Diameter Measurements Research Articles

Evaluation of the effects of physiotherapy on intracranial pressure in intensive care patients by ultrasonographic optic nerve sheats diameter measurement

Evaluation of the effects of physiotherapy on intracranial pressure in intensive care patients by ultrasonographic optic nerve sheats diameter measurement

The relationship between optic nerve sheath diameter measurements and serum ammonia level and systemic diseases in patients followed in the ICU

The relationship between optic nerve sheath diameter measurements and serum ammonia level and systemic diseases in patients followed in the ICU

Validation of bedside manual versus automated measurements of brain arterial diameters from MR angiography.

Brain arterial luminal diameters are reliably measured with automated imaging software. Nonautomated imaging software alternatives such as a Picture Archiving Communication System are more common bedside tools used for manual measurement. This study is aimed at validating manual measurements against automated methods. We randomly selected 600 participants from the Northern Manhattan Study (NOMAS) and 260 participants from the Atahualpa Project studied with 1.5 Tesla MR angiography. Using the Radiant measuring tool, three independent readers (general practitioner, neurology resident, and vascular neurologist) measured manually the diameter of arterial brain vessels. The same vessels were also measured by LKEB Automated Vessel Analysis (LAVA). We calculated the intraclass correlation coefficient (ICC) of each rater's diameters versus those obtained with LAVA. The ICC between diameters obtained by the general practitioner or the neurology resident compared to LAVA was excellent for both internal carotid arteries (ICA) and Basilar Arteries (BA) (ICC>.80 in all comparisons) in NOMAS. In the Atahualpa Project, ICC between diameters obtained by a vascular neurologist and LAVA was good for both ICA and BA (ICC>.60 in all comparisons). The ICCs for the measurements of the remaining arteries were moderate to poor. Results suggest that manual measurements of ICA and BA diameters, but not MCA or ACA, are valid and could be used to identify dilated brain arteries at the bedside and for eventual selection of patients with dolichoectasia into clinical trials.

#1024 Lung ultrasound in 28 versus 8 places and volume status in chronic hemodialysis patients

Abstract Background and Aims Overhydration is considered a significant risk factor for cardiovascular and all-cause mortality in end-stage kidney disease patients. Measurement of total and extracellular water with bioelectrical impedance analysis (BIA), inferior vena cava diameter (IVCd) measurement, and circulating pro-B-type natriuretic peptide (proBNP) levels have previously been tested as possible indicators of volume status in hemodialysis (HD) patients, with BIA showing the most potential. Recently, it has been shown that lung ultrasound (LUS)-guided volume depletion is an effective strategy for relieving lung congestion in chronic HD patients. The aim of our study was to determine whether performing LUS on only 8 places was comparable to the regular 28 places. Method LUS was performed on 29 randomly selected patients before their regular HD procedure in 28 regular places and correlated with 8 places (4 on each side). In addition, BIA with a body composition monitor (BCM) was performed, IVCd was measured using ultrasound and serum NT-proBNP value was determined. Statistical analysis was performed using a commercially available SPSS® for Windows® (version 29.0; Chicago, IL, USA). Spearman's non-parametric test was used to determine a correlation between variables. P-values less than 0.05 were considered statistically significant. Results We included 29 chronic HD patients, 15 male (51.7 %), with a mean age of 66.3 ± 12.5 years and a median dialysis vintage of 53.0 (95% CI (40.9, 100.6)) months. Most patients (96.6 %) had a functional arteriovenous fistula, whereas only one patient (3.4 %) was dialysed using a Hickman catheter. A very strong, directly proportional correlation was found between performing LUS in 28 and 8 places (ρ=0.909; p<0.001). A significant moderate correlation was also found between both LUS in 28 and 8 places and systolic blood pressure (ρ=0.503; p=0.005 and ρ=0.467; p=0.011, respectively) (Table 1). Neither of the LUS methods statistically correlated with other tested volume markers – overhydration, intracellular and extracellular volume measured with BIA, IVCd in inspiration and expiration and IVC index, or serum NT-proBNP levels. Conclusion In our study, we found a very strong, positive, and significant correlation between performing LUS in 28 regular places and 8 places. Both also moderately correlated with systolic blood pressure. However, we did not find a statistically significant correlation between LUS and other tested volume markers.

