Direct Visualization Techniques Research Articles

The anatomy of pain relief: Lumbar oxygen-ozone epidural infiltrations for cervicobrachialgia

Objective: This study investigates the efficacy and safety of epidural infiltration with drugs and an oxygen-ozone mixture for treating cervicobrachialgia due to disc-radicular conflict or on a degenerative basis, utilizing both retrospective analysis and direct visualization techniques. Methods: A retrospective study involving 10 patients treated with epidural infiltrations of an oxygen-ozone mixture and cortisone was conducted. The procedures were performed under CT guidance to ensure precise delivery and to monitor the diffusion of the injected substances. Pain levels were assessed using the Numerical Rating Scale (NRS) and treatment efficacy was evaluated based on symptom relief and reduction in NSAID intake. Results: Significant pain reduction was observed post-treatment, with median NRS scores decreasing from 9 (baseline) to 2 (follow-up), and a significant decrease in on-demand NSAID intake. Only one minor complication of a headache was reported. The study also demonstrated the ability of ozone to diffuse through the epidural adipose tissue, potentially enhancing treatment efficacy. Conclusion: The combined use of an oxygen-ozone mixture and cortisone for epidural infiltration is an effective and safe treatment for cervicobrachialgia, offering significant pain relief and minimizing the risk associated with traditional epidural injections. This technique presents a viable non-surgical option for patients suffering from disc-radicular conflict or degenerative conditions.

An improved technique for direct visualization of plasmid patterns in strains of Paenibacillus larvae

American Foulbrood disease (AFB) caused by Paenibacillus larvae is the most devastating bacterial disease affecting honey bee brood worldwide. Beekeepers have been using oxytetracycline for decades to prevent and control AFB. In some countries with high disease incidence, antibiotics are still employed with the consequent risks of the appearance of tetracycline-resistant phenotypes associated with small plasmids carrying a tetracycline-resistance gene. Techniques for plasmid visualization in Gram-positive bacteria, particularly spore-forming, are not always successful. The present study aims to improve a method for direct visualization of plasmid patterns in P. larvae and other spore-forming bacteria isolated from apiarian sources. We tested 51 P. larvae strains from different geographical areas, including tetracycline-sensitive and resistant ones. The results revealed six different plasmid profiles, named I, II, III, IV, and V. Within tetracycline-resistant strains, four strains showed pattern IV with two plasmids of 5,000 and 8,000 bp, and two strains exhibited pattern V, with bands of about 5,000, 7,000, and 8,000 bp. The plasmid band of 5,000 bp present in the six resistant strains corresponds to the tetracycline-resistance mobilizable plasmid reported for P. larvae. Within the tetracycline-sensitive phenotypes, 33 strains showed no plasmids (pattern I); while two additional profiles were detected in the rest, i.e., pattern III with three plasmids in one strain and pattern VI showing two plasmids in six strains. Patterns II, III, and VI are probably related to the presence of cryptic plasmids. In conclusion, the improved technique allows us to identify plasmid patterns in P. larvae, ensuring their reproducibility and feasibility.

Blending Conventional Learning Approach with Contemporary Visualization Technologies: Prerequisite Toward Evidence-Based Surface Anatomy.

Proficiency in surface anatomy knowledge plays a pivotal role in fostering complication-free and efficacious clinical practice across a wide spectrum of healthcare specialties. This comprehensive understanding and adept utilization of surface anatomy principles serve as the linchpin for deciphering normal anatomical structures within medical imaging and the aptitude to articulate the topographical attributes, visual characteristics, and interrelations of palpable anatomical entities. Despite the advent of advanced direct visualization techniques, such as ultrasound guidance, which assist in interventional procedures, clinicians have not relinquished the indispensable requirement for pertinent surface anatomy knowledge to ensure the successful and secure execution of procedures. Regrettably, evidence-based surface anatomy remains an underemphasized facet in the pedagogy of anatomical sciences. The current narrative review underscores the various methodologies employed in imparting surface anatomy education to students. However, it is noteworthy that no singular, unequivocal best practice has emerged for the teaching and acquisition of surface anatomy knowledge. Therefore, as custodians of anatomical education, there is a pressing need to innovate and amalgamate contemporary pedagogical approaches with state-of-the-art technologies to furnish students with evidence-based surface anatomy insights, thereby enhancing comprehension, retention, and the lasting utility of this essential domain of medical knowledge.

