scholarly journals The endonasal patient reference tracker: a novel solution for accurate noninvasive electromagnetic neuronavigation

2020 ◽  
pp. 1-8
Author(s):  
Ayguel Wurzer ◽  
Georgi Minchev ◽  
Claudia Cervera-Martinez ◽  
Alexander Micko ◽  
Gernot Kronreif ◽  
...  
Keyword(s):  
Clinical Setting ◽  
Ex Vivo ◽  
Reference Method ◽  
Patient Positioning ◽  
Ground Truth ◽  
Flap Fixation ◽  
Electromagnetic Neuronavigation ◽  
Nasal Tamponade ◽  
The Stability ◽  
Median Deviation

OBJECTIVEElectromagnetic (EM) navigation provides the advantages of continuous guidance and tip-tracking of instruments. The current solutions for patient reference trackers are suboptimal, as they are either invasively screwed to the bone or less accurate if attached to the skin. The authors present a novel EM reference method with the tracker rigidly but not invasively positioned inside the nasal cavity.METHODSThe nasal tracker (NT) consists of the EM coil array of the AxiEM tracker plugged into a nasal tamponade, which is then inserted into the inferior nasal meatus. Initially, a proof-of-concept study was performed on two cadaveric skull bases. The stability of the NT was assessed in simulated surgical situations, for example, prone, supine, and lateral patient positioning and skin traction. A deviation ≤ 2 mm was judged sufficiently accurate for clinical trial. Thus, a feasibility study was performed in the clinical setting. Positional changes of the NT and a standard skin-adhesive tracker (ST) relative to a ground-truth reference tracker were recorded throughout routine surgical procedures. The accuracy of the NT and ST was compared at different stages of surgery.RESULTSEx vivo, the NT proved to be highly stable in all simulated surgical situations (median deviation 0.4 mm, range 0.0–2.0 mm). In 13 routine clinical cases, the NT was significantly more stable than the ST (median deviation at procedure end 1.3 mm, range 0.5–3.0 mm vs 4.0 mm, range 1.2–11.2 mm, p = 0.002). The loss of accuracy of the ST was highest during draping and flap fixation.CONCLUSIONSApplication of the EM endonasal patient tracker was found to be feasible with high procedural stability ex vivo as well as in the clinical setting. This innovation combines the advantages of high precision and noninvasiveness and may, in the future, enhance EM navigation for neurosurgery.

A NOVEL EXTENSIVE EX-VIVO OCT DATABASE FROM MURINE MODELS OF COLORECTAL CANCER

2021 ◽  
Vol 108 (Supplement_3) ◽  
Author(s):  
J Bote ◽  
J F Ortega-Morán ◽  
C L Saratxaga ◽  
B Pagador ◽  
A Picón ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Machine Learning ◽  
Structural Information ◽  
Ex Vivo ◽  
Ground Truth ◽  
Colon Polyps ◽  
Learning Methods ◽  
Non Invasive ◽  
Machine Learning Methods ◽  
In Situ Methods

Abstract INTRODUCTION New non-invasive technologies for improving early diagnosis of colorectal cancer (CRC) are demanded by clinicians. Optical Coherence Tomography (OCT) provides sub-surface structural information and offers diagnosis capabilities of colon polyps, further improved by machine learning methods. Databases of OCT images are necessary to facilitate algorithms development and testing. MATERIALS AND METHODS A database has been acquired from rat colonic samples with a Thorlabs OCT system with 930nm centre wavelength that provides 1.2KHz A-scan rate, 7μm axial resolution in air, 4μm lateral resolution, 1.7mm imaging depth in air, 6mm x 6mm FOV, and 107dB sensitivity. The colon from anaesthetised animals has been excised and samples have been extracted and preserved for ex-vivo analysis with the OCT equipment. RESULTS This database consists of OCT 3D volumes (C-scans) and 2D images (B-scans) of murine samples from: 1) healthy tissue, for ground-truth comparison (18 samples; 66 C-scans; 17,478 B-scans); 2) hyperplastic polyps, obtained from an induced colorectal hyperplastic murine model (47 samples; 153 C-scans; 42,450 B-scans); 3) neoplastic polyps (adenomatous and adenocarcinomatous), obtained from clinically validated Pirc F344/NTac-Apcam1137 rat model (232 samples; 564 C-scans; 158,557 B-scans); and 4) unknown tissue (polyp adjacent, presumably healthy) (98 samples; 157 C-scans; 42,070 B-scans). CONCLUSIONS A novel extensive ex-vivo OCT database of murine CRC model has been obtained and will be openly published for the research community. It can be used for classification/segmentation machine learning methods, for correlation between OCT features and histopathological structures, and for developing new non-invasive in-situ methods of diagnosis of colorectal cancer.

