Volume Scans Research Articles

Predictive coding compressive sensing optical coherence tomography hardware implementation

Compressed sensing (CS) is an approach that enables comprehensive imaging by reducing both imaging time and data density, and is a theory that enables undersampling far below the Nyquist sampling rate and guarantees high-accuracy image recovery. Prior efforts in the literature have focused on demonstrations of synthetic undersampling and reconstructions enabled by compressed sensing. In this paper, we demonstrate the first physical, hardware-based sub-Nyquist sampling with a galvanometer-based OCT system with subsequent reconstruction enabled by compressed sensing. Acquired images of a variety of samples, with volume scanning time reduced by 89% (12.5% compression rate), were successfully reconstructed with relative error (RE) of less than 20% and mean square error (MSE) of around 1%.

Development of an evaluation method for precipitation particle types by using disdrometer data

Abstract A method for evaluating precipitation particle types from the size-fall velocity data observed by disdrometers by combining an expectation-maximization (EM) algorithm and a self-organizing map (SOM) was developed. An EM algorithm was used to estimate the particle size-fall velocity relationships according to previous work, and the SOM map was used to classify the relationships into graupel or snow categories. The method was applied for snowfall data observed by the volume scanning video disdrometer at a site in Sapporo, Japan, and the daily graupel-to-solid precipitation ratio (G/S ratio) from 1 December, 2017 to 28 February, 2018 was obtained. The sensitivity of the results to different SOM configurations, SOM node groupings, and training datasets was also tested. The G/S ratio obtained from the simulation data of a meteorological model was compared as an example of the application of the product created by the new method.

First in-vivo magic angle directional imaging using dedicated low-field MRI.

To report the first in-vivo results from exploiting the magic angle effect, using a dedicated low-field MRI scanner that can be rotated about two axes. The magic angle directional imaging (MADI) method is used to depict collagen microstructures with 3D collagen tractography of knee ligaments and the meniscus. A novel low-field MRI system was developed, based on a transverse field open magnet, where the magnet can be rotated about two orthogonal axes. Sets of volume scans at various orientations were obtained in healthy volunteers. The experiments focused on the anterior cruciate ligament (ACL) and the meniscus of the knee. The images were co-registered, anatomical regions of interest (ROIs) were selected and the collagen fiber orientations in each voxel were estimated from the observed image intensity variations. The 3D collagen tractography was superimposed on conventional volume images. The MADI method was successfully employed for the first time producing in-vivo results comparable to those previously reported for excised animal specimens using conventional MRI. Tractography plots were generated for the ACL and the menisci. These results are consistent with the known microstructure of collagen fibers in these tissues. Images obtained using low-field MRI with 1 mm3 resolution were of sufficient quality for the MADI method, which was shown to produce high quality in-vivo information of collagen microstructures. This was achieved using a cost effective and sustainable low-field magnet making the technique potentially accessible and scalable, potentially changing the way we image injuries or disease in joints.

Preoperative discrimination of invasive and non-invasive breast cancer using machine learning based on automated breast volume scanning (ABVS) radiomics and virtual touch quantification (VTQ)

PurposeEvaluating the efficacy of machine learning for preoperative differentiation between invasive and non-invasive breast cancer through integrated automated breast volume scanning (ABVS) radiomics and virtual touch quantification (VTQ) techniques.MethodsWe conducted an extensive retrospective analysis on a cohort of 171 breast cancer patients, differentiating them into 124 invasive and 47 non-invasive cases. The data was meticulously divided into a training set (n = 119) and a validation set (n = 52), maintaining a 70:30 ratio. Several machine learning models were developed and tested, including Logistic Regression (LR), Random Forest (RF), Decision Tree (DT), and Support Vector Machine (SVM). Their performance was evaluated using the Area Under the Receiver Operating Characteristic (ROC) Curve (AUC), and visualized the feature contributions of the optimal model using Shapley Additive Explanations (SHAP).ResultsThrough both univariate and multivariate logistic regression analyses, we identified key independent predictors in differentiating between invasive and non-invasive breast cancer types: coronal plane features, Shear Wave Velocity (SWV), and Radscore. The AUC scores for our machine learning models varied, ranging from 0.625 to 0.880, with the DT model demonstrating a notably high AUC of 0.874 in the validation set.ConclusionOur findings indicate that machine learning models, which integrate ABVS radiomics and VTQ, are significantly effective in preoperatively distinguishing between invasive and non-invasive breast cancer. Particularly, the DT model stood out in the validation set, establishing it as the primary model in our study. This highlights its potential utility in enhancing clinical decision-making processes.

