Notaris, Matteo de

BACKGROUND AND OBJECTIVE: In skull base surgery, endoscopic endonasal approaches require precise evaluation of the area of exposure and the maneuverability provided by each approach. Current neuroanatomical methodologies for quantifying these parameters primarily rely on computed tomography (CT) scans and neuronavigation systems, which entail significant financial investment. The aim of this study was to develop and validate an innovative, cost-effective methodology using an endoscopic photogrammetric model to measure the exposure area and maneuverability in endoscopic endonasal approaches, offering an accessible alternative to existing techniques. METHODS: Six cadaveric specimens were used to validate the accuracy of endoscopic photogrammetric measurements by comparing them with direct measurements. Subsequently, the exposure area, angle of attack, and surgical freedom were analyzed for 3 endoscopic approaches to the parasellar region: contralateral transmaxillary, single-nostril, and double-nostril approaches. RESULTS: Photogrammetric measurements demonstrated a high level of concordance with direct cadaveric measurements, with a mean difference of 0.02 mm as shown in the Bland-Altman plot. In addition, measurements obtained in comparative analysis describing the exposure area and maneuverability of 3 endoscopic approaches were congruent with those reported in existing literature derived using CT scans and neuronavigation systems. CONCLUSION: To our knowledge, this study is the first to validate endoscopic photogrammetric models as a measurement tool in neuroanatomy. Performing direct measurements on 3D models might eliminate the necessity of expensive CT and neuronavigation systems for volumetric quantification. Our cost-effective methodology allows for the widespread democratization of anatomical quantification within skull base neuroanatomy.

BACKGROUND AND OBJECTIVES: Photogrammetry application is rapidly growing within the anatomical field as a new technique, underlining the need for the development of a comprehensive step-by-step methodology and guide to facilitate the pursuit of high-definition photogrammetry. Therefore, the aim of this study was to describe 2 photogrammetry techniques and their step-by-step from positioning and preparing the specimens for photodocumentation to the final 3-dimensional (3D) model displayed on online platforms. METHODS: Two dry skulls, 2 embalmed brains, and 30 embalmed and latex-injected heads were used for the study, rendering a total of 130 3D models. The specimens were placed on a turntable and photodocumented using a digital single-lens reflex camera or smartphone, and the key steps and notes were methodically described. RESULTS: The photogrammetry technique using either a digital single-lens reflex camera or smartphone required images captured in 3 different steps: overview images, close range photographs, and images of depth-located structures. All images were then upload to Agisoft Metashape software, postprocessed and rendered into the final 3D model and displayed using Sketchfab ® . CONCLUSION: This article provided a detailed description of a high-resolution photogrammetry scanning technique, highlighting the advantages and relevance of acquiring 3D models through mobile devices to demystify and clarify the technique to enhance the experience in clinical and neuroanatomical application.