Individual Template Research Articles

Automated landmarking via multiple templates.

Manually collecting landmarks for quantifying complex morphological phenotypes can be laborious and subject to intra and interobserver errors. However, most automated landmarking methods for efficiency and consistency fall short of landmarking highly variable samples due to the bias introduced by the use of a single template. We introduce a fast and open source automated landmarking pipeline (MALPACA) that utilizes multiple templates for accommodating large-scale variations. We also introduce a K-means method of choosing the templates that can be used in conjunction with MALPACA, when no prior information for selecting templates is available. Our results confirm that MALPACA significantly outperforms single-template methods in landmarking both single and multi-species samples. K-means based template selection can also avoid choosing the worst set of templates when compared to random template selection. We further offer an example of post-hoc quality check for each individual template for further refinement. In summary, MALPACA is an efficient and reproducible method that can accommodate large morphological variability, such as those commonly found in evolutionary studies. To support the research community, we have developed open-source and user-friendly software tools for performing K-means multi-templates selection and MALPACA.

Characteristics of preplan-based three-dimensional individual template-guided brachytherapy compared to freehand implantation.

Image-guided adaptive intracavitary/interstitial brachytherapy (IC/IS IGABT) has exhibited superior dosimetry advantage and local control for locally advanced cervical cancer (LACC). Our group designed a type of cylindrical three-dimensional (3D) printed vaginal template combining an intracavitary applicator with straight and oblique interstitial needles according to the preplan on computed tomography images. This work aimed to research the consistency of the preplan with the treatment plan at every fraction to verify the practical guiding significance of the preplan. We also investigated the difference between 3D-printed template-guided implantation compared with freehand implantation for LACC. Twenty-six patients were treated with 3D-printed individual templates (3D template group), and 20 patients were treated by using freehand insertion (freehand group). Patients in the 3D template group would take a preplan one week before treatment to design and print the individual template, while the freehand group did not. All patients accepted volumetric rotational intensity-modulated radiotherapy at a dose of 49.4 Gy in 26 fractions and subsequent brachytherapy at a dose of 26 Gy in four fractions. All analyses were performed by utilizing SPSS 26. The insertion depth was decreased in fractions 1 and 4 compared with the preplan. None of the dose volume histogram parameters of fractions 1-3, nor the D2cc of bladder and bowel at fraction 4 were barely changed compared with the preplan. The D90 and D98 of the high-risk clinical target volume in the 3D template group were statistically higher than those in the freehand group (p < 0.01). The D2cc of the rectum, bladder, bowel, and sigmoid in the 3D template group were all lower than those in the freehand group (p < 0.01). The preplan in this research is consistent with treatment plans, which is important to ensure the feasibility of applying a 3D-printed template in brachytherapy. The 3D-printed individual guidance template was an effective method in brachytherapy for locally advanced cervical cancer.

Individual navigation templates for pedicle screw placement in spine surgery: a systematic review

The literature review presents data from world studies on the use of individual navigation templates in spine surgery and analyzes the published results of the application of individual navigation templates on different parts of the spine. The accuracy and safety of fixed transpedicular screws were evaluated using the templates. The main stages of template creation were highlighted, including the visualization methods for 3D modeling, 3D printing methods, available materials, as well as the time and costs associated with 3D printing were determined. For information analysis 23 publications were selected, 8 of them relate to the cervical spine, 10 — to the thoracic, and 5 — to the lumbar spine. The data of 460 patients in whom 3,294 screws had been fixed using the templates were analyzed, and the analysis has revealed that out of 3,294 screws, 3,059 (92.8%) have the highest level of safe fixation.

Individual navigation templates for pedicle screw placement in spine surgery: a systematic review

The literature review presents data from world studies on the use of individual navigation templates in spine surgery and analyzes the published results of the application of individual navigation templates on different parts of the spine. The accuracy and safety of fixed transpedicular screws were evaluated using the templates. The main stages of template creation were highlighted, including the visualization methods for 3D modeling, 3D printing methods, available materials, as well as the time and costs associated with 3D printing were determined. For information analysis 23 publications were selected, 8 of them relate to the cervical spine, 10 — to the thoracic, and 5 — to the lumbar spine. The data of 460 patients in whom 3,294 screws had been fixed using the templates were analyzed, and the analysis has revealed that out of 3,294 screws, 3,059 (92.8%) have the highest level of safe fixation.

