Oblique Views Research Articles

The Influence of Scar Patterns After Reduction Mammoplasty on Eye Movement and Gaze Pattern: An Eye-Tracking Investigation

BackgroundGiven that scars are acknowledged as the primary cause of postoperative dissatisfaction following reduction mammoplasty, it is imperative to comprehend the patient’s visual perception of different scar patterns in order to enhance patient satisfaction. To achieve this, eye-tracking technology provides an unbiased method of evaluating how observers assess breast scars.Methods58 participants (32 females and 26 males) between the ages of 19 and 82 years (mean age of 29.47 ± 10.98 years) were shown 18 color photographs, taken at 3 viewing angles (right 45° oblique, frontal and frontal view with arms raised), from 6 patients undergone reduction mammoplasty with the inverted T-scar technique (3 patients) or no-vertical-scar technique (3 patients). The images were presented to every participant for a fixed duration of 5 s each. Eye-tracking device was used to collect and analyze the gaze data of viewers.ResultsThe nipple-areola complex (NAC) and the periareolar scar captured observers’ gaze faster, had longer duration and more count of eye fixation than all other parts of breast scars, regardless of the viewing angle and scar pattern. Moreover, the scar region in the inverted T-scar pattern received greater and faster visual attraction of observer’s gaze than the no-vertical-scar pattern.ConclusionThe NAC and the periareolar scar seem to be perceived as the most important regions for breast aesthetics. The findings can be helpful to assist plastic surgeons in determining the most appropriate technique for reduction mammoplasty, meanwhile underlining the importance of a fine periareolar scar and symmetric NAC for excellent aesthetic outcomes.This is to our best knowledge the first study using eye-tracking technology in evaluating reduction mammoplasty outcomes.This study explored the influence of different scar patterns after reduction mammoplasty on eye movements and gaze patterns among observers.The study have validated the significance of the NAC and the periareolar scar for breast aesthetics and revealed that the scar region in the inverted T-scar pattern may be judged less visually attractive than the no-vertical-scar pattern.Level of Evidence VThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Axilla View of Mammography in Preoperative Axillary Lymph Node Evaluation of Breast Cancer Patients: A Pilot Study

PurposeThis study aimed to explore a novel position of mammography named axilla view in axillary lymph node (ALN) evaluation in breast cancer. Patients and MethodsPatients were prospectively enrolled and scheduled for mammography before surgery. Investigated imaging patterns included mediolateral oblique (2D-MLO) and axilla view (2D-axilla) of mammography, and axilla view of digital breast tomosynthesis (3D-axilla). The correlation of ALN numbers between imaging and pathology was analyzed. Diagnostic performance was analyzed via AUC. Results75 patients were included. A larger and clearer axillary region was displayed in axilla view. The total number of ALNs detected under 2D/3D-axilla view was significantly higher than that under 2D-MLO view (4.6 vs. 2.5, P < .001; 5.6 vs. 4.6, P = .034). Correlations between number of positive ALNs detected under 2D/3D-axilla view and pathologically confirmed metastatic ALNs were stronger than 2D-MLO view (Pearson correlation coefficients: 0.7084,0.7044 and 0.4744). The proportion of cases with ≥5 positive ALNs detected under 3D-axilla view was significantly higher than that under 2D-MLO (38.2% vs. 14.7%, P = .028). The overweight and obese group showed a higher AUC value than the underweight and lean group in ALN evaluation, although not significantly (2D-MLO: 0.7643 vs. 0.6458, P = .2656; 2D-axilla: 0.8083 vs. 0.6586, P = .1522; 3D-axilla: 0.8045 vs. 0.6615, P = .1874). This difference was more pronounced in axilla view. ConclusionAxilla view exhibited advantages over conventional MLO view in the extent of axilla displayed by mammography in breast cancer. Further studies with larger sample sizes are needed.

