Normal human craniofacial growth and development from 0 to 4 years

Quantitative morphological analysis framework of infant cranial sutures and fontanelles based on CT images

Characterizing the suture morphological variation is a crucial step to investigate the influence of sutures on infant head biomechanics. This study aimed to establish a comprehensive quantitative framework for accurately capturing the cranial suture and fontanelle morphologies in infants. A total of 69 CT scans of 2-4 month-old infant heads were segmented to identify semilandmarks at the borders of cranial sutures and fontanelles. Morphological characteristics, including length, width, sinuosity index (SI), and surface area, were measured. For this, an automatic method was developed to determine the junction points between sutures and fontanelles, and thin-plate-spline (TPS) was utilized for area calculation. Different dimensionality reduction methods were compared, including nonlinear and linear principal component analysis (PCA), as well as deep-learning-based variational autoencoder (VAE). Finally, the significance of various covariates was analyzed, and regression analysis was performed to establish a statistical model relating morphological parameters with global parameters. This study successfully developed a quantitative morphological framework and demonstrate its application in quantifying morphologies of infant sutures and fontanelles, which were shown to significantly relate to global parameters of cranial size, suture SI, and surface area for infants aged 2-4 months. The developed framework proved to be reliable and applicable in extracting infant suture morphology features from CT scans. The demonstrated application highlighted its potential to provide valuable insights into the morphologies of infant cranial sutures and fontanelles, aiding in the diagnosis of suture-related skull fractures. Infant suture, Infant fontanelle, Morphological variation, Morphology analysis framework, Statistical model.

Conceptual Principles in Pediatric Craniomaxillofacial Reconstruction

Pediatric craniomaxillofacial reconstruction must be approached through the lens of growth and durability. A systematic approach of matching defects to donor tissue drives the selection of autologous reconstructive technique. The menu of available methods for reconstruction can be organized in a manner similar to adults, with special considerations for growth and development. Reconstructive surgeons have the opprtunity to promote and maintain young patients' sense of identity during psychosocial development.

A computational modelling tool for prediction of head reshaping following endoscopic strip craniectomy and helmet therapy for the treatment of scaphocephaly

BACKGROUND

Endoscopic strip craniectomy followed by helmet therapy (ESCH) is a minimally invasive approach for correcting sagittal craniosynostosis. The treatment involves a patient-specific helmet designed to facilitate lateral growth while constraining sagittal expansion. In this study, finite element modelling was used to predict post-treatment head reshaping, improving our comprehension of the necessary helmet therapy duration.

METHOD

Six patients (aged 11 weeks to 9 months) who underwent ESCH at Connecticut Children's Hospital were enrolled in this study. Day-1 post-operative 3D scans were used to create skin, skull, and intracranial volume models. Patient-specific helmet models, incorporating areas for growth, were designed based on post-operative imaging. Brain growth was simulated through thermal expansion, and treatments were modelled according to post-operative Imaging available. Mechanical testing and finite element modelling were combined to determine patient-specific mechanical properties from bone samples collected from surgery. Validation compared simulated end-of-treatment skin surfaces with optical scans in terms of shape matching and cranial index estimation.

RESULTS

Comparison between the simulated post-treatment head shape and optical scans showed that on average 97.3 ± 2.1 % of surface data points were within a distance range of -3 to 3 mm. The cranial index was also accurately predicted (r = 0.91).

CONCLUSIONS

In conclusion, finite element models effectively predicted the ESCH cranial remodeling outcomes up to 8 months postoperatively. This computational tool offers valuable insights to guide and refine helmet treatment duration. This study also incorporated patient-specific material properties, enhancing the accuracy of the modeling approach.

Charting facial growth and development for Bantu Africans: Central tendencies, variational properties and sexual dimorphisms

Current studies on facial growth and development have been largely based on European populations. Less studied are African populations, who because of their distinct genetic makeup and environmental conditions, provide deeper insights into patterns of facial development. Patterns of facial shape development in African populations remain largely uncharacterised. Our study aimed to establish facial growth and development trajectories based on a cohort of 2874 Bantu Africans from Tanzania aged 6-18 years, with particular focus on identifying morphogenetic processes that lead to observed developmental shape changes. Procrustes ANCOVA suggested sexually dimorphic patterns of facial shape development (p = 0.0036). The forehead was relatively contracted during development in both sexes. The glabella region was more anteriorly displaced in females due to expansion in the region laterosuperior to the eyes. Nasal protrusion increased with development, which was found to arise from local expansion in the nasal alae and columella. Local expansion in the upper and lower labial regions resulted in forward displaced lips in both sexes, with the effect more pronounced in males. The mentum was displaced more anteriorly in females due to comparatively more expanded mental regions with development. The lateral facial region corresponding to the underlying body of the mandible were developmentally expanded but were posteriorly positioned due to protrusive growth of surrounding structures. Generalised additive modelling of Procrustes variance suggested that facial variation decreased non-linearly with age (p < 0.05). Relative principal component analysis suggested that variations in facial outline shape were developmentally constrained, whereas nasolabial and mental regions, where developmental changes were significant, became morphologically diversified with development. In contrast to simple descriptive illustration of facial shape development, we gained transformative insights into patterns of facial shape development by analysing morphogenetic processes and variational properties. Our analytical framework is broadly applicable to morphometric studies on ontogenetic shape changes.

