Search Results (501)

Background/Objectives: To evaluate the influence of different DIXON contrasts on the quality of subtraction images in dynamic breast MRI using maximum intensity projections (MIPs). Methods: This retrospective study included n = 40 women (median age: 53.5 years, range 23–83) undergoing clinically indicated breast MRI (3T). For each MRI examination, two independent readers individually evaluated GBCA-enhanced subtraction MIPS for different timepoints (n = 5) and DIXON contrasts (n = 4) per breast, resulting in a total of 800 individual evaluations. Evaluations comprised (a) qualitative measures, using Likert-scores for artefact strength, breast parenchyma visibility, lesion visibility and reading confidence; and (b) signal intensity, measured in three regions of interest with the apparent signal-to-noise ratio (aSNR) and apparent contrast-to-noise ratio (aCNR) calculated. The evaluation results were analysed to identify differences between DIXON contrasts. Results: The “only water” DIXON contrast at ~120s after GBCA injection achieved the highest lesion conspicuity and reading confidence scores and lowest artefact scores; however, its performance was not statistically significant (p > 0.05) compared to the “in-phase” and “opposed-phase” subtractions. The aCNR at the second timepoint was slightly, but not significantly (p > 0.05), lower than the first timepoint, whilst aSNR increased significantly from the first to second timepoint in all contrasts. Conclusions: Subtraction MIPs derived from the “only water” DIXON contrast achieved the highest qualitative scoring for lesion conspicuity and confidence, with the aSNR increasing and aCNR decreasing between the first and second timepoints. Full article

Background/Objectives: Breast MRI surveillance for women with a personal history of breast cancer (PHBC) is often limited by costs and acquisition times. This study aims to identify the optimal abbreviated breast MR (ABMR) protocol for this population by assessing the diagnostic performance of different sequence additions. Methods: This retrospective study included 1002 women with PHBC who underwent postoperative breast MRI with ultrafast sequences. Propensity score matching using 12 variables yielded recurrence (n = 21) and nonrecurrence (n = 42) groups with balanced characteristics. Four ABMR protocols were simulated by sequentially combining sequences: Step 1 (FAST protocol) included precontrast T1-weighted imaging (T1WI), early-phase T1WI, and subtracted maximal intensity projection (MIP). Step 2 added ultrafast MIP; Step 3 incorporated delayed-phase T1WI; and Step 4 included T2WI and diffusion weighted imaging (DWI). Three expert breast radiologists independently reviewed MRIs. Sensitivity, specificity, accuracy, and area under the curve (AUC) were assessed. Results: Sensitivity, specificity, and accuracy for ABMR protocols ranged from 76.2% to 90.5%, 88.1% to 92.9%, and 85.7% to 90.5%, respectively. The FAST protocol alone provided reliable performance (sensitivity: 81%; specificity: 88.1–90.5%; accuracy: 85.7–87.3%). Additional sequences yielded modest improvements, but no statistically significant differences were observed across all 3 readers (p > 0.05). ABMR protocols demonstrated equivalent diagnostic performance for PHBC surveillance. Conclusions: The FAST protocol alone provided reliable results, indicating its potential as a primary ABMR protocol. While additional sequences slightly improved specificity, they did not significantly enhance diagnostic accuracy. Full article

Difference visual question answering (Diff-VQA) aims to answer questions by identifying and reasoning about differences between medical images. Existing methods often rely on simple feature subtraction or fusion to model image differences, while overlooking the asymmetric descriptive requirements of changed and unchanged cases and providing limited task-specific guidance to pretrained language decoders. To address these limitations, we propose D²MNet (Difference-aware Decoupling and Multi-prompt Network), a framework for medical Diff-VQA that combines change-aware reasoning with prompt-guided answer generation. Specifically, a Change Analysis Module (CAM) predicts whether a change is present and produces a binary change-aware prompt; a Difference-Aware Module (DAM) uses dual attention to capture fine-grained difference features; and a multi-prompt learning mechanism (MLM) injects question-aware, change-aware, and learnable prompts into the language decoder to improve contextual alignment and response generation. Experiments on the MIMIC-DiffVQA benchmark show that D2MNet achieves a CIDEr score of 2.907 ± 0.040, outperforming the strongest baseline, ReAl (2.409), under the same evaluation setting. These results demonstrate the effectiveness of the proposed design on benchmark medical Diff-VQA and suggest its potential for assisting difference-aware medical answer generation. Full article