Energy-Efficient Liquid Crystal Smart Window with a Clear View

In this study, we enhance the angular-selective light absorption capabilities of guest–host liquid crystal (GHLC) cells by introducing a novel design featuring a uniform lying helix (ULH) structure. Previously GHLC cells, predominantly vertically aligned cells absorbed obliquely incident light but compromised x-direction visibility. In stark contrast, our ULH-based design allows incident light to seamlessly traverse transmittance in both z- and x-directions while efficiently obstructing oblique incident light in the y-direction. Our innovative ULH-based GHLC cell achieves an impressive optical performance. Specifically, it attains a substantial transmittance rate of 56.7% in the z-direction. Furthermore, in oblique views encompassing both the x- and y-directions, it maintains competitive transmittance rates of 44.2% and 29.5%, respectively. This strategic design not only ensures clear and unobstructed views for building occupants in the z- and x-directions but also contributes significantly to energy conservation by preventing oblique incident light from penetrating, thus reducing cooling requirements. Our ULH-based GHLC cell represents a breakthrough in smart window technology, offering an elegant solution to the challenge of balancing energy efficiency and occupant comfort in architectural settings. This advancement holds promising implications for sustainable building designs by enhancing indoor environmental quality while mitigating energy consumption for cooling, ultimately redefining the potential of smart windows in contemporary architecture.

Comparison of Bone Healing and Delayed or Nonunion Rates Between Operatively and Non- operatively Treated Displaced Zone 1 Fifth Metatarsal Fractures

Category: Midfoot/Forefoot; Other Introduction/Purpose: Acute fractures of the proximal fifth metatarsal are one of the most common injuries to the foot, occurring in up to 70% of all metatarsal fractures1. Displaced zone 1 fractures of the fifth metatarsal with greater than 2 mm fracture gap or those comprising greater than 30% of the cubometatarsal joint warrant operative treatment with open reduction internal fixation (ORIF)2,7, as satisfactory bone healing and patient-reported outcomes have been reported previously8–13. More recently, a few studies have demonstrated good functional outcomes after conservative treatment of zone 1 fractures with initial displacement greater than 2 mm7,13. Nevertheless, the lack of comparative studies and conflicting available evidence of outcomes warrant further investigation on this topic. Methods: A chart review was conducted to identify patients with displaced zone 1 fractures of the fifth metatarsal. Age at time of injury, gender, smoking and diabetes history, were collected. Degree of fracture displacement were measured (mm) on AP, lateral, and oblique view radiographs obtained at the initial encounter. Non-operatively treated patients were instructed to weightbear as tolerated in a Controlled Ankle Motion (CAM) boot for 6 weeks. Surgically-treated patients were placed in a short-leg splint for 2 weeks, and remained non-weightbearing in a CAM boot until 6 week period. They transitioned to normal shoe wear at the 8 week postoperative period. Chart notes were reviewed to identify the time to complete healing and incidences of delayed or nonunion. Means were compared using a one-way ANOVA or Kruskal Wallis test depending on normality, and categorical variables were compared using Chi-square or Fisher’s exact test. Results: The average time to complete healing was greater in non-operatively treated patients by 3 weeks (17.1 vs. 14.1, p=0.282). 4/37 (10.8%) non-operatively treated patients experienced delayed or non-union whereas 4/38 (13.2%) operatively-treated patients experienced delayed or non-union. This difference was statistically non-significant. The average fracture displacement (mm) on the oblique view was significantly greater in operatively-treated patients (2.68 vs. 5.40, p&lt; 0.001). For patients with fracture gaps greater than 2 mm on the oblique view, non-operatively treated patients took 20.9 weeks whereas operatively- treated patients took 11.8 weeks to reach complete healing (p &lt; 0.01). Conclusion: Patients who were treated non-operatively for displaced zone 1 fractures of the fifth metatarsal took on average 3 weeks longer to reach complete healing than operatively-treated patients. For patients with fracture gap greater than 2 mm on the oblique view, operative treatment was associated with significantly reduced time to complete healing.

Ultrasound: A novel alternative technique for cervical epidural space visualization-A pilot study.

