Reliability of orbital volume measurements based on computed tomography segmentation: Validation of different algorithms in orbital trauma patients

Automated 3-D Computer-Aided Measurement of the Bony Orbit: Evaluation of Correlations among Volume, Depth, and Surface Area

(1)The study aimed to measure the depth, volume, and surface area of the intact human orbit by applying an automated method of CT segmentation and to evaluate correlations among depth, volume, and surface area. Additionally, the relative increases in volume and surface area in proportion to the diagonal of the orbit were assessed. (2) CT data from 174 patients were analyzed. A ball-shaped mesh consisting of tetrahedral elements was inserted inside orbits until it encountered the bony boundaries. Orbital volume, area depth, and their correlations were measured. For the validation, an ICC was used. (3) The differences between genders were significant (p < 10-7) but there were no differences between sides. When comparing orbit from larger to smaller, a paired sample t-test indicated a significant difference in groups (p < 10-10). A simple linear model (Volume~1 + Gender + Depth + Gender:Depth) revealed that only depth had a significant effect on volume (p < 10-19). The ICCs were 1.0. (4) Orbital volume, depth, and surface area measurements based on an automated CT segmentation algorithm demonstrated high repeatability and reliability. Male orbits were always larger on average by 14%. There were no differences between the sides. The volume and surface area ratio did not differ between genders and was approximately 0.75.

Insights into Orbital Symmetry: A Comprehensive Retrospective Study of 372 Computed Tomography Scans

Background: The operation planning and production of individualized implants with the help of AI-based software after orbital fractures have become increasingly important in recent years. This retrospective study aimed to investigate the healthy orbitae of 372 patients from CT images in the bone and soft tissue windows using the Disior™ Bonelogic™ CMF Orbital software. (version 2.1.28). Methods: We analyzed the variables orbital volume, length, and area as a function of age and gender and compared bone and soft tissue windows. Results: For all variables, the intraclass correlation showed excellent agreement between the bone and soft tissue windows (p < 0.001). All variables showed higher values when calculated based on bone fenestration with, on average, 1 mL more volume, 0.35 mm more length, and 0.71 cm2 more area (p < 0.001). Across all age groups, men displayed higher values than women with, on average, 8.1 mL larger volume, a 4.78 mm longer orbit, and an 8.5 cm2 larger orbital area (p < 0.001). There was also a non-significant trend in all variables and both sexes toward growth with increasing age. Conclusions: These results mean that, due to the symmetry of the orbits in both the bone and soft tissue windows, the healthy orbit can be mirrored for surgical planning in the event of a fracture.

Automatic segmentation of orbital wall from CT images via a thin wall region supervision-based multi-scale feature search network

PURPOSE

Orbital wall segmentation is critical for orbital measurement and reconstruction. However, the orbital floor and medial wall are made up of thin walls (TW) with low gradient values, making it difficult to segment the blurred areas of the CT images. Clinically, doctors have to manually repair the missing parts of TW, which is time-consuming and laborious.

METHODS

To address these issues, this paper proposes an automatic orbital wall segmentation method based on TW region supervision using a multi-scale feature search network. First of all, in the encoding branch, the densely connected atrous spatial pyramid pooling based on the residual connection is adopted to achieve a multi-scale feature search. Then, for feature enhancement, multi-scale up-sampling and residual connection are applied to perform skip connection of features in multi-scale convolution. Finally, we explore a strategy for improving the loss function based on the TW region supervision, which effectively increases the TW region segmentation accuracy.

RESULTS

The test results show that the proposed network performs well in terms of automatic segmentation. For the whole orbital wall region, the Dice coefficient (Dice) of segmentation accuracy reaches 96.086 ± 1.049%, the Intersection over Union (IOU) reaches 92.486 ± 1.924%, and the 95% Hausdorff distance (HD) reaches 0.509 ± 0.166 mm. For the TW region, the Dice reaches 91.470 ± 1.739%, the IOU reaches 84.327 ± 2.938%, and the 95% HD reaches 0.481 ± 0.082 mm. Compared with other segmentation networks, the proposed network improves the segmentation accuracy while filling the missing parts in the TW region.

CONCLUSION

In the proposed network, the average segmentation time of each orbital wall is only 4.05 s, obviously improving the segmentation efficiency of doctors. In the future, it may have a practical significance in clinical applications such as preoperative planning for orbital reconstruction, orbital modeling, orbital implant design, and so on.