Clinical application of the surgical navigation template construction for soft tissue transplantation to increase the width of the added keratinized gingiva

BACKGROUND: In surgical periodontology, modifications of soft tissues help achieve a series of important tasks: increase the area of keratinized attached gums, increase the volume of soft tissues, and consequently improve the biological and esthetic state of soft tissues. To achieve these goals, the most common method is the extraction and transplantation of tissue grafts from the hard upper palate. To date, no design of a surgical navigation template allows taking a gingival graft by pre-programmed parameters. The article justifies the necessity of the development and clinical application of a navigational surgical template made with modern digital technologies and used in operations modifying the frontal oral cavity with the transplantation of free gingival grafts from the hard upper palate.&#x0D; AIM: To develop and apply in clinical practice a navigational surgical template for a programmable sampling of a free gingival graft for vestibuloplasty in patients with periodontal diseases.&#x0D; MATERIALS AND METHODS: With the use of modern digital technologies, the designs of individual surgical navigation templates for the intake and transplantation of free mucosal transplantation during vestibuloplasty were developed. The developed templates are used in clinical practice.&#x0D; RESULTS: For vestibuloplasty, navigational surgical templates for the extraction and transplantation of free gingival graft were developed and manufactured using modern digital technologies. As a result of this development, patents were obtained for the inventions Guiding template for soft tissue transplantation and Method of gum transplantation. The case study demonstrates the benefits of using the aforementioned navigational surgical templates. The invented method makes it possible to obtain donor tissues procured from an anatomically harmless portion of the hard upper palate. Moreover, the surgical templates make it possible to produce a recipient bed identical in shape and size to the removed donor transplant tissue, thereby making it possible to avoid the necessity of adapting the transplant in an artificial recipient bed outside the oral cavity and reducing the time spent by donor tissue detachment from any real oral cavity.&#x0D; CONCLUSIONS: Taking into account the positive results of the clinical testing of the proposed technology, a randomized study is warranted to evaluate the effectiveness of vestibuloplasty with a free gingival graft using a surgical navigation template in comparison with a similar operation performed using classical technology. It is necessary to identify the statistical significance of the obtained clinical results of treatment.

The connectivity-based parcellation of the angular gyrus: fiber dissection and MR tractography study.

The angular gyrus (AG) wraps the posterior end of the superior temporal sulcus (STS), so it is considered a continuation of the superior temporal gyrus (STG)/ middle temporal gyrus (MTG) and forms the inferior parietal lobule (IPL) with the supramarginal gyrus (SMG). The AG was functionally divided in the literature, but there is no fiber dissection study in this context. This study divided AG into superior (sAG) and inferior (iAG) parts by focusing on STS. Red, blue silicone-injected eight and four non-silicone-injected human cadaveric cerebrums were dissected via the Klingler method focusing on the AG. White matter (WM) tracts identified during dissection were then reconstructed on the Human Connectome Project 1065 individual template for validation. According to this study, superior longitudinal fasciculus (SLF) II and middle longitudinal fasciculus (MdLF) are associated with sAG; the anterior commissure (AC), optic radiation (OR) with iAG; the arcuate fasciculus (AF), inferior frontooccipital fasciculus (IFOF), and tapetum (Tp) with both parts. In cortical parcellation of AG based on STS, sAG and iAG were associated with different fiber tracts. Although it has been shown in previous studies that there are functionally different subunits with AG parcellation, here, for the first time, other functions of the subunits have been revealed with cadaveric dissection and tractography images.