Neuraxial ultrasound (US), a newer modality, can be used for neuraxial imaging, helping in visualizing and aiding in epidural space catheterization. The aim of this study was to evaluate the efficacy of the US for cervical epidural access and to determine the failure rate and complication associated with this technique. A prospective single-arm pilot study was conducted on 21 participants. The neuraxial US image quality assessment by Ultrasound Visibility Score (UVS), epidural space depth measurement by US and by conventional loss of resistance (LOR) technique, and post-procedure epidural catheter confirmation by real-time US were the study parameters. Any procedural complications or failure rate were recorded. The Kolmogorov-Smirnov test, paired-samples t-test, and Chi-square test were used for the statistical comparison. The pre-procedural UVS by the transverse interlaminar view (x/21) was 2.81 ± 1.94 and by the oblique paramedian sagittal view was 16.66 ± 2.39 with UVS being best in the paramedian oblique sagittal view (P- value < 0.05). The comparison of depth of the epidural space identified by USG and that by the LOR technique was statistically insignificant (P = 0.83). The average puncture attempts were 1.1 ± 0.3. Post-procedure US epidural catheter confirmation score (x/3) was 1.44 ± 0.44 with either epidural space expansion or microbubbles seen or both. The pilot study has successfully demonstrated the implication of US for visualizing and aiding in epidural space catheterization. Also, the failure rate and procedural complications were drastically minimized with the help of US as compared to the traditional blind technique.

Oblique projection for scalable rank-adaptive reduced-order modelling of nonlinear stochastic partial differential equations with time-dependent bases

Time-dependent basis reduced-order models (TDB ROMs) have successfully been used for approximating the solution to nonlinear stochastic partial differential equations (PDEs). For many practical problems of interest, discretizing these PDEs results in massive matrix differential equations (MDEs) that are too expensive to solve using conventional methods. While TDB ROMs have the potential to significantly reduce this computational burden, they still suffer from the following challenges: (i) inefficient for general nonlinearities, (ii) intrusive implementation, (iii) ill-conditioned in the presence of small singular values and (iv) error accumulation due to fixed rank. To this end, we present a scalable method for solving TDB ROMs that is computationally efficient, minimally intrusive, robust in the presence of small singular values, rank-adaptive and highly parallelizable. These favourable properties are achieved via oblique projections that require evaluating the MDE at a small number of rows and columns. The columns and rows are selected using the discrete empirical interpolation method (DEIM), which yields near-optimal matrix low-rank approximations. We show that the proposed algorithm is equivalent to a CUR matrix decomposition. Numerical results demonstrate the accuracy, efficiency and robustness of the new method for a diverse set of problems.

Establishment of national diagnostic reference levels for full field digital mammography and digital breast tomosynthesis in Lebanon

This study aims to establish Lebanese national diagnostic reference levels (NDRLs) for full field digital mammography (FFDM) and digital breast tomosynthesis (DBT). Data were collected from 34% of the total number of health facilities with FFDM and/or DBT units in Lebanon. NDRLs were set as the third quartile of mammography units’ median value of average glandular dose (AGD). NDRLs for different compressed breast thickness (CBT) and age groups were also proposed. Statistical analysis were performed to test the difference of AGD between cranio caudal (CC) and medio lateral oblique (MLO) views, FFDM and DBT, and AGD across health facilities, CBT and age groups. Data from 2803 women with a total of 10462 images were included in the study. For FFDM and DBT, NDRLs for CC and MLO views were equal to 1.85 and 2.24 mGy, and 2.65 and 3.04 mGy, respectively. Lebanese NDRLs were higher than most published DRLs while remaining below the European Commission’s maximum acceptable dose level (2.5 mGy) for FFDM. AGD increased significantly (p &lt; 0.05) with the increase in CBT for both views and techniques. This first set of mammography DRLs reveals the need for optimizing the radiation exposure in Lebanon and will serve as a national/international benchmark.

