A de novo substitution in BCL11B leads to loss of interaction with transcriptional complexes and craniosynostosis.

Craniosynostosis, the premature ossification of cranial sutures, is a developmental disorder of the skull vault, occurring in approximately 1 in 2250 births. The causes are heterogeneous, with a monogenic basis identified in ~25% of patients. Using whole-genome sequencing, we identified a novel, de novo variant in BCL11B, c.7C>A, encoding an R3S substitution (p.R3S), in a male patient with coronal suture synostosis. BCL11B is a transcription factor that interacts directly with the nucleosome remodelling and deacetylation complex (NuRD) and polycomb-related complex 2 (PRC2) through the invariant proteins RBBP4 and RBBP7. The p.R3S substitution occurs within a conserved amino-terminal motif (RRKQxxP) of BCL11B and reduces interaction with both transcriptional complexes. Equilibrium binding studies and molecular dynamics simulations show that the p.R3S substitution disrupts ionic coordination between BCL11B and the RBBP4-MTA1 complex, a subassembly of the NuRD complex, and increases the conformational flexibility of Arg-4, Lys-5 and Gln-6 of BCL11B. These alterations collectively reduce the affinity of BCL11B p.R3S for the RBBP4-MTA1 complex by nearly an order of magnitude. We generated a mouse model of the BCL11B p.R3S substitution using a CRISPR-Cas9-based approach, and we report herein that these mice exhibit craniosynostosis of the coronal suture, as well as other cranial sutures. This finding provides strong evidence that the BCL11B p.R3S substitution is causally associated with craniosynostosis and confirms an important role for BCL11B in the maintenance of cranial suture patency.

ROCK-TAZ signaling axis regulates mechanical tension-induced osteogenic differentiation of rat cranial sagittal suture mesenchymal stem cells.

Mechanical force across sutures is able to promote suture osteogenesis. Orthodontic clinics often use this biological characteristic of sutures to treat congenital cranio-maxillofacial malformations. However, the underlying mechanisms still remain poorly understood. Craniofacial sutures provide a special growth source and support primary sites of osteogenesis. Here, we isolated rat sagittal suture cells (rSAGs), which had mesenchymal stem cell characteristics and differentiating abilities. Cells were then subjected to mechanical tension (5% elongation, 0.5 Hz; sinusoidal waveforms) showing that mechanical tension could enhance osteogenic differentiation but hardly affect proliferation of rSAGs. Besides, mechanical tension could increase Rho-associated kinase (ROCK) expression and enhance transcriptional coactivator with PDZ-binding motif (TAZ) nuclear translocation. Inhibiting ROCK expression could suppress tension-induced osteogenesis and block tension-induced upregulation of nuclear TAZ. In addition, our results indicated that TAZ had direct combination sites with runt-related transcription factor 2 (Runx2) in rSAGs, and knock-downed TAZ simultaneously decreased the expression of Runx2 no matter with or without mechanical tension. In summary, our findings demonstrated that the multipotency of rSAGs in vitro could give rise to early osteogenic differentiation under mechanical tension, which was mediated by ROCK-TAZ signal axis.

Temporal mapping of the closure of the anterior fontanelle and contiguous sutures using computed tomography, in silico models of modern infants.

The aim of this study is to quantify and statistically model the age-related decline in the fibrous connective tissue interface of the anterior fontanelle in modern Australian infants, using three-dimensional, semi-automated computed-assisted design protocols. Non-linear regression with variance models, using power functions, combined with quantile regression of the 5th and 95th population percentiles, were utilised to assess absolute anterior fontanelle surface area (AFSA) as a function of age, using multi-slice cranial computed tomography scans obtained from 256 infants aged < 30 months (males: n = 126, females: n = 109) from Brisbane children's hospitals. Normalised AFSA (NFSA), standardised for variation in cephalic size, followed a progressive decline from birth, the greatest velocity change occurring between the 3-6 and 6-9 month cohorts. Growth of the neurocranium is the most significant within the first 8 months postpartum, with a mean increase of 19.03 mm in maximum cranial length and 10.04 mm in breadth. Directionality of fontanelle closure, quantified using spline curves refutes fundamental assumptions that the anterior fontanelle is consistent with a quadrilateral, and contiguous sutures exhibit constant velocity of closure. The present study provides normative values for fontanelle size and diameters as well as new predictive non-linear models for age substantiation, screening of developmental abnormalities and indicators of suspected child maltreatment in modern infants aged birth to 30 months.

Cranial growth in isolated sagittal craniosynostosis compared with normal growth in the first 6 months of age.

