## 2 Materials and Methods  
The deepLive(tm) LC-OCT device from DAMAE Medical (Paris, France) is used in the dermatology department at Augsburg University Hospital for the rapid diagnosis of benign and malignant skin changes, as well as for study purposes. It consists of a mobile unit on four castors, which includes the housing with all the hardware and software. The handpiece, which is connected to the housing with a tubular cable harness, enables the skin images to be captured and displayed on a 23-inch EIZO full HD touchscreen. The LC-OCT device uses a class 1 supercontinuum laser according to EN 60825-1 with a wavelength between 600 nm and 900 nm. It achieves a maximum axial and lateral resolution of less than 1.3 \(\upmu\)m. The skin is visualised live at a frame rate of 8 frames per second (fps), while a 3D stack can be created at up to 26 fps. The dermatoscope integrated into the handpiece offers a resolution of 5 \(\upmu\)m and a field of view of 2.5 mm. The deepLiveTM LC-OCT offers multiple modes for tissue visualisation. The Vertical Live Mode shows a vertical section through the skin, similar to histology. In Horizontal Live Mode, horizontal vessels can be visualised in longitudinal and partially in cross-section. The 3D stack mode, which enables isotropic cellular resolution, allows a block of maximum 1200 \(\upmu\)m \(\times\) 500 \(\upmu\)m \(\times\) 500 \(\upmu\)m to be generated [19; 20; 21]. The rendering modes are filters available in the deepLiveTM software 2.0.1. In this study, different rendering and filtering modes of the LC-OCT system were used to visualize the vascular structures as precisely as possible and to capture the different morphological characteristics. The applied modes included the deepGaussian mode and the minimum rendering mode. The deepGaussian mode is applying a gaussian filter combining several consecutive slices, which enhances contrast differences between vessels and the surrounding tissue. The minimum mode projects the minimal intensity of all considered slices, which is particularly suitable for highlighting thick-caliber vessels. The deepGaussian mode was used to detail fine, polymorphic vascular structures that are often difficult to recognize in the original image. In contrast, the minimum rendering mode facilitated the visualization of large-diameter main vascular structures, such as those frequently found in basal cell carcinomas or melanoma metastases. Users can manually adjust the number of consecutive slices to which the filter is applied, according to their rendering preferences. The choice of the appropriate rendering mode was specifically adapted to the respective properties of the vascular structures and the specific problem in order to create the best possible basis for the three-dimensional reconstruction. The deepLiveTM LC-OCT system is a direct skin contact method in which the optical head of the device is placed on the skin surface to create high-resolution images of the vascular structures. To minimize pressure artifacts, the contact pressure during the examination was deliberately kept low. This was controlled by gradually adjusting the pressure, using increased blood flow in the imaged vessels as visual feedback. This increase in blood flow served as an indicator that the pressure was minimal and that the tissue structure was affected as little as possible. The measurements were carried out exclusively by trained and experienced personnel who had extensive experience in using the LC-OCT device. This standardized procedure contributed significantly to ensuring the quality of the images and the validity of the reconstructed vascular structures. Extreme care was also taken during the complementary dermoscopy to keep contact with the skin as light as possible and to avoid tissue deformation. These measures were crucial in order to display the natural vascular morphologies without distortion and to obtain reliable results for the three-dimensional segmentation of the vascular structures.