Operative Treatment of Jones Fractures (OTA Type 87,5.2A) is not Associated with Earlier Clinical or Radiographic Healing

Category: Midfoot/Forefoot; Trauma Introduction/Purpose: The purpose of this study was to compare the time to radiographic and clinical healing between patients with metadiaphyseal metatarsal fractures (True Jones) treated operatively and those treated nonoperatively. Methods: This was a retrospective cohort study of patients presenting to a single large, urban, academic hospital center with Jones fractures between December 2012 and April 2022. Jones fractures were defined as 5th metatarsal base fractures occurring in the proximal metadiaphyseal region, just distal to the articulation of the 4th and 5th metatarsals on the oblique radiographic view (Zone 3). Information regarding patient demographics, injury mechanism, clinical presentation, management, and time to healing was collected. A fracture was defined as clinically healed when the patient had returned to their baseline ambulatory status without pain and there was an absence of tenderness to palpation on physical examination. Radiographic healing was defined as the presence of complete osseous consolidation. A total of 2,466 patients presented with 5th metatarsal fractures during the study period. Results: Among all 5th metatarsal fractures, 170 patients (6.9%) were classified as “true Jones” fractures. The mean age of patients presenting with Jones fractures was 46.1 +/- 18.6 years, and 65.8% were female. 19.9% were treated operatively (92.9% with screw fixation and 7.1% with ORIF), and 80.1% were treated nonoperatively. 95.9% of patients with Jones fractures went on to heal with no difference in time to radiographic healing (p = 0.296) or clinical healing between both groups (p = 0.228). Furthermore, there was no difference between groups with respect to the proportion of patients who developed delayed radiographic union with incomplete osseous healing at 6 months post-injury (9.3% in the nonoperative group versus 10.7% in the operative group, p = 0.098). Conclusion: Contrary to popular opinion, operative treatment of true Jones fractures was not associated with faster or more reliable radiographic union or time to clinical healing compared to patients treated nonoperatively. The overall rate of nonunion in true Jones fractures was found to be lower than previously described, and there was no evidence of any difference in nonunion rate with operative treatment compared to nonoperative management.

Variations in the Management of Zone 2 5th Metatarsal Fractures Based on Physician Specialty

Category: Midfoot/Forefoot; Trauma Introduction/Purpose: There is a wide variation in the management of acute “Zone 2” 5th metatarsal (MT) base fractures. The purpose of this study was to quantify these differences and evaluate the effect of treating physician specialty. Methods: This was a retrospective cohort study of patients with acute Zone 2 5th MT fractures who presented to a single large, urban, academic medical center between December 2012 and April 2022. Zone 2 was defined as the region of the 5th MT base bordered by the 4th and 5th MT articulation on the oblique radiographic view. Logistic regression was used to evaluate the odds of undergoing operative treatment based on provider specialty. Results: A total of 633 patients presented with Zone 2 fractures during the study period. 40.6% of patients initially presented to the ED, 36.3% to an urgent care (UC) center, and 23.1% directly to the office. Ultimately, 57.2% of patients were treated by orthopedic surgeons, 39.6% by podiatrists, and 3.2% by primary care physicians. For patients treated nonoperatively, the management plan significantly differed by treating specialty. Compared to podiatrists, patients treated by orthopedic surgeons were more likely to be treated in a hard sole shoe (30.8% versus 7.6%, p&lt; 0.001) and less likely to be treated using a CAM boot (57.3% versus 76.3%, p&lt; 0.001). Similarly, patients treated by orthopedic surgeons were more likely to be made WBAT compared to patients treated by podiatrists (71.8% versus 42.0%, p&lt; 0.001). Conclusion: Overall, 2.5% of patients with Zone 2 metatarsal fractures were treated operatively. 0.5% of patients treated by orthopedic surgeons underwent surgery compared to 6.1% of patients treated by podiatrists (p=0.001). Furthermore, when controlling for age, sex, and time between injury and initial presentation to the office, the likelihood of undergoing operative treatment was still significantly greater when being treated by a podiatrist (OR=16.5, p=0.009). There is considerable heterogeneity among the treatment strategies for Zone 2 proximal 5th MT fractures. Compared to podiatrists, orthopedic surgeons are less likely to treat patients operatively and more likely to allow early weight bearing.

