate alternatives as resonating best with the full range of the initiative's stakeholders. The materials were accompanied by implementation toolkits specifying and reinforcing workflows involving both in-person and telehealth visits. Meaningful and authentic stakeholder engagement allowed our deliberate, iterative, and human-centered co-design aimed at increasing the use of shared access. Our initiative has been launched as a part of a 12-month demonstration that will include quantitative and qualitative analysis of registration and use of shared access. Educational materials are publicly available at Coalition for Care Partners.

Alignment of 3D woven textile composites towards their ideal configurations

The objective of the present study is to create a parametric model of an ideal 3D woven textile from a computed tomography at mesoscale without prior knowledge of the fabric architecture. The model is constructed by identifying a minimal number of parameters from the tomography and includes further assumptions about the textile properties (e.g., equally-spaced vertical yarn columns). A novel registration procedure called Model-based Digital Image Correlation (MDIC) is introduced for mapping the whole textile image onto its own model. It leads to a realignment of the yarn columns after deforming the textile image, from which the model is updated. Model extraction and registration steps are iterated up to a stationary solution. The final result is a perfect textile geometry with straight and orthogonal yarn columns and its mapping onto the original tomography image. The proposed procedure is applied successfully to a 3D woven textile and a 3D-injected woven composite. This novel technique is useful as a pre-processing step to image segmentation procedures or to ease the visual inspection performed by operators in correcting the yarn paths and yarn column deformations occurring during composite material manufacturing. Additionally, this alignment procedure could be used to deform a numerical ideal model to better fit the geometry of a real weave.

Tightly coupled laser-inertial pose estimation and map building based on B-spline curves

Simultaneous localization and mapping (SLAM) plays a key role in 3D environment modeling and mobile robot environment perception. However, the traditional discrete-time Laser-inertial SLAM methods are not robust due to the imbalanced registration steps between a single LiDAR frame and the global map. This paper proposes a tightly coupled laser-inertial pose estimation and map building method that uses B-spline curves to represent continuous-time trajectory and achieve high robustness of the registration steps. To ensure efficiency, the proposed method separates the SLAM task into an odometer module and a mapping module. The odometer module performs a coarse pose estimation, while the mapping module performs a fine one and builds a global map with 3D LiDAR points. B-spline curves are utilized to integrate both IMU measurement constraints and LiDAR point constraints in the proposed mapping module, which can enhance the association of consecutive LiDAR frames in the optimization step. Besides, the explicit expression of the Jacobi matrix derivation for B-spline-based laser residuals is also introduced to furtherly improve the computation efficiency. Both indoor and outdoor experiments are conducted on a self-collected dataset and a public dataset. Experimental results show that the proposed method can achieve superior performance than the baseline method LIO-mapping.

Practical Strategies for Addressing Video Visit Access Barriers in Urology.

Purpose: Since March 2020, telehealth has been a major part of health care delivery. Observational studies have shown that seniors, minorities, low-income Americans, and rural Americans have proportionally greater challenges in accessing telehealth compared with their counterparts. However, strategies to overcome these challenges have not been fully addressed. The objective of this study was to understand in greater detail the challenges patients face with video visits and introduce specific strategies to address these problems. Methods: We collected data on the technical barriers faced by patients through phone calls from a medical student-run volunteer program that assisted patients with telehealth visits through an electronic health record referral system. Results: Our study identified 4 main issues faced by patients that prevent successful video visits: (1) completion of registration steps, (2) familiarity with accessing and using video conferencing software, (3) attainment of proxy access for parents of a pediatric patient, and (4) resolution of miscellaneous technical queries. We addressed these issues through a structured workflow algorithm, which provided patients with an opportunity to receive a live walk-through of the steps for registering for a video visit, practice with video conferencing software, and guidance to resources and answers to any issues in the process. Conclusion: This study provides practical guidance for overcoming the challenges that patients face with video visits. These strategies can be used in any urology practice to improve video visit adoption and telehealth access in patient populations where challenges may exist.