Investigation of Spray Characteristics for Detonability: A Study on Liquid Fuel Injector and Nozzle Design

Detonation engines are gaining prominence as next-generation propulsion systems that can significantly enhance the efficiency of existing engines. This study focuses on developing an injector utilizing liquid fuel and a gas oxidizer for application in detonation engines. In order to better understand the spray characteristics suitable for the pulse detonation engine (PDE) system, an injector was fabricated by varying the Venturi nozzle exit diameter ratio and the geometric features of the fuel injection hole. Analysis of high-speed camera images revealed that the Venturi nozzle exit diameter ratio plays a crucial role in determining the characteristics of air-assist or air-blast atomization. Under the conditions of an exit diameter ratio of Re/Ri = 1.0, the formation of a liquid film at the exit was observed, and it was identified that the film’s length is influenced by the geometric characteristics of the fuel injection hole. The effect of the fuel injection hole and Venturi nozzle exit diameter ratio on SMD was analyzed by using droplet diameter measurement. The derived empirical correlation indicates that the atomization mechanism varies depending on the Venturi nozzle exit diameter ratio, and it also affects the distribution of SMD. The characteristics of the proposed injector, its influence on SMD, and its velocity, provide essential groundwork and data for the design of detonation engines employing liquid fuel.

Ultrasound Guided Measurement of Inferior Vena Cava Diameter, Common Carotid Artery Diameter versus Central Venous Pressure for Estimation of Intravascular Volume Status in Septic Shock Patients

Background: In critically ill patients, the fluid resuscitation is crucial and is the first step in treatment protocol. Invasive CVP measurement was used to guide fluid resuscitation. However, it is time consuming and invasive maneuver. Ultrasound measurement of inferior vena cave and common carotid arteries are suggest to predict the fluid response as well as CVP or even better. The current work designed to compare inferior vena cava diameter and common carotid artery diameter with central venous pressure for estimation of intravascular volume status in septic shock. Patients and Methods: The study included 60 subjects with septic shock who received vasopressor support. CVP and ultrasound were performed before and after fluid challenge test. Values of inferior vena cava and common carotid arteries were documented and compared to CVP values. This was performed after full clinical assessment by detailed clinical examination and laboratory workup. Results: The MAP was significantly increased and HR decreased after than before procedure. In addition, CVP, (inferior vena cava), ICVmax, ICV min and common carotid artery diameter (CCAD) were significantly increased, IVC CI (%) was significantly reduced after procedure than basal values. There was significant decrease of IVCmax, IVCmin and CCAD while there was significant increase of IVC CI% with lower (<8) than higher (> 8) CVP values. CVP was positively and significantly correlated with IVCmax, IVCmin and CCAD, while it was inversely correlated with IVC CI%. The AUC was over 0.75 for IVCmax, IVCmin and CCAD for prediction of CVP while it was lower than 0.7 for IVC CI%. These data reflected the better predictive power of IVCmax, IVCmin and CCAD. The best cutoff value was 1.35, 1.25, 10.45 and 4.15 for IVCmax, IVCmin, IVC CI% and CCAD successively. Conclusion: IVC and CCA diameters measurement by US may replace CVP measurement for estimation of intravascular volume status in septic shock patients.

Experimental study on promotion of peripheral nerve regeneration by selenium-methylselenocysteine