Zone 2 5th Metatarsal Fractures Treated Nonoperatively Have Similar Time to Healing to Those Treated Operatively

Category: Midfoot/Forefoot; Trauma Introduction/Purpose: The purpose of this study was to quantify the time to clinical and radiographic healing in Zone 2 proximal 5th metatarsal (MT) fractures and to compare these outcomes to those of Zone 2 fractures treated operatively. Methods: A retrospective cohort study of all Zone 2 metatarsal fractures seen at a single large, urban, academic medical center between December 2012 and April 2022 was performed. Zone 2 injuries were defined as fractures entering the proximal 4-5 MT articulation on the oblique radiographic view. Clinical healing was characterized by the return to baseline ambulatory function without discomfort and a lack of tenderness on physical examination. Radiographic healing was defined as complete osseous consolidation. A total of 374 patients with Zone 2 proximal 5th MT fractures were included in the analysis. The mean age of patients was 53.8 +/- 16.6 years, and 74.3% were female. Results: 93.3% of patients with Zone 2 metatarsal fractures were treated nonoperatively. In the nonoperative group, 6.6% experienced delayed bony union with incomplete radiographic healing after 6 months, compared to 16.0% of the operative group (p = 0.095). However, by 1 year post-injury, 98.9% of patients who underwent nonoperative management and 96.0% of operative patients demonstrated radiographic union. Two patients failed nonoperative management and underwent operative fixation for symptomatic nonunions. There was no difference in time to radiographic healing between patients treated nonoperatively and those treated operatively (4.4 +/- 2.8 months vs 5.4 +/- 4.7 months, p = 0.413). Similarly, there was no difference in time to clinical healing between both groups (2.3 +/- 1.9 months vs 2.6 +/- 3.8 months, p = 0.723). Conclusion: Zone 2 5th metatarsal base fractures, which are often incorrectly referred to as Jones fractures despite being proximal to the fractures originally characterized by Jones, can be successfully treated with nonoperative management. There is no evidence that operative treatment leads to significantly faster clinical or radiographic healing for patients.

PosNet: Estimating lettuce fresh weight in plant factory based on oblique image

Fresh weight is a crucial indicator for assessing crop growth in plant factory. To date, the majority of non-destructive techniques employed for estimating crop fresh weight rely on the top view images. Nevertheless, these approaches are limited in performance due to the constrained and non-open environment of plant factories. In this paper, we propose a novel position-guided network (PosNet) to estimate the fresh weight of crop using oblique view images. Precisely, we first build the crop (i.e., lettuce) dataset by positioning the camera vertically in an oblique angle, with the Mask R-CNN framework trained for individual lettuces segmentation from the background. The segmented lettuce images are then fed into the PosNet for network training and testing purpose. By integrating the shallow feature extraction module and the position information extraction module, the proposed PosNet attains superior performance on assessing the lettuce fresh weight from oblique view images against other models. We further conducted the ablation studies and generalization testing to verify the efficacy and robustness of the proposed network model. Moreover, by comparing three variations (i.e., position, growth stage and posture orientation) of the lettuce separately and the sensitivity analysis of oblique shooting angles, our method demonstrates plausible adaptability for lettuce fresh weight estimation. Taking the accuracy, robustness, generalization capability, and adaptability into account, the integration of PosNet with oblique images not only enjoys great potentials in assessing the fresh weight, but also provides a practical support for agronomic management of crops cultivated in plant factories.

THA-AID: Deep Learning Tool for Total Hip Arthroplasty Automatic Implant Detection With Uncertainty and Outlier Quantification

BackgroundRevision total hip arthroplasty (THA) requires preoperatively identifying in situ implants, a time-consuming and sometimes unachievable task. Although deep learning (DL) tools have been attempted to automate this process, existing approaches are limited by classifying few femoral and zero acetabular components, only classify on anterior-posterior (AP) radiographs, and do not report prediction uncertainty or flag outlier data. MethodsThis study introduces Total Hip Arhtroplasty Automated Implant Detector (THA-AID), a DL tool trained on 241,419 radiographs that identifies common designs of 20 femoral and 8 acetabular components from AP, lateral, or oblique views and reports prediction uncertainty using conformal prediction and outlier detection using a custom framework. We evaluated THA-AID using internal, external, and out-of-domain test sets and compared its performance with human experts. ResultsTHA-AID achieved internal test set accuracies of 98.9% for both femoral and acetabular components with no significant differences based on radiographic view. The femoral classifier also achieved 97.0% accuracy on the external test set. Adding conformal prediction increased true label prediction by 0.1% for acetabular and 0.7 to 0.9% for femoral components. More than 99% of out-of-domain and >89% of in-domain outlier data were correctly identified by THA-AID. ConclusionsThe THA-AID is an automated tool for implant identification from radiographs with exceptional performance on internal and external test sets and no decrement in performance based on radiographic view. Importantly, this is the first study in orthopedics to our knowledge including uncertainty quantification and outlier detection of a DL model.