Primary weight loss failure after Roux-en-Y gastric bypass is characterized by impaired gut-hormone mediated regulation of food intake

Background/ObjectivesAfter Roux-en-Y gastric bypass (RYGB) a subset of patients never obtain excess BMI loss (EBMIL) > 50% and are categorized as having primary weight loss (WL) failure. We hypothesized that postprandial concentrations of glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) would be lower in patients with primary WL failure compared with patients with successfully maintained WL. Furthermore, that inhibition of gut hormone secretions would increase ad libitum food intake less in patients with primary WL failure.Subjects/MethodsTwenty women with primary WL failure (LowEBMIL < 50%) were individually matched to twenty women with successful WL (HighEBMIL > 60%) on age, preoperative BMI and time from RYGB. On separate days performed in a random order, patient-blinded subcutaneous injections of octreotide or saline (placebo) were followed by a fixed breakfast and an ad libitum lunch with blood sampling for appetite regulating hormones and Visual-Analogue-Scale (VAS)-scoring of hunger/satiety. Furthermore, participants underwent gene variant analysis for GLP-1, PYY and their receptors, indirect calorimetry, dual-energy X-ray absorptiometry (DXA)-scans, 4-days at-home food registration and 14-days step counting.ResultsOn placebo days, postprandial GLP-1, PYY and cholecystokinin (CCK) concentrations were similar between groups after breakfast. Fasting ghrelin was lower in LowEBMIL, but the postprandial suppression was similar. LowEBMIL had lower satiety VAS-scores and less suppression of hunger VAS-scores. Gene variants did not differ between groups. Octreotide diminished GLP-1, PYY, CCK and ghrelin concentrations in both groups. Octreotide did not affect ad libitum food intake in LowEBMIL (−1% [−13, 12], mean [95%CI]), while food intake increased in HighEBMIL (+23% [2,44]).ConclusionsPrimary WL failure after RYGB was not characterized by impaired secretions of appetite regulating gut hormones. Interestingly, inhibition of gut hormone secretions with octreotide only increased food intake in patients with successful WL post-RYGB. Thus, an impaired central anorectic response to gut hormones may contribute to primary WL failure after RYGB.

Registration-Free Localization of Defects in Three-Dimensional Parts from Mesh Metrology Data Using Functional Maps

We consider a common problem occurring after using a statistical process control (SPC) method based on three-dimensional measurements: locate where on the surface of the part that triggered an out-of-control alarm there is a significant shape difference with respect to either an in-control part or its nominal (computer-aided design (CAD)) design. In the past, only registration-based solutions existed for this problem, which first orient and locate the part and its nominal design under the same frame of reference. Recently, spectral Laplacian methods have been proposed for the SPC of discrete parts and their measured surface meshes. These techniques provide an intrinsic solution to the SPC problem: that is, a solution exclusively based on data whose coordinates lie on the surfaces without making reference to their ambient space, thus avoiding registration. Registration-free methods avoid the computationally expensive, nonconvex registration step needed to align the parts as required by previous methods, eliminating registration errors, and they are important in industry because of the increasing use of portable noncontact scanners. In this paper, we first present a new registration-free solution to the post-SPC part defect localization problem. The approach uses a spectral decomposition of the Laplace–Beltrami operator in order to construct a functional map between the CAD and measured manifolds to locate defects on the suspected part. A computational complexity analysis demonstrates the approach scales better with the mesh size and is more stable than a registration-based approach. To reduce computational expense, a new mesh partitioning algorithm is presented to find a region of interest on the surface of the part where defects are more likely to exist. The functional map method involves a large number of point-to-point comparisons based on noisy measurements, and a new statistical thresholding method used to filter the false positives in the underlying massive multiple comparisons problem is also provided. Funding: This research was partially funded by the National Science Foundation [Grant CMMI 2121625]. Data Ethics &amp; Reproducibility Note: There are no data ethics considerations. The code capsule is available on Code Ocean at https://codeocean.com/capsule/4615101/tree/v1 and in the e-Companion to this article (available https://doi.org/10.1287/ijds.2023.0030 ).

A systematic comparison of VBM pipelines and their application to age prediction

Voxel-based morphometry (VBM) analysis is commonly used for localized quantification of gray matter volume (GMV). Several alternatives exist to implement a VBM pipeline. However, how these alternatives compare and their utility in applications, such as the estimation of aging effects, remain largely unclear. This leaves researchers wondering which VBM pipeline they should use for their project. In this study, we took a user-centric perspective and systematically compared five VBM pipelines, together with registration to either a general or a study-specific template, utilizing three large datasets (n>500 each). Considering the known effect of aging on GMV, we first compared the pipelines in their ability of individual-level age prediction and found markedly varied results. To examine whether these results arise from systematic differences between the pipelines, we classified them based on their GMVs, resulting in near-perfect accuracy. To gain deeper insights, we examined the impact of different VBM steps using the region-wise similarity between pipelines. The results revealed marked differences, largely driven by segmentation and registration steps. We observed large variability in subject-identification accuracies, highlighting the interpipeline differences in individual-level quantification of GMV. As a biologically meaningful criterion we correlated regional GMV with age. The results were in line with the age-prediction analysis, and two pipelines, CAT and the combination of fMRIPrep for tissue characterization with FSL for registration, reflected age information better.