Use of computed tomography to compare two femoral head and neck excision ostectomy techniques as performed by two novice veterinarians

2015 ◽  
Vol 28 (05) ◽  
pp. 295-300 ◽  
Author(s):  
M. D. O’Donnell ◽  
G. Bobe ◽  
R. P. Scholz ◽  
J. E. Wiest ◽  
S. Nemanic ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Femoral Head ◽  
Femoral Neck ◽  
Head And Neck ◽  
Clinical Setting ◽  
Ex Vivo ◽  
Bone Volume ◽  
Bone Trauma ◽  
Before And After ◽  
Bone Fragments

Summary Objectives: To compare the results of femoral head and neck excision (FHNE) ostectomy performed by two novice veterinarians using an osteotome and mallet or microsagittal saw. Methods: In this ex vivo cadaveric study, hindlimbs of eight canine cadavers were randomized to FHNE with osteotome or micro sagittal saw as performed by two recently graduated veterinarians. The hindimbs were imaged by computed tomography (CT) before and after the osteotomy. Post FHNE CT images were evaluated by a board certified radiologist blinded to the ostectomy technique for assessment of the number of bone fragments, fissures, smoothness of osteotomy margination, and volume of residual fe-moral neck. Results: Femoral head and neck excision performed with the osteotome produced more peri-ostectomy bone fragments, cortical fissures, irregular margins, and residual femoral neck volume, compared with osteotomy using a saw. Clinical relevance: Compared to FHNE performed with a sagittal saw, osteotome FHNE resulted in a greater bone trauma and residual neck bone volume, which would require post-ostectomy modification in a clinical setting.

scholarly journals Olive Oil Based Organogels for Effective Topical Delivery of Fluconazole: In-vitro Antifungal Study

2020 ◽  
pp. 29-36
Author(s):  
Mohammad Muqtader Ahmed ◽  
Farhat Fatima ◽  
Abdul Bari Mohammed
Keyword(s):  
Olive Oil ◽  
Ex Vivo ◽  
Similarity Index ◽  
Ex Vivo Permeation ◽  
Efficient Delivery ◽  
In Vitro Diffusion ◽  
Permeation Studies ◽  
The Stability ◽  
Hot Melt

The objective of the study was to formulate olive oil based organogels for the topical application of fluconazole (FLZ), to ensure the efficient delivery of the drug deeper in to the skin layers. Methods: Nine formulations developed by hot-melt method using olive oil, sorbitan monostearate (SMS) and FLZ. Prepared formulations characterized for macro evaluations, pH, spreadibility, viscosity, gel-sol transition, in-vitro diffusion study. Further optimized formulation evaluated for ex-vivo percutaneous permeation, in-vitro antifungal studies and stability studies by similarity index. Results: The results of evaluated parameters ensure the stability and effectiveness of the prepared olive oil based organogels. In-vitro diffusion studied reflects decrease in drug release with increase in surfactant concentration due to increase in viscosity. Moreover, ex-vivo permeation studies revealed that the permeation of FLZ was enhanced for optimized formulations (F6) as compared to the marketed gel formulation. Further, the optimized formulation exhibits the broad zone of inhibition against fungal strains in comparison to control and marketed product during in-vitro antifungal study. Conclusion: The olive oil based organogels formulation shown the enhanced permeation of FLZ from organogel network structure with good antifungal activity as compared to the marketed formulation. Henceforth, the FLZ organogel formulations could be used topically for the effective treatment of fungal infection.