To investigate the feasibility of selenium-methylselenocysteine (SMC) to promote peripheral nerve regeneration and its mechanism of action. Rat Schwann cells RSC96 cells were randomly divided into 5 groups, which were group A (without any treatment, control group), group B (adding 100 μmol/L H 2O 2), group C (adding 100 μmol/L H 2O 2+100 μmol/L SMC), group D (adding 100 μmol/L H 2O 2+200 μmol/L SMC), group E (adding 100 μmol/L H 2O 2+400 μmol/L SMC); the effect of SMC on cell proliferation was detected by MTT method, and the level of oxidative stress was detected by immunofluorescence for free radicals [reactive oxygen species (ROS)] after determining the appropriate dose group. Thirty-six 4-week-old male Sprague Dawley rats were randomly divided into 3 groups, namely, the sham operation group (Sham group), the sciatic nerve injury group (PNI group), and the SMC treatment group (SMC group), with 12 rats in each group; the rats in the PNI group were fed with food and water normally after modelling operation, and the rats in the SMC group were added 0.75 mg/kg SMC to the drinking water every day. At 4 weeks after operation, the sciatic nerves of rats in each group were sampled for neuroelectrophysiological detection of highest potential of compound muscle action potential (CMAP). The levels of inflammatory factors [interleukin 17 (IL-17), IL-6, IL-10 and oxidative stress factors catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA)] were detected by ELISA assay. The luxol fast blue (LFB) staining was used to observe the myelin density, fluorescence intensity of glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) was observed by immunofluorescence staining, and myelin morphology was observed by transmission electron microscopy with measurement of axon diameter. Western blot was used to detect the protein expressions of p38 mitogen-activated protein kinases (p38MAPK), phosphorylated p38MAPK (p-p38MAPK), heme oxygenase 1 (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2). MTT assay showed that the addition of SMC significantly promoted the proliferation of RSC96 cells, and the low concentration could achieve an effective effect, so the treatment method of group C was selected for the subsequent experiments; ROS immunofluorescence test showed that group B showed a significant increase in the intensity of ROS fluorescence compared with that of group A, and group C showed a significant decrease in the intensity of ROS fluorescence compared with that of group B ( P<0.05). Neuroelectrophysiological tests showed that the highest potential of CMAP in SMC group was significantly higher than that in PNI and Sham groups ( P<0.05). ELISA assay showed that the levels of IL-6, IL-17, and MDA in PNI group were significantly higher than those in Sham group, and the levels of IL-10, SOD, and CAT were significantly lower; the levels of IL-6, IL-17, and MDA in SMC group were significantly lower than those in PNI group, and the levels of IL-10, SOD, and CAT were significantly higher ( P<0.05). LFB staining and transmission electron microscopy showed that the myelin density and the diameter of axons in the SMC group were significantly higher than those of the PNI group and the Sham group ( P<0.05). Immunofluorescence staining showed that the fluorescence intensity of GFAP and MBP in the SMC group were significantly stronger than those in the PNI group and Sham group ( P<0.05). Western blot showed that the relative expressions of Nrf2 and HO-1 proteins in the SMC group were significantly higher than those in the PNI group and Sham group, and the ratio of p-p38MAPK/p38MAPK proteins was significantly higher in the PNI group than that in the SMC group and Sham group ( P<0.05). SMC may inhibit oxidative stress and inflammation after nerve injury by up-regulating the Nrf2/HO-1 pathway, and then inhibit the phosphorylation of p38MAPK pathway to promote the proliferation of Schwann cells, which ultimately promotes the formation of myelin sheaths and accelerates the regeneration of peripheral nerves.

Fetal lower urinary tract obstruction: international Delphi consensus on management and core outcomes set.

To reach a Delphi-generated international expert consensus on the diagnosis, prognostic, management, and core outcome set (COS) of fetal Lower Urinary Tract Obstruction (LUTO). A three-round Delphi procedure was conducted among an international panel of LUTO experts. The panel was provided with a list of literature review-generated parameters for the diagnosis, prognostic, management, and outcomes. A parallel procedure was conducted along with patient groups during the development of COS. A total of 160 experts were approached, of whom 99 completed the first round and 80 (80/99, 80.8%) completed all three rounds. In the first trimester, an objective measurement of longitudinal bladder diameter (with ≥7 mm being abnormal) should be used to suspect LUTO. In the second trimester, imaging parameters of LUTO could include: a) an enlarged bladder, b) a keyhole sign, c) bladder wall thickening, d) bilateral hydro (uretero) nephrosis, and e) male sex. There was a lack of consensus on the current prognostic scoring literature. However, experts agreed on the value of amniotic fluid volume (< 24 weeks) to predict survival and that the value of fetal intervention is to improve neonatal survival. While experts endorsed the role of sonographic parameters of renal dysplasia, at least one vesicocentesis, and urine biochemistry for prognosis and counseling, these items did not reach a consensus for determining fetal intervention candidacy. On the other hand, imaging parameters suggestive of LUTO, absence of life-limiting structural or genetic anomalies, gestational age of ≥16 weeks, and oligohydramnios defined as deepest vertical pocket (DVP) <2 cm should be used as candidacy criteria for fetal intervention based on experts' consensus. If a bladder refill was evaluated, it should be assessed subjectively. Vesicoamniotic shunt should be the first line of fetal intervention. In the presence of suspected fetal renal failure, serial amnioinfusion should only be offered as an experimental procedure under research protocols. The core outcome set for future studies was agreed upon. International consensus on the diagnosis, prognosis, and management of fetal LUTO, as well as the Core Outcome Set, should inform clinical care and research to optimize perinatal outcomes. This article is protected by copyright. All rights reserved.

