3D Facial Landmark Localization for cephalometric analysis

Abstract

Cephalometric analysis is an important and routine task in the medical field to assess craniofacial development and to diagnose cranial deformities and midline facial abnormalities. The advance of 3D digital techniques potentiated the development of 3D cephalometry, which includes the localization of cephalometric landmarks in the 3D models. However, manual labeling is still applied, being a tedious and time-consuming task, highly prone to intra/inter-observer variability. In this paper, a framework to automatically locate cephalometric landmarks in 3D facial models is presented. The landmark detector is divided into two stages: (i) creation of 2D maps representative of the 3D model; and (ii) landmarks' detection through a regression convolutional neural network (CNN). In the first step, the 3D facial model is transformed to 2D maps retrieved from 3D shape descriptors. In the second stage, a CNN is used to estimate a probability map for each landmark using the 2D representations as input. The detection method was evaluated in three different datasets of 3D facial models, namely the Texas 3DFR, the BU3DFE, and the Bosphorus databases. An average distance error of 2.3, 3.0, and 3.2 mm were obtained for the landmarks evaluated on each dataset. The obtained results demonstrated the accuracy of the method in different 3D facial datasets with a performance competitive to the state-of-the-art methods, allowing to prove its versability to different 3D models.Clinical Relevance-Overall, the performance of the landmark detector demonstrated its potential to be used for 3D cephalometric analysis. I. INTRODUCTIONCephalometric analysis refers to the assessment of the craniofacial structure to evaluate its growth and development and to diagnose cranial deformities, midline facial abnormalities, and orthodontic problems [1]. Traditionally, 2D radiographs are used for cephalometric analysis, but Computed Tomography (CT) and Magnetic Resonance (MR) imaging systems have been enabling 3D cephalometry [2]. More recently, some works proposed to use 3D digital models (e.g. laser scans) to perform the cephalometric analysis [3]. To

Three-dimensional cephalometric analysis of virtual dentoskeletal model

“…pose several challenges, particularly in the dental region [13,14,19]. The presence of noise, especially in complex dental structures, introduces difficulties in accurate landmark identification and directly impacts the 3D cephalometric measurements [4,7,20,21]. This issue not only hampers precision in diagnosing craniofacial deformities but also adversely affects the reliability of treatment planning [11].…”