Kualitas Informasi Anatomi Radiograf pada Pemeriksaan Sternum dengan Variasi Penyudutan Arah Sinar

Background: The sternum's radiographic examination involves the use of Right Anterior Oblique (RAO) and Lateral projections. However, if a patient cannot undergo RAO projection, Left Posterior Oblique (LPO) projection in the supine position and adjusting the central ray angle are alternatives. On another note, deviations from perpendicular alignment among the central ray, image receptor, and object can lead to distortions in shape, impacting image quality. Hence, a study is conducted to investigate the impact of beam angle variations on the quality of anatomical information in sternum radiographs to identify the optimal angle that yields the highest quality anatomical information in sternum radiographs. Methods: This research was quantitative research employing an experimental methodology. Data collection involved employing a single-body phantom, which underwent three exposures at each of the specified angle variations Results: Based on the results of the Kruskal Wallis test, there were significant differences in the quality of radiographic anatomic information (p value 0.05). The angle with the most optimal quality of radiographic anatomical information was an angle of 25° to the left with a mean rank value of 11.00. Conclusions: There was a significant difference in the quality of radiographic anatomic information (p value 0.05). The angle with the most optimal quality of radiographic anatomic information was the angle with the highest mean rank value, which was an angle of 25° to the left.

Anterior Malreduction is Associated With Lag Screw Cutout After Internal Fixation of Intertrochanteric Fractures.

Lag screw cutout is a devastating complication after internal fixation of an intertrochanteric fracture. Although the tip-apex distance (TAD) is known to be associated with this complication, another factor we thought was potentially important-fracture reduction on an oblique lateral view-has not, to our knowledge, been explored. (1) Is a well-reduced fracture position on an oblique lateral view after internal fixation of intertrochanteric fracture associated with a lower odds of postoperative cutout, independently of the TAD? (2) Is postoperative sliding of the lag screw after fixation associated with postoperative cutout? Patients with intertrochanteric fractures who were at least 65 years old and who had been treated with internal fixation in one of six facilities between July 2011 and December 2017 were included. All patients in the study group had lag screw cutout, and controls were selected by risk-set sampling of age-matched and sex-matched patients using a ratio of 4:1 for patients from each hospital. Of the 2327 intertrochanteric fractures, there were 36 patients (0.02 per person-year), with a mean age of 85 years; 89% (32) were women. In the control group, there were 135 controls. There was no difference in age or sex between the two groups. Sagittal reduction was evaluated using an immediate postoperative oblique lateral radiograph (anterior malreduction versus anatomic reduction or posterior malreduction). The association between anterior malreduction and the odds of cutout was estimated by conditional logistic regression analysis with the TAD and interaction between the TAD and the reduced position as covariates. As a sensitivity analysis, we estimated whether sliding within 2 weeks postoperatively was associated with cutout. After controlling for the potentially confounding variables of age and sex, we found that anterior malreduction was independently associated with a higher odds of cutout compared with anatomic reduction or posterior malreduction (adjusted OR 4.2 [95% CI 1.5 to 12]; p = 0.006). There was also an independent association between cutout and larger TAD (≥ 20 mm) (adjusted OR 4.4 [95% CI 1.4 to 14]; p = 0.01). However, the association between cutout and reduction was not modified by the TAD (adjusted OR of interaction term 0.6 [95% CI 0.08 to 4]; p = 0.54). Postoperative sliding ≥ 6 mm within 2 weeks was associated with higher odds of cutout after adjusting for age and sex (adjusted OR 11 [95% CI 3 to 40]; p < 0.001). In patients older than 65 years with intertrochanteric fractures, anterior malreduction on a lateral oblique view was associated with much greater odds of postoperative cutout than anatomic reduction or posterior malreduction. Because anterior malreduction is within the surgeon's control, our findings may help surgeons focus on intraoperative reduction on an oblique lateral view to prevent cutouts. Although this factor is a reliable indicator, the results should be applied to cephalomedullary nails, because there was only one patient with cutout among those with sliding hip screws. Because this study was conducted in a homogenous Japanese population, future studies should focus on the association between anterior malreduction and cutout in people of different ethnicities, adjusting for confounding factors such as implant type and surgeon level. Level III, therapeutic study.