Investigation of the Reproducibility of Portable Optical Coherence Tomography in Diabetic Macular Edema

Background: Diabetic macular edema (DME) causes vision impairment and significant vision loss. Portable optical coherence tomography (OCT) has the potential to enhance the accessibility and frequency of DME screening, facilitating early diagnosis and continuous monitoring. This study aimed to evaluate the reliability of a portable OCT device (ACT100) in assessing DME compared with a traditional stationary OCT device (Cirrus 5000 HD-OCT plus). Methods: This prospective clinical investigation included 40 eyes of 33 patients with DME. Participants with significant refractive errors (myopia > −6.0 diopters or hyperopia > +3.0 diopters), vitreous hemorrhage, tractional retinal detachment, or other ocular diseases affecting imaging were excluded. Spectral-domain OCT was performed by a single examiner using both devices to capture macular volume scans under mydriasis. Central macular thickness (CMT) was evaluated using the analysis software for each device: Cirrus used version 6.0.4, and ACT100 used version V20. We analyzed inter-evaluator and inter-instrument agreements for qualitative assessments of the intraretinal fluid (IRF), subretinal fluid (SRF), and epiretinal membrane (ERM) using Cohen’s kappa coefficient, whereas quantitative CMT assessments were correlated using Spearman’s correlation coefficient. Results: Substantial inter-evaluator agreement for IRF/SRF (κ = 0.801) and ERM (κ = 0.688) with ACT100 and inter-instrument agreement (κ = 0.756 for IRF/SRF, κ = 0.684 for ERM) were observed. CMT values measured using ACT100 were on average 29.6 μm lower than that of Cirrus (285.8 ± 56.6 vs. 315.4 ± 84.7 μm, p < 0.0001) but showed a strong correlation (R = 0.76, p < 0.0001). Conclusions: ACT100 portable OCT demonstrated high reliability for DME evaluations, comparable to that of stationary systems.

Critical Impact of Working Distance on OCT Imaging: Correction of Optical Distortion and Its Effects on Measuring Retinal Curvature.

To assess the impact of working distance (WD) on optical distortion in optical coherence tomography (OCT) imaging and to evaluate the effectiveness of optical distortion correction in achieving consistent retinal Bruch's membrane (BM) layer curvature, regardless of variations in WD. Ten subjects underwent OCT imaging with four serial macular volume scans, each employing distinct WD settings adjusted by balancing the sample and reference arm of the OCT interferometer (eye length settings changed). Either of two types of 30° standard objectives (SOs) was used. A ray tracing model was used to correct optical distortion, and BM layer curvature (represented as the second derivative of the curve) was measured. Linear mixed effects (LME) modeling was used to analyze factors associated with BM layer curvature, both before and after distortion correction. WD exhibited significant associations with axial length (β = -1.35, P < 0.001), SO type (P < 0.001), and eye length settings (P < 0.001). After optical distortion correction, the mean ± SD BM layer curvature significantly increased from 16.80 ± 10.08µm-1 to 49.31 ± 7.50µm-1 (P < 0.001). The LME model showed a significant positive association between BM layer curvature and WD (β = 1.94, P < 0.001). After distortion correction, the percentage change in BM layer curvature due to a 1-mm WD alteration decreased from 9.75% to 0.25%. Correcting optical distortion in OCT imaging significantly mitigates the influence of WD on BM layer curvature, enabling a more accurate analysis of posterior eye morphology, especially when variations in WD are unavoidable.