Sagittal craniosynostosis (SCS), the most common type of premature perinatal cranial suture fusion, results in abnormal head shape that requires extensive surgery to correct. It is important to find objective and repeatable measures of severity and surgical outcome to examine the effect of timing and technique on different SCS surgeries. The purpose of this study was to develop statistical models of infant (0-6 months old) skull growth in both normative and SCS subjects (prior to surgery). Our goal was to apply these models to the assessment of differences between these two groups in overall post-natal growth patterns and sutural growth rates as a first step to develop methods for predictive models of surgical outcome. We identified 81 patients with isolated, non-syndromic SCS from Seattle Children's Craniofacial Center patient database who had a preoperative CT exam before the age of 6 months. As a control group, we identified 117 CT exams without any craniofacial abnormalities or bone fractures in the same age group. We first created population-level templates from the CT images of the SCS and normal groups. All CT images from both groups, as well as the canonical templates of both cohorts, were annotated with anatomical landmarks, which were used in a growth model that predicted the locations of these landmarks at a given age based on each population. Using the template images and the landmark positions predicted by the growth models, we created 3D meshes for each week of age up to 6 months for both populations. To analyze the growth patterns at the suture sites, we annotated both templates with additional semi-landmarks equally spaced along the metopic, coronal, sagittal and lambdoidal cranial sutures. By transferring these semi-landmarks to meshes produced from the growth model, we measured the displacement of the bone borders and suture closure rates. We found that the growth at the metopic and coronal sutures were more rapid in the SCS cohort than in the normal cohort. The antero-posterior displacement of the semi-landmarks also indicated a more rapid growth in the sagittal plane in the SCS model than in the normal model. Statistical templates and geometric morphometrics are promising tools for understanding the growth patterns in normal and synostotic populations and to produce objective and reproducible measurements of severity and outcome. Our study is the first of its kind to quantify the bone growth for the first 6 months of life in both normal and sagittal synostosis patients.

Classification of the midpalatal suture maturation in individuals older than 15 years: a cone beam computed tomographic study.

PURPOSE: The aim of this study was to classify the maturation of the midpalatal suture (MPS) in a sample of individuals aged 15 years and older. METHODS: Tomographic images in axial sections of the MPS of 289 female individuals and 198 male individuals aged between 15 and 40 years were analyzed and classified in stages of maturation (A, B, C, D, and E), stage A represents the earliest maturation stage of the suture and in stage E the fusion of the MPS has occurred in the maxilla. The Kruskal-Wallis and Student-Newman-Kells tests were used to compare the chronological ages among different maturation stages. Spearman's correlation coefficient was used to assess the correlation between patient's age and the maturation stages of the MPS. RESULTS: Stage A was not observed in the sample. Stages B and C represent, respectively, 1.03% and 34.09% of the sample, stage D was found in 16.63% of the sample while stage E was the most prevalent stage found (48.25%). For females, it was revealed no statistically significant difference in the mean ages among stages C, D and E (p = 0.4753). For males, a statistically significant difference was observed, with the mean age of individuals in stages D and E of the MPS maturation higher than in other stages (p = 0.0001). There was a significant, but weak, correlation between patient's age and the maturation stages of the suture (rs = 0.11/p = 0.01). CONCLUSION: No individuals in stage A of suture maturation were found and stage B was identified in only 1% of the sample. The majority of the patients (64.88%) presented at least partial fusion of the MPS (stages D and E).

Incidence and morphology of the incisive suture in CT scanning of young children and human fetuses.

PURPOSE: Incisive suture is a suture classically described on the oral face of the palate in fetuses and young children. The aim of our study was to describe the evolution of the incisive suture in human fetuses and to evaluate the incidence of this suture in a population of young children under 4 years, to determine if there is a possibility of improving the anterior growth of the maxilla, by stimulation of this suture. METHODS: One hundred and thirty CT scan images of patients aged from birth to 48 months have been studied and nine fetal palates aged from 18 to 26 weeks of development, have been scanned using high-resolution X-ray micro-computed tomography RESULTS: The CT scan images of patients showed that an incisive suture was present in 33/130 cases (25,4%). All the patients with a suture were under 2 years old. The fetal palate study showed that the suture was present in the inferior aspect of the palate (oral cavity) in all cases. The incisive suture increased from 18 to 24 weeks. At 26 weeks it stopped growing although the intercanine length increased. Considering the closure of the suture in a vertical plane, our study on fetuses has shown that the incisive suture is closing from its superior side (nasal side) to its inferior side. CONCLUSIONS: Considering all these results it appears to us that the incisive suture is partially ossified after birth, it cannot be stimulated by orthodontic appliances.

Cdc42 regulates cranial suture morphogenesis and ossification.