Evaluating the Accuracy and Reliability of Blowout Fracture Area Measurement Methods: A Review and the Potential Role of Artificial Intelligence

Blowout fractures are a common type of facial injury that requires accurate measurement of the fracture area for proper treatment planning. This systematic review aimed to summarize and evaluate the current methods for measuring blowout fracture areas and explore the potential role of artificial intelligence (AI) in enhancing accuracy and reliability. A comprehensive search of the PubMed database was conducted, focusing on studies published since 2000 that investigated methods for measuring blowout fracture area using computed tomography scans. The review included 20 studies, and the results showed that automatic methods, such as computer-aided measurements and computed tomography-based volumetric analysis, provide higher accuracy and reliability compared with manual and semiautomatic techniques. Standardizing the method for measuring blowout fracture areas can improve clinical decision-making and facilitate outcome comparison across studies. Future research should focus on developing AI models that can account for multiple factors, including fracture area and herniated tissue volume, to enhance their accuracy and reliability. Integration of AI models has the potential to improve clinical decision-making and patient outcomes in the assessment and management of blowout fractures.

Unilateral Cleft Lip and Palate Has Asymmetry of Bony Orbits: A Retrospective Study

Facial asymmetry is common in unilateral clefts. Since virtual surgical planning (VSP) is becoming more common and automated segmentation is utilized more often, the position and asymmetry of the orbits can affect the design outcome. The aim of this study is to evaluate whether non-syndromic unilateral cleft lip and palate (UCLP) patients requiring orthognathic surgery have asymmetry of the bony orbits. Retrospectively, we analyzed the preoperative cone-beam computed tomography (CBCT) or computed tomography (CT) data of UCLP (n = 15) patients scheduled for a Le Fort 1 (n = 10) or bimaxillary osteotomy (n = 5) with VSP at the Cleft Palate and Craniofacial Center, Helsinki University Hospital. The width, height, and depth of the bony orbit and the distance between the sella turcica and infraorbital canal were measured. A volumetric analysis of the orbits was also performed. The measurements were tested for distribution, and the cleft side and the contralateral side were compared statistically with a two-sided paired t-test. To assess asymmetry in the non-cleft population, we performed the same measurements of skeletal class III patients undergoing orthognathic surgery at Päijät-Häme Central Hospital (n = 16). The volume of bony orbit was statistically significantly smaller (p = 0.014), the distance from the infraorbital canal to sella turcica was shorter (p = 0.019), and the anatomical location of the orbit was more medio-posterior on the cleft side than on the contralateral side. The non-cleft group showed no statistically significant asymmetry in any measurements. According to these preliminary results, UCLP patients undergoing orthognathic surgery show asymmetry of the bony orbit not seen in skeletal class III patients without a cleft. This should be considered in VSP for the correction of maxillary hypoplasia and facial asymmetry in patients with UCLP.

Orbital Volume and Axial Length Development in Individuals Ages 12 to 60 Years With Congenital Microphthalmia: A Retrospective Cohort Study

OBJECTIVE

To analyze the stimulating effect of axial length development on orbital volume development in patients (ages 12-60 years) with congenital microphthalmia.

METHODS

This retrospective cohort study included 43 patients (86 eyes) with congenital microphthalmia. Three-dimensional images of the orbit were generated from past computed tomography scans, and digital orbital volume and axial length measurements were taken. The patients were divided into four age groups for analyses. Paired t tests and one-way analysis of variance tests were used to compare orbital volume and axial length between the affected and unaffected eyes. Pearson correlation analyses and scatter plots were used to investigate the correlations between age, orbital volume, and axial length in the affected and unaffected eyes. Linear regression analysis was used to determine the association between orbital volume and axial length.

RESULTS

The mean orbital volume in the affected and unaffected eyes was 17.08 ± 2.88 and 20.80 ± 2.55 cm3, respectively. The mean axis length in the affected and the unaffected groups was 12.73 ± 3.54 and 23.84 ± 1.43 mm, respectively. Significant differences were observed among orbital (t = 13.538, P < 0.001) volume and axial length (t = 21.339, P < 0.001) in the affected and the unaffected groups. There were no significant differences in affected orbital volume (F = 0.527, P > 0.05), unaffected orbital volume (F = 1.628, P > 0.05), affected axial length (F = 0.946, P > 0.05), and unaffected axial length (F = 2.217, P > 0.05) among the four age groups. According to the Pearson correlations, there were no significant correlations between age and affected volume, unaffected volume, affected axis, and unaffected axis (r = 0.095, 0.097, 0.084, and 0.022, respectively; all P > 0.05). Orbital volume was moderately correlated with axial length in the affected and unaffected groups (r = 0.470 and 0.410, respectively; both P < 0.01). Linear regression analysis revealed that a 1 mm change in axis length was associated with a 0.38 cm3 and 0.73 cm3 change in orbital volume in the affected and unaffected groups, respectively.

CONCLUSIONS

In individuals ages 12 to 60 years old with congenital microphthalmia, the effect of axis length on the orbital volume growth of the affected eye is only half that of the unaffected eye. The eyeball, orbital tissue, and craniofacial development all play an important role in the growth of orbital volume.