scholarly journals DEVELOPMENT AND EVALUATION OF MUCOADHESIVE NANOGEL OF NEVIRAPINE FOR VAGINAL APPLICATION

2019 ◽  
pp. 144-149
Author(s):  
Sheikh Sofiur Rahman ◽  
ABDUL BAQUEE AHMED
Keyword(s):  
Hiv Infection ◽  
Ex Vivo ◽  
Vaginal Fluid ◽  
Content Uniformity ◽  
Vaginal Mucosa ◽  
Salting Out ◽  
Zero Order Kinetics ◽  
The Stability ◽  
Ph Range

Objectives: The main objective of this study was to develop and evaluate Nevirapine nanoparticle loaded mucoadhesive gel (NVP-Np mucoadhesive gel) for vaginal application for the treatment of HIV infection.  Methods: NVP loaded nanoparticles were prepared by salting out method followed by incorporation in different gel bases to produce NVP-Np mucoadhesive gel The prepared gels were evaluated for their physicochemical parameters, rheological characteristics, mucoadhesion, in-vitro drug release and ex-vivo permeation of drug across porcine vaginal mucosa.  Results: The result of FT-IR and DSC study confirmed the absence of incompatibility of NVP with excipients used in the formulations. The particle size of the prepared NVP-Np was found to be 243.8 ± 3.15 nm, a polydispersity index (PI) of 0.787± 0.002 and zeta potential value -17.12 mV, which revealed the stability of nanoparticles. All the formulations showed good homogeneity, spreadability, physical appearance and content uniformity. The pH of the mucoadhesive gel formulations was in the range of 3.70 ± 0.03 to 4.56 ± 0.02, which lies in the normal pH range of the vaginal fluid.  The cumulative amounts permeated at 6 h were 832.23 ± 63.45 μg/cm2 , 592.13 ± 82.55 μg/cm2 and 941.32 ± 81.10 μg/cm2 from F1(1% Chitosan), F2(1% Carbopol 974P) and F3 (1% HPMC K100M )  respectively. A linear relationship [r2 > 0.9 (0.97 n 0.99)] was observed between the percentage cumulative amount permeated and time, indicating zero order kinetics. Conclusion: In conclusion, NVP-Np mucoadhesive gel was prepared successfully using salting out followed by a homogenization technique for vaginal application of NVP for the prophylaxis of HIV infection.

scholarly journals Brain Tissue Conductivity Measurements with MR-Electrical Properties Tomography: An In Vivo Study

2020 ◽  
Author(s):  
Stefano Mandija ◽  
Petar I. Petrov ◽  
Jord J. T. Vink ◽  
Sebastian F. W. Neggers ◽  
Cornelis A. T. van den Berg
Keyword(s):  
Electrical Properties ◽  
Healthy Subjects ◽  
Ex Vivo ◽  
Simulated Data ◽  
Ground Truth ◽  
In Vivo Study ◽  
Conductivity Measurements ◽  
Tissue Conductivity ◽  
Before And After

AbstractFirst in vivo brain conductivity reconstructions using Helmholtz MR-Electrical Properties Tomography (MR-EPT) have been published. However, a large variation in the reconstructed conductivity values is reported and these values differ from ex vivo conductivity measurements. Given this lack of agreement, we performed an in vivo study on eight healthy subjects to provide reference in vivo brain conductivity values. MR-EPT reconstructions were performed at 3 T for eight healthy subjects. Mean conductivity and standard deviation values in the white matter, gray matter and cerebrospinal fluid (σWM, σGM, and σCSF) were computed for each subject before and after erosion of regions at tissue boundaries, which are affected by typical MR-EPT reconstruction errors. The obtained values were compared to the reported ex vivo literature values. To benchmark the accuracy of in vivo conductivity reconstructions, the same pipeline was applied to simulated data, which allow knowledge of ground truth conductivity. Provided sufficient boundary erosion, the in vivo σWM and σGM values obtained in this study agree for the first time with literature values measured ex vivo. This could not be verified for the CSF due to its limited spatial extension. Conductivity reconstructions from simulated data verified conductivity reconstructions from in vivo data and demonstrated the importance of discarding voxels at tissue boundaries. The presented σWM and σGM values can therefore be used for comparison in future studies employing different MR-EPT techniques.