To investigate the effects of distribution characteristics of microscopic voids (including the connectivity degree, pore-throat morphology, and size) on the permeability performance of open-graded friction course (OGFC) asphalt mixtures with steel slag as the anti-skid wearing course, two-dimensional computed tomography (CT) images of OGFC steel slag asphalt mixture specimens were first obtained via X-ray technology. The MATLAB R2022b-based image subtraction algorithm was then adopted to identify the interconnected voids inside the specimens to quantitatively characterize the morphological differences in interconnected voids in OGFC steel slag asphalt mixtures with different gradations. Furthermore, Finite Element simulation by ANSYS 2021 R1 was conducted to explore the influences of the diversion angle of interconnected voids on the water flow characteristics of OGFC steel slag asphalt mixtures, involving the variation laws of water flow velocity, water pressure and flow path in the diversion structure, thereby analyzing the resultant effects on the permeability performance of the mixtures. The results show that the combination of X-ray CT scanning and image processing technology enables more convenient, accurate and intuitive characterization of the internal void distribution characteristics of the mixtures. It was found that the pore-throat properties, including size, length, quantity and equivalent diameter, are the dominant factors restricting the permeability capacity of OGFC steel slag asphalt mixtures. As the diversion angle increases from 20° to 60°, the pressure gradient increases by up to 103.92%. After passing through the diversion section, the flow velocity increases by approximately four times. The streamline density at the channel axis is 4.2–4.5 times that near the channel wall. This study realizes the rapid extraction of void characteristics and the identification of key influencing factors on the permeability performance of OGFC steel slag asphalt mixtures, an achievement that cannot be attained by the previous macroscopic research on the permeability performance of such mixtures. Full article

Moyamoya disease (MMD) is a chronic, progressive cerebrovascular disorder characterized by steno-occlusive changes in the intracranial internal carotid arteries and the development of fragile collateral networks. Imaging plays a pivotal role in diagnosis, disease staging, and management, yet the expanding range of available imaging modalities has resulted in heterogeneous evidence that remains difficult to synthesize. This scoping review aimed to systematically map and critically appraise imaging-based diagnostic approaches used in MMD, summarizing their diagnostic performance, clinical utility, and limitations. A comprehensive literature search was conducted across major databases, and original studies evaluating imaging modalities in human MMD were included. Thirty-three studies published between 1995 and 2023 were analyzed, encompassing digital subtraction angiography, magnetic resonance imaging and angiography, perfusion and functional MRI, computed tomography-based techniques, nuclear medicine, ultrasound, neurophysiological methods, and emerging artificial intelligence applications. Digital subtraction angiography remains the diagnostic reference standard, particularly for disease confirmation and surgical planning. However, noninvasive modalities provide critical complementary information. Magnetic resonance-based techniques offer multiparametric assessment of vascular morphology, hemodynamics, vessel wall pathology, and parenchymal injury. Computed tomography angiography and perfusion imaging provide accessible alternatives with high sensitivity for vascular changes, while functional and neurophysiological methods contribute additional hemodynamic and regional assessments. Artificial intelligence applications show promising diagnostic performance but remain in early validation stages. The evidence base is limited by methodological heterogeneity, inconsistent reference standards, incomplete reporting of diagnostic accuracy metrics, and a scarcity of longitudinal and multimodal studies. Collectively, the findings support a multimodal imaging strategy in MMD, integrating structural and functional information to inform diagnosis and management. Future research should prioritize standardized protocols, longitudinal designs, and clinically validated imaging biomarkers to enable evidence-based diagnostic pathways. Full article