Deep learning based multi-view stereo matching and 3D scene reconstruction from oblique aerial images

In this paper, we propose a practical three-dimensional (3D) real-scene reconstruction framework named Deep3D, which is paired with a deep learning based multi-view stereo (MVS) matching model named the adaptive multi-view aggregation matching (Ada-MVS) model, to obtain a 3D textured mesh model from multi-view oblique aerial images. Deep3D is the first deep learning based framework for 3D scene reconstruction, in which aerial triangulation and view selection are first performed on the input images, and the depth map of each image is then inferred using the pretrained Ada-MVS model. All the inferred depth maps are then fused into a dense point cloud after filtering the outliers. Finally, the 3D textured mesh is extracted from the dense 3D points as the final product. In the Ada-MVS model, a novel adaptive inter-view aggregation module is specially proposed to address the inconsistent information among oblique views and to fuse the multi-view costs into a robust cost volume. A lightweight recurrent regularization module is also designed for high-efficiency processing of high-capacity aerial images with large depth variations. Moreover, as oblique aerial image datasets are currently lacking, we built a large-scale synthetic multi-view oblique aerial image dataset (WHU-OMVS dataset) for deep learning based model training and methodology evaluation for the task of 3D scene reconstruction. The experimental results show that, firstly, the proposed Ada-MVS model has obvious advantages when used with high-capacity oblique aerial images, compared with several relevant learning-based MVS methods. Secondly, through a comprehensive comparison with popular commercial software packages and open-source solutions, it is shown that the proposed Deep3D framework outperforms all the other solutions in terms of reconstruction quality, and outperforms all the open-source solutions and some of the software packages in terms of efficiency on the WHU-OMVS dataset. Thirdly, the Deep3D framework shows a stable generalization ability and excellent performance when applied to other oblique or nadir aerial images, without any further fine-tuning. The dataset and code will be available at http://gpcv.whu.edu.cn/data.

Pectoral muscle removal in mammogram images: A novel approach for improved accuracy and efficiency

PurposeAccurate pectoral muscle removal is critical in mammographic breast density estimation and many other computer-aided algorithms. We propose a novel approach to remove pectoral muscles form mediolateral oblique (MLO) view mammograms and compare accuracy and computational efficiency with existing method (Libra).MethodsA pectoral muscle identification pipeline was developed. The image is first binarized to enhance contrast and then the Canny algorithm was applied for edge detection. Robust interpolation is used to smooth out the pectoral muscle region. Accuracy and computational speed of pectoral muscle identification was assessed using 951 women (1,902 MLO mammograms) from the Joanne Knight Breast Health Cohort at Washington University School of Medicine.ResultsOur proposed algorithm exhibits lower mean error of 12.22% in comparison to Libra’s estimated error of 20.44%. This 40% gain in accuracy was statistically significant (p < 0.001). The computational time for the proposed algorithm is 5.4 times faster when compared to Libra (5.1 s for proposed vs. 27.7 s for Libra per mammogram).ConclusionWe present a novel approach for pectoral muscle removal in mammogram images that demonstrates significant improvement in accuracy and efficiency compared to existing method. Our findings have important implications for the development of computer-aided systems and other automated tools in this field.