Influence of CBCT filters and contrast adjustments on peri-implant buccal bone thickness measurement and blooming expression.

To assess whether filter and contrast adjustments can improve the accuracy of CBCT in measuring the buccal bone thickness (BBT) adjacent to dental implants by reducing blooming artifacts. Homogeneous bone blocks with peri-implant BBT of 0.3mm, 0.5mm, and 1mm were scanned using the Orthophos SL system. Three dentists measured the BBT in 234 CBCT scans under different settings of contrast adjustments and 'Sharpen' filter activation. Additionally, implant diameter measurements were taken to assess blooming artifact expression. The differences between tomographic and actual measurements of BBT and implant diameter [(CBCT - actual) * 100 / actual] were subjected to Mixed ANOVA (α = 0.05). The group with the thinnest BBT (0.3mm) had the greatest difference between tomographic and actual measurements (79.9% ± 29.0%). Conversely, the 0.5mm (36.1% ± 38.4%) and 1mm (29.4% ± 12.3%) groups exhibited lower differences (p < 0.05). 'Sharpen' filter activation reduced blooming expression since it resulted in a lower difference for implant diameter (p < 0.05), but it did not influence BBT measurements (p = 0.673). Contrast settings had no impact on BBT (p = 0.054) or implant diameter measurements (p = 0.079). Although filter activation reduced blooming artifacts, neither filter nor contrast adjustments improved the accuracy of CBCT in measuring peri-implant BBT; actual BBT influenced this task. When assessing the peri-implant buccal bone plate in the CBCT system studied, dental surgeons may find it beneficial to adjust contrast and apply filters according to their preferences, since such adjustments were found to have no adverse effects on the diagnostic accuracy of this task. The use of the 'Sharpen' filter may lead to improved representation of implant dimensions.

Meta-analysis: Intestinal ultrasound to evaluate colonic contents and constipation.

Constipation can be diagnosed clinically using the Rome criteria. Ultrasound (US), which lacks the radiation exposure of conventional X-ray, holds promise as a non-invasive tool to evaluate colonic contents and constipation. To examine the role of US in the assessment of constipation. We performed a systematic search of Embase (OVID, 1984), Medline (Ovid, 1946), Cochrane Central, ClinicalTrials.gov and Australia New Zealand Clinical Trials Registry from database inception to 26 January 2024 according to PRISMA guidelines and prospectively registered with PROSPERO. All studies using US to assess constipation or colonic contents in either adults or children were included. Rectal diameter measurements were pooled in meta-analysis. Risk of bias was assessed using the Newcastle Ottawa Scales and Joanna Briggs Institute checklists. Of 12,232 studies screened, 51 articles (6084 patients; 3422 children) describing US to assess symptoms in patients with constipation were included. Most studies used Rome criteria to diagnose constipation. Rectal diameter was associated with clinical constipation in 29 paediatric studies (3331 patients). Meta-analysis showed the mean rectal diameter of constipated patients was significantly higher than controls (mean difference 12 mm, 95% confidence intervals (CI): 6.48, 17.93, p < 0.0001, n = 16 studies). Other features of constipation on US included posterior acoustic shadowing and echogenicity of luminal contents. US is an appealing imaging modality to assess luminal contents and constipation. Further well-designed studies are required to validate US metrics that accurately identify constipation.

Unraveling the Impact of Adsorbed Molecules on Photocatalytic Processes: Advancements in Understanding Facet-Controlled Semiconductor Photocatalysts.