scholarly journals The ESA Permanent Facility for Altimetry Calibration: Monitoring Performance of Radar Altimeters for Sentinel-3A, Sentinel-3B and Jason-3 Using Transponder and Sea-Surface Calibrations with FRM Standards

2020 ◽  
Vol 12 (16) ◽  
pp. 2642
Author(s):  
Stelios Mertikas ◽  
Achilleas Tripolitsiotis ◽  
Craig Donlon ◽  
Constantin Mavrocordatos ◽  
Pierre Féménias ◽  
...  
Keyword(s):  
Objective Assessment ◽  
Ground Truth ◽  
Sea Surface ◽  
Crossover Analysis ◽  
Operational Phase ◽  
The Stability ◽  
Independent Calibration ◽  
Monitoring Performance

This work presents the latest calibration results for the Copernicus Sentinel-3A and -3B and the Jason-3 radar altimeters as determined by the Permanent Facility for Altimetry Calibration (PFAC) in west Crete, Greece. Radar altimeters are used to provide operational measurements for sea surface height, significant wave height and wind speed over oceans. To maintain Fiducial Reference Measurement (FRM) status, the stability and quality of altimetry products need to be continuously monitored throughout the operational phase of each altimeter. External and independent calibration and validation facilities provide an objective assessment of the altimeter’s performance by comparing satellite observations with ground-truth and in-situ measurements and infrastructures. Three independent methods are employed in the PFAC: Range calibration using a transponder, sea-surface calibration relying upon sea-surface Cal/Val sites, and crossover analysis. Procedures to determine FRM uncertainties for Cal/Val results have been demonstrated for each calibration. Biases for Sentinel-3A Passes No. 14, 278 and 335, Sentinel-3B Passes No. 14, 71 and 335, as well as for Jason-3 Passes No. 18 and No. 109 are given. Diverse calibration results by various techniques, infrastructure and settings are presented. Finally, upgrades to the PFAC in support of the Copernicus Sentinel-6 ‘Michael Freilich’, due to launch in November 2020, are summarized.

scholarly journals The Gold Standard Paradox in Digital Image Analysis: Manual Versus Automated Scoring as Ground Truth

2017 ◽  
Vol 141 (9) ◽  
pp. 1267-1275 ◽  
Author(s):  
Famke Aeffner ◽  
Kristin Wilson ◽  
Nathan T. Martin ◽  
Joshua C. Black ◽  
Cris L. Luengo Hendriks ◽  
...  
Keyword(s):  
Image Analysis ◽  
Gold Standard ◽  
Quantitative Methods ◽  
Reference Method ◽  
Ground Truth ◽  
Visual Assessment ◽  
Human Observer ◽  
Cellular Mechanisms ◽  
Visual Evaluation ◽  
Scoring Accuracy

Context.— Novel therapeutics often target complex cellular mechanisms. Increasingly, quantitative methods like digital tissue image analysis (tIA) are required to evaluate correspondingly complex biomarkers to elucidate subtle phenotypes that can inform treatment decisions with these targeted therapies. These tIA systems need a gold standard, or reference method, to establish analytical validity. Conventional, subjective histopathologic scores assigned by an experienced pathologist are the gold standard in anatomic pathology and are an attractive reference method. The pathologist's score can establish the ground truth to assess a tIA solution's analytical performance. The paradox of this validation strategy, however, is that tIA is often used to assist pathologists to score complex biomarkers because it is more objective and reproducible than manual evaluation alone by overcoming known biases in a human's visual evaluation of tissue, and because it can generate endpoints that cannot be generated by a human observer. Objective.— To discuss common visual and cognitive traps known in traditional pathology-based scoring paradigms that may impact characterization of tIA-assisted scoring accuracy, sensitivity, and specificity. Data Sources.— This manuscript reviews the current literature from the past decades available for traditional subjective pathology scoring paradigms and known cognitive and visual traps relevant to these scoring paradigms. Conclusions.— Awareness of the gold standard paradox is necessary when using traditional pathologist scores to analytically validate a tIA tool because image analysis is used specifically to overcome known sources of bias in visual assessment of tissue sections.

scholarly journals Sparse Representation of Deformable 3D Organs with Spherical Harmonics and Structured Dictionary