Equal parallel and cone-beam projections: a curious property of D-symmetric object functions

In tomographic image reconstruction, the object density function is the unknown quantity whose projections are measured by the scanner. In the three-dimensional case, we define the D-reflection of such a density function as the object obtained by a particular weighted reflection about the plane z = D, and a D-symmetric function as one whose D-reflection is equal to itself. D-symmetric object functions have the curious property that their parallel projection onto the detector plane z = D is equal to their cone-beam projection onto the same detector with x-ray source location at the origin. Much more remarkable is the additional fact that for any fixed D-symmetric object, every oblique parallel projection onto this same detector plane equals the cone-beam projection for a corresponding source location. The mathematical proof is straight forward but not particularly enlightening, and we also provide here an alternative physical demonstration that explains the various weighting terms in the context of classical tomosynthesis. Furthermore, we clarify the distinction between the new formulation presented here, and the original formulation of Edholm and co-workers who obtained similar properties but for a pair of objects whose divergent and parallel projections matched, but with no D-symmetry. We do not claim any immediate imaging application or useful physics from these notions, but we briefly comment on consequences for methods that apply data consistency conditions in image reconstruction.

On a cube and subspace projections

We consider the arrangement of vertices of a unit multidimensional cube, an affine subspace, and its orthogonal projections onto coordinate subspaces. Upper and lower bounds on the subspace dimension are given under which some orthogonal projection always preserves the incidence relation between the subspace and cube vertices. Some oblique projections are also considered. Moreover, a brief review of the history of the development of multidimensional descriptive geometry is given. Analytic and synthetic methods in geometry diverged since the 17th century. Although both synthesis and analysis are tangled, from this time forth many geometers as well as engineers keep up a nice distinction. One can find references to the idea of higher-dimensional spaces in the 18th-century works, but proper development has been since the middle of the 19th century. Soon such works have appeared in Russian. Next, mathematicians generalized their theories to many dimensions. Our new results are obtained by both analytic and synthetic methods. They illustrate the complexity of pseudo-Boolean programming problems because reducing the problem dimension by orthogonal projection meets obstacles in the worst case.

Commissural alignment in the Evolut TAVR procedure: conventional versus hat marker-guided shaft rotation methods.

Coronary cannulation after TAVR is sometimes difficult due to an overlap between native and neo-commissures, especially in Evolut devices with a supra-annular position. The Evolut C-tab corresponds to a neo-commissure, and the hat marker is in a fixed position. Therefore, the orientation of the hat marker can be adjusted to minimise overlaps. We investigated whether the HAt marker-guided SHaft rotation method (HASH, stylised as the #rotation method) is effective in facilitating coronary artery access after transcatheter aortic valve replacement (TAVR) with an Evolut system. We retrospectively analysed 95 patients who underwent electrocardiogram-gated cardiac computed tomography after TAVR. In the #rotation method, the hat marker of the delivery catheter was adjusted to face the greater curvature of the descending thoracic aorta in the left anterior oblique view. Its orientation was maintained while the system passed through the aortic arch. In total, 60 and 35 patients underwent TAVR with the #rotation and non-#rotation methods, respectively. A ±15° angle between the native and neo-commissures was more frequent in the #rotation group (p=0.001). Favourable angles and appropriate frame orientation for access to the left coronary artery were significantly more frequent in the #rotation group than in the non-#rotation group (p<0.001 and p=0.001). Although the #rotation method showed a higher rate of favourable angles and frames in the right coronary artery, statistically significant differences were not found. The #rotation method is useful for improving commissural post alignment in TAVR with Evolut devices, especially in the ostium of the left coronary artery.

High‐accuracy DOA estimation via parallel sparse nested array with extended aperture and reduced mutual coupling

AbstractThis letter proposes a novel parallel sparse nested array and then provides a matrix reconstruction‐based method with three steps, to enhance the performance of direction of arrival (DOA) estimation in practice. The spacings between the closest antennas along x‐ and y‐axes, are coprime and much greater than half‐wavelength in the proposed array, which contributes to efficiently eliminate the mutual coupling and achieve larger aperture with limited physical antennas. By using the oblique projection operator with iteration, the proposed method can employ all items of covariance matrix of the received data to construct a virtual covariance matrix with increased degrees of freedom, for effectively improving angle estimation performance. Then the unique and high‐accuracy DOA estimation is obtained via the coprime‐ness. The simulation results show the superiority of the proposed array and method for DOA estimation in the presence of mutual coupling and limited antennas.