Retracted: Treatment of Upper Cervical Spinal Cord Injury (Unstable C1-C2) by Direct Visualization and Nailing Technique and the Advantages of Early MRI.

[This retracts the article DOI: 10.1155/2021/4562618.].

Clinical quantitative coronary artery stenosis and coronary atherosclerosis imaging: a Consensus Statement from the Quantitative Cardiovascular Imaging Study Group.

The detection and characterization of coronary artery stenosis and atherosclerosis using imaging tools are key for clinical decision-making in patients with known or suspected coronary artery disease. In this regard, imaging-based quantification can be improved by choosing the most appropriate imaging modality for diagnosis, treatment and procedural planning. In this Consensus Statement, we provide clinical consensus recommendations on the optimal use of different imaging techniques in various patient populations and describe the advances in imaging technology. Clinical consensus recommendations on the appropriateness of each imaging technique for direct coronary artery visualization were derived through a three-step, real-time Delphi process that took place before, during and after the Second International Quantitative Cardiovascular Imaging Meeting in September 2022. According to the Delphi survey answers, CT is the method of choice to rule out obstructive stenosis in patients with an intermediate pre-test probability of coronary artery disease and enables quantitative assessment of coronary plaque with respect to dimensions, composition, location and related risk of future cardiovascular events, whereas MRI facilitates the visualization of coronary plaque and can be used in experienced centres as a radiation-free, second-line option for non-invasive coronary angiography. PET has the greatest potential for quantifying inflammation in coronary plaque but SPECT currently has a limited role in clinical coronary artery stenosis and atherosclerosis imaging. Invasive coronary angiography is the reference standard for stenosis assessment but cannot characterize coronary plaques. Finally, intravascular ultrasonography and optical coherence tomography are the most important invasive imaging modalities for the identification of plaques at high risk of rupture. The recommendations made in this Consensus Statement will help clinicians to choose the most appropriate imaging modality on the basis of the specific clinical scenario, individual patient characteristics and the availability of each imaging modality.

Solids Mixing in Marinized Bubbling Fluidized Beds: Gas Distribution Study

Marinized bubbling fluidized beds hold promise for reducing CO2, NOX, and SOX in ship exhaust gases, but their use at sea is hampered by a limited understanding of the influence of sea waves on hydrodynamics, heat transfer, and efficiency. To address this gap, this study used direct visualization techniques to investigate the solids mixing and hydrodynamics of bubbling fluidized beds under different gas distribution patterns in pseudo-2D vertical, inclined, and rolling beds. Digital Image Analysis (DIA) was used to determine the Lacey mixing index and the local void fraction, while Particle Image Velocimetry (PIV) was used to capture the particle velocity fields. Additionally, the effects of tilt angles and oscillation parameters of the nonvertical beds were compared with the conventional straight bubbling fluidized bed unit. The uniform inlet distribution of the fluidizing agent was compared with a variety of convex feed distributions at the bed entrance to correct for the negative effects of static/dynamic deviations from bed verticality necessary for optimal operation of bubbling fluidized bed reactors in marine environments.

A novel videoscope and tool kit for percutaneous pericardial access under direct visualization