2011 ◽  
Vol 2011 ◽  
pp. 1-17
Author(s):  
Dan Wang ◽  
Ahmed H. Tewfik ◽  
Yingchun Zhang ◽  
Yunhe Shen
Keyword(s):  
Sparse Representation ◽  
Spherical Harmonic ◽  
Ex Vivo ◽  
Ground Truth ◽  
Maximum Error ◽  
Training Data ◽  
Data Set ◽  
Low Dimensionality ◽  
Reconstructed Surface

This paper proposed a novel algorithm to sparsely represent a deformable surface (SRDS) with low dimensionality based on spherical harmonic decomposition (SHD) and orthogonal subspace pursuit (OSP). The key idea in SRDS method is to identify the subspaces from a training data set in the transformed spherical harmonic domain and then cluster each deformation into the best-fit subspace for fast and accurate representation. This algorithm is also generalized into applications of organs with both interior and exterior surfaces. To test the feasibility, we first use the computer models to demonstrate that the proposed approach matches the accuracy of complex mathematical modeling techniques and then both ex vivo and in vivo experiments are conducted using 3D magnetic resonance imaging (MRI) scans for verification in practical settings. All results demonstrated that the proposed algorithm features sparse representation of deformable surfaces with low dimensionality and high accuracy. Specifically, the precision evaluated as maximum error distance between the reconstructed surface and the MRI ground truth is better than 3 mm in real MRI experiments.

Comparative Ex Vivo Evaluation of Two Electronic Percussive Testing Devices Measuring the Stability of Dental Implants

2014 ◽  
Vol 85 (12) ◽  
pp. 1786-1791 ◽  
Author(s):  
Onur Geckili ◽  
Hakan Bilhan ◽  
Altug Cilingir ◽  
Caglar Bilmenoglu ◽  
Gokcen Ates ◽  
...  
Keyword(s):  
Dental Implants ◽  
Ex Vivo ◽  
The Stability

scholarly journals Sonar using chaotic sounding signals

2021 ◽  
pp. 36-40
Author(s):  
Ш.С. Фахми ◽  
С.В. Горяинов ◽  
А.В. Калач
Keyword(s):  
Signal To Noise Ratio ◽  
Water Environment ◽  
Deterministic Chaos ◽  
Reference Method ◽  
Current Approach ◽  
Arbitrary System ◽  
Simulated Environment ◽  
Before And After ◽  
Probing Signal ◽  
The Stability

В данной работе рассматривается подход к генерации зондирующего сигнала гидролокатора, основанный на применении систем с детерминированным хаосом. Рассматриваются актуальные подход к генерации зондирующего сигнала при проектировании гидролокаторов. Приводится описание полуявного метода Верле для произвольной системы обыкновенных дифференциальных уравнений. Приводится методология построения композиционных схем для получения методов численного интегрирования произвольного порядка на основе симметричного опорного метода. Приводятся результаты компьютерного моделирования форм различных сигналов до и после прохождения через имитацию водной среды. Приводятся экспериментальные результаты оценки погрешности в распознавании сигнала при различных значениях соотношения сигнал/шум имитируемой среды, проводится сравнительная оценка в значениях, полученных с использованием различных сигналов. Приводятся результаты оценки устойчивости исследуемых сигналов к перекрёстным помехам, проведена сравнительная оценка рассмотренных подходов к генерации зондирующего сигнала. Сделаны выводы о применимости хаотических сигналов в качестве зондирующих In this paper, we consider an approach to generating a sonar sounding signal based on the use of systems with deterministic chaos. The current approach to the generation of sounding singal in the design of sonar is considered. The semi-implicit Wehrle method for an arbitrary system of ordinary differential equations is described. A methodology for constructing composite schemes for obtaining methods of numerical integration of arbitrary order based on the symmetric reference method is presented. The results of computer simulation of the forms of various signals before and after passing through the simulated water environment are presented. Experimental results of estimating the error in signal recognition at different values of the signal-to-noise ratio of the simulated environment are presented, and a comparative assessment is made in the values obtained using different signals. The results of the evaluation of the stability of the studied signals to crosstalk are presented, and a comparative evaluation of the considered approaches to the generation of the probing signal is carried out. Conclusions are drawn about the applicability of chaotic signals as probing signals

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