3D statistical shape analysis of the face in Apert syndrome

Timely diagnosis of craniofacial syndromes as well as adequate timing and choice of surgical technique are essential for proper care management. Statistical shape models and machine learning approaches are playing an increasing role in Medicine and have proven its usefulness. Frameworks that automate processes have become more popular. The use of 2D photographs for automated syndromic identification has shown its potential with the Face2Gene application. Yet, using 3D shape information without texture has not been studied in such depth. Moreover, the use of these models to understand shape change during growth and its applicability for surgical outcome measurements have not been analysed at length. This thesis presents a framework using state-of-the-art machine learning and computer vision algorithms to explore possibilities for automated syndrome identification based on shape information only. The purpose of this was to enhance understanding of the natural development of the Apert syndromic face and its abnormality as compared to a normative group. An additional method was used to objectify changes as result of facial bipartition distraction, a common surgical correction technique, providing information on the successfulness and on inadequacies in terms of facial normalisation. Growth curves were constructed to further quantify facial abnormalities in Apert syndrome over time along with 3D shape models for intuitive visualisation of the shape variations. Post-operative models were built and compared with age-matched normative data to understand where normalisation is coming short. The findings in this thesis provide markers for future translational research and may accelerate the adoption of the next generation diagnostics and surgical planning tools to further supplement the clinical decision-making process and ultimately to improve patients’ quality of life

Skin measurement devices to assess skin quality:A systematic review on reliability and validity

Background Many treatments aim to slow down or reverse the visible signs of skin aging and thereby improve skin quality. Measurement devices are frequently employed to measure the effects of these treatments to improve skin quality, for example, skin elasticity, color, and texture. However, it remains unknown which of these devices is most reliable and valid. Materials and methods MEDLINE, Embase, Cochrane Central, Web of Science, and Google Scholar databases were searched. Instruments were scored on reporting construct validity by means of convergent validity, interobserver, intraobserver, and interinstrument reliability. Results For the evaluation of skin color, 11 studies were included describing 16 measurement devices, analyzing 3172 subjects. The most reliable device for skin color assessment is the Minolta Chromameter CR-300 due to good interobserver, intraobserver, and interinstrument reliability. For skin elasticity, seven studies assessed nine types of devices analyzing 290 subjects in total. No intra and interobserver reliability was reported. Skin texture was assessed in two studies evaluating 72 subjects using three different types of measurement devices. The PRIMOS device reported excellent intra and interobserver reliability. None of the included reviewed devices could be determined to be valid based on construct validity. Conclusion The most reliable devices to evaluate skin color and texture in ordinary skin were, respectively, the Minolta Chromameter and PRIMOS. No reliable device is available to measure skin elasticity in ordinary skin and none of the included devices could be determined to be designated as valid

The Rainbow Scale for the Assessment of the Cervicomental Angle:A Validated Scale

Background: Aging of the neck results in an increased cervicomental angle, which can be treated by various surgical and nonsurgical procedures. To measure the success of these procedures, standardized validated objective photographic measurement tools are needed. However, no online standardized photographic measurement tools exist for the assessment of the cervicomental angle. Objectives: The purpose of this study was to establish a validated and reliable measurement tool for the assessment of the cervicomental angle based on the Rainbow Scale. Methods: A 5-point photographic rating scale was developed and created from 1 photograph with Adobe Photoshop. Fifteen reference photographs of women, 3 photographs per grade, were included for validation. Seven panelists (ie, plastic and maxillofacial surgeons) assessed the reference photographs 3 times with a minimal interval of 3 days in an online survey. Intra- and inter-observer agreements were calculated utilizing the weighted kappa coefficient. Results: Mean intra-observer agreement was 0.93 (0.78-1.00). Mean interobserver agreement was 0.796 (0.574-0.961) for survey 1, 0.868 (0.690-0.960) for survey 2, and 0.820 (0.676-0.959) for survey 3. Conclusions: The Rainbow Scale for the assessment of the cervicomental angle has been validated in an online fashion. The scale is reproducible and reliable and requires no learning curve. Potential applications include objective assessment of neck treatment planning and surgical outcome

Reply:The Effects of Facial Lipografting on Skin Quality: A Systematic Review

BACKGROUND: Autologous lipografting for improvement of facial skin quality was first described by Coleman in 2006. The current dogma dictates that adipose tissue-derived stromal cells that reside in the stromal vascular fraction of lipograft contribute to skin rejuvenation (e.g., increased skin elasticity), a more homogenous skin color, and softening of skin texture. Nowadays, many studies have been reported on this "skin rejuvenation" effect of autologous fat grafting. This systematic review was undertaken to assess the efficacy of autologous lipografting on skin quality.METHODS: The MEDLINE, Embase, Cochrane Central, Web of Science, and Google Scholar databases were searched for studies evaluating the effect of autologous lipografting on facial skin quality (May 11, 2018). Outcomes of interest were skin texture, color, and elasticity in addition to histologic outcomes and number of complications.RESULTS: Nine studies were included, with 301 patients treated in total. No meta-analysis could be performed because of heterogeneity of the metrics and outcomes. Eight studies reported increased skin elasticity; improvement in skin texture; and a more homogeneous skin color after treatment with lipografting, cellular stromal vascular fraction, or nanofat. One study reported no increased skin elasticity after lipografting. Histologic improvement was seen after lipografting and adipose tissue-derived stromal cell injections. However, in general, the level of evidence of the included studies was low. No serious complications were reported.CONCLUSION: Autologous facial lipografting and cellular stromal vascular fraction and adipose tissue-derived stromal cell injections hardly seem to improve facial skin quality but can be considered a safe procedure.</p