MIXED PATHOPHYSIOLOGIES OF LAMELLAR MACULAR HOLES AND RELATED DISEASES: A Multimodal Optical Coherence Tomography-Based Study.

To investigate the characteristics of mixed pathophysiologies in lamellar macular holes (LMHs) and related diseases using multimodal optical coherence tomography. Overall, 126 eyes diagnosed with LMH, epiretinal membrane foveoschisis, or macular pseudohole using the horizontal B-scan image according to the definition proposed by Hubschman et al in 2020 were analyzed using multimodal optical coherence tomography imaging including horizontal and vertical 5-line B-scan, radial scan, and macular three-dimensional volume scan images. If at least two diagnostic criteria for LMH, epiretinal membrane foveoschisis, or macular pseudohole were satisfied in these scans, the patient was diagnosed as having a "mixed type." Retinal traction force was quantitatively evaluated by measuring the maximum depth of the retinal folds using en-face images. Mixed types constituted 34.1% of the cases. The LMH-related mixed group demonstrated intermediate characteristics between the epiretinal membrane foveoschisis/macular pseudohole and true LMH groups in terms of retinal traction and LMH-specific features and had a significant positive correlation between the maximum depth of the retinal folds and mean M-CHARTS scores (P = 0.034). A thorough optical coherence tomography analysis is necessary to accurately diagnose LMH and related diseases. A significant positive correlation was observed between the maximum depth of the retinal folds and the degree of metamorphopsia in the LMH-related mixed group.

Location and Extent of Paravascular Nerve Fiber Layer Clefts in Eyes with Epiretinal Membranes.

Purpose: The clinical use of en face optical coherence tomography (OCT) has revealed nerve fiber layer clefts in the retinal nerve fibers in eyes with macula-centered epiretinal membranes (ERMs). The purpose of this study is to describe the location and the extent of retinal nerve fiber layer (RNFL) clefts in eyes with symptomatic ERMs. Methods: We conducted a retrospective review of 17 individual eyes in 17 patients with symptomatic ERMs and a control group of 10 healthy eyes from 10 subjects who had been examined for unrelated causes. The examinations performed included best-corrected visual acuity, rebound tonometry, fundus photography, structural OCT and angiographic OCT (OCTA) made in the form of 12 × 12 mm angiographic volume scans. Results: Hyporeflective RNFL clefts, seen in 14 out of 17 eyes with ERMs, were sharply demarcated in the en face presentation of slabs extending from the internal limiting membrane through the RNFL or including only the latter. The clefts were capillary-free on OCTA scans and formed depressions of the retinal surface. Most of the clefts were adjacent to and followed the course of the retinal trunk vessels, but clefts were also seen along smaller macular vessels and beyond the retinal vascular arcades. Conclusions: Paravascular RNFL clefts can be observed beyond the vascular arcades and adjacent to small vessels on OCTA block scan data. This suggests that the direction and magnitude of tractional displacement of the inner retina in eyes with epimacular membranes can extend beyond the vascular arcades and add to an improved analysis of abnormal fundus findings.

Intra‐arterial contrast enhanced computed tomography of the deep digital flexor tendon and palmar veins in the distal forelimb in Jeju horses: Evaluating contrast‐enhancing factors

AbstractBackgroundFew studies have investigated the adequate contrast enhancement (CE) evaluation depending on concentration, volume, and rate of administration of contrast media (CM) and the scan parameters in equine contrast enhanced computed tomography (CECT).ObjectivesTo investigate CE of the deep digital flexor tendon (DDFT) and veins depending on the computed tomography (CT) voltage and concentration, volume, and rate of CM administration during intra‐arterial CECT of equine distal forelimbs.Study DesignIn vivo experiments.MethodsSix horses underwent 54 CT scans. First, the CE of DDFT and veins was evaluated depending on the voltage (80 kV and 250 mA or 120 kV and 150 mA) and CM concentration (150, 120, or 90 mg I/mL in 50 mL of CM). Second, CE of DDFT and veins was evaluated depending on the CM volume (50, 100, or 150 mL) and administration rate (2, 4, or 6 mL/s) with a fixed iodine delivery rate (IDR; 300 or 180 mg I/s).ResultsContrast enhancement of DDFT was significantly higher at 80 kV of voltage and 150 mg I/mL of CM concentration (Median: 29.65; IQR: 1.74; p &lt; 0.05). CE of the DDFT positively correlated with CM concentration (p &lt; 0.001; r = 0.75). At 180 mg I/s IDR, contrast attenuation in the medial and lateral palmar veins significantly decreased at a CM of 30 mg I/mL, rate of 6 mL/s, and volume of 150 mL (median and IQR: 985.93 and 71.8 Hounsfield units [HU] and 988.73 and 41.16 HU, respectively); the CE was sufficient to distinguish between the vessels and the adjacent structures.Main LimitationsThe number of animals was small.ConclusionsOur results suggest that a low CM concentration could yield sufficient CE of the DDFT and arteries with adjusted CT scanning parameters or volume and injection rate of CM.

Diagnostic utility of brain MRI volumetry in comparing traumatic brain injury, Alzheimer disease and behavioral variant frontotemporal dementia

BackgroundBrain MRI with volumetric quantification, MRI volumetry, can improve diagnostic delineation of patients with neurocognitive disorders by identifying brain atrophy that may not be evident on visual assessments.ObjectiveTo investigate diagnostic utility of MRI volumetry in traumatic brain injury (TBI), early-onset Alzheimer disease (EOAD), late-onset Alzheimer disease, and behavioral variant frontotemporal dementia (bvFTD).MethodWe utilized 137 participants of TBI (n = 40), EOAD (n = 45), LOAD (n = 32), and bvFTD (n = 20). Participants had 3D T1 brain MRI imaging amendable to MRI volumetry. Scan volumes were analyzed with Neuroreader. One-way ANOVA compared brain volumes across diagnostic groups. Discriminant analysis was done with leave-one-out cross validation on Neuroreader metrics to determine diagnostic delineation across groups.ResultLOAD was the oldest compared to other groups (F = 27.5, p < .001). There were no statistically significant differences in sex (p = .58) with women comprising 54.7% of the entire cohort. EOAD and LOAD had the lowest Mini-Mental State Exam (MMSE) scores compared to TBI (p = .04 for EOAD and p = .01 for LOAD). LOAD had lowest hippocampal volumes (Left Hippocampus F = 13.1, Right Hippocampus F = 7.3, p < .001), low white matter volume in TBI (F = 5.9, p < .001), lower left parietal lobe volume in EOAD (F = 9.4, p < .001), and lower total gray matter volume in bvFTD (F = 32.8, p < .001) and caudate atrophy (F = 1737.5, p < .001). Areas under the curve ranged from 92.3 to 100%, sensitivity between 82.2 and 100%, specificity of 78.1-100%. TBI was the most accurately delineated diagnosis. Predictive features included caudate, frontal, parietal, temporal lobar and total white matter volumes.ConclusionWe identified the diagnostic utility of regional volumetric differences across multiple neurocognitive disorders. Brain MRI volumetry is widely available and can be applied in distinguishing these disorders.

Foveal avascular zone area measurement in diabetic patients: Superficial, deep or combined retinal vascular complex?

PurposeTo compare differences in the foveal avascular zone (FAZ) area, measured in the Superficial Vascular Complex (SVC), Deep Vascular Complex (DVC) and a combined analysis of both (SDVC), using two Spectral Domain OCT angiography (OCT-A) protocols, High Speed (HS) and High Resolution (HR). MethodsA total of 26 eyes of diabetic patients, with and without macular oedema, were examined with two different fovea centered OCT-A volume scans. The two protocols were HS and HR volume scans, and the foveal avascular zone was manually measured in the SVC, DVC, and SDVC slabs by two masked investigators. Inter and intraoperator variability was analysed using Intraclass Correlation Coefficient (ICC) and differences were compared between the HR and HS acquisitions throughout the different vascular slabs. ResultsIntraoperator variability was low in all slabs (ICC > 0.9) and interoperator variability was lower for HR (ICC 0.835–0.911) compared to HS (ICC between 0.604 and 0.865). Comparing HS and HR measurements for the same slab, the correlation was only moderate in SVC and DVC (ICC was 0.640 and 0.568 respectively) but was good in the SDVC (ICC = 0.823). FAZ area measurement in SDVC also showed the smallest bias (mean difference 0.009 mm2) and the narrowest limits of agreement (−0.175 to 0.193 mm2). ConclusionsEven in cases of diabetic macular oedema, when measuring the FAZ area, the reproducibility was better between HS and HR protocols when using the SDVC slab, compared to the SVC or DVC slabs alone. Further studies should evaluate the use of the combined SDVC slab for the FAZ assessment, compared to the SVC and DVC slabs alone, in the detection and progression of different retinal diseases.

EP45 - Improving Management of Patients undergoing Inguinal Hernia Repair Who Experience Post-Operative Urinary Retention

Abstract Aims Post-operative urinary retention (POUR) is a common complication following inguinal hernia repair. Left untreated POUR can result in significant patient discomfort, acute kidney injury, detrusor muscle damage and infection. It was observed that the detection and management of POUR in our trust following planned day case inguinal hernia repair was varied, often resulting in unplanned admission. We therefore carried out a review of how our trust is managing these patients. Methods A retrospective analysis of all patients undergoing planned day case inguinal hernia repair in a single institution between March 2023 and August 2023 was performed. Patients having open, laparoscopic, or robotic repair were included. Data was collected on demographics, documentation of POUR, time to diagnosis, bladder scan volume, catheterisation, overnight stay and follow up for all patients. Results 124 patients underwent inguinal hernia repair. 13 patients reported experiencing POUR (10.4%). 9 patients experienced POUR during their initial admission, of which 8 had unplanned overnight admissions. 5 patients were not managed with catheterisation despite having significant volume of urine detected on bladder scan (&amp;gt;700ml). Time to diagnosis varied with POUR not being detected for 24 hours for one patient. 4 patients went into retention after discharge and re-presented via the emergency department. Conclusion Significant variation in the detection and management of patients with POUR was noted in this cohort. Introduction of a POUR pathway in day-surgery describing both diagnosis and management has therefore been created to try and address this, to improve outcomes and reduce hospital admission.

410. THE RELATIONSHIP BETWEEN GASTRIC CONDUIT EMPTYING, FUNCTIONAL ANATOMY AND PERISTALSIS: A DETAILED ANALYSIS USING DYNAMIC MAGNETIC RESONANCE IMAGING

Abstract Background Gastric conduit peristalsis post oesophagectomy is an important mediator of conduit emptying and consequently gastrointestinal symptoms and quality of life. The relationship between anatomical variations of the conduit, peristaltic function and transpyloric flow are incompletely defined. We aimed to analyse gastric conduit function using dynamic MRI to evaluate functional anatomy, quantify peristaltic function and measure emptying. Methods Eighteen patients with gastric conduit reconstruction post oesophagectomy and 12 controls with normal gastric anatomy were recruited. Dynamic and static sequences of MRI following ingestion of a semi solid meal were obtained. Peristalsis variables including Gastric Motor Index (GMI - Velocity x Amplitude) were measured at 4 time points throughout the MRI, and volume scans were taken at the beginning and end of the 20-minute scanning period. Nuclear Scintigraphy conduit emptying studies were obtained from 17/18 (94%) of patients. Quality of Life questionnaire data was collected. Results Nine (50%) conduits demonstrated coordinated peristalsis, 3(16.7%) had no measurable peristalsis and 6 (33.3%) had incoordinate peristalsis. Regarding conduits vs controls, there was no difference in peristaltic wave frequency (5 vs 5/90 seconds) or GMI (35.45 vs 36.5, p=0.61), but emptying was decreased (0.10% vs 15% p=0.01). Acute angulation of the conduit was associated with a slower emptying half time (444 vs 127 min, p=0.025). Conduit width and location of the pylorus relative to the hiatus made no significant difference to peristalsis or emptying. Quality of life scores were significantly better in controls compared with conduits. Conclusion Although coordinate peristalsis was present in many conduits, it did not appear to be a key mediator of conduit emptying. Conduit shape and location within the mediastinum significantly affected emptying. These data demonstrate that construction of the conduit at the index operation may be a key factor in long term function and reducing gastrointestinal symptoms. Dynamic MRI is a promising research and diagnostic tool to assess conduit function due to its capacity to accurately delineate the key elements of conduit function.

Validation of Breast Idea Volume Estimator Application in Transfeminine People.

Accurate estimation of breast volume is important as researchers aim to achieve optimal feminization for transfeminine people. The Breast Idea Volume Estimator (BIVE) application allows estimation of breast volume using two-dimensional (2D) photographs but has not been validated in the chests of people who have undergone testosterone-mediated puberty. To estimate breast volume, clinical photographs and 3D scans were collected at baseline and 6 months, as a prespecified secondary outcome of a randomized clinical trial of antiandrogen therapy in transfeminine people commencing hormone therapy. BIVE was used to estimate breast volume by two independent researchers and compared with the gold standard of 3D scan calculated volume at different timepoints. Statistical analysis was performed, including the mean absolute difference, standard error of measurement, and intraclass correlation, to determine accuracy, precision, and interrater agreement. Clinical photography and 3D scans were collected from 82 breasts of 41 participants. The median (interquartile range) age of participants was 25 (22-28) years, and the median (interquartile range) body mass index was 24.6 (21.2-28.9) kg/m2. The BIVE sagittal and transverse algorithms demonstrated robust performance, with mean absolute difference less than 20 mL and intraclass correlation greater than 0.87 indicating clinical reliability with high interrater agreement. BIVE provided an accurate, precise, and reliable measure of breast volume in the chests of people who have undergone testosterone-mediated puberty, compared with the gold standard of 3D scan.

Quantitative analysis of peripapillary capillary volume using dense B-scan OCT angiography in normal and diabetic retina

BackgroundThe value of quantitatively analyzing peripapillary capillary volume (PPCV) distribution was explored in normal and diabetic retinopathy (DR) eyes using dense B-scan optical coherence tomography angiography (DB OCTA).MethodsThis was a cross-sectional observational study followed by prospective follow-up for those with DR, which enrolled 101 healthy subjects and 140 DR patients. Dense, automatic, real-time (DART) volume scans of DB OCTA were performed using a Spectralis HRA + OCT2. ImageJ and MATLAB were used to process and calculate PPCV distribution detected by DB OCTA.ResultsIn normal subjects, PPCV distribution were significantly correlated with the age and quadrant location (all P < 0.001). The PPCV distribution in each quadrant was significantly lower in severe nonproliferative DR patients than in normal subjects in all age groups (all P < 0.05, t-test). Compared to normal subjects, the PPCV distribution improved significantly in the pan-retinal photocoagulation treatment and surgery groups (all P < 0.001). No significant variation was observed in the anti-VEGF treatment group and normal subjects (P > 0.05). The PPCV distribution is significantly correlated with post-treatment best-corrected visual acuity in both the pan-retinal photocoagulation treatment and surgery groups (all P < 0.003) but not in the anti-VEGF treatment group (P = 0.940).ConclusionsQuantitative assessment of PPCV distribution using DB OCTA is valuable in prognosis evaluation of DR with pan-retinal photocoagulation and surgery.

Sources of Discrepancy between Retinal Nerve Fiber Layer and Bruch’s Membrane Opening-Minimum Rim Width Thickness in Eyes with Glaucoma

To compare the discrepancies between circumpapillary retinal nerve fiber layer (RNFL) and Bruch's membrane opening-minimum rim width (BMO-MRW) thickness in glaucoma eyes. A cross-sectional observational study. One hundred eighty-six eyes (118 patients) with glaucoma. OCT optic nerve head volume scans of patients enrolled in the Advanced Glaucoma Progression Study at the final available visit were exported. The RNFL and BMO-MRW measurements were averaged into corresponding 7.5° sectors, and the nasal sector data were excluded from analyses. A 2-stage screening process was used to identify true mismatches between the RNFL and BMO-MRW measurements, in which either the RNFL or BMO-MRW value was in the less than first percentile range while its counterpart was in the greater than first percentile range on the temporal-superior-nasal-inferior-temporal curve. The prevalence of these mismatches was mapped, and corresponding images were reviewed to determine the underlying cause of these discrepancies. Proportion of mismatches between RNFL and BMO-MRW, location of mismatches between RNFL and BMO-MRW, anatomical causes of mismatches between RNFL and BMO-MRW. Mismatch analysis revealed true mismatches between RNFL and BMO-MRW in 7.7% of sectors. High BMO-MRW with low corresponding RNFL mismatches were most frequently located at the 45° and 322.5° sectors, whereas high RNFL with corresponding low BMO-MRW mismatches peaked at the 75° sector. Large blood vessels accounted for 90.9% of high RNFL with low BMO-MRW mismatches. Small to large blood vessels accounted for 62.9% of high BMO-MRW with low RNFL mismatches; the remaining mismatches could be attributed to retinoschisis or inclusion of outer retinal layers in BMO-MRW measurements. Although overall agreement between RNFL and BMO-MRW measurements is good in areas with advanced damage, blood vessels and other anatomical factors can cause discrepancies between the 2 types of structural measurements and need to be considered when evaluating the utility of such measurements for detection of change. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

A Corrugated Edged Tapered Slot Antenna with Low Cross-Polarization and Moderate Gain for Phased Array Systems

ABSTRACT This paper presents a miniaturized Vivaldi antenna with a scan volume of ± 30° designed for the 6–18 GHz tactical operational band, commonly employed in phased array systems and modern surveillance applications. The proposed antenna offers enhanced radiation characteristics, low cross polarization, broad beam width, and moderate gain. The design presented in this paper follows a step-by-step approach to achieve enhanced performance in terms of multi-octave bandwidth and compact size. Initially, a traditional Vivaldi antenna was designed and examined, with a modified feed structure. Subsequently, corrugated edges were inserted into the antenna, increasing its electrical length and resulting in good impedance matching, especially in the 6–10 GHz frequency band. A prototype model is fabricated and tested to validate its performance against the simulation results. The measured results demonstrate that the return loss (S11) remains below −10 dB across the operating frequency range, achieving a 50% bandwidth, with a gain of 3–7 dB, and improved co-cross polarization of −23 dB at 6 GHz and −26 dB at 18 GHz.

Prediction of presence and severity of metabolic syndrome using regional body volumes measured by a multisensor white-light 3D scanner and validation using a mobile technology

Abstract Aims To test whether an index based on the combination of demographics and body volumes obtained with a multisensor 3D body volume (3D-BV) scanner and biplane imaging using a mobile application (myBVI®) will reliably predict the severity and presence of metabolic syndrome (MS). Methods and results We enrolled 1280 consecutive subjects who completed study protocol measurements, including 3D-BV and myBVI®. Body volumes and demographics were screened using the least absolute shrinkage and selection operator to select features associated with an MS severity score and prevalence. We randomly selected 80% of the subjects to train the models, and performance was assessed in 20% of the remaining observations and externally validated on 133 volunteers who prospectively underwent myBVI® measurements. The mean ± SD age was 43.7 ± 12.2 years, 63.7% were women, body mass index (BMI) was 28.2 ± 6.2 kg/m2, and 30.2% had MS and an MS severity z-score of −0.2 ± 0.9. Features β coefficients equal to zero were removed from the model, and 14 were included in the final model and used to calculate the body volume index (BVI), demonstrating an area under the receiving operating curve (AUC) of 0.83 in the validation set. The myBVI® cohort had a mean age of 33 ± 10.3 years, 61% of whom were women, 10.5% MS, an average MS severity z-score of −0.8, and an AUC of 0.88. Conclusion The described BVI model was associated with an increased severity and prevalence of MS compared with BMI and waist-to-hip ratio. Validation of the BVI had excellent performance when using myBVI®. This model could serve as a powerful screening tool for identifying MS.

Reproducibility of a single-volume dynamic CT myocardial blood flow measurement technique: validation in a swine model

BackgroundWe prospectively assessed the reproducibility of a novel low-dose single-volume dynamic computed tomography (CT) myocardial blood flow measurement technique.MethodsThirty-four pairs of measurements were made under rest and stress conditions in 13 swine (54.3 ± 12.3 kg). One or two acquisition pairs were acquired in each animal with a 10-min delay between each pair. Contrast (370 mgI/mL; 0.5 mL/kg) and a diluted contrast/saline chaser (0.5 mL/kg; 30:70 contrast/saline) were injected peripherally at 5 mL/s, followed by bolus tracking and acquisition of a single volume scan (100 kVp; 200 mA) with a 320-slice CT scanner. Bolus tracking and single volume scan data were used to derive perfusion in mL/min/g using a first-pass analysis model; the coronary perfusion territories of the left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA) were automatically assigned using a previously validated minimum-cost path technique. The reproducibility of CT myocardial perfusion measurement within the LAD, LCx, RCA, and the whole myocardium was assessed via regression analysis. The average CT dose index (CTDI) of perfusion measurement was recorded.ResultsThe repeated first (Pmyo1) and second (Pmyo2) single-volume CT perfusion measurements were related by Pmyo2 = 1.01Pmyo1 − 0.03(ρ = 0.96; RMSE = 0.08 mL/min/g; RMSE = 0.07 mL/min/g) for the whole myocardium, and by Preg2 = 0.86Preg1 + 0.13(ρ = 0.87; RMSE = 0.31 mL/min/g; RMSE = 0.29 mL/min/g) for the LAD, LCx, and RCA perfusion territories. The average CTDI of the single-volume CT perfusion measurement was 10.5 mGy.ConclusionThe single-volume CT blood flow measurement technique provides reproducible low-dose myocardial perfusion measurement using only bolus tracking data and a single whole-heart volume scan.Relevance statementThe single-volume CT blood flow measurement technique is a noninvasive tool that reproducibly measures myocardial perfusion and provides coronary CT angiograms, allowing for simultaneous anatomic-physiologic assessment of myocardial ischemia.Key PointsA low-dose single-volume dynamic CT myocardial blood flow measurement technique is reproducible.Motion misregistration artifacts are eliminated using a single-volume CT perfusion technique.This technique enables combined anatomic-physiologic assessment of coronary artery disease.Graphical

Point-of-Care Ultrasound Track in an Academic Family Medicine Department.

Point-of-care ultrasound (POCUS) is increasingly being employed in family medicine. Residency tracks can be an effective way to increase mastery in a specific subdiscipline for interested residents, but no studies exist on the implementation of a POCUS track in family medicine. We address this gap in the literature by assessing POCUS use by POCUS track residents compared to non-POCUS track residents and faculty in an academic family medicine department. We performed a retrospective review of all POCUS scans completed in the first year after implementation of a family medicine residency POCUS track. Scans were analyzed by two reviewers. We compared scan volume and type between POCUS track residents, non-POCUS track residents, and faculty. A blinded quality analysis was performed on each group of scans. A total of 572 scans were completed on 536 patients over 1 year. POCUS track residents scanned significantly more than non-POCUS track residents (mean difference of 72.2, CI 59.1 to 85.4; P<.0001). The most common scan types across groups were musculoskeletal and soft tissue. POCUS track residents showed statistically improved scan quality in all scan types, while non-POCUS track residents showed statistical improvement only in soft tissue, shoulder, and abdominal aortic aneurysm scans. This is the first longitudinal study of a novel academic family medicine residency POCUS track. Participation in a POCUS track can increase the number, variety, and quality of scans performed. Our curriculum can be a model for family medicine residency programs that wish to provide robust POCUS training.