Reusable Ontology Modelling Patterns for Biodiversity Data with Reasonable Ontology Templates (OTTR)

The Norwegian Biodiversity Information Centre (NBIC) is currently building a traitbank for Norwegian species. The purpose of the NBIC TraitBank is to enhance sharing of traits and other information about species to support conservation actions and ecological research. The traitbank will cover a subset of traits for all multicellular species and taxa that are found in Norway. Observations of traits, collected through citizen science as well as by experts, are connected to the NBIC TraitBank ontology, forming a knowledge base. We have modeled TraitBank’s ontology in accordance with NBIC’s data management requirements, focusing on the domain knowledge necessary for ontology-based data integration of internal databases and queries specified by use cases. Our initial steps in ontology construction included outlining competency questions, which are natural language sentences expressing the questions system users expect an ontology to answer (Bezerra et al. 2013, Ren et al. 2014). The ontology for the TraitBank is populated using expert input (manual entry) and through harvesting of traits from existing internal databases at NBIC. We will present our experiences with implementing Reasonable Ontology Templates (OTTR) (Skjæveland et al. 2021) as the means for modeling the ontology and populating the TraitBank ontology. OTTR is a language for formally representing and instantiating ontology modeling patterns and is designed to support knowledge base construction and interaction at a higher level of abstraction. In the case of the TraitBank, ontology patterns are edited and published using a Semantic MediaWiki (SMW) extension for OTTR (FloSchroeder 2022), thereby providing a tool for the domain expert to work directly with templates. We build the TraitBank ontology by instantiating the templates directly in SMW as wiki pages. We argue that templates are an effective means to support the integration and use of digital biodiversity data in transparent ways, leading to successful collaboration and reuse of data. Following the "Don't repeat yourself" (DRY) principle of software development (Hunt and Thomas 1999), OTTR templates lend themselves well to easier ontology maintenance, allowing updates to occur through changes in individual template definitions rather than to repeated statements spread throughout the ontology. OTTR reshapes how domain experts work with ontologies and the data connected to the knowledge base, lifting the biodiversity expert away from dealing directly with logical axioms and Web Ontology Language (OWL). The template libraries have the power to improve international collaboration, making it easier to exchange and reuse specific templates and suggest improvements. Our templates include mappings to standards developed by Biodiversity Information Standards (TDWG) and biodiversity-related ontologies, linking to the international community. Use of OTTR supports the principles of Findable, Accessible, Interoperable, and Reusable (FAIR) data and demonstrates a new technology that can support the creation of an extensive online network of knowledge. Example: Scientific Name The NBIC uses Scientific Name as the main identifier and means to track a species. The OTTR template shown below captures the NBIC’s modelling pattern for Scientific Name. The signature of the template specifies the Internationalized Resource Identifier (IRI) of the template (adb-t:ScientificName), and six parameters (where ?iri is the 1st parameter). The parameters are used in the body of the template and define how instances of the template are expanded to Resource Description Framework (RDF) statements. Template instance expansion is done in a recursive manner, similar to many macro programming languages. With the OTTR template definition given in Fig. 1, a template instance can be expanded, as shown in the example for Metopa glacialis Fig. 2. The benefits of using the OTTR framework is that modeling patterns are explicitly represented as an OTTR template, allowing for instances of patterns to be compactly and consistently captured. The format of template instances lends itself to instantiation from tabular data sources like spreadsheets and databases.

Clinical application and accuracy assessment of imaging-based surgical navigation guided 125I interstitial brachytherapy in deep head and neck regions

Brachytherapy has the advantages of being minimally invasive and highly conformal, and it achieves good results in head and neck tumors. To precisely implant the radioactive seeds according to the preplan in deep head and neck regions, the surgical navigation is applied. This study aims to explore the clinical application and accuracy of imaging-based surgical navigation-guided 125I interstitial brachytherapy in terms of seed position. We included 41 patients with tumors in deep head and neck regions. The brachytherapy treatment plan was designed, and the preplanned data were transferred to the navigation system. Needle implantation and seed delivery were performed under surgical navigation system guidance with or without the combination of individual template. The treatment accuracy was evaluated by comparing seed cluster locations between the preoperative treatment plan and the postoperative treatment outcome. A total of 2879 seeds were delivered. The range, mean and median distances between the geometric centers of the preoperative seed point clusters and the postoperative seed point clusters were 0.8–10.5 mm, 4.5 ± 2.3 mm and 4.1 mm, respectively. The differences between preoperative and postoperative volumes of the minimum bounding box of seed point clusters were nonsignificant. In conclusion, the imaging-based surgical navigation system is a promising clinical tool to provide the preplanned data for interstitial brachytherapy intraoperatively, and it is feasible and accurate for the real-time guidance of needle implantation and seed delivery in deep head and neck regions.