(1) Purpose: To compare the fabrication accuracy, internal fit, and marginal adaptation of three-unit definitive resin fixed dental prostheses (FDPs) produced by subtractive milling and additive manufacturing. (2) Materials and Methods: A typodont mandible was prepared for a three-unit FDP, with full crown preparations on teeth mandibular left canine and mandibular left second premolar featuring 1 mm chamfer finish lines. The FDP was designed with a 16 mm² connector and a 100 µm cement gap. Two milling materials (Ambarino High-Class, IPS e.max CAD) and two experimental 3D printing hybrid resins (3D-1, 3D-2) were used. All restorations were scanned using an intraoral scanner and compared to the original STL using reverse engineering software for surface trueness and deviation analysis. The internal fit was evaluated using the triple-scan method, while marginal fit was assessed via micro-CT imaging. Statistical analysis was conducted using one-way ANOVA and Kruskal–Wallis tests (α = 0.05). (3) Results: Milled groups demonstrated a lower prevalence of external, marginal, and overall surface deviations (p < 0.001), while 3D-1 exhibited comparable deviations within the internal region with M-E (p = 0.067). Milled groups had average gap values that were similar to 3D-1 (p > 0.08), but significantly lower than 3D-2 (p < 0.002). In marginal adaptation evaluated by micro-CT, the M-A and M-E groups provided significantly lower gaps, while the 3D-1 and 3D-2 groups exhibited wider marginal and axial gaps. (4) Conclusions: These results indicate that while milling remains a more reliable manufacturing method for achieving external and marginal precision, position 3D-1 is a compelling, chairside alternative to milling. Full article

Background: Anatomical variations in visceral arteries are not so uncommon (up to 20% of cases in general population), with splenic and hepatic artery anomalies being the most frequently reported. Aberrant arteries may be affected with aneurysmal lesions that are rare but potentially fatal conditions. In their treatment, a comprehensive understanding and knowledge of the underlining anatomical variation are pivotal to prevent potential ischemic complications for the end organ. Methods: A comprehensive literature search on the PubMed, Cochrane and Scopus databases was done using the terms: “anomalous visceral artery aneurysm”, “Aberrant visceral arteries”, and “anomalous origin visceral vessels”. Eligible studies published from inception to 30 June 2024 were identified. Only those that had included the adopted treatment strategies (open, endovascular or hybrid repair) and the related outcomes (mortality, bleeding, end-organ ischemia, lesions of the surrounding organ, need for reintervention) were analyzed to evaluate the safety and efficacy of each approach. A narrative analysis of the indications informing the selection of each interventional treatment, based on individual procedural risks, was also presented. Results: A total of 30 publications describing 36 patients (mean age 48.9 ± 12.8 years, range 22–73 years) with aneurysms involving aberrant visceral arteries were included. Most patients were female (25/36, 69.4%). True aneurysms predominated (with a mean size of 30.5 ± 11.5 mm, range 6–60 mm), being reported in 33/36 (91.7%) patients. Most lesions involved a splenic artery arising from the superior mesenteric artery (27/36, 75.0%). Overall, 26/36 (72.2%) patients were symptomatic upon presentation, most commonly with abdominal or epigastric pain, often associated with nausea or vomiting, back pain or shortness of breath. All patients underwent preoperative Computed angiotomography or subtraction angiography to define the operative strategy. Most cases were managed electively (31/36, 86.1%), but 11.1% (4/36) of cases required urgent intervention (in one case the urgency status was not specified). Overall, 19/36 (52.8%) patients underwent purely endovascular repair, 15/36 (41.7%) were treated with open surgery, and 2/36 (5.6%) had hybrid procedures combining endovascular coiling with laparoscopic splenic artery ligation. Indication for treatment was based on vessel tortuosity, landing zones, and the presence of side branches supplying end organs. Early outcomes were favorable regardless of treatment strategies. A single organ-related complication was reported (1/36, 2.8%) following open/endovascular repair, consisting of mild pancreatitis, which resolved with conservative management. No perioperative or aneurysm-related deaths were reported in any of the included cases. No recurrent aneurysms or late aneurysm-related complications were described during the reported follow-up intervals (mean ≈ 10.5 months, range 1.5–42 months). Conclusions: Aneurysms arising from aberrant visceral arteries present unique challenges because their origin, course, and collateral networks deviate from standard anatomy. Patient selection and detailed anatomic mapping preoperatively are decisive as inadequate imaging or failure to recognize an aberrant origin can lead to the incomplete exclusion or inadvertent sacrifice of critical branches. Understanding the anatomy of visceral arteries and their variations is paramount in clinical practice, particularly when planning interventions for minimizing procedural risks, optimizing outcomes, and preventing potential complications. Contemporary practice favors endovascular repair due to lower perioperative morbidity, but success depends on vessel tortuosity, landing zones, and the presence of important side branches that supply end organs. Full article

Background/Objectives: Operator experience, the implementation of low frame rates during both fluoroscopy and digital subtraction angiography (DSA), and the use of modern angiographic systems are essential for maintaining diagnostic image quality while minimizing ionizing radiation exposure during stent-assisted endovascular treatment of intracranial aneurysms. At the study center, a low-dose protocol is employed, using the lowest available fluoroscopy frame rate (3.125 frames per second) and a nominal acquisition rate of 2 frames per second for DSA, three-dimensional (3D) rotational angiography, 2D/3D mapping, and roadmapping. Methods: A retrospective analysis was performed on 132 stent-assisted procedures conducted at a single tertiary center between 2018 and 2024. For each procedure, data were collected for dose-area product (DAP), reference air kerma (Ka,r), fluoroscopy time (FT), and the total number of DSA frames. Local diagnostic reference levels (DRLs; 75th percentile [P75]) and typical values (50th percentile [P50]) were established and compared with values reported in the literature. Results: For all patients the P75 values, representing DRLs, were 19.89 Gy·cm² for DAP, 332 mGy for Ka,r, 25 min 32 s for FT, and 354 DSA frames. The P50 values were 13.71 Gy·cm² for DAP, 219.5 mGy for Ka,r, 20 min 36 s for FT, and 277 DSA frames. Conclusions: In this single-center cohort, dose metrics for stent-assisted coil embolization were within the lower range of published values. Cross-study comparisons remain descriptive and require cautious interpretation. The proposed local DRLs may support quality assurance, dose optimization, and patient safety in similar clinical settings. Further multicenter and multi-operator studies are necessary to assess transferability and applicability beyond coil-only procedures. Limitations include the retrospective single-center design (single operator) and the lack of a contemporaneous control group and formal image-quality/outcome assessment. Full article

Background: Transcatheter aortic valve implantation (TAVI) is increasingly performed in fluoroscopy-intensive environments, raising concerns about occupational eye lens dose (equivalent dose to the eye lens, Hp (3)) and the risk of radiation-induced cataract, particularly after the reduction of recommended annual eye lens dose limits to 20 mSv. Purpose: To summarize evidence on eye lens radiation exposure during TAVI, identify procedural and occupational determinants, and review strategies to reduce exposure with a focus on imaging optimization. Methods: We performed a narrative review of observational and prospective studies reporting direct eye-level dose measurements or validated surrogate eye lens dose estimates (head-level, chest-level, or DAP-normalized) during TAVI and related structural heart procedures. This approach was chosen to provide a qualitative synthesis of the available evidence rather than a formal systematic review. Results: Reported operator eye lens doses typically ranged from 30 to 110 µSv per procedure, with higher exposure during transapical/transaortal access and among staff working close to the patient (e.g., anesthesiologists and circulating nurses). Additional shielding and lead-free drapes reduced normalized eye dose by approximately 25–40%, and RADPAD^® use reduced operator eye-level dose from 24.3 to 14.8 µSv per procedure (p = 0.008). At these levels, cumulative exposure may approach recommended regulatory limits after approximately 150–300 procedures, depending on role, access route, and shielding practices. Conclusion: In conclusion, Occupational eye lens exposure during TAVI is clinically relevant and strongly influenced by access route, staff positioning, and imaging-system use. Dose reduction should combine routine eye protection and dedicated eye-level dosimetry with imaging optimization (low pulse-rate fluoroscopy, minimized Digital-Subtraction-Angiography (DSA)/cine acquisitions, tight collimation, avoidance of unnecessary magnification, and correct positioning of ceiling-suspended shields and table skirts). Full article

Remote sensing change detection (CD) is a technique for quantitatively analyzing and determining the characteristics and processes of surface change using bi-temporal remote sensing data. Deep convolutional networks have achieved remarkable success in CD tasks. However, due to the complexity of the natural lighting environment and other factors, how to use bi-temporal images and segment objects more accurately and effectively has become a focus of research. Many existing studies have overlooked the relationship between samples, disregarding the potential connection between the same semantics across the entire sample set. Moreover, they have ignored the semantic connection between bi-temporal images and have resorted to simple techniques such as concatenation or absolute value subtraction to achieve bi-temporal feature fusion, resulting in information loss. We propose a cross-image feature interaction network consisting of three modules to address the above issues: cross-image non-local enhancement (CINE) module, which can enhance the spatial dimensional links between the same type of objects in the sample space and explores the potential relationship between the same semantics samples on the whole sample set; cross-temporal feature enhancement (CTFE) module, which interacts with bi-temporal image features to enhance real change features while suppressing irrelevant change features; and difference feature adaptive fusion (DFAF) module, which can make effective use of the bi-temporal image features extracted by the network and adaptively learns the fusion parameters. We conducted extensive experiments on two CD datasets, LEVIR-CD and DSIFN-CD, and obtained evaluation scores of 90.75%/83.07% and 69.94%/53.78% on the F1-score and IoU metrics, respectively. Our strategy surpasses existing attention-based approaches such as BIT. Full article

Unmanned aerial vehicles (UAVs) have revolutionized plant protection spraying due to their high efficiency and adaptability. However, the lack of rapid, portable tools for assessing droplet deposition remains a bottleneck for optimizing spray quality and improving pesticide utilization. The main purpose of this study is to develop a portable, image-based detection device with improved algorithms for real-time analysis (<3 s per card) of droplet deposition on spray cards during UAV plant protection spraying, addressing the limitations of existing methods in portability, real-time capability, and field robustness. This study presents a portable detection device integrated with advanced image processing algorithms for real-time analysis of droplet deposition on copperplate paper cards during UAV operations. The device employs a Raspberry Pi 5 as the core processor, coupled with a high-resolution camera and a standard chessboard calibration board for field-portable image acquisition. Key innovations include an adaptive background subtraction and local contrast enhancement method to address variable field lighting conditions, and an improved adhesion droplet segmentation algorithm combining iterative morphological opening operations with refined distance transform-based concave point matching. Validation on 21 field-collected cards using ImageJ as reference demonstrated a droplet extraction accuracy of 89.4%, with coverage rate improvements of 25.4% and 15.2% compared to OTSU and block thresholding methods, respectively. The adhesion segmentation relative error averaged 6.3%. This low-cost, lightweight device provides farmers and researchers with an effective tool for on-site spray quality evaluation, contributing to precision agriculture and reduced pesticide waste. Full article

This paper proposes an advanced three-dimensional optical encryption technique based on double random phase encryption for the simultaneous encryption of two primary datasets. While conventional double random phase encryption offers high-speed encryption, it suffers from low data efficiency. To address this issue, the proposed method assigns the first primary dataset to the amplitude and the second to the phase. However, this approach faces a critical limitation: the phase information becomes undefined or lost when the amplitude is zero. Therefore, we introduce a biased amplitude encoding scheme for double random phase encryption to ensure the mathematical recoverability of the phase component. In the proposed method, a biased value $ϵ$ is added to the amplitude part during the double random phase encryption encryption process and subsequently subtracted from the decrypted data to recover the two primary datasets. To verify the effectiveness of our approach, we employ synthetic aperture integral imaging and volumetric computational reconstruction. The experimental results show that while the first dataset remains lossless, the lossy characteristics of the second dataset are significantly mitigated. Full article

