A Degraded Finger Vein Image Recovery and Enhancement Algorithm Based on Atmospheric Scattering Theory.

With the development of biometric identification technology, finger vein identification has received more and more widespread attention for its security, efficiency, and stability. However, because of the performance of the current standard finger vein image acquisition device and the complex internal organization of the finger, the acquired images are often heavily degraded and have lost their texture characteristics. This makes the topology of the finger veins inconspicuous or even difficult to distinguish, greatly affecting the identification accuracy. Therefore, this paper proposes a finger vein image recovery and enhancement algorithm using atmospheric scattering theory. Firstly, to normalize the local over-bright and over-dark regions of finger vein images within a certain threshold, the Gamma transform method is improved in this paper to correct and measure the gray value of a given image. Then, we reconstruct the image based on atmospheric scattering theory and design a pixel mutation filter to segment the venous and non-venous contact zones. Finally, the degraded finger vein images are recovered and enhanced by global image gray value normalization. Experiments on SDUMLA-HMT and ZJ-UVM datasets show that our proposed method effectively achieves the recovery and enhancement of degraded finger vein images. The image restoration and enhancement algorithm proposed in this paper performs well in finger vein recognition using traditional methods, machine learning, and deep learning. The recognition accuracy of the processed image is improved by more than 10% compared to the original image.

Adrenal Vein Sampling: Tips and Tricks.

Adrenal vein sampling (AVS) is the standard method for distinguishing unilateral from bilateral sources of autonomous aldosterone production in patients with primary aldosteronism. This procedure has been performed at limited specialized centers due to its technical complexity. With recent advances in imaging technology and knowledge of adrenal vein anatomy in parallel with the development of adjunctive techniques, AVS has become easier to perform, even at nonspecialized centers. Although rare, anatomic variants of the adrenal veins can cause sampling failure or misinterpretation of the sampling results. The inferior accessory hepatic vein and the inferior emissary vein are useful anatomic landmarks for right adrenal vein cannulation, which is the most difficult and crucial step in AVS. Meticulous assessment of adrenal vein anatomy on multidetector CT images and the use of a catheter suitable for the anatomy are crucial for adrenal vein cannulation. Adjunctive techniques such as intraprocedural cortisol assay, cone-beam CT, and coaxial guidewire-catheter techniques are useful tools to confirm right adrenal vein cannulation or to troubleshoot difficult blood sampling. Interventional radiologists should be involved in interpreting the sampling results because technical factors may affect the results. In rare instances, bilateral adrenal suppression, in which aldosterone-to-cortisol ratios of both adrenal glands are lower than that of the inferior vena cava, can be encountered. Repeat sampling may be necessary in this situation. Collaboration with endocrinology and laboratory medicine services is of great importance to optimize the quality of the samples and for smooth and successful operation. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Histopathological analysis of the wall enhancement of the spinal dural arteriovenous fistulae's draining veins.

OBJECTIVE: The mechanism behind SDAVF is still unclear. We discovered that the vessel wall of the SDAVF-DV occasionally showed enhancement in MRI, and this study assessed the relationship between the enhancement of the draining vein's wall and its histology. METHODS: For histopathologic analysis, 16 draining vein samples from 16 patients with SDAVF were included, 3 normal arteries and 3 normal veins were chosen as comparison. We assessed the imaging and microscopic characteristics of the draining veins in SDAVF patients. The former included the presence of significant enhancement of the wall of the draining vein in MRI, and the latter included the adherence, aggregation, infiltration of pro-inflammatory factors and inflammatory cells. Immuno-histochemical staining was performed using IL-1ß, IL-8, TGF-ß as well as MPO and MMP-9, and positive results were counted. Multiple logistic regression analysis was used to determine whether the infiltration of inflammatory cells was connected to vessel wall enhancement in the SDAVF-DV. RESULTS: Infiltration of inflammatory cells was significantly higher in SDAVF-DV compared to normal vessels, 7 out of 16 patients significantly had enhancement of the vessel wall of SDAVF-DV, and logistic regression analysis showed that samples with more infiltration of inflammatory cells were more likely to show enhancement of the SDAVF-DV walls. CONCLUSION: There was considerable inflammatory cells infiltration in SDAVF-DV, and this may explain why their vessel wall had such a significant enhancement in MRI.

