A Novel Voxel-based Technique for 3-Dimensional Transparent Visualization of Lip–Nasal Vasculature

Summary:

Conventional imaging cannot capture the spatial relationship between soft tissue and vasculature in patients with cleft lip. Here, a novel technique integrating micro–computed tomography imaging with voxel-based 3-dimensional reconstruction was developed using the Bioxel Nodes plugin in Blender. High-resolution modeling of both vasculature and surrounding soft tissue with adjustable transparency was achieved by segmenting computed tomography data based on intensity thresholds. This method allows intuitive visualization of the superior labial artery, columellar branches, and lateral nasal arteries. Notably, a spatial correlation was observed between these vessels and embryonic fusion zones of facial prominences, suggesting a potential link to cleft lip pathogenesis. Compared with traditional modeling methods, the current workflow offers improved anatomical clarity, enhanced interactivity, and lower technical barriers. In this study, Blender-based voxel rendering was applied for simultaneous reconstruction of blood vessels and transparent soft tissue in the perioral and perinasal region. This technique may assist in flap design, injection planning, and intraoperative vascular preservation, and thus provides a valuable tool for craniofacial surgery and education.

Takeaways

Question: How can surgeons and anatomists obtain a fully transparent, high-resolution 3D view of lip–nasal vasculature with overlying soft tissue?

Findings: In a perfused cadaver, micro–computed tomography data were processed with an open-source voxel workflow (Blender + Bioxel) to render vessels and soft tissue with adjustable transparency and enable live digital slicing.

Meaning: This low-cost, reproducible workflow creates an intuitive 3-dimensional atlas to guide flap design, filler injection, and cleft lip surgery and to enhance anatomical education.

INTRODUCTION

Visualization of facial vasculature, especially in the lip and nose region, is critical for surgical planning and anatomical understanding. In cleft lip repair, an accurate understanding of vascular pathways can help preserve blood supply and minimize complications. However, conventional imaging techniques lack the resolution to depict small vessels or to present their relationship with soft tissue in 3 dimensions. Current 3-dimensional (3D) modeling approaches are typically performed on the surface, limiting internal structure visualization and transparency adjustment. In this study, a voxel-based reconstruction method was introduced using micro–computed tomography (micro-CT) data and the Bioxel Nodes plugin in Blender. This open-source technique allows simultaneous rendering of vasculature and soft tissue with dynamic transparency. It was applied to the perioral and perinasal region, highlighting both the vascular network and its spatial correlation with embryonic fusion lines.

METHODS

Micro-CT has been widely used for small specimens or tissue blocks.¹ In this study, micro-CT was used to collect ultra–high-resolution volumetric data. We studied 1 cadaveric lip–nasal tissue block (ex vivo) acquired by micro-CT and used the resulting Digital Imaging and Communications in Medicine (DICOM) volumes for voxel-based 3D reconstruction in Blender (Bioxel Nodes).² The generated micro-CT DICOM datasets were imported into Blender using the Bioxel Nodes plugin to obtain a container object and geometry nodes for volumetric processing. CT data were voxelized and segmented by intensity thresholds. Blood vessels, with higher CT values than surrounding tissue, were isolated using a Cutout by Threshold node set at 4500. Soft tissue was segmented using a Cutout by Range node spanning 100–6000.

RESULTS

Plane Cutter node was introduced for dynamic slicing and rotation to expose internal anatomy. Threshold parameters were adjusted to improve anatomical accuracy. Cross-sectional verification ensures fidelity. Material properties were assigned using Set Color by Ramp 3 nodes. Vessels were visualized in the 4000–4500 range to simulate a realistic appearance, whereas soft tissue was rendered semitransparent (range 100–2500) to emphasize the spatial interplay between vessels and surrounding musculature. Here, a fully manipulable, high-resolution 3D model was produced. After vascular perfusion and muscle staining, lip–nasal specimens were successfully reconstructed in 3D via a voxel-based method. (See figure, Supplemental Digital Content 1, which displays a 3D reconstruction of the lip–nasal region following microvascular perfusion and muscle fiber staining, https://links.lww.com/PRSGO/E659.)

Major arteries became clearly visible after segmentation and transparency processing (Fig. 1). The facial artery gave rise to branches near the oral commissure, including the lateral nasal artery ascending toward the ala and the superior labial artery along the upper vermilion border. The superior labial arteries from both sides met medially and gave off columellar branches at the philtral crest. These branches ascended as the superficial septal artery and entered the columella base or extended toward the nasal tip. Other branches included the inferior and superior alar arteries along the nasal sill and lateral alar regions.

Fig. 1.

Three-dimensional reconstruction of the lip–nasal tissue block from micro-CT DICOM data. Frontal (A), oblique superior (B), posterior (C), and oblique lateral views (D) of the reconstructed model. Vascular and soft tissue structures are clearly visualized through segmentation and transparency processing. The left half of the model was digitally sectioned using a plane-cutting algorithm to better demonstrate the spatial relationship between the upper labial vasculature and surrounding soft tissues.