Application of Patient-Specific Implants as Alternative Approach to Zygoma Defect Management - A Retrospective Study

Introduction:

Zygoma defects are a challenging clinical problem and are frequently connected with the alteration of facial harmony, horizontal asymmetry of the face, and significant functional deficit. The application of patient-specific implants (PSIs) has the potential to improve the effectiveness of zygoma defect management. The aim of this study was to evaluate the anatomic, esthetic, and functional outcomes of PSI application for zygoma reconstruction.

Materials and Methods:

A retrospective study was conducted on data from 11 patients with zygoma defects who underwent a reconstruction procedure in which a PSI was applied and was followed for >1 year after surgery with the evaluation of esthetic and functional outcomes. Precision of PSI position and anatomy reconstruction was estimated by superimposition of the models with automatic point-to-point measurement and determination of the existing deviations between models.

Results:

The mean follow-up period in our study was 21.6 ± 6.2 months (range 14–39 months). No major complications occurred in the postoperative period: There were no clinical or computed tomography symptoms of maxillary sinusitis, implant-related infection, or implant exposure. The mean deviation between the planned and real positions of PSIs in our series was 0.72 ± 0.41 mm. The mean deviation between the reconstructed zygomatic complex and the mirrored intact side in our series was 1.45 ± 0.7 mm. The mean volume difference between the intact and damaged orbits was 1.7 ± 0.8 mm³.

Discussion:

The results of the present study support the wider clinical application of PSIs in orbital and zygoma reconstructions, as it is an effective option to achieve precise reconstruction of the complex zygoma anatomy.

Angular and linear measurements of adult flexible flatfoot via weight-bearing CT scans and 3D bone reconstruction tools

Acquired adult flatfoot is a frequent deformity which implies multiple, complex and combined 3D modifications of the foot skeletal structure. The difficult thorough evaluation of the degree of severity pre-op and the corresponding assessment post-op can now be overcome by cone-beam (CBCT) technology, which can provide access to the 3D skeletal structure in weight-bearing. This study aims to report flatfoot deformities originally in 3D and in weight-bearing, with measurements taken using two different bone segmentation techniques. 21 such patients, with indication for surgical corrections, underwent CBCT (Carestream, US) while standing on one leg. From these scans, 3D models of each bone of the foot were reconstructed by using two different state-of-the-art segmentation tools: a semi-automatic (Mimics Innovation Suite, Materialise, Belgium), and an automatic (Bonelogic Ortho Foot and Ankle, Disior, Finland). From both reconstructed models, Principal Component Analysis was used to define anatomical reference frames, and original foot and ankle angles and other parameters were calculated mostly based on the longitudinal axis of the bones, in anatomical plane projections and in 3D. Both bone model reconstructions revealed a considerable valgus of the calcareous, plantarflexion and internal rotation of the talus, and typical Meary’s angles in the lateral and transverse plane projections. The mean difference from these angles between semi-automatic and automatic segmentations was larger than 3.5 degrees for only 3 of the 32 measurements, and a large number of these differences were not statistically significant. CBCT and the present techniques for bone shape reconstruction finally provide a novel and valuable 3D assessment of complex foot deformities in weight-bearing, eliminating previous limitations associated to unloaded feet and bidimensional measures. Corresponding measurements on the bone models from the two segmentation tools compared well. Other more representative measurements can be defined in the future using CBCT and these techniques.

Three-Dimensional Computer-Aided Analysis of 293 Isolated Blowout Fractures - Which Radiological Findings Guide Treatment Decision?

PURPOSE

Our study purpose was to clarify the extent of isolated unilateral orbital blowout fracture in relation to surgical treatment and other factors behind the treatment decision. The specific aim was to determine which computer-aided measurements based on radiological images associate with treatment choice.

METHODS

A retrospective cohort study was implemented on patients with an isolated unilateral orbital blowout fracture. Computer-aided measurement of fracture extent was performed. The study variables included treatment as primary outcome (surgical vs nonsurgical), post-traumatic orbital volume difference (mL) compared to contralateral orbit, fracture area (mm²), fracture depth (mm) as predictor variables, and age, sex, injury mechanism, side and site of orbital fracture and positions of recti muscles as explanatory variables. Postoperative outcomes were reported. Logistic regression analysis was used to determine the risk factors for surgery. The statistical significance level was set at P < .05.

RESULTS

Of 293 patients, 28.0% received surgical and 72.0% nonsurgical treatment. Volume difference, fracture area and fracture depth predicted surgical outcome (P < .001). In adjusted univariate regression analyses, fractures with moderate and severe displacement of recti muscles were more likely to receive surgical treatment than fractures with mild or no displacement (OR 6.15 and 30.75, respectively, P < .001). Isolated medial wall fractures were significantly less often (OR 0.05, P = .006) and patients with older age (OR 0.97, P = .013) slightly less often treated with surgery. Patients with preoperative symptoms had more often persisting postoperative symptoms than patients without preoperative symptoms.