Performance of Composite Glass-Diarylethene Crystal Photomechanical Actuator Membranes.

Hybrid organic-inorganic composites based on organic photochromic crystals embedded in inorganic templates provide a new approach to photomechanical materials. Diarylethene (DAE) nanowire crystals grown in Al2O3 membranes have exhibited reversible photoinduced bending and lifting [Dong, X., Chem. Mater. 2019, 31, 1016-1022]. In this paper, the hybrid approach is extended to porous SiO2 membranes. Despite the different template material (SiO2 instead of Al2O3) and much larger channels (5 μm diameter instead of 0.2 μm diameter), similar photomechanical behavior is observed for this new class of organic-inorganic hybrid actuators. The ability to reuse individual glass templates across different DAE filling cycles allows us to show that the DAE filling step is crucial for determining the mechanical work done by the bending template. The bending curvature also depends quadratically on the template thickness, in good agreement with theory. The light-induced bending can be repeated for up to 150 cycles without loss of performance, suggesting good fatigue resistance. The results in this paper demonstrate that the hybrid organic-inorganic approach can be extended to other host materials and template geometries. They also suggest that optimizing the organic filling and template thickness could improve the work output by an order of magnitude.

COMPUTER SYSTEM FOR MECHANISMS DIAGNOSIS

The computer system proposed in this work is aimed at solving the problem of automating a comprehensive assessment of the technical functioning of mechanisms. The system’s computational equipment have the minimum necessary computing requirements. No additional paid software is required for installation. Unlike existing systems, the proposed one has a moderate cost. For the majority of industrial enterprises, this factor is crucial when choosing the most beneficial computer system. In addition, the developed system is simple and comfortable to use. Thus, the system has an intuitive and intelligible interface for the operator, which allows the operator to quickly familiarize themselves with it and put it to use immediately; the system monitors the correctness entries in the electronic history - it corrects basic fields that are not properly indicated (repair data, repair requests, part price, etc.). The system has the ability to add individual templates for a specific unit. Unlike existing systems, the proposed system is multifunctional.

A comparative survey of SSVEP recognition algorithms based on template matching of training trials

PurposeSteady-state visual evoked potential (SSVEP) has been widely used in the application of electroencephalogram (EEG) based non-invasive brain computer interface (BCI) due to its characteristics of high accuracy and information transfer rate (ITR). To recognize the SSVEP components in collected EEG trials, a lot of recognition algorithms based on template matching of training trials have been proposed and applied in recent years. In this paper, a comparative survey of SSVEP recognition algorithms based on template matching of training trails has been done.Design/methodology/approachTo survey and compare the recently proposed recognition algorithms for SSVEP, this paper regarded the conventional canonical correlated analysis (CCA) as the baseline, and selected individual template CCA (ITCCA), multi-set CCA (MsetCCA), task related component analysis (TRCA), latent common source extraction (LCSE) and a sum of squared correlation (SSCOR) for comparison.FindingsFor the horizontal comparative of the six surveyed recognition algorithms, this paper adopted the “Tsinghua JFPM-SSVEP” data set and compared the average recognition performance on such data set. The comparative contents including: recognition accuracy, ITR, correlated coefficient and R-square values under different time duration of the SSVEP stimulus presentation. Based on the optimal time duration of stimulus presentation, the author has also compared the efficiency of the six compared algorithms. To measure the influence of different parameters, the number of training trials, the number of electrodes and the usage of filter bank preprocessing were compared in the ablation study.Originality/valueBased on the comparative results, this paper analyzed the advantages and disadvantages of the six compared SSVEP recognition algorithms by considering application scenes, real-time and computational complexity. Finally, the author gives the algorithms selection range for the recognition of real-world online SSVEP-BCI.

Abstract TP18: Progressive White Matter Degeneration After Ischemic Stroke

Background: White matter degeneration after ischemic stroke may herald post-stroke cognitive decline. FLAIR white matter hyperintensity (WMH) reflects tissue injury and accumulates around the infarct and in remote regions. But WMH volumetry is insensitive to regional or short-term progression. We compared WMH volumetry to a voxel-wise approach for detecting FLAIR WMH change longitudinally after stroke. Methods: Ischemic stroke patients enrolled in an observational cohort study underwent serial MRI acutely, at 1 month and every 3 months thereafter. Patients with 6 to 12-month follow-ups were included. WMH lesion volumes were automatically segmented on serial FLAIR MRI. In the hemisphere contralateral to the infarct from 30 days onward, we compared longitudinal change in WMH volume to a voxel-wise regression of FLAIR signal change over time. We used T1 images as an intermediate to nonlinearly align serial FLAIR images to individual templates. FLAIR intensities were normalized, corrected for local expansion/contraction, and smoothed. Within voxels identified as lesion at any timepoint, significant WMH change was determined relative to the normal appearing white matter and converted to a percentage of the intracranial volume. Results: 22 ischemic stroke patients (mean age 73 ± 8 years, NIHSS 4 ± 4, infarct volume 10.3 ± 23 cc) had on average 3 follow-ups over 343 days. In the non-stroke hemisphere, volumetry revealed lesion growth in 12. Mean lesion increase was 0.01 ± 0.20% per year. In voxel-wise analysis 15 patients had increasing FLAIR signal. Intensity increased in mean 0.11 ± 0.23% of intracranial voxels. Lesion growth was associated with the volume of voxel-wise signal increase (Beta = 0.51, p = 0.018). In the stroke hemisphere, progressive WMH expansion of peri-infarct tissue, consistent with Wallerian degeneration, was present in 10 patients. WMH regression, consistent with atrophy and infarct cavitation, was present in 14. Stroke hemisphere WMH expansion was associated with initial NIHSS (B = 0.58, p = 0.0086) while regression was associated with acute infarct volume (B = 0.80, p &lt; 0.001). Conclusions: Voxel-wise longitudinal WMH analysis detects progressive white matter degradation and regional variation continuing 30 days after stroke.

Distinguishability of keystroke dynamic template.

When keystroke dynamics are used for authentication, users tend to get different levels of security due to differences in the quality of their templates. This paper addresses this issue by proposing a metric to quantify the quality of keystroke dynamic templates. That is, in behavioral biometric verification, the user's templates are generally constructed using multiple enrolled samples to capture intra-user variation. This variation is then used to normalize the distance between a set of enrolled samples and a test sample. Then a normalized distance is compared against a predefined threshold value to derive a verification decision. As a result, the coverage area for accepted samples in the original space of vector representation is discrete. Therefore, users with the higher intra-user variation suffer higher false acceptance rates (FAR). This paper proposes a metric that can be used to reflect the verification performance of individual keystroke dynamic templates in terms of FAR. Specifically, the metric is derived from statistical information of user-specific feature variations, and it has a non-decreasing property when a new feature is added to a template. The experiments are performed based on two public keystroke dynamic datasets comprising of two main types of keystroke dynamics: constrained-text and free-text, namely the CMU keystroke dynamics dataset and the Web-Based Benchmark for keystroke dynamics dataset. Experimental results based on multiple classifiers demonstrate that the proposed metric can be a good indicator of the template's false acceptance rate. Thus, it can be used to enhance the security of the user authentication system based on keystroke dynamics.

Enhancing detection of SSVEP-based BCIs via a novel CCA-based method

ObjectiveFrequency recognition methods based on spatial filtering have been widely studied to enhance the classification performance of steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) systems. This paper proposes a novel canonical correlation analysis (CCA)-based method to improve the recognition performance of SSVEPs. MethodsThe proposed method is based on a novel framework in which two spatial filters are trained using individual training data and SSVEP templates constructed from sine-cosine reference signals for SSVEP denoising and correlation coefficient generation, and then two correlation coefficients are integrated for target frequency recognition. The proposed method was compared with five frequency recognition algorithms requiring spatial filter training. Besides, the ensemble version of the proposed method was further developed and evaluated. Main resultsThe experimental results on two 40-class benchmark datasets recorded from 35 subjects and 70 subjects respectively show that the proposed method outperformed the five competing methods significantly in most cases. ConclusionThe proposed method achieved higher classification accuracy and information transmission rate, shorter training time, and more stable performance. Thus, the proposed CCA-based method is more suitable for SSVEP-based BCI systems.