This work aims to demonstrate that the Fe2O3 nanocrystals' adsorptive and photocatalytic properties can be adjusted by exposing the crystal facets that are functionalized. To this end, cube- and disc-like structures were synthesized using a metal ion-mediated hydrothermal route. Thereafter, some of the samples were annealed at 500 °C for 3 h. Our paper combines the experimental part with theoretical calculations of the obtained materials' band edge positions. The results reveal that-aside from hematite-the as-synthesized discs also contain γ-FeOOH and β-Fe2O3 phases, which transform into α-Fe2O3 during annealing. The hydrodynamic diameter, zeta potential, and adsorption kinetics measurements show that the cube-like samples exhibit the highest affinity for cationic, whereas the discs have an affinity for anionic dye. Measurements of the wall zeta potential also reveal that annealing the discs modifies their surface state and ability to adsorb molecules. Photocatalytic tests show that the as-synthesized powders have better photocatalytic performance toward methylene blue decomposition than the annealed ones. The observed small changes in the concentration of the MO during illumination result from the energy band structure of the cube-like crystal orientation.

Deep Learning-Based Detect-Then-Track Pipeline for Treatment Outcome Assessments in Immunotherapy-Treated Liver Cancer.

Accurate treatment outcome assessment is crucial in clinical trials. However, due to the image-reading subjectivity, there exist discrepancies among different radiologists. The situation is common in liver cancer due to the complexity of abdominal scans and the heterogeneity of radiological imaging manifestations in liver subtypes. Therefore, we developed a deep learning-based detect-then-track pipeline that can automatically identify liver lesions from 3D CT scans then longitudinally track target lesions, thereby providing the evaluation of RECIST treatment outcomes in liver cancer. We constructed and validated the pipeline on 173 multi-national patients (344 venous-phase CT scans) consisting of a public dataset and two in-house cohorts of 28 centers. The proposed pipeline achieved a mean average precision of 0.806 and 0.726 of lesion detection on the validation and test sets. The model's diameter measurement reliability and consistency are significantly higher than that of clinicians (p = 1.6 × 10-4). The pipeline can make precise lesion tracking with accuracies of 85.7% and 90.8% then finally yield the RECIST accuracies of 82.1% and 81.4% on the validation and test sets. Our proposed pipeline can provide precise and convenient RECIST outcome assessments and has the potential to aid clinicians with more efficient therapeutic decisions.

Evaluating geometric measurement accuracy based on 3D model reconstruction of nursery tomato plants by Agisoft photoscan software

Measuring the vegetation structure of a plant with the help of 3D images is a non-destructive method that can be used to monitor the plant’s status during the growing season. Structure from motion (SfM) is a popular optical distance measurement method that uses 2D images to create 3D models. Identifying factors that influence the precision of SfM is important due to its increasing use in phenotyping. The primary objectives of this study were, i) to scrutinize the impact of imaging parameters—including, color checkerboard location, overlap size of images, and background filtering—on the quality indices of 3D models, and ii) to attain precise measurements of leaf area, stem diameter, and height through the combination of images captured from different camera shooting angles. The three nursery tomato plants were photographed at every five-degree rotation of the turntable, five different locations of color checkerboards, and five camera shooting angles. Results indicated the color checkerboard’s presence and position affect the quality indices of the 3D models. Visually and by the lowest mean keypoint size value, the least noisy 3D model was obtained when the wall of the plant pot was covered with a checkerboard. When the base-to-distance (b/y) ratio as the image overlap index increased from 0.1 to 0.2, the generation time of the 3D models decreased by more than two times. Optimal Mean Absolute Percentage Error (MAPE) values of 1.08 %, 1.01 %, and 1.38 % were achieved for the estimation of leaf area, stem diameter, and height, respectively. This was recorded by using images taken at 0°, 30°, and 105° vertical azimuth angles. Constructing a 3D model by integrating images captured from other angles or more azimuth angles represents numerous visual challenges and leads to problems of point mismatch, which affects the accuracy of measurements.