Ultrasound diagnosis of Mondor's disease involving the superficial scrotal veins: Unveiling a rare mimicker of acute scrotal emergencies.

We describe a rare case of Mondor disease of the superficial scrotal veins, which can clinically mimic acute testicular pathologies such as testicular torsion or epididymo-orchitis, and highlight the value of grayscale/Doppler ultrasound examination in distinguishing these entities, which have different management implications.

Anatomical features of a crossing vein connecting left and right internal mammary veins: A preliminary study with computerized tomography or magnetic resonance imaging.

BACKGROUND: In breast reconstruction with free flaps, retrograde venous anastomosis into the internal mammary vein (IMV) is often unavoidable. Utility of a crossing vein between the right and left IMV, one of the anatomical foundations which make retrograde flow possible, has been reported but only with a few detailed features. This study evaluated the presence, actual location, and diameter of the crossing veins using preoperative imaging such as contrast-enhanced computed tomography (CECT), or contrast-enhanced magnetic resonance imaging (CEMRI). Moreover, this is a preliminary non-invasive study to clarify these processes on a larger scale. METHODS: We included 29 cases of unilateral breast reconstruction performed between July 2018 and September 2023 at our institution using unipedicled or bipedicled free deep inferior epigastric artery perforator (DIEP) flaps with retrograde venous anastomosis to only one IMV at the level of anastomosis. No congestion or necrosis was observed. In the final 24 cases with sufficient imaging coverage of preoperative contrast-enhanced images (15 CECT and 9 CEMRI), the crossing veins of IMVs were detected and the number, localization, and diameter were measured. RESULTS: In 20 cases of 24 images, the crossing veins between IMVs were completely identified (83%). In 18 of the cases, only one crossing vein was established immediately ventral to the xiphoid process, averaging 19.3 ± 7.18 mm caudal to the fibrous junction between the sternal body and xiphoid process. The average diameter of the veins was 1.57 ± 0.42 mm. In two other cases, the second crossing vein originated on the dorsal surface of the sternum, but it was a very thin vein of about 0.4 mm. Three images indicated incomplete identification of the crossing vein at the xiphoid process, and in one case, no crossing vein was observed between bilateral IMVs. CONCLUSION: The contrast-enhanced imaging study revealed an anatomic feature that the crossing veins (about 1.5 mm in diameter) connecting the right and left IMVs are located just ventral to the xiphoid process. Furthermore, the crossing veins can be identified on contrast-enhanced images, and refinement of this method is expected to lead to future non-invasive anatomical investigations in an even larger number of cases.

Finger Vein Identification Based on Large Kernel Convolution and Attention Mechanism.

FV (finger vein) identification is a biometric identification technology that extracts the features of FV images for identity authentication. To address the limitations of CNN-based FV identification, particularly the challenge of small receptive fields and difficulty in capturing long-range dependencies, an FV identification method named Let-Net (large kernel and attention mechanism network) was introduced, which combines local and global information. Firstly, Let-Net employs large kernels to capture a broader spectrum of spatial contextual information, utilizing deep convolution in conjunction with residual connections to curtail the volume of model parameters. Subsequently, an integrated attention mechanism is applied to augment information flow within the channel and spatial dimensions, effectively modeling global information for the extraction of crucial FV features. The experimental results on nine public datasets show that Let-Net has excellent identification performance, and the EER and accuracy rate on the FV_USM dataset can reach 0.04% and 99.77%. The parameter number and FLOPs of Let-Net are only 0.89M and 0.25G, which means that the time cost of training and reasoning of the model is low, and it is easier to deploy and integrate into various applications.

Automated hyperspectral imaging for non-invasive characterization of human eye vasculature: A potential tool for ocular vascular evaluation.

The vascular supply to the human eye plays a vital role in maintaining ocular health, making its non-invasive evaluation essential for diagnosing and managing various ocular disorders. This paper presents a novel approach utilizing hyperspectral imaging (HSI) to non-invasively characterize human eye vasculature. The proposed system aims to specifically identify the blood atrium and veins of the human eye at 470 nm and 750 nm, respectively, using quantitative phase analysis and k-means clustering. The study involved capturing diffused reflection spectra and hyperspectral images of the human eye at different wavelengths to reveal distinctive vascular features. The results of ten volunteers demonstrate promising capabilities in automated differentiation of atrium and veins, as well as the potential for mapping varicose veins in the lower limb. This non-invasive and non-contact imaging technique shows great promise in facilitating accurate and detailed evaluation of ocular blood flow, providing valuable information for clinical diagnosis and treatment in ophthalmology and vascular medicine fields.

Overlapping lockup lymphaticovenous anastomosis: A useful addition to supermicrosurgery.

BACKGROUND: Lymphaticovenular anastomosis (LVA) is a minimally invasive surgical procedure used to treat lymphedema. This surgical procedure connects the superficial lymphatic vessels to nearby veins to establish lymphatic-venous pathways. One of the most common challenges encountered by lymphatic surgeons when performing LVA is a mismatch in the sizes of the veins and lymphatic vessels, with the effectiveness limited by technical constraints. We conducted a pilot study to evaluate the feasibility of an overlapping lockup anastomosis (OLA) LVA technique to address these problems. METHODS: In this study, we present a novel OLA technique for LVA that addresses the challenges with conventional techniques. The OLA technique was used in 10 lymphedema patients between September 2022 and March 2023 to compare OLA and end-to-end anastomosis. The time required for anastomosis, method of anastomosis, patency rates, and lymphedema volume were evaluated in this study. RESULTS: Of 123 LVAs, 44 were performed using the OLA technique in 10 patients, with indocyanine green lymphangiography revealing unobstructed drainage. A single case of slight fluid leakage occurred, which was resolved by reinforcing the sutures. The average anastomosis time for OLA and the end-to-end technique was 5.55 minutes and 12.1 minutes, respectively. The wounds of the patients healed without infection, and the subjective limb circumference decreased. CONCLUSIONS: The OLA technique could serve as a valuable addition to the current LVA technique, especially for cases with a mismatch in the sizes of the lymphatic vessels and veins. This technique has the potential to promote the broader application of LVA in the treatment and prevention of lymphedema.

Comparison of wireless handheld ultrasound and high-end ultrasound in pediatric patients with venous malformations - First results.

AIM: To evaluate the usefulness of handheld ultrasound in comparison with high-end ultrasound for lesion evaluation before and after sclerotherapy in pediatric patients with venous malformations (VMs). MATERIAL AND METHODS: 10 pediatric patients prior to and after sclerotherapy were scanned by an experienced examiner using handheld ultrasound (Vscan AirTM) and high-end ultrasound (LOGIQ E9/E10) as reference. Patients with associated venous thromboses and intralesional aneurysms had been excluded. Results were interpreted independently by two readers in consensus. RESULTS: 10 patients (4-17 years; 10.0±4.32 years; female n = 6, male n = 4) with 10 VMs (4 of the head and neck region, 4 of the upper and 2 of the lower extremities) were examined. 7 phleboliths were detected. The average rating score achieved by the high-end device never was less than 4, by Vscan AirTM never less than 3. An exception was the assessment of AV fistulas. In comparison with the evaluation of variables examined, we found a significant difference between the high-end scanner and the handheld device regarding the achieved image quality. CONCLUSION: Vscan AirTM ultrasound device allows new possibilities for procedure planning and post-procedural control of pediatric patients with VMs.

Simultaneous time-of-flight MR angiography and quantitative susceptibility mapping with key time-of-flight features.

A technique for combined time-of-flight (TOF) MR angiography (MRA) and quantitative susceptibility mapping (QSM) was developed with key features of standard three-dimensional (3D) TOF acquisitions, including multiple overlapping thin slab acquisition (MOTSA), ramped RF excitation, and venous saturation. The developed triple-echo 3D TOF-QSM sequence enabled TOF-MRA, susceptibility-weighted imaging (SWI), QSM, and R2* mapping. The effects of ramped RF, resolution, flip angle, venous saturation, and MOTSA were studied on QSM. Six volunteers were scanned at 3 T with the developed sequence, conventional TOF-MRA, and conventional SWI. Quantitative comparison of susceptibility values on QSM and normalized arterial and venous vessel-to-background contrasts on TOF and SWI were performed. The ramped RF excitation created an inherent phase variation in the raw phase. A generic correction factor was computed to remove the phase variation to obtain QSM without artifacts from the TOF-QSM sequence. No statistically significant difference was observed between the developed and standard QSM sequence for susceptibility values. However, maintaining standard TOF features led to compromises in signal-to-noise ratio for QSM and SWI, arising from the use of MOTSA rather than one large 3D slab, higher TOF spatial resolution, increased TOF background suppression due to larger flip angles, and reduced venous signal from venous saturation. In terms of vessel contrast, veins showed higher normalized contrast on SWI derived from TOF-QSM than the standard SWI sequence. While fast flowing arteries had reduced contrast compared with standard TOF-MRA, no statistical difference was observed for slow flowing arteries. Arterial contrast differences largely arise from the longer TR used in TOF-QSM over standard TOF-MRA to accommodate additional later echoes for SWI. In conclusion, although the sequence has a longer TR and slightly lower arterial contrast, provided an adequate correction is made for ramped RF excitation effects on phase, QSM may be performed from a multiecho sequence that includes all key TOF features, thus enabling simultaneous TOF-MRA, SWI, QSM, and R2* map computation.

Assessment of skin and associated soft tissue changes with ultrasonography in chronic venous disease.

OBJECTIVE: Chronic venous disease (CVD) is accompanied by a spectrum of skin changes. The aim of this study was to assess skin changes in CVD in different classes of the classifications such as the Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification using ultrasound (US). METHODS: This study was conducted from July 2020 to July 2021 after obtaining approval from Institutional Ethical Committee. Patients with chronic venous insufficiency were enrolled after taking informed consent. Assessment of cutaneous layer (CL), subcutaneous layer (SCL), dermo-hypodermal junction (D-HJ), and other significant US findings were noted. RESULTS: Ninety-eight limbs were evaluated. Most common skin finding was dermal edema in 59 (60.2%) legs. Other findings included infiltrates, CL thickening, hyper echogenicity and thickening of SCL, anechoic lacunae, disappearance of D-HJ, and epidermal loss or change in thickness of epidermis. Notably, US detected dermal edema in 15 and infiltrates in five C2 legs (normal on inspection). CONCLUSION: US evaluation of skin changes adds insight to clinical assessment and may reveal skin changes in legs affected with CVD that may appear normal on clinical examination.

Outcomes of one-stage and two-stage aneurysm repair in arteriovenous fistulae.

OBJECTIVE: Maintenance of long-term arteriovenous access is important in long-term care for patients with end-stage renal disease. Arteriovenous access is associated in the long term with the development of fistula aneurysms (FAs). This study aims to evaluate the outcomes of staged FA treatment in dialysis access arteriovenous fistulae (AVF). METHODS: A retrospective review of all patients over a 12-year period with primary autogenous AVF was undertaken at a single center. Patients undergoing elective open aneurysm repair were identified and were categorized into three groups: single FA repair (single, control group) and staged and unstaged repair of two FAs (staged and unstaged). A staged repair was a procedure in which the initial intent was to treat both aneurysms in the AVF and in which the most symptomatic aneurysm was treated first. When the incision from the first surgery had healed, the second symptomatic aneurysm in the AVF was treated. An unstaged repair was a procedure in which the initial intent was to repair both symptomatic aneurysms simultaneously. All patients had a fistulogram before the FA repair. Thirty-day outcomes, cannulation failure, line placement, reintervention, and functional dialysis (continuous hemodialysis for 3 consecutive months) were examined. RESULTS: Five hundred twenty-seven patients presented with FA that met requirements for open intervention; 44% underwent single FA repair, whereas the remaining 34% and 22% underwent staged and unstaged repair of two FAs, respectively. The majority of patients were diabetic and Hispanic. Ninety-one percent of the patients required percutaneous interventions of the outflow tract (37%) and the central veins (54%). Thirty-day major adverse cardiovascular events were equivalent across all modalities. Thirty-day morbidity and early thrombosis (<18 days) were significantly higher in the unstaged group (4.3%) compared with the two other groups (1.3% and 2.1%, single and staged, respectively), which led to an increased need for a short-term tunneled catheter (8.9%) compared with the two other groups (3.4% and 4.4%, single and staged, respectively), Unstaged repair resulted in an increased incidence of secondary procedures (5.0%) compared with the two other groups (2.6% and 3.1%, single and staged, respectively). Functional dialysis at 5 years was equivalent in the single and staged groups but was significantly decreased in the unstaged group. CONCLUSIONS: Open interventions are successful therapeutic modalities for FAs, but unstaged rather than staged repair of two concurrent FAs results in a higher early thrombosis, an increased secondary intervention rate, and a need for a short-term tunneled central line. Staged and single FA repairs have equivalent results. In the setting of two symptomatic FAs, staged repair is recommended.

Multispectral Imaging for Vein Localization and Contrast Enhancement.

Intravenous (IV) catheterization is a common procedure. Still, there is a 26% chance of the first attempt catheterization failure due to the changing visibility of veins because of the patient's skin tone and body fat content. Ultrasound assistive devices help locate deeper veins but are not practical in emergencies, and transillumination assistive devices have a low field of view. Commercial near-infrared (NIR) imaging devices are effective in vein localization but are expensive and are not used in low-cost clinical settings. To overcome this, NIR Multispectral Imaging (MSI) was used to find the optimal wavelength that provides the enhanced visualization of veins for all skin types and Body Mass Index (BMI). The band with the highest vein-to-skin contrast ratio was selected and contrast enhancement was done using our proposed method. The primary blocks of the proposed method are Gamma correction, Contrast Limited Adaptive Histogram Equalization (CLAHE), Adaptive Thresholding, and image Fusion. The optimal spectral range was found to be 814-876 nm and our method increased the contrast by 0.41, 0.375, and 0.39 for fair, brown, and dark brown skin types, respectively, with different BMI.Clinical relevance- From the study, we can develop a potentially low-cost vein localization assistive device for training medical and nursing students and use it in emergencies for venous access to improve confidence in IV catheterization.

A Finger Vein Liveness Detection System Based on Multi-Scale Spatial-Temporal Map and Light-ViT Model.

Prosthetic attack is a problem that must be prevented in current finger vein recognition applications. To solve this problem, a finger vein liveness detection system was established in this study. The system begins by capturing short-term static finger vein videos using uniform near-infrared lighting. Subsequently, it employs Gabor filters without a direct-current (DC) component for vein area segmentation. The vein area is then divided into blocks to compute a multi-scale spatial-temporal map (MSTmap), which facilitates the extraction of coarse liveness features. Finally, these features are trained for refinement and used to predict liveness detection results with the proposed Light Vision Transformer (Light-ViT) model, which is equipped with an enhanced Light-ViT backbone, meticulously designed by interleaving multiple MN blocks and Light-ViT blocks, ensuring improved performance in the task. This architecture effectively balances the learning of local image features, controls network parameter complexity, and substantially improves the accuracy of liveness detection. The accuracy of the Light-ViT model was verified to be 99.63% on a self-made living/prosthetic finger vein video dataset. This proposed system can also be directly applied to the finger vein recognition terminal after the model is made lightweight.

Fast and Accurate ROI Extraction for Non-Contact Dorsal Hand Vein Detection in Complex Backgrounds Based on Improved U-Net.

In response to the difficulty of traditional image processing methods to quickly and accurately extract regions of interest from non-contact dorsal hand vein images in complex backgrounds, this study proposes a model based on an improved U-Net for dorsal hand keypoint detection. The residual module was added to the downsampling path of the U-Net network to solve the model degradation problem and improve the feature information extraction ability of the network; the Jensen-Shannon (JS) divergence loss function was used to supervise the final feature map distribution so that the output feature map tended to Gaussian distribution and improved the feature map multi-peak problem; and Soft-argmax is used to calculate the keypoint coordinates of the final feature map to realize end-to-end training. The experimental results showed that the accuracy of the improved U-Net network model reached 98.6%, which was 1% better than the original U-Net network model; the improved U-Net network model file was only 1.16 M, which achieved a higher accuracy than the original U-Net network model with significantly reduced model parameters. Therefore, the improved U-Net model in this study can realize dorsal hand keypoint detection (for region of interest extraction) for non-contact dorsal hand vein images and is suitable for practical deployment in low-resource platforms such as edge-embedded systems.