Automatic healthy liver segmentation for holmium-166 radioembolization dosimetry

BackgroundFor safe and effective holmium-166 (166Ho) liver radioembolization, dosimetry is crucial and requires accurate healthy liver definition. The current clinical standard relies on manual segmentation and registration of a separately acquired contrast enhanced CT (CECT), a prone-to-error and time-consuming task. An alternative is offered by simultaneous imaging of 166Ho and technetium-99m stannous–phytate accumulating in healthy liver cells (166Ho–99mTc dual-isotope protocol). This study compares healthy liver segmentation performed with an automatic method using 99mTc images derived from a 166Ho–99mTc dual-isotope acquisition to the manual segmentation, focusing on healthy liver dosimetry and corresponding hepatotoxicity. Data from the prospective HEPAR PLuS study were used. Automatic healthy liver segmentation was obtained by thresholding the 99mTc image (no registration step required). Manual segmentation was performed on CECT and then manually registered to the SPECT/CT and subsequently to the corresponding 166Ho SPECT to compute absorbed dose in healthy liver.ResultsThirty-one patients (66 procedures) were assessed. Manual segmentation and registration took a median of 30 min per patient, while automatic segmentation was instantaneous. Mean ± standard deviation of healthy liver absorbed dose was 18 ± 7 Gy and 20 ± 8 Gy for manual and automatic segmentations, respectively. Mean difference ± coefficient of reproducibility between healthy liver absorbed doses using the automatic versus manual segmentation was 2 ± 6 Gy. No correlation was found between mean absorbed dose in the healthy liver and hepatotoxicity.Conclusions166Ho–99mTc dual-isotope protocol can automatically segment the healthy liver without hampering the 166Ho dosimetry assessment.Trial registration: ClinicalTrials.gov, NCT02067988. Registered 20 February 2014. https://clinicaltrials.gov/ct2/show/NCT02067988

Feature-Based Electromagnetic Tracking Registration Using Bioelectric Sensing

Catheter tracking is essential during minimally invasive endovascular procedures, and Electromagnetic (EM) tracking is a widely used technology for this purpose. When preoperative patient images are available, they can be used to guide EM-tracked interventions. However, a registration step between preoperative images and intraoperative EM tracking space is usually required. Most existing solutions for this registration process require manual interactions, which can add additional steps to the workflow. In this paper, a novel automatic feature-based registration method is proposed, based on electric sensing of vascular geometry by the catheter, also known as Bioelectric sensing. The technique employs the Bioelectric sensing capabilities of the catheter to identify vascular features, such as bifurcations, aneurysms, or stenosis. The known EM position of these features is then utilized to register the EM tracking space and the preoperative images. The registration is refined using iterative closest point (ICP) registration algorithms. Unlike existing solutions, the proposed method does not require external markers, interventional imaging, or additional surgeon actions, and hence does not impact the interventional workflow.

An accurate scapula registration process in shoulder arthroplasty using mixed reality.

Arthroplasty surgery can be challenging because of limited exposure of the bones. However, in shoulder arthroplasty for example, a good positioning of the glenoid component is essential to mitigate risks of revision surgeries. To improve the procedure's outcomes, mixed reality can be used as a guidance system relying on a fundamental registration step between the patient's bone and its corresponding 3D model. We present a complete registration workflow for shoulder arthroplasty using Hololens 2 Head Mounted Display. We rely on acquisitions made thanks to our marker-based tracking system, an improved Iterative Closest Point algorithm and verification steps. Our accuracy targets are 1.5 ± 1.5mm for the glenoid guidewire entry point on both antero-posterior and supero-inferior axes, and 1.5 ± 1[Formula: see text] for inclination and version. The overall process must last less than 5min. We have evaluated our process on a cohort of 13 3D printed glenoid bones of all types, showing an average accuracy of 0.84 ± 0.58mm on the antero-posterior axis and 0.49 ± 0.41mm on the supero-inferior one for the entry point. As for inclination and version, we have 0.89±0.6[Formula: see text] and 0.97±0.8[Formula: see text], respectively. The mean process time is about 1min 24s. We have developed a complete, embedded registration workflow and a verification protocol to evaluate our accuracy. Our results are promising for the improvement of the glenoid guidewire placement. Moreover, everything is performed in the field of view of the surgeon, which allows them to fully concentrate on the surgical site.