Growth patterns and shape development of the paediatric mandible – A 3D statistical model

BACKGROUND/AIM: To develop a 3D morphable model of the normal paediatric mandible to analyse shape development and growth patterns for males and females. METHODS: Computed tomography (CT) data was collected for 242 healthy children referred for CT scan between 2011 and 2018 aged between 0 and 47 months (mean, 20.6 ± 13.4 months, 59.9% male). Thresholding techniques were used to segment the mandible from the CT scans. All mandible meshes were annotated using a defined set of 52 landmarks and processed such that all meshes followed a consistent triangulation. Following this, the mandible meshes were rigidly aligned to remove translation and rotation effects, while size effects were retained. Principal component analysis (PCA) was applied to the processed meshes to construct a generative 3D morphable model. Partial least squares (PLS) regression was also applied to the processed data to extract the shape modes with which to evaluate shape differences for age and sex. Growth curves were constructed for anthropometric measurements. RESULTS: A 3D morphable model of the paediatric mandible was constructed and validated with good generalisation, compactness, and specificity. Growth curves of the assessed anthropometric measurements were plotted without significant differences between male and female subjects. The first principal component was dominated by size effects and is highly correlated with age at time of scan (Spearman's r = 0.94, p < 0.01). As with PCA, the first extracted PLS mode captures much of the size variation within the dataset and is highly correlated with age (Spearman's r = −0.94, p < 0.01). Little correlation was observed between extracted shape modes and sex with either PCA or PLS for this study population. CONCLUSION: The presented 3D morphable model of the paediatric mandible enables an understanding of mandibular shape development and variation by age and sex. It allowed for the construction of growth curves, which contains valuable information that can be used to enhance our understanding of various disorders that affect the mandibular development. Knowledge of shape changes in the growing mandible has potential to improve diagnostic accuracy for craniofacial conditions that impact the mandibular morphology, objective evaluation, surgical planning, and patient follow-up

Two-Center Review of Posterior Vault Expansion following a Staged or Expectant Treatment of Crouzon and Apert Craniosynostosis

Background: The timing of posterior cranial expansion for the management of intracranial pressure can be "staged" by age and dysmorphology or "expectant" by pressure monitoring. The authors report shared outcome measures from one center performing posterior vault remodeling (PCVR) or distraction (PVDO) following a staged approach and another performing spring-assisted expansion (SAPVE) following an expectant protocol. Methods: Apert or Crouzon syndrome patients who underwent posterior expansion younger than 2 years were included. Perioperative outcomes and subsequent cranial operations were recorded up to last follow-up and intracranial volume changes measured and adjusted using growth curves. Results: Thirty-eight patients were included. Following the expectant protocol, Apert patients underwent SAPVE at a younger age (8 months) than Crouzon patients (16 months). The initial surgery time was shorter but total operative time, including device removal, was longer for PVDO (3 hours 52 minutes) and SAPVE (4 hours 34 minutes) than for PCVR (3 hours 24 minutes). Growth-adjusted volume increase was significant and comparable. Fourteen percent of PCVR, 33% of PVDO, and 11% of SAPVE cases had complications, but without long-term deficits. Following the staged approach, 5% underwent only PVDO, 85% had a staged posterior followed by anterior surgery, and 10% required a third expansion. Following the expectant approach, 42% of patients had only posterior expansion at last follow-up, 32% had a secondary cranial surgery, and 26% had a third cranial expansion. Conclusion: Two approaches involving posterior vault expansion in young syndromic patients using three techniques resulted in comparable early volume expansion and complication profiles. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.</p

Comparison of Internal and External Distraction in Frontofacial Monobloc Advancement:A Three-Dimensional Quantification

Background: Crouzon syndrome is characterized by complex craniosynostosis and midfacial hypoplasia. Where frontofacial monobloc advancement (FFMBA) is indicated, the method of distraction used to achieve advancement holds an element of equipoise. This two-center retrospective cohort study quantifies the movements produced by internal or external distraction methods used for FFMBA. Using shape analysis, this study evaluates whether the different distraction forces cause plastic deformity of the frontofacial segment, producing distinct morphologic outcomes. Methods: Patients with Crouzon syndrome who underwent FFMBA with internal distraction [Hôpital Necker-Enfants Malades (Paris, France)] or external distraction [Great Ormond Street Hospital for Children (London, United Kingdom)] were compared. Digital Imaging and Communications in Medicine files of preoperative and postoperative computed tomographic scans were converted to three-dimensional bone meshes and skeletal movements were assessed using nonrigid iterative closest point registration. Displacements were visualized using color maps and statistical analysis of the vectors was undertaken. Results: Fifty-one patients met the strict inclusion criteria. Twenty-five underwent FFMBA with external distraction and 26 with internal distraction. External distraction provides a preferential midfacial advancement, whereas internal distractors produce a more positive movement at the lateral orbital rim. This confers good orbital protection but does not advance the central midface to the same extent. Vector analysis confirmed this to be statistically significant (P &lt; 0.01). Conclusions: Morphologic changes resulting from monobloc surgery differ depending on the distraction technique used. Although the relative merits of internal and external distraction still stand, it may be that external distraction is more suited to addressing the midfacial biconcavity seen in syndromic craniosynostosis. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.</p