Cdc42 (cell division cycle 42) is ubiquitously expressed small GTPases belonging to the Rho family of proteins. Previously, we generated limb bud mesenchyme-specific Cdc42 inactivated mice (Cdc42 conditional knockout mice; Cdc42 fl/fl; Prx1-Cre), which showed short limbs and cranial bone deformities, though the mechanism related to the cranium phenotype was unclear. In the present study, we investigated the role of Cdc42 in cranial bone development. Our results showed that loss of Cdc42 caused a defect of intramembranous ossification in cranial bone tissues which is related to decreased expressions of cranial suture morphogenesis genes, including Indian hedgehog (Ihh) and bone morphogenetic proteins (BMPs). These findings demonstrate that Cdc42 plays a crucial role in cranial osteogenesis, and is controlled by Ihh- and BMP-mediated signaling during cranium development.

Digital radiomorphometric analysis of the frontal sinus and assessment of the relation between persistent metopic suture and frontal sinus development.

OBJECTIVES: This study aimed to establish the frequency of the frontal sinus (FS) aplasia, to compare metopic and nonmetopic series and thus to assess the relationship between the preservation of metopic suture and FS development. MATERIALS AND METHODS: FSs were investigated in 230 dry skulls of adult males distributed into control (137) and metopic (93) series. They were visualized through industrial digital radiography. RESULTS: In the control series, the FS aplasia was observed in 12.41% of the skulls, and it was mostly unilateral (8.76%) than bilateral (3.65%). The left-sided aplasia (5.11%) slightly prevailed over the right-sided one (3.65%). In the metopic series, the aplasia was observed with a frequency of 19.35%, and the bilateral aplasia (7.53%) was rarer that the unilateral one (11.83%), while the right-sided aplasia was clearly predominant (9.68%) compared to the left-sided one (2.15%). DISCUSSION: The significant differences between both series showed a tendency for the persistence of metopic suture to be frequently related with FS underdevelopment in the vertical plate of the frontal bone, but in cases of pneumatization, it was preferentially on the left side. Taking into account that the cranial hypertension leads to suture diastasis and hinders development of the FS, it could be suggested that persistence of the metopic suture along with underdevelopment of the FS in nonsyndromic adults could be an expression of an elevated intracranial pressure during early development as an after-effect of certain condition.

Rescue of Premature Coronal Suture Fusion with TGF-ß2 Neutralizing Antibody in Rabbits with Delayed-Onset Synostosis.

OBJECTIVES: An overexpression of Tgf-ß2 leads to calvarial hyperostosis and suture fusion in individuals with craniosynostosis. Inhibition of Tgf-ß2 may help rescue fusing sutures and restore normal growth. The present study was designed to test this hypothesis. DESIGN: Twenty-eight New Zealand White rabbits with delayed-onset coronal synostosis had radiopaque markers placed on either side of the coronal sutures at 10 days of age. The rabbits were randomly assigned to: (1) sham control rabbits (n = 10), (2) rabbits with control IgG (100 µg/suture) delivered in a collagen vehicle (n = 9), and (3) rabbits with Tgf-ß2 neutralizing antibody (100 µg/suture) delivered in a collagen vehicle (n = 9). Longitudinal growth data were collected at 10, 25, 42, and 84 days of age. Sutures were harvested at 84 days of age for histomorphometry. RESULTS: Radiographic analysis showed significantly greater ( P < .05) coronal suture marker separation, craniofacial length, cranial vault length, height, shape indices, cranial base length, and more lordotic cranial base angles in rabbits treated with anti-Tgf-ß2 antibody than in controls at 42 and 84 days of age. Histologically, rabbits treated with anti-Tgf-ß2 antibody at 84 days of age had patent and significantly ( P < .05) wider coronal sutures and greater sutural area compared to controls. CONCLUSIONS: These data support our hypothesis that antagonism of Tgf-ß2 may rescue fusing coronal sutures and facilitate craniofacial growth in this rabbit model. These findings also suggest that cytokine therapy may have clinical significance in infants with progressive postgestational craniosynostosis.

Skeletal Age-related Changes of Midpalatal Suture Densities in Skeletal Maxillary Constriction Patients: CBCT Study.

AIM: To determine if density measurements of the midpalatal suture and cervical vertebral maturation index (CVMI) are related, and to investigate if CVMI could help in predicting of the developmental status of the midpalatal suture. MATERIALS AND METHODS: Cone-beam computed tomography (CBCT) images of 95 skeletal maxillary constriction patients (aged 8 to 18 years) were examined. The maturational stages of the cervical vertebrae were visually defined, and midpalatal suture density in the anterior region, the middle region, and the posterior region were measured. One-way ANOVA and Fisher's least significant difference (LSD) post-hoc test were used for statistical assessment. RESULTS: Significant differences were found in MPDS: in anterior region between (c1,c2,c3,c4) and (c5,c6) stages, in middle region between (c1,c2,c3) and (c5,c6) stages, and in posterior region between (c1,c2,c3) and (c4,c5,c6) stages. CONCLUSION: Midpalatal suture densities in all regions increase with skeletal maturation advancement.The significant increase after puberty may have the key role in decreasing the skeletal effects of RME after that age. Clinical significances: It is important to assess the midpalatal suture density to choose between rapid maxillary expansion (RME) and surgically assisted rapid maxillary expansion (SARME). This study revealed a significant increase in the midpalatal suture density after puberty. Thus, it may better to perform RME before puberty.