BackgroundPericardial access is necessary for the application of epicardial cardiac therapies including ablation catheters, pacing and defibrillation leads, and left atrial appendage closure systems. Pericardial access under fluoroscopic guidance is difficult in patients without pericardial effusions and may result in coronary artery damage, ventricular injury, or perforation with potentially life-threatening pericardial bleeding in up to 10% of cases. There is a clinical need for a pericardial access technique to safely deliver epicardial cardiac therapies.MethodsIn this paper, we describe the design and evaluation of a novel videoscope and tool kit to percutaneously access the pericardial space under direct visualization. Imaging is performed by a micro-CMOS camera with an automatic gain adjustment software to prevent image saturation. Imaging quality is quantified using known optical targets, while tool performance is evaluated in pediatric insufflation and pericardial access simulators. Device safety and efficacy is demonstrated by infant porcine preclinical studies (N = 6).ResultsThe videoscope has a resolution of 400 × 400 pixels, imaging rate of 30 frames per second, and fits within the lumen of a 14G needle. The tool can resolve features smaller than 39.4 µm, achieves a magnification of 24x, and has a maximum of 3.5% distortion within the field of view. Successful pericardial access was achieved in pediatric simulators and acute in vivo animal studies. During in vivo testing, it took the electrophysiologist an average of 66.83 ± 32.86 s to insert the pericardial access tool into the thoracic space and visualize the heart. After visualizing the heart, it took an average of 136.67 ± 80.63 s to access the pericardial space under direct visualization. The total time to pericardial access measured from needle insertion was 6.7 × quicker than pericardial access using alternative direct visualization techniques. There was no incidence of ventricular perforation.ConclusionsPercutaneous pericardial access under direct visualization is a promising technique to access the pericardial space without complications in simulated and in vivo animal models.

Precision Navigation of Venous Thrombosis Guided by Viscosity-Activatable Near-Infrared Fluorescence.

Thrombus are blood clots formed by abnormal hemostasis in blood vessels and are closely associated with various diseases such as pulmonary embolism, myocardial infarction and stroke. Early diagnosis and treatment of thrombus is the key to reducing the high risk of thrombotic disease. Given that early thrombus is small in early size, free instability, wide regional distribution and fast formation, it is urgent to develop all-inclusive detection methods that combine high signal-to-noise ratio, in situ dynamic and rapid in-depth tissue imaging. Near-infrared (NIR) fluorescence imaging, with its excellent high spatiotemporal resolution and tissue penetration depth, is a powerful technique for direct visualization of thrombotic events in situ. Considering the fibrin highly expressed in the thrombus is a typical thrombotic target. Moreover, the viscosity of the thrombus is markedly higher than its surroundings. Therefore, we developed a fibrin-targeting and viscosity-activating thrombus NIR fluorescent probe (TIR-V) for high-resolution and high-sensitivity in situ lighten-up thrombus. TIR-V has the advantages of good thrombus targeting, significant "off-on" fluorescence specific response to viscosity, bright NIR fluorescence and good biocompatibility. The thrombus is clearly delineated by a high signal-to-noise ratio NIR fluorescence imaging, enabling imaging detection and precise navigation of thrombotic regions. This work demonstrates the potential of TIR-V as a bifunctional probe for definitive diagnostic imaging and direct navigation of thrombotic lesions in clinical applications.

Effect of non-condensable gas on submerged steam jet condensation in a narrow pipe

A visualization study was performed to investigate the effect of non-condensable gas on stable submerged steam jet condensation in water flow in a narrow pipe. The direct contact condensation (DCC) characteristics including jet plume shapes, dimensionless penetration length and average heat transfer coefficient were analyzed in a wide range of water flow subcooling, Reynolds number of water flow and steam–air mixture flow rates. As four different steam plume shapes for pure steam jet in subcooled water flow in a pipe were reported in the previous research, the effect of non-condensable gas on the four steam plume shapes was investigated by introducing a certain amount of air into steam. In the current study, the submerged steam–air mixture jet behavior was investigated through direct visualization techniques. The effect of non-condensable gas on jet plume shapes was recorded by using a high speed camera. The gas–liquid interface and the dimensionless penetration length was obtained by digital image processing method implemented by a MATLAB subroutine. Then the average heat transfer coefficient was calculated based on thermal equilibrium of gas–liquid interface. In the experiment, the gas mass flux at nozzle exit was within 320–780 kg/m2/s, with no more than 1 % non-condensable gas. The results indicated that the non-condensable gas plays an important role on the gas–liquid interface, jet penetration length and heat transfer coefficient. It was found that when 1 % non-condensable gas was mixed with steam jet, the dimensionless penetration length was extended by 16–70 %, and the average heat transfer coefficient decreased by 12–50 %. Based on the force-balance of jet plume, a new quantitative correlation for the steam–air mixture jet penetration length was proposed. The predicted jet penetration length agrees well with the experimental measured values.