Signal-to-noise-ratio and maximum-signal-to-noise-ratio detection statistics in template-bank searches for exotic physics transients with networks of quantum sensors

Quantum sensor networks such as the existing networks of atomic clocks and magnetometers offer intriguing capabilities in searches for transient signals such as dark matter or fields sourced by powerful astrophysical events. The common matched-filter technique relies on the signal-to-noise-ratio (SNR) detection statistic to probe such transients. For macroscopic dark matter objects, the network would register a sweeping signal as the object propagates through at galactic velocities. A potential event is registered when the SNR from a specific template exceeds a threshold set by a desired false positive rate. Generically, to span the continuous parameter space for the network-exotic-physics encounter, one has to deal with multiple templates. In such template-bank searches, the natural generalization of the SNR statistic is the maximum-signal-to-noise-ratio (SNR-max) statistic, defined as the maximum of the absolute values of SNRs determined from individual template matching. While individual SNR realizations are Gaussian distributed, SNR-max probability distribution is non-Gaussian. Moreover, as the individual template-bank SNRs are computed using the same network data streams, SNRs become correlated between the templates. Cross-template correlations have a sizable effect on the SNR-max probability and cumulative distributions, and on the threshold SNR-max values. Computing threshold SNR-max values for large template banks is computationally prohibitive and we develop analytic approaches to computing properties of the SNR-max statistic. This is done for cases when the template bank is nearly orthogonal (small cross-template correlations) and for banks with cross-template correlation coefficient distribution ``squeezed'' about the most probable cross-template correlation value. Since the cross-template correlation coefficients quantify the similarity of templates, increasing correlations tend to decrease SNR-max thresholds for specific values of false positive rates. Increasing the number of templates in the bank increases the SNR-max thresholds. Our derivations are carried out for networks that may exhibit colored noise and cross-node correlations. Specific applications are illustrated with a dark matter search with atomic clocks onboard satellites of a Global Positioning System and with a ``toy'' planar network with cyclic rotational symmetry.

Multi-Objective Optimization-Based High-Pass Spatial Filtering for SSVEP-Based Brain–Computer Interfaces

Many spatial filtering methods have been proposed to enhance the target identification performance for the steady-state visual evoked potential (SSVEP)-based brain–computer interface (BCI). The existing approaches tend to learn spatial filter parameters of a certain target using only the training data from the same stimulus, and they rarely consider the information from other stimuli or the volume conduction problem during the training process. In this article, we propose a novel multi-objective optimization-based high-pass spatial filtering method to improve the SSVEP detection accuracy and robustness. The filters are derived via maximizing the correlation between the training signal and the individual template from the same target whilst minimizing the correlation between the signal from other targets and the template. The optimization will also be subject to the constraint that the sum of filter elements is zero. The evaluation study on two self-collected SSVEP datasets (including 12 and four frequencies, respectively) shows that the proposed method outperformed the compared methods such as canonical correlation analysis (CCA), multiset CCA (MsetCCA), sum of squared correlations (SSCOR), and task-related component analysis (TRCA). The proposed method was also verified on a public 40-class SSVEP benchmark dataset recorded from 35 subjects. The experimental results have demonstrated the effectiveness of the proposed approach for enhancing the SSVEP detection performance.

Learning Temporal-Correlated and Channel- Decorrelated Siamese Networks for Visual Tracking

Recently, Siamese network based trackers have attracted growing popularity in visual tracking, which tackle the tracking by template matching between the initial template and successive search regions. The initial template patch is generally encoded into a convolutional feature for matching. However, the limited representational capability of the template feature limits the tracking accuracy. Besides, this fixed representation also fails to adapt to the target appearance changes. To alleviate these issues, we improve the Siamese trackers by introducing temporal correlation and channel decorrelation mechanisms. On the one hand, we consider the channel-wise correlations between the initial and historical template features to adaptively aggregate informative channel-wise representations for template update. On the other hand, we propose a decorrelation regularization to weaken the channel-wise correlations of individual template features. By end-to-end training, we learn a more complete and adaptive template for accurate object tracking. We demonstrate the generality of our approach by applying it to two prevalent Siamese trackers, i.e., SiamFC and SiamRPN. Extensive experiments on seven benchmark datasets verify the effectiveness of our method.