Functional adaptation of the infant craniofacial system to mechanical loadings arising from masticatory forces

The morphology and biomechanics of infant crania undergo significant changes between the pre- and post-weaning phases due to increasing loading of the masticatory system. The aims of this study were to characterize the changes in muscle forces, bite forces and the pattern of mechanical strain and stress arising from the aforementioned forces across crania in the first 48 months of life using imaging and finite element methods. A total of 51 head computed tomography scans of normal individuals were collected and analysed from a larger database of 217 individuals. The estimated mean muscle forces of temporalis, masseter and medial pterygoid increase from 30.9 to 87.0 N, 25.6 to 69.6 N and 23.1 to 58.9 N, respectively (0-48 months). Maximum bite force increases from 90.5 to 184.2 N (3-48 months). There is a change in the pattern of strain and stress from the calvaria to the face during postnatal development. Overall, this study highlights the changes in the mechanics of the craniofacial system during normal development. It further raises questions as to how and what level of changes in the mechanical forces during the development can alter the morphology of the craniofacial system.

Multiscale mechanical characterisation of the craniofacial system under external forces

Premature fusion of craniofacial joints, i.e. sutures, is a major clinical condition. This condition affects children and often requires numerous invasive surgeries to correct. Minimally invasive external loading of the skull has shown some success in achieving therapeutic effects in a mouse model of this condition, promising a new non-invasive treatment approach. However, our fundamental understanding of the level of deformation that such loading has induced across the sutures, leading to the effects observed is severely limited, yet crucial for its scalability. We carried out a series of multiscale characterisations of the loading effects on normal and craniosynostotic mice, in a series of in vivo and ex vivo studies. This involved developing a custom loading setup as well as software for its control and a novel in situ CT strain estimation approach following the principles of digital volume correlation. Our findings highlight that this treatment may disrupt bone formation across the sutures through plastic deformation of the treated suture. The level of permanent deformations observed across the coronal suture after loading corresponded well with the apparent strain that was estimated. This work provides invaluable insight into the level of mechanical forces that may prevent early fusion of cranial joints during the minimally invasive treatment cycle and will help the clinical translation of the treatment approach to humans.

Craniofacial phenotyping with fetal MRI: a feasibility study of 3D visualisation, segmentation, surface-rendered and physical models

This study explores the potential of 3D Slice-to-Volume Registration (SVR) motion-corrected fetal MRI for craniofacial assessment, traditionally used only for fetal brain analysis. In addition, we present the first description of an automated pipeline based on 3D Attention UNet trained for 3D fetal MRI craniofacial segmentation, followed by surface refinement. Results of 3D printing of selected models are also presented.Qualitative analysis of multiplanar volumes, based on the SVR output and surface segmentations outputs, were assessed with computer and printed models, using standardised protocols that we developed for evaluating image quality and visibility of diagnostic craniofacial features. A test set of 25, postnatally confirmed, Trisomy 21 fetal cases (24-36 weeks gestational age), revealed that 3D reconstructed T2 SVR images provided 66-100% visibility of relevant craniofacial and head structures in the SVR output, and 20-100% and 60-90% anatomical visibility was seen for the baseline and refined 3D computer surface model outputs respectively. Furthermore, 12 of 25 cases, 48%, of refined surface models demonstrated good or excellent overall quality with a further 9 cases, 36%, demonstrating moderate quality to include facial, scalp and external ears. Additional 3D printing of 12 physical real-size models (20-36 weeks gestational age) revealed good/excellent overall quality in all cases and distinguishable features between healthy control cases and cases with confirmed anomalies, with only minor manual adjustments required before 3D printing.Despite varying image quality and data heterogeneity, 3D T2w SVR reconstructions and models provided sufficient resolution for the subjective characterisation of subtle craniofacial features. We also contributed a publicly accessible online 3D T2w MRI atlas of the fetal head, validated for accurate representation of normal fetal anatomy.Future research will focus on quantitative analysis, optimizing the pipeline, and exploring diagnostic, counselling, and educational applications in fetal craniofacial assessment.

Facial growth and development trajectories based on three-dimensional images: geometric morphometrics with a deformation perspective

Developmental changes of facial shape are commonly investigated through geometric morphometrics. A limitation with this approach is the inability to investigate patterns of morphological changes at local scale. This could be addressed through quantifying the deformation required to deform one shape to another. This study aimed to investigate changes in mean, rate and variance of facial shape at local scale using geometric morphometrics through deformation perspective. A total of 2112 Europeans 3 to 40 years old from the three-dimensional Facial Norms project were included. Shape and rate trajectories from partial least-squares regressions revealed that the developmentally protrusive nasal bridge was due to local expansion in surrounding tissues as opposed to shape changes in nasal bridge per se. Local expansion of the supraorbital region, in particular the medial part in males, resulted in the sloping forehead and deep-situated eyes with development. Facial shape variation increased nonlinearly with age (p < 0.05), with features having larger rate of change becoming more developmentally diversified. In summary, our deformation perspective facilitates unravelling morphogenetic processes underlying shape changes. Our extended analytical scope inspires novel measures worthy of consideration while establishing facial growth charts. The analytical framework in this study is broadly applicable for analysis of shape changes in general.

Pediatric Craniofacial Tumor Reconstruction

Effective management of pediatric craniofacial tumors requires coordinated input from medical, oncologic, and surgical specialties. Reconstructive algorithms must consider limitations in pediatric donor tissue and account for future growth and development. Immediate reconstruction is often focused on filling dead space, protecting underlying structures, and ensuring skeletal symmetry. Staged reconstruction occurs after the patient has reached skeletal maturity and is focused on restoring permanent dentition. Reconstructive options vary depending on the location, size, and composition of resected tissue. Virtual surgical planning (VSP) reduces the complexity of pediatric craniofacial reconstruction and ensures more predictable outcomes.