Experimental Studies of Combustion and Emission Characteristics of Biomass Producer Gas (BPG) in a Constant Volume Combustion Chamber (CVCC) System

Most of the world’s energy requirements are still derived from natural resources. This will result in a catastrophic energy crisis with negative environmental consequences. The increased energy supply will result in greater consumption of non-renewable sources. The production of biomass producer gas (BPG) from biomass gasification has received significant attention as an alternative fuel due to the depletion of non-renewable resources. This experimental study aimed to determine the flame propagation, flame propagation speed, and chamber pressure trace of BPG at different equivalence ratios. Understanding the characteristics of the BPG’s combustion, finding lower greenhouse gas emissions of BPG, and minimizing the use of fossil fuels is necessary to mitigate these problems. Using the direct visualization technique, an optical constant volume combustion chamber (CVCC) was developed to measure combustion characteristics. Liquid petroleum gas (LPG) was used to compare the flame propagation speed in the CVCC calibration. In comparison to wood pellet (WP), coconut husk (CH), and palm kernel shell (PKS), the chamber peak pressure at ϕ equal to 1 of CH for the combustion of BPG was the lowest at 20.84 bar. At ϕ of 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, and 1.3, the chamber peak pressure of CH was discovered to be around 17.77, 18.12, 18.81, 20.84, 20.39, 17.25, and 16.37 bar, respectively. Compared to the other two types of BPG, CH produced the lowest emissions of CO2 and CO at 2.03% and 0.022%, respectively. In conclusion, the CH had the lowest chamber peak pressure and emissions due to the lower heating value (LHV) being relatively lower.

Second-Harmonic Response in Magnetic Nodal-Line Semimetal Fe3GeTe2

We experimentally investigate second-harmonic transverse voltage response to ac electrical current for a magnetic nodal-line semimetal Fe3GeTe2 (FGT). For zero magnetic field, the observed second-harmonic voltage behaves as a square of the longitudinal current, as it should be expected for nonlinear Hall effect. The magnetic field behavior is found to be sophisticated: while the first-harmonic response shows the known anomalous Hall hysteresis in FGT, the second-harmonic Hall voltage is characterized by the pronounced high-field hysteresis and flat (B-independent) region with curves touching at low fields. The high-field hysteresis strongly depends on the magnetic field sweep rate, so it reflects some slow relaxation process. For the lowest rates, it is also accomplished by multiple crossing points. Similar shape of the second-harmonic hysteresis is known for skyrmion spin textures in nonlinear optics. Since skyrmions have been demonstrated for FGT by direct visualization techniques, we can connect the observed high-field relaxation with deformation of the skyrmion lattice. Thus, the second-harmonic Hall voltage response can be regarded as a tool to detect spin textures in transport experiments.

Accuracy of Four Apex Locators in Premolars with Root Resorption: An In vitro Study.

The aim of the present in vitro study was to compare the accuracy of the working length measurements of four foramen locators: Root ZX mini, Raypex 6, Woodpex III and Propex Pixi in uniradicular premolars with simulated root resorption. For this study, 30 single-rooted permanent premolars were selected. The samples were divided into two groups: 15 teeth with simulated external root resorption and 15 teeth with internal resorption. Each sample was immersed in containers with alginate covering only the root part. Measurements were acquired from the four foramen locators and compared with the working length measurements that have been previously obtained with the direct visual technique and the use of a Digital USB Microscope under 5×. Next, the Shapiro-Wilk normality test was applied. The ANOVA test and t-test for related samples were performed, in order to analyze the measurements obtained. In the teeth with external resorption, no statistically significant differences in the measurements were obtained with Raypex 6 and Propex Pixi foramen locators, but there were statistically significant differences with Root ZX mini and Woodpex III Root Zx mini [Root Zx mini (P=0.040) and Woodpex III (P=0.000)]. On the other hand, in the samples with internal root resorption, there were no statistically significant differences in measurements with the Root ZX mini, Propex Pixi and Raypex 6 foramen locators. However, there were significant differences with Woodpex III. Based on this in vitro study, Raypex 6 had the highest accuracy in premolars with simulated external resorption and Root ZX mini was the most accurate in teeth with simulated internal resorption. Furthermore, external root resorption affects the accuracy of foramen locators more than internal resorption.

Unraveling Dispersion Characteristics of Electrocatalyst Inks for Proton Exchange Membrane Fuel Cells

The membrane electrode assembly (MEA) forms the core of the proton electrolyte membrane fuel cell (PEMFC).1 Catalyst layers (CLs) that are home to the electrochemical reactions are an active component of an MEA. CLs are typically manufactured by various dispersion-coating methods where a catalyst ink is applied onto a membrane. Controlling the CL preparation methods to obtain the ideal microstructure and morphology of the CL is of utmost importance, where tailoring of inks represents a key aspect.2 For the large-scale manufacturing of PEMFCs, obtaining favorable dispersion characteristics of inks is indispensable.In this study, we propose new tools to study dispersion state and stability based on analytical centrifugation (AC) in order to facilitate a knowledge-based approach for ink development. The dispersion behavior of catalyst inks prepared by different processing techniques were compared. The effects of processing methods were characterized by the proposed techniques and by rheological measurements, structural characterization of diluted inks was carried out by electron microscopy.New concepts, S score and stability trajectory 3 were introduced for a time-resolved assessment of inks in their native state by means of AC. S score is a quantitative number calculated from the transmission data recorded by AC. The time-series of S scores results in a stability trajectory that defines the degree of heterogeneity in the dispersion. The findings were validated via a direct visualization technique namely, transmittogram4 and correlated with flow behavior and structural properties. References V. Mehta and J. S. Cooper, J. Power Sources, 114, 32–53 (2003).M. Bredol et al., J. Power Sources, 402, 15–23 (2018).S. Bapat et al., ChemRxiv, preprint, DOI: 10.26434/chemrxiv.13125401.v3 (2021).S. Bapat and D. Segets, ACS Appl. Nanomater., 3, 7384–7391 (2020).

Treatment of Upper Cervical Spinal Cord Injury (Unstable C1-C2) by Direct Visualization and Nailing Technique and the Advantages of Early MRI.

Background The treatment of C1-C2 fractures mainly depends on fracture type and the stability of the atlantoaxial joint. Disruption of the C1-C2 combination is a big challenge, especially in avoiding vertebral artery, nerve, and vein sinus injury during the operation. Purpose This study aims to show the benefit of using the posterior approach and pedicle screw insertion by nailing technique and direct visualization to treat unstable C1-C2 and, moreover, to determine the advantages of performing early MRI in patients with limited neck movement after trauma. Method Between Jan 2017–Feb 2019, we present 21 trauma patients who suffered from C1, C2, or unstable atlantoaxial joint. X-ray, computed tomography (CT), and magnetic resonance image (MRI) were performed preoperatively. All the patients underwent our surgical procedure (posterior approach and pedicle screw placement by direct visualization and nailing technique). Result The mean age was 41.1 years old, 8 females and 14 males. The average follow-up time was 2.6 years. Four patients were with C1 fracture, seven with C2 fracture, six with atlantoaxial dislocation, and four with C1 and C2 fractures. The time of MRI was between 12 hours and 48 hours; neck movement symptoms appeared between 2 days and 2 weeks. Conclusion The posterior approach to treat the C1 and C2 fractures or dislocation by direct visualization and nailing technique can reduce the risk of the vertebral artery, vein sinus, and nerve root injuries with significant improvement. It can show a better angle view while inserting the pedicle screws. An early MRI (12–48 hours) is essential even if no symptoms appear at the time of admission, and if it is normal, it is necessary to repeat it. The presence of skull bleeding can be associated with upper neck instability.

On the state and stability of fuel cell catalyst inks

Catalyst layers (CL), as an active component of the catalyst coated membrane (CCM), form the heart of the polymer electrolyte membrane fuel cell (PEMFC). For optimum performance of the fuel cell, obtaining suitable structural and functional characteristics for the CL is crucial. Direct tuning of the microstructure and morphology of the CL is non-trivial; hence catalyst inks as CL precursors need to be modulated, which are then applied onto a membrane to form the CCM. Obtaining favorable dispersion characteristics forms an important prerequisite in engineering catalyst inks for large scale manufacturing. In order to facilitate a knowledge-based approach for developing fuel cell inks, this work introduces new tools and methods to study both the dispersion state and stability characteristics, simultaneously. Catalyst inks were prepared using different processing methods, which include stirring and ultrasonication. The proposed tools are used to characterize and elucidate the effects of the processing method. Structural characterization of the dispersed particles and their assemblages was carried out by means of transmission electron microscopy. Analytical centrifugation (AC) was used to study the state and stability of the inks. Herein, we introduce new concepts, S score, and stability trajectory, for a time-resolved assessment of inks in their native state using AC. The findings were validated and rationalized using transmittograms as a direct visualization technique. The flowability of inks was investigated by rheological measurements. It was found that probe sonication only up to an optimum amplitude leads to a highly stable colloidal ink.