Glomerular Diameter Measurements on Light Microscopy: A New Parameter Available to Pathologists and its Utility in IgA Nephropathy

Background: With the availability of whole slide digital scanners, fairly accurate glomerular diameter (GD) measurements are now possible on light microscopy. The value of these measurements in prognosis and diagnosis of immunoglobulin A nephropathy (IgAN) have not been studied widely. IgAN is a major cause of end-stage renal disease (ESRD) worldwide, and its progression is currently assessed using Oxford scores, serum creatinine, and 24-h urinary protein. We aimed to correlate the mean and maximum GDs with serum creatinine, 24-h urinary protein, and Oxford scores in patients with IgAN. Materials and Methods: One hundred biopsies of IgAN with a minimum of eight viable glomeruli were collected along with data of their 24-h proteinuria, serum creatinine, and Oxford scores. The slides were scanned using the Philips IntelliSite Pathology Solution-Ultra Fast Scanner. Mean GD of each glomerulus was calculated as the mean of two measurements, that is, the maximal diameter of the glomerulus and the maximal chord perpendicular to the maximal diameter. Maximum GD was also recorded for each case. The Spearman rho/Pearson R correlation coefficient was used to make this correlation. P-values &lt;0.05 were considered statistically significant. Results: The mean age of the patients was 34.67 ± 12.03 years, and they showed a male preponderance. The overall mean GD was 151.82 ± 28.69 µm, and maximum GD was 205.40 ± 32.76 µm. No statistically significant correlation was observed between the mean or maximum GD and the 24-h proteinuria, serum creatinine levels, and Oxford scores. Conclusion: GD in IgAN does not correlate with proteinuria, serum creatinine, or Oxford scores.

Metallographic Etching of Al–Mg–Zn–(Cu) Crossover Alloys

Various alloys demand customized etchants due to their diverse chemical compositions, particularly in the realm of aluminum alloys. Consequently, in this study, a technique is proposed for metallographic visualization of small grain structures within Al–Mg–Zn–(Cu) crossover alloys. In this method, a thermal pretreatment combined with an etching process is relied on. In the study, it is primarily sought to comprehend how grain‐boundary precipitation affects etchability, addressing the complexities of characterizing these alloys. The demonstrated approach facilitates the swift assessment of grain sizes &lt;10 μm using light optical microscopy. Exploring the etchability of Al–Mg–Zn–(Cu) crossover alloys across a standard heat‐treatment pathway identifies the optimal treatment and suitable etchant for grain visualization. Through process refinement, a reduction in processing time is achieved by employing a single‐step preheat treatment lasting 20 min at 180 °C post solution annealing. Transmission electron microscope analysis reveals continuous occupancy of the grain boundary with T‐phase as the key factor influencing the alloy's etchability. Grain size assessment involves line intercept counting and equivalent circle diameter measurement for precise characterization.

Updated 2022 ACC/AHA Guideline Improves Concordance Between TTE and CT in Monitoring Marfan Snydrome and Related Disorders, but Relevant Measurement Differences Remain Frequent.

Patients diagnosed with Marfan syndrome or a related syndrome require frequent aorta monitoring using imaging techniques like transthoracic echocardiography (TTE) and computed tomography (CT). Accurate aortic measurement is crucial, as even slight enlargement (>2 mm) often necessitates surgical intervention. The 2022 ACC/AHA guideline for Aortic Disease Diagnosis and Management includes updated imaging recommendations. We aimed to compare these with the 2010 guideline. This retrospective study involved 137 patients with Marfan syndrome or a related disorder, undergoing TTE and ECG-triggered CT. Aortic diameter measurements were taken based on the old 2010 guideline (TTE: inner edge to inner edge, CT: external diameter) and the new 2022 guideline (TTE: leading edge to leading edge, CT: internal diameter). Bland-Altman plots compared measurement differences. Using the 2022 guideline significantly reduced differences outside the clinical agreement limit from 49% to 26% for the aortic sinus and from 41% to 29% for the ascending aorta. Mean differences were -0.30 mm for the aortic sinus and +1.12 mm for the ascending aorta using the 2022 guideline, compared to -2.66 mm and +1.21 mm using the 2010 guideline. This study demonstrates for the first time that the 2022 ACC/AHA guideline improves concordance between ECG-triggered CT and TTE measurements in Marfan syndrome patients, crucial for preventing life-threatening aortic complications. However, the frequency of differences >2 mm remains high. Accurate aortic diameter measurement is vital for patients at risk of fatal aortic complications. While the 2022 guideline enhances concordance between imaging modalities, frequent differences >2 mm persist, potentially impacting decisions on aortic repair. The risk of repeat radiation exposure from ECG-triggered CT, considered the 'gold standard', continues to be justified.