Does the Mutation Type Affect the Response to Cranial Vault Expansion in Children With Apert Syndrome?

Most cases of Apert syndrome are caused by mutations in the FGFR2 gene, either Ser252Trp or Pro253Arg. In these patients, over the last decades, spring-assisted posterior vault expansion (SA-PVE) has been the technique of choice for cranial vault expansion in the Craniofacial Unit of Great Ormond Street Hospital for Children (GOSH), London. The aim of this study was to investigate if there is a difference in preoperative intracranial volume (ICV) in patients with Apert syndrome with Ser252Trp or Pro253Arg mutation and whether these mutations affect the change in ICV achieved by SA-PVE. The GOSH craniofacial SA-PVE database was used to select patients with complete genetic testing and preoperative and postoperative computed tomography scans. ICV was calculated using FSL (FMRIB Analysis Group, Oxford) and adjusted based on Apert-specific growth curves. Sixteen patients were included with 8 having Ser252Trp mutation and 8 having Pro253Arg mutation. The mean preoperative adjusted computed tomography volume for patients in the Ser252Trp group was 1137.7 cm3 and in the Pro253Arg group was 1115.8 cm3 (P=1.00). There was a significant increase in ICV following SA-PVE in all patients (P<0.001) with no difference in mean change in ICV between the groups (P=0.51). Four (50%) patients with Ser252Trp mutation and 3 (37.5%) with Pro253Arg mutations required a second operation after primary SA-PVE. The results demonstrate that regardless of the mutation present, SA-PVE was successful in increasing ICV in patients with Apert syndrome and that a repeat volume expanding procedure was required by a similar number of patients in the 2 groups

Hyoid Bone Morphology in Patients with Robin Sequence &amp;#8211; a Case-Control Study Utilizing 3d Morphable Models

Background: Abnormalities of the hyoid bone are associated with impairment of oropharyngeal functions including feeding, swallowing, and breathing. Few studies have characterized anatomic abnormalities of the hyoid in patients with Robin sequence (RS). The purposes of this study were to compare normal hyoid bone morphology and hyoid bone morphology in children with isolated RS.&amp;#60;br&amp;#62;&amp;#60;br&amp;#62;Methods: Three-dimensional (3D) reconstructions of the hyoid bone were obtained from CT-imaging of children with RS and unaffected controls. A 3D morphable model was constructed using Principal Component Analysis (PCA). Partial least squares &amp;#8211; Discriminant Analysis (PLS-DA) and multivariate analysis of variance (MANOVA) were used to characterize and compare hyoid shape differences between patients with RS and an age-matched control group.&amp;#60;br&amp;#62;&amp;#60;br&amp;#62;Results: The study included 23 subjects with RS (mean age 9.8&amp;#177;10.3 months) and 46 age-matched control samples. A less voluminous hyoid was observed for the RS group with a larger lateral divergence of the greater horns compared to controls (MANOVA, p-value&amp;#60;0.001). The first shape variable from the PLS-DA model showed a significant correlation for the observed variance between the two groups (Spearman R = -0.56, p-value&amp;#60;0.001). The control samples and 151 CT-scans of subjects up to age 4 years were used to create a 3D morphable model of normal hyoid shape variation (n=197, mean age 22.1&amp;#177;13.1 months). For the normal 3D morphable model, a high degree of allometric shape variation was observed along the first principal component.&amp;#60;br&amp;#62;&amp;#60;br&amp;#62;Conclusions: The 3D morphable models provide a comprehensive and quantitative description of variation in normal hyoid bone morphology, and allow detection of distinct differences between patients with isolated RS and controls

Latent Disentanglement in Mesh Variational Autoencoders Improves the Diagnosis of Craniofacial Syndromes and Aids Surgical Planning

The use of deep learning to undertake shape analysis of the complexities of the human head holds great promise. However, there have traditionally been a number of barriers to accurate modelling, especially when operating on both a global and local level. In this work, we will discuss the application of the Swap Disentangled Variational Autoencoder (SD-VAE) with relevance to Crouzon, Apert and Muenke syndromes. Although syndrome classification is performed on the entire mesh, it is also possible, for the first time, to analyse the influence of each region of the head on the syndromic phenotype. By manipulating specific parameters of the generative model, and producing procedure-specific new shapes, it is also possible to simulate the outcome of a range of craniofacial surgical procedures. This opens new avenues to advance diagnosis, aids surgical planning and allows for the objective evaluation of surgical outcomes