Approach to Mitral Valve Repair in Infective Endocarditis: Single Center, Single Surgeon, Cross Sectional Study

Objective: The traditional approach was to replace the mitral valve on infective endocarditis when the response to antibiotic therapy is poor. The decision to repair the mitral valve (MV) in this setting is more challenging. This study analysed the different approaches adopted to perform a successful repair. Methods: This retrospective cross sectional study composed of all the patients referred to a single surgeon at Kandy National Hospital, Sri Lanka over a period from June 2011 to August 2020. Repair of MV in every case was the primary approach. Different types of lesion found on direct visual assessment, techniques adopted and outcome of MV repair in native MV infective endocarditis were analysed. Results: Total number of cases was 23, (16 males, 7 females) with a mean age of 42 years. MV repair was successful in all (95%) except one case, as per the intra-operative assessment made (saline test and trans esophageal echocardiography). Vegetation or leaflet perforation were the most common lesions (Posterior mitral valve leaflet/PMVL: 18, Anterior leaflet/AMVL: 7) followed by chordal rupture (6). The table shows the repair strategies used. One death occurred on postoperative third day following MV repair due to rupture of cerebral mycotic aneurysm. 22 patients were discharged home with satisfactory pre-discharge transthoracic 2D echocardiography. Conclusions: The study shows successful repair of MV on infective endocarditis is possible in majority of cases with skilled modulation of surgical approach to individual patient pathology found at the time of surgery. Long term follow-up data requires for the assessment of durability of this approach. Procedure Number Annuloplasty ring (flexible, rigid) 22 Pericardial patchAMVLPMVL 12 Folding plasty 2 Neochords 5 Triangular resection and repairAMVLPMVL 12 Quadrangular resection and repairAMVLPMVL 50 Resection and slidingplastyAMVLPMVL 26

Accuracy of Subaxial Cervical Pedicle Screw Placement Using Direct Visualization Versus Computed Tomography-Based Navigation.

Retrospective analysis of operative data from cadaveric cervical spines. To evaluate the accuracy of neuronavigation compared with laminotomy with direct visualization (DV) of the pedicle for placement of subaxial pedicle screws. Subaxial pedicle screws provide superior fixation compared with other posterior cervical fixation strategies. However, high accuracy is required for safe placement, given the proximity of critical neurovascular structures. Computed tomography (CT)-based neuronavigation has increased in popularity for placement of spinal implants, including subaxial pedicle screws. However, the accuracy of the technique for this application has not been extensively evaluated. Six fresh-frozen cadaveric spines (occiput to T2) were prepared. Pedicle screws were placed from C3 to C7 on either side using either the DV or neuronavigation technique (alternating sides between specimens). Pedicles with diameters <4 mm were excluded. For the DV technique, a hemilaminotomy was performed for DV of pedicle borders and to determine appropriate screw medialization and trajectory. Neuronavigation screws were placed using CT-based navigation with a reference frame mounted on the C2 spinous process. Screw position was evaluated using postoperative CT, and breaches were classified using the Neo classification. Fifty pedicle screws were placed at 25 levels in 6 cadaveric spines; 25 screws each were placed using neuronavigation or DV. No significant difference in accuracy was found between the 2 techniques. Three (12%) breaches occurred in the DV group, and 9 (36%) breaches occurred in the neuronavigation group (P=0.10). The breaches were evenly distributed across all levels. There were no high-grade breaches with DV and only 1 (4.0%) with neuronavigation (P>0.99). Average pedicle cortical and medullary bone widths were higher for levels with no breach (P=0.009 and P=0.02, respectively). High accuracy can be achieved with both neuronavigation and DV for placement of subaxial cervical pedicle screws in cadavers.

