Significance: Dry or moist skin-contact thermal stimulation for vein puncture (VP) and vein cannulation (VC) may not be feasible for sensitive skin. For a damaged, burned, or dark skin, near-infrared (NIR) imaging is preferred to visualize a vein. Postprocessing of NIR images is always required because the skin is a reflective material and veins need segmentation for quantitative analysis. Aim: Our pilot study aims to observe the effect of noncontact local heating on the superficial metacarpal veins in the dorsal surface of the hand and to visualize vein dynamics using an NIR imaging system. Approach: Our experiment consists of studies A and B at two ambient temperatures, 19°C and 25°C. A simple reflection-based NIR imaging system was installed to acquire sequential vein images for 5 min before and after applying 10 min of radiant thermal stimulation. To measure the vein diameter (VD), we trained a convolutional neural network (CNN) on sequential raw images to predict vein-segmentation masks as output images. Later these masked images were postprocessed for the VD measurements. Results: The average VD was significantly increased after thermal stimulation in study A. The maximum increments in VD were 39.3% and 9.19%, 1 min after thermal stimulation in studies A and B, respectively. Both the VD and skin temperature (Tskin) follow negative exponentials in time, and the VD is proportional to Tskin. A multiple linear-regression model was made to predict the final VD. A significant difference was observed in the change of the VD. Conclusions: NIR imaging with CNN can be used for quantitative analyses of vein dynamics. This finding can be further extended to develop real-time, image-guided medical devices by integrating them with a radiant heater and to assist medical practitioners in achieving high success rates for VP or VC.

中文翻译：

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响应局部温度升高的近红外成像可视化手背浅静脉动力学

意义：用于静脉穿刺 (VP) 和静脉插管 (VC) 的干燥或潮湿皮肤接触热刺激可能不适用于敏感皮肤。对于受损、烧伤或深色皮肤，首选近红外 (NIR) 成像来可视化静脉。NIR 图像的后处理总是需要的，因为皮肤是一种反射材料，静脉需要分割以进行定量分析。目的：我们的试点研究旨在观察非接触式局部加热对手背表面掌骨浅静脉的影响，并使用 NIR 成像系统可视化静脉动态。方法：我们的实验包括在两个环境温度 19°C 和 25°C 下的研究 A 和 B。安装了一个简单的基于反射的 NIR 成像系统，以在应用 10 分钟的辐射热刺激之前和之后获取连续 5 分钟的静脉图像。为了测量静脉直径 (VD)，我们在连续原始图像上训练了一个卷积神经网络 (CNN)，以预测作为输出图像的静脉分割掩模。后来这些蒙版图像被后处理用于 VD 测量。结果：研究 A 中热刺激后平均 VD 显着增加。研究 A 和 B 中热刺激后 1 分钟，VD 的最大增量分别为 39.3% 和 9.19%。VD 和皮肤温度 (Tskin) 都随时间呈负指数关系，并且 VD 与 Tskin 成正比。建立了多元线性回归模型来预测最终的 VD。在 VD 的变化中观察到显着差异。结论：使用 CNN 的 NIR 成像可用于静脉动力学的定量分析。这一发现可以进一步扩展到通过将它们与辐射加热器集成来开发实时、图像引导的医疗设备，并帮助医生实现 VP 或 VC 的高成功率。