Synthetic aperture radar (SAR) imaging is highly vulnerable to radio-frequency interference (RFI) in complex electromagnetic environments, which can introduce structured artifacts and obscure targets in single-look complex (SLC) products. Most existing suppression methods rely on separability along a single dimension or require interference-specific parameter tuning, limiting robustness under multidimensional coupling and strong scatterers. We propose a range-domain sliding-window local tensorization that rearranges SLC data into localized range–azimuth–block-index tensors to better expose multi-mode correlations. On this representation, an energy-guided tensor CUR low-rank projector is embedded into an alternating-projection scheme that alternates complex-valued soft-thresholding for the sparse scene-plus-noise term and CUR-based projection for the structured RFI term. The cleaned SLC image is obtained by de-tensorizing the estimated RFI component and subtracting it from the input SLC. Experiments on semi-synthetic data, where controlled RFI is superimposed on real SLC scenes, and on real Sentinel-1 SLC data containing RFI demonstrate improved Pearson correlation coefficient (PCC) and perceptual image quality while preserving target signatures and scene textures, particularly under strong interference and strong coupling. The proposed approach provides a practical SLC-domain RFI mitigation tool for post-focusing SAR products without requiring explicit interference parameterization. Full article

Terahertz waves are located in the “transition zone” between millimeter waves and infrared light. Terahertz video synthetic aperture radar (THz-ViSAR) utilizes the high operating frequency, strong radar cross-section intensity, and high azimuth repetition frequency of terahertz waves to detect and track ground moving targets. The conventional methods for detecting moving targets do not take into account the imaging characteristics of moving targets in THz-ViSAR. The constant false alarm rate (CFAR) detection method is used together with other methods to detect moving targets, resulting in unsatisfactory detection performance. This article proposes a new detection method for single channel slow-moving targets in THz-ViSAR based on shadows and light spots, which extracts the features of the shadow and spot areas of the moving target, and determines the position and direction of the moving target through the identification of the shadow and spot areas. The progressiveness of this method is verified by simulation and experimental tests. Full article

The light-trap attraction rate (LTARI) is an important metric for characterizing diel activity patterns and supports studies in insect behavioral ecology and pest management. However, conventional automatic light-trap devices often rely on lethal methods (e.g., high-voltage grids or infrared heating), causing high mortality of non-target insects and severe image obstruction due to stacking of insect bodies. These issues disturb natural populations and bias attempts to quantify LTARI. Our primary objective is to develop and evaluate a non-lethal monitoring system as a methodological basis for future LTARI research, rather than to provide head-to-head quantitative comparisons with conventional traps. To address the above limitations, we propose a live-insect monitoring instrument that integrates a wind-suction trap with a Water-Flow Dispersion and Transport Structure (WF-DTS). The non-destructive trapping–dispersion–release process limits body stacking, allows captured insects to be released, and yields a community-level post-capture survival rate of 94% under the conditions tested. Experimental results show that the prototype maintains image integrity with clearly isolated single insects and achieves a detection performance of 95.6% (mAP@0.5) using the YOLOv8s model. At the inference stage, only the standard resizing and normalization operations of YOLOv8s are applied, without additional denoising, background subtraction, or data augmentation. These observations suggest that the WF-DTS generates images that are easier to segment and classify than those from conventional devices. The high detection accuracy is largely attributable to the physical dispersion of specimens and the uniform white matte background provided by the hardware design. Overall, the system constitutes a non-lethal hardware–software platform that may reduce backend processing complexity and provide a methodological basis for more accurate LTARI estimation in future, dedicated field studies. Full article