The Accuracy and Safety for C2 Transpedicular Screw Placement by Freehand Using the Anatomical Visualization Technique Under Fluoroscopy

Background: The C2 transpedicular screw trajectory does not have an exact guideline for the screw placement because the anatomical variation in this region could results in injury to the vertebral artery during surgery. Objective: To assess the accuracy and safety for C2 transpedicular screw placement by freehand under lateral fluoroscopy with an anatomical landmark using the direct visualization technique. Materials and Methods: The present study was a retrospective data that reviewed 19 consecutive patients who underwent C2 transpedicular screw fixation by freehand placement with lateral fluoroscopic-guided and an anatomical landmark by direct visualization technique between March 2017 and February 2019 in Pathum Thani Hospital. The preoperative CT cervical spine was evaluated before the operation and postoperative CT angiogram images of the neck were taken in all patients after they were clinically stable to evaluate the vertebral artery and accuracy in the transpedicular screw placement. Results: An anatomical landmark by direct visualization technique is accurate and safe for C2 transpedicular screw placement. Conclusion: The C2 transpedicular screw insertion should be positioned using clear anatomical landmarks and determined by direct visualization to avoid vertebral artery injury during surgery. Keywords: C2 transpedicular screw, Vertebral artery injury, Anatomical landmark, The anatomical visualized technique

Confirmation of Femoral Button Deployment Under Direct Visualization During ACL Reconstruction Is Not Beneficial.

The purpose of this study was to determine whether direct visualization of adjustable-loop cortical suspensory button deployment onto the lateral femur increases the cortical contact rate of the button, thereby improving clinical outcomes after anterior cruciate ligament (ACL) reconstruction. Sixty-five single-bundle anteromedial portal ACL reconstructions using an adjustable-loop button were retrospectively divided into 2 groups according to use of the blind pulling technique (control group; 32 patients) or the direct visualization technique (visualization group; 33 patients) when confirming deployment of the button. Cortical contact rate of the button on immediate and 2-year postoperative radiographs, knee stability measured using a KT-1000 arthrometer, and functional scores (Lysholm score and International Knee Documentation Committee score) at 2 years postoperative were compared between the groups. There was no significant difference in femoral cortical contact rate between the groups immediately (56% control group vs 55% visualization group; P=1.000) and at 2 years postoperative (78% control group vs 82% visualization group; P=.764). At 2 years postoperative, there was no difference between the groups regarding knee stability (1.3±0.9 mm vs 1.5±0.8 mm, respectively; P=.404), Lysholm score (P=.436), and International Knee Documentation Committee score (P=.507). Confirmation of adjustable-loop button deployment under direct visualization during anteromedial portal ACL reconstruction neither increased cortical contact rate nor improved clinical outcomes. [Orthopedics. 2020;43(5);270-276.].

Visualization of aluminum dust flame propagation in a square-section tube: comparison of schlieren, shadowgraphy and direct visualization techniques

This paper presents the results of aluminum dust flame propagation inside a vertical prototype of 700 mm height and 150 × 150 mm square cross section. The study considers three visualization techniques. At first, direct visualization is employed to record the flame light with high speed camera. Special attention is given to collect images without saturation. This is especially important with aluminum flames as they are very luminous. To ensure that the exact delimitation of the flame is well defined, two additional optical techniques have been implemented: schlieren and shadowgraphy. For each explosion test, these three techniques were used simultaneously to compare the flame propagation and the burning velocity. The first one corresponds to the flame speed in the laboratory referential, determined from the obtained images, while the burning velocity corresponds to the consumption rate of the reactants by the flame front. The method used for the determination of burning velocity from the images obtained is exposed. A pulsating behavior of the light emitted by the flame is observed with the direct visualization technique. This behavior confused the determination of the flame front. This contour is easier to define with shadowgraphy images. Nevertheless, results of flame front propagation velocity are close for each technique. Burning velocity is then determined only from direct visualization and shadowgraphy images, to avoid uncertainties due to flame contour detection from schlieren images. Again, results of burning velocity are fairly close for both techniques.