Propagation constant-based diameter measurement technique for a submicrometer-scale optical fiber.

Diameter is a critical parameter for determining the physical properties of a submicrometer optical fiber and requires an accurate measurement. In this study, we proposed, to our knowledge, a novel diameter measurement technique derived from the waveguide theory, utilizing the pitch of a standing-wave near-field light generated by two counter-propagating lights within the submicrometer optical fiber. In a submicrometer optical fiber, the propagating light extends into the surrounding air as near-field light, existing within a range approximately equivalent to one wavelength from the surface of the fiber. By generating the standing-wave near-field light with the incident lights from both ends of the fiber, the pitch of the standing-wave near-field light can be measured by scanning along the fiber's central axis with a scanning near-field optical microscopy probe. The fiber diameter is subsequently acquired by solving the optical fiber eigenvalue equation. Based on the feasibility verification experiment, a high-precision measurement of approximately 0.50 µm was realized for the diameter of the optical fiber.

Measuring Tree Diameter Using LiDAR Equipped iPad: An Evaluation of ForestScanner and Arboreal Forest Applications

Abstract Forest owners need simple and efficient tools to capture and understand forest metrics. Additionally, they could benefit from emerging technologies in forest analysis. Light detection and ranging (LiDAR) sensors allow for precise measurements of different variables and can be used more easily in forestry settings thanks to their introduction into smartphones and tablets. ForestScanner and Arboreal Forest are two applications (apps) that allow for the measurement of tree diameter at breast height (DBH) on LiDAR-equipped devices. Our study sought to analyze and compare (1) the timing of traditional and LiDAR-based forest inventory methods and (2) the accuracy of traditional and LiDAR-based forest measurements. We established a series of plots to record and compare tree DBH and measurement time between a traditional diameter tape, ForestScanner, and Arboreal Forest. We found that DBH measurements from the apps were in good agreement with diameter tape measurements; however, both apps tended to underestimate DBH. Additionally, measurement time for both apps was found to be significantly shorter than traditional tape measurements. Further improvements in LiDAR apps can present a simple and efficient way for future forest analysis by seasoned foresters and private landowners. Study Implications: LiDAR smartphone applications represent a cost-effective and time-efficient method for wide-spread forest management, especially among landowners who have little access to forestry-specific equipment. As these technologies continue to advance, the incorporation of functions for plot establishment, height measurements, biomass estimations, and ecosystem dynamics could become valuable assets in the forest industry. We encourage individuals to further test LiDAR measurement applications themselves, as further training on these applications will help developers to improve application accuracy.

Morphometric analysis of the foramen ovale in the Mexican population using computed tomography scan.

