Reliability of Different Anterior Cranial Base Reference Areas for Voxel-Based Superimposition

Abstract

The study aimed to evaluate the reliability and reproducibility and compare the outcomes of two 3D voxel-based superimposition techniques for craniofacial CBCT images, using anterior cranial base areas of different extent as references. Fifteen preexisting pairs of serial CBCTs (initial age: 11.7 ± 0.6 years; interval: 1.7 ± 0.4 years) were superimposed on total anterior cranial base (TACB) or middle anterior cranial base (MACB) structures through the Dolphin 3D software. The overlap of the reference structures was assessed visually to indicate reliability. All superimpositions were repeated by the same investigator. Outcomes were compared to assess the agreement between the two methods. Reliability was perfect for the TACB and moderate for the MACB method (p = 0.044). Both areas showed good overall reproducibility, though in individual cases there were notable differences for MACB superimpositions, ranging from −1.84 to 1.64 mm (TACB range: −0.48 to 0.31 mm). The overall agreement in the detected T0/T1 changes was also good, though it was significantly reduced for individual measurements (median < 0.01 mm, IQR: 0.46 mm, range: −2.81 to 0.73 mm). In conclusion, the voxel-based superimposition on TACB was more reliable and showed higher reproducibility than the superimposition on MACB. Thus, the extended anterior cranial base area is recommended for the assessment of craniofacial changes.

Novel Anterior Cranial Base Area for Voxel-Based Superimposition of Craniofacial CBCTs

“…In all cases there were adequate clinical indications to justify the use of CBCT imaging. The sample size was considered adequate based on previous similar investigations [ 21 , 22 , 23 ]. The mean age of the participants at T0 (time of 1st CBCT) was 11.75 ± 0.59 (range: 11.0–12.8) years with a time lap between T0 and T1 (time of 2nd CBCT) of 1.69 ± 0.37 years.…”

“…The distance between the reference area and the measurement area [ 11 , 16 , 17 ], the anatomical accuracy of the three-dimensional renderings of the reference area, and the area of interest [ 14 , 18 ], as well as the morphological stability of the reference area over time [ 9 , 18 , 19 ], should be considered when selecting the reference area. For voxel-based superimpositions of serial CBCTs, the most widely researched and used area includes the central anterior cranial base structures and extends laterally to those structures, as described in previous investigations [ 20 , 21 , 22 , 23 , 24 ]. This area has been shown to be highly reproducible [ 20 , 21 , 22 , 23 , 24 ] and can be used for treatment outcome assessments or the evaluation of craniofacial changes in growing individuals [ 21 , 22 , 23 , 24 ].…”

“…For voxel-based superimpositions of serial CBCTs, the most widely researched and used area includes the central anterior cranial base structures and extends laterally to those structures, as described in previous investigations [ 20 , 21 , 22 , 23 , 24 ]. This area has been shown to be highly reproducible [ 20 , 21 , 22 , 23 , 24 ] and can be used for treatment outcome assessments or the evaluation of craniofacial changes in growing individuals [ 21 , 22 , 23 , 24 ]. However, this area includes soft and hard tissues that extend beyond the stable midline anterior cranial base (ACB) structures after an early age [ 3 , 4 ].…”

“…This has been addressed by a previous study proposing a smaller area including only the midline ACB structures to be used for the voxel-based superimposition of serial CBCTs [ 25 ]. However, this area has shown reduced trueness and reproducibility, which may be attributed to its very small size, allowing higher range of superimposition error [ 23 ].…”

“…This novel area contains the robust midline ACB structures and extends slightly laterally to include the width of the anterior clinoid process of the sphenoid bone. This small extension may potentially counterbalance the inaccuracies stemming from the very narrow axial dimension of the previously proposed central reference area (MACB) [ 23 , 25 ], while still principally including the stable midline anterior cranial base structures. The present investigation evaluated the reliability and reproducibility of a novel Extended Middle Anterior Crania Base area (EMACB) and compared it to the commonly used Total Anterior Cranial Base area (TACB), as well as to the smaller MACB area, including only midline anterior cranial base structures.…”