Measurement of Lead Localization Accuracy Based on Magnetic Resonance Imaging.

Post-implantation localization of deep brain stimulation (DBS) lead based on a magnetic resonance (MR) image is widely used. Existing localization methods use artifact center method or template registration method, which may lead to a considerable deviation of > 2 mm, and result in severe side effects or even surgical failure. Accurate measurement of lead position can instantly inform surgeons of the imprecise implantation. This study aimed to identify the influencing factors in DBS lead post-implantation localization approach, analyze their influence, and describe a localization approach that uses the individual template method to reduce the deviation. We verified that reconstructing direction should be parallel or perpendicular to lead direction, instead of the magnetic field. Besides, we used simplified relationship between magnetic field angle and deviation error to correct the localization results. The mean localization error can be reduced after correction and favors the feasibility of direct localization of DBS lead using MR images. We also discussed influence of in vivo noise on localization frequency and the possibility of using only MR images to localize the contacts.

Signal Quality Index Based on Template Cross-Correlation in Multimodal Biosignal Chair for Smart Healthcare.

We investigated the effects of a quality screening method on unconstrained measured signals, including electrocardiogram (ECG), photoplethysmogram (PPG), and ballistocardiogram (BCG) signals, in our collective chair system for smart healthcare. Such an investigation is necessary because unattached or unbound sensors have weaker connections to body parts than do conventional methods. Using the biosignal chair, the physiological signals collected during sessions included a virtual driving task, a physically powered wheelchair drive, and three types of body motions. The signal quality index was defined by the similarity between the observed signals and noise-free signals from the perspective of the cross-correlations of coefficients with appropriate individual templates. The goal of the index was to qualify signals without a reference signal to assess the practical use of the chair in daily life. As expected, motion artifacts have adverse effects on the stability of physiological signals. However, we were able to observe a supplementary relationship between sensors depending on each movement trait. Except for extreme movements, the signal quality and estimated heart rate (HR) remained within the range of criteria usable for status monitoring. By investigating the signal reliability, we were able to confirm the suitability of using the unconstrained biosignal chair to collect real-life measurements to improve safety and healthcare.

Individual Navigation Templates for Subcortical Screw Placement in Lumbar Spine.

Subcortical screw placement is currently performed using frontal view fluoroscopy or intraoperative O-arm navigation system. The emergence of a novel technique for spinal navigation based on individual navigation templates created using 3D printing technology determines the need to study their safety and effectiveness in subcortical implantation.The aim of the study was to evaluate and compare the efficacy of subcortical implantation of pedicle screws in the lumbar spine using individual navigation templates versus intraoperative fluoroscopy.Materials and MethodsThe study was based on the analysis of treatment results in 39 patients who underwent surgery with subcortical implantation of 130 screws using the MidLIF technique. In group 1, navigation templates were used, in group 2 — intraoperative fluoroscopic control. Comparative analysis of implantation correctness and time, the total operation time, and radiation load was performed.ResultsThe mean distance between the screw and the cortical plate recorded in the groups ranged within 1.20–3.97 mm, without statistically significant difference (p>0.05). The mean time of pedicle screw implantation was 137.0 [115.25; 161.50] s in group 1 and 314.0 [183.50; 403.25] s in group 2. The total operation time was reduced from 173.0 [155.0; 192.25] min in group 2 to 119.0 [108.0; 128.75] min in group 1. The average of 1.0 [1.0; 2.0] X-ray image was performed to place one screw in group 1, while it was 12.0 [10.0; 13.25] in group 2. The differences between the groups in terms of implantation time and radiation load were statistically significant (p<0.05).ConclusionCompared with intraoperative fluoroscopy, the use of individual navigation templates for subcortical implantation of pedicle screws provides their correct positioning with a significant reduction in both operation time and radiation load at similar safety.