The assessment of cranial foramina is an important part of the objective diagnostic and therapeutic study relevant to pathologies involving structures of the skull base. The study of the foramen ovale not only holds significance for anatomical development but also bears profound surgical importance, such as in trigeminal neuralgia, and diagnostic importance in tumors and various types of epilepsy. It becomes relevant in fine-needle aspiration techniques in perineural tumor procedures, for electroencephalographic analysis in seizures, and therapeutic procedures such as percutaneous trigeminal rhizotomy for trigeminal neuralgia. A cross-sectional study at the Department of Neurosurgery, Specialties Hospital, La Raza National Medical Center, Mexico City, involved 70 patients aged >18 years who underwent a single skull computed tomography scan between July 2023 and March 2024. Patients with sufficient scan quality and optimal visualization of skull base foramina were included in the study. Measurements of tomographic images were taken using Inobitec's DICOM file viewer. Data analysis in Microsoft Excel yielded mean, standard deviation, and 95% confidence interval (CI) for morphometric parameters of the foramen ovale. Analysis of tomographies from 70 patients revealed a total of 140 foramen ovale, evenly split between 25 males (35.7%) and 45 females (64.3%). The measurements for the maximum anteroposterior diameter, transverse diameter, and surface area of all foramina were as follows: 6.61 ± 0.25 mm (95% CI), 3.97 ± 0.21 mm (95% CI), and 20.84 ± 1.58 mm2 (95% CI), respectively. Specific measurements for the right and left sides were obtained: for the right side, 6.59 ± 0.26 mm (95% CI) and 3.89 ± 0.21 mm (95% CI) for the maximum anteroposterior and transverse diameters, respectively, and 20.38 ± 1.62 mm2 (95% CI) for the surface area. For the left side, the measurements were 6.63 ± 0.24 mm (95% CI), 4.05 ± 0.21 mm (95% CI), and 21.31 ± 1.55 mm2 (95% CI) for the maximum anteroposterior diameter, transverse diameter, and surface area, respectively. The maximum and minimum dimensions for anteroposterior and transverse diameters were 10.67 mm, 4.41 mm, 7.09 mm and 2.36 mm, respectively, with a corresponding range for the surface area of 10.16 mm2-44.13 mm2. The average minimum distance between the foramen ovale and the foramen spinosum was 2.32 ± 0.24 mm (95% CI). In males, the average size of the foramen ovale was 23.66 ± 1.61, which was 22% larger than the average size in females (19.28 ± 1.45) (P = 0.0001). The foramen ovale is one of the main anatomical structures of the skull base, and besides that, it is complex and not directly accessible for clinical evaluation, useful information can be obtained through morphometric analysis. The present study provides specific anatomical data with morphological patterns to increase the understanding of the characteristics of the foramen ovale in the Mexican population. These are intended to be helpful in the pursuit of acknowledging the morphometrics and thus being able to plan neurosurgical procedures in the middle cranial fossa.

Cerebral hemodynamics and optic nerve sheath diameter acquired via neurosonology in critical patients with severe coronavirus disease: experience of a national referral hospital in Peru.

We aimed to describe the neurosonological findings related to cerebral hemodynamics acquired using transcranial Doppler and to determine the frequency of elevated ICP by optic nerve sheath diameter (ONSD) measurement in patients with severe coronavirus disease (COVID-19) hospitalized in the intensive care unit of a national referral hospital in Peru. We included a retrospective cohort of adult patients hospitalized with severe COVID-19 and acute respiratory failure within the first 7 days of mechanical ventilation under deep sedoanalgesia, with or without neuromuscular blockade who underwent ocular ultrasound and transcranial Doppler. We determine the frequency of elevated ICP by measuring the diameter of the optic nerve sheath, choosing as best cut-off value a diameter equal to or >5.8 mm. We also determine the frequency of sonographic patterns obtained by transcranial Doppler. Through insonation of the middle cerebral artery. Likewise, we evaluated the associations of clinical, mechanical ventilator, and arterial blood gas variables with ONSD ≥5.8 mm and pulsatility index (PI) ≥1.1. We also evaluated the associations of hemodynamic findings and ONSD with mortality the effect size was estimated using Poisson regression models with robust variance. This study included 142 patients. The mean age was 51.39 ± 13.3 years, and 78.9% of patients were male. Vasopressors were used in 45.1% of patients, and mean arterial pressure was 81.87 ± 10.64 mmHg. The mean partial pressure of carbon dioxide (PaCO2) was elevated (54.08 ± 16.01 mmHg). Elevated intracranial pressure was seen in 83.1% of patients, as estimated based on ONSD ≥5.8 mm. A mortality rate of 16.2% was reported. In the multivariate analysis, age was associated with elevated ONSD (risk ratio [RR] = 1.07). PaCO2 was a protective factor (RR = 0.64) in the cases of PI ≥ 1.1. In the mortality analysis, the mean velocity was a risk factor for mortality (RR = 1.15). A high rate of intracranial hypertension was reported, with ONSD measurement being the most reliable method for estimation. The increase in ICP measured by ONSD in patients with severe COVID-19 on mechanical ventilation is not associated to hypercapnia or elevated intrathoracic pressures derived from protective mechanical ventilation.