CONCLUSIONS

Positions of the recti muscles are an independent radiological factor guiding orbital blowout fracture treatment decision. The bony fracture extent is a combination of volume difference, fracture area and fracture depth which are strongly correlated to each other. A computer-aided method significantly facilitates the systematic evaluation of bone fragments, and the extent of orbital fractures.

Implant malposition and revision surgery in primary orbital fracture reconstructions

The aim of the study was to assess factors leading to revision surgery and implant position of primary orbital fracture reconstructions. A retrospective cohort included patients who underwent orbital floor and/or medial wall fracture reconstruction for recent trauma. Demographics, fracture type, surgery and implant-related variables, and postoperative implant position were analyzed. The overall revision surgery rate was 6.5% (15 of 232 surgeries). The rate was highest in combined midfacial fractures with rim involvement (14.0%), lower in zygomatico-orbital fractures (8.7%), and lowest in isolated blowout fractures (3.8%). Fracture type, orbital rim fixation and implant malposition predicted revision. The best positioning was achieved with patient-specific milled titanium implants (mtPSI) and resorbable materials, whereas the poorest with preformed three-dimensional titanium plates. Combined midfacial fractures with rim involvement in particular have a high risk for orbital revision surgery. Within the limitations of the present study, mtPSIs should be preferred in the reconstruction of primary orbital fractures if possible.

Clinical outcome of patients with orbital fractures treated with patient specific CAD/CAM ceramic implants - A retrospective study

The aim of this study was to determine whether patients benefit from a secondary reconstruction since it carries the risks of no improvement or worsening of their current situation. Patients treated with individual computer-aided-design/computer-aided-manufacturing (CAD/CAM) ceramic implants were reviewed. To ascertain changes throughout the secondary reconstruction, the study investigators reviewed ophthalmological examinations, took volumetric measurements of the orbits and asked the patients for evaluation of their situation before and after the reconstruction. Points addressed were double vision, visual acuity, field of vision, limitations in daily life and aesthetic considerations. A total of 14 patients were reviewed and 11 answered the questionnaire. Ophthalmological examinations showed that the physical integrity of the eye was maintained. Volumetric measurements preopeatively (33.94 ± 3.24 cm³) and postoperatively (30.67 ± 2.07 cm³) showed that a statistically significant overcorrection of orbital volume leads to good functional and aesthetic outcomes. Patients' subjective opinions were that they greatly benefitted, especially concerning limitations in daily life, which improved by 4.4 ± 2.8 points out of 10 possible points, and aesthetics, with an improvement of 5.9 ± 1.78 points. Based on these findings, we conclude that secondary reconstructions contribute to improvement of the patients' quality of life and therefore should be considered as an option to improve patients' condition.

Three-dimensional periorbital asymmetry assessment of congenital microphthalmia children with a structured light 3D scanning system

Congenital microphthalmia is a rare phenotype characterized by eye growth retardation. Due to the lack of eyeball stimulation, children suffering from congenital microphthalmia always have bony orbital maldevelopment, which leads to facial asymmetry. In the present study, a structured light 3D scanning system was used as a novel method to measure the three-dimensional periorbital asymmetry in children with congenital microphthalmia. Children with unilateral congenital microphthalmia of 0-6 years old were enrolled in the present study. All participants underwent an ultrasound scan to measure the axial length, and accepted the structured light 3D scanning system for their periorbital appearance. The degree of periorbital asymmetry was evaluated using 17 facial landmarks within a three-dimensional cartesian coordinate system (the X-axis represented the horizontal direction, the Y-axis represented the vertical direction, and the Z-axis represented the sagittal direction). Paired student t-test and ANOVA were used in the present study. A three-dimensional periorbital topography was also established to further illustrate the periorbital asymmetry. A total of 67 children were recruited, which included 31 boys and 34 girls. The axial length on the affected side (12.28 ± 3.35 mm) was generally smaller than that on the unaffected side (20.54 ± 1.65 mm, P < 0.001). When grouped by age, the periorbital asymmetry mainly manifested in the Y-axis and Z-axis directions. The unaffected side had a higher orbitale superior (5.09 ± 0.35 vs. 3.02 ± 0.30, P < 0.001) and a lower orbitale inferior (-19.52 ± 0.51 vs. -16.90 ± 0.53, P < 0.001) in 0-1 year old group. Same performances were also found in the 1-3 and 3-6 age groups. When grouped according to the proportion of axial length on the bilateral sides, seven of the 12 Y-values and all 12 Z-values had statistical differences. The structured Light 3D scanning system may serve as a beneficial complementary tool for computed tomography, in order to better understand the periorbital deformities caused by congenital microphthalmia.