Zygomaticomaxillary suture maturation: A predictor of maxillary protraction? Part I - A classification method.

OBJECTIVE: The aim of this study was to present a method of classifying the maturational level of the zygomaticomaxillary sutures (ZMSs). METHODS: Cone-beam CT (CBCT) images from 74 subjects (5.6-58.4 years) were examined to define the radiographic stages of ZMS maturation. Five stages of maturation of the ZMS were identified and defined: Stage A-uniform high-density sutural line, with no or little interdigitation; Stage B-scalloped appearance of the high-density sutural line; Stage C-two parallel, scalloped, high-density lines, separated in some areas by small low-density spaces; Stage D-fusion in the inferior portion of the suture; and Stage E-complete fusion. Intra- and inter-examiner agreements were evaluated by weighted kappa tests. RESULTS: The intra- and inter-examiners reproducibility values demonstrated substantial to almost perfect agreement. No fusion of ZMSs was observed in patients up to 10 years of age. From 10 to 15 years, all maturational stages were identified. After 15 years of age, the majority of patients showed fusion of ZMSs. CONCLUSIONS: The classification of ZMS maturation using CBCT is a reliable method that allows the assessment of the morphology of the ZMSs in the individual patient.

Calvarial bone development and suture closure in Dicer-deficient mice.

OBJECTIVE: To evaluate whether lack of Dicer during calvaria development would lead to dysmorphology of calvaria and suture closure in mice. MATERIALS AND METHODS: A conditional Dicer deficient under Osx promoter mouse was employed in this study. The 4- and 10-week-old conditional Dicer-deficient mice control littermates and Osx-cre transgenic mice were studied for calvarial bone morphology and suture closure. Dry skull, microcomputed tomography (µCT), histological and gene expression studies were investigated to evaluate the effect of Dicer deficiency on calvarial bone morphology and their related genes during calvaria development. RESULTS: The results elucidated that complete suture closure was observed in 10-week-old conditional Dicer-deficient mice while incomplete closure suture was observed in age-matched Osx-cre control mice. The µCT and histological sections demonstrated complete fusion of posterior frontal suture and dysmorphic calvarial bones in Dicer deficient mice compared to the ones in their littermates and age-matched Osx-cre control mice. Gene expression study demonstrated significantly increased expression of suture and calvarial bone-related genes, that is Tgf-beta family, Bmp3, Msx2, Alx4, Runx2 and Osx in Dicer-deficient mice during suture closure time. CONCLUSIONS: The results suggest mature miRNAs are important for suture closure and calvarial morphology during calvaria development.

Zygomaticomaxillary suture maturation: Part II-The influence of sutural maturation on the response to maxillary protraction.

OBJECTIVE: To evaluate the influence of the maturational stages of zygomaticomaxillary sutures (ZMS) on the response to maxillary protraction. SUBJECTS AND METHODS: A total of 40 Class III patients were treated retrospectively with either a combination of rapid maxillary expansion and facial mask (RME/FM) or bone-anchored maxillary protraction (BAMP). The RME/FM group consisted of 18 patients (mean age 8.3 years), while the BAMP group was comprised of 22 patients (mean age 11.8 years). The initial CBCT images (T1) of the ZMSs were classified blindly. 3D models from CBCT images at the start and at the end of orthopaedic treatment were registered on the anterior cranial base, and corresponding structures were measured on colour-coded maps and semitransparent overlays. The amounts of protraction of the maxilla, zygoma, orbitale and maxillary first molars for both groups were analysed with two-way ANOVA with Holm-Sidak post hoc test for multiple comparisons. RESULTS: A significant association was found between the early maturation stages of the ZMSs and the amount of maxillary protraction, regardless of the protraction method used. Class III patients with ZMS stages A and B showed greater maxillary protraction than patients at stage C. CONCLUSION: The maturational stages of ZMS are associated with the response maxillary protraction.

Midpalatal suture density ratio: A novel predictor of skeletal response to rapid maxillary expansion.

INTRODUCTION: During adolescence, increasing interdigitation of the midpalatal suture increases resistance to rapid maxillary expansion (RME); this decreