# Texture Analysis of Near-Infrared Vein Images During Reactive Hyperemia in Healthy Subjects
###### Abstract  
Venous perfusion plays a crucial role in vascular health, yet functional assessment of superficial veins remains limited. Near-infrared reflectance imaging (NIRI) devices, commonly used for vein visualization, may offer untapped potential in this context. We investigated whether texture analysis (TA) applied to NIRI-based vein finder images can detect dynamic changes in superficial venous structure during reactive hyperemia. Fourteen healthy adults underwent a suprasystolic occlusion protocol, with real-time images acquired from the hand dorsum. From defined regions of interest, we extracted classical texture parameters (e.g., contrast, correlation, entropy, energy, fractal dimension, and lacunarity) and vein width. While vein width significantly increased during occlusion (\(p<0.001\)), most individual texture parameters remained stable. Notably, correlation increased during occlusion (\(p=0.023\)), and lacunarity decreased during recovery (\(p=0.024\)). We developed composite indices combining texture and morphological features. Entropy-to-width and correlation-to-width ratios decreased during occlusion (\(p<0.001\)), while total entropic content rose (\(p<0.001\)). A modest increase in the correlation-to-entropy ratio during recovery (\(p=0.026\)) suggested delayed reorganization of venous texture. These findings indicate that TA of vein finder images captures functional vascular responses beyond morphology alone. Composite parameters enhance sensitivity and may support the development of non-invasive, low-cost tools for assessing venous function. v 2025 15 5702 2025 17 April 2025 17 April 2025 17 April 2025 17 April 2025 17 May  
including impaired flow, reduced compliance, or increased pressure. Despite their clinical relevance, such alterations are not routinely assessed outside specialized vascular laboratories. Conventional imaging techniques, including Doppler ultrasound [7], computed tomography (CT) [4; 8], magnetic resonance imaging (MRI) [9], and phlebgography (venography) [10], provide detailed vascular information but are often costly, time-consuming, and operator-dependent. These limitations hinder their widespread use in primary care, bedside assessments, and low-resource settings, where simplified approaches could offer substantial clinical value [11]. In this context, near-infrared imaging devices, commonly known as'vein finders', have gained popularity as non-invasive tools for visualizing superficial veins. Their current applications remain mostly restricted to procedural assistance and educational use, particularly in venipuncture [12; 13; 14; 15; 16; 17]. However, they have also proven useful in assisting the identification of venous malformations [18] and in intraoperative applications, such as locating veins during specific phases of surgery [19]. The real-time images generated by these devices display a rich texture profile and high contrast between vascular and non-vascular tissues, raising the possibility of broader diagnostic applications. Specifically, they may enable the quantification of superficial venous morphology and perfusion, thus transforming vein finders from simple guidance tools into instruments of functional vascular assessment. Texture analysis (TA) offers a powerful computational approach to characterize spatial variations in gray-level distributions within an image [20]. It has been extensively used in medical imaging to extract diagnostic-relevant features that may not be perceptible to the human eye, enhancing objectivity and reproducibility. Applications of TA in mammography [21], ultrasound [22], CT [23], and MRI [24] have contributed to improved diagnostic sensitivity and the development of quantitative biomarkers. In the specific area of venous assessment, texture analysis has been employed for the assessment of venous invasion of tumor masses [25], characterization of thrombosis [26], and assessment of venous malformations [27].