Transparency processing revealed superficial and deep vascular networks. High-density networks were observed in the infralobular triangle, the proximal lateral nasal origin, and the central philtrum. By contrast, a quadrilateral zone—bounded by the columellar base, alar side, oral commissure, and Cupid’s bow—showed sparse superficial vasculature but denser deep vessels.

Major arteries—including the lateral nasal, alar, superior labial, superficial septal, and columellar branches—were spatially aligned with the embryonic fusion zones of the medial nasal, lateral nasal, and maxillary prominences. (See figure, Supplemental Digital Content 2, which displays the major arteries of the upper lip vasculature. The schematic diagram shows the major arteries: green, lateral nasal artery; purple, superior labial artery; pink, inferior and superior alar arteries; yellow, superficial septal branch, https://links.lww.com/PRSGO/E660.) This correlation suggests a developmental link between vascular formation and facial fusion.

DISCUSSION

Accurate visualization of perioral vasculature is essential for procedures such as cleft lip repair, yet conventional imaging rarely clarifies the spatial relationships between vessels and soft tissue in 3 dimensions. We developed a voxel-based 3D reconstruction workflow using ex vivo micro-CT and the Bioxel Nodes plugin for Blender to simultaneously render both structures with adjustable transparency.

Segmentation underpinned the reconstruction. We used a CT-threshold strategy that exploits attenuation contrast between vessels and surrounding soft tissue. Assigning material properties to segmented voxels yielded translucent renderings that display the spatial relationship between subcutaneous vasculature and external landmarks, enabling interactive “digital sectioning.”

Our reconstructions showed the superficial septal artery coursing along the philtral crest, in spatial alignment with the fusion zones of medial nasal and maxillary prominences. This observation is consistent with Garcia de Mitchell et al,³ who described ascending philtral arteries flanking the central fat compartment and posited that disruption of this vascular architecture may contribute to cleft formation. The workflow provides a 3D, hypothesis-generating view of these relationships and a nondestructive ex vivo reference for planning.

Compared with surface-based models or destructive preparations, this ex vivo voxel approach preserves soft-tissue context and affords greater operator control over transparency and slicing. Similar Bioxel-based planning models have been reported to qualitatively match intraoperative findings in other domains,⁴ suggesting broader surgical relevance.

Beyond anatomy, the method may have clinical and educational implications. For example, Liu et al⁵ used micro-CT with Sihler staining to define intramuscular neurovascular “risk zones” in the upper lip. Although our current model does not include nerves, its vascular precision could support future adaptations that integrate neurovascular information for zoning strategies and training.

This proof-of-concept study was restricted to a single cadaveric lip–nasal specimen, which limits statistical inference and does not capture interindividual vascular variability. The workflow also relied on ex vivo micro-CT, constraining immediate clinical translation. Cone-beam CT (CBCT) is referenced here only as a potential in vivo clinical modality for future translation; unlike micro-CT, CBCT is obtained in vivo and provides lower spatial resolution appropriate for indication-based clinical decision-making,⁶ and it was not used to acquire any data in the present study. In view of radiation exposure—particularly in children—any in vivo CBCT application should be strictly indication-based and dose-optimized (smallest feasible field-of-view, pediatric low-dose protocols).⁷ Future work will be performed to (1) test reproducibility in multicenter cadaveric cohorts and in vivo CBCT datasets, and quantify interindividual variability using template registration, centerline metrics, and probabilistic vessel-density maps⁸; (2) couple the voxel model with augmented-reality navigation to provide real-time vascular road maps for flap harvest, filler injection, and cleft repair; (3) integrate contrast-enhanced perfusion scanning to generate quantitative heatmaps⁹ and seed patient-specific digital twins for surgical simulation and 3D printing¹⁰; and (4) develop curriculum-aligned teaching modules using these transparent voxel models (simultaneous inspection of surface landmarks and subcutaneous arteries, case-based rehearsal of flap/injection planes, and mapping of danger zones). These steps will convert the present static atlas into an immersive platform for precision plastic and reconstructive surgery.

CONCLUSIONS

A voxel-based visualization workflow was developed that reconstructs lip–nasal vasculature and soft tissue in 3D from micro-CT data. Specimens were perfused and muscle-stained, and then processed in Blender with Bioxel Nodes to achieve transparent rendering and precise spatial separation. Digital sectioning using the Plane Cutter node exposed major arteries along embryonic fusion zones, shedding light on cleft lip pathogenesis. Compared with conventional techniques, this approach improves anatomical clarity and modeling flexibility, enabling promising applications for flap harvest, filler injection, and interactive anatomy education.

DISCLOSURES

The authors have no financial interest to declare in relation to the content of this article. This work was supported by the Chinese Academy of Medical Sciences Initiative for Innovative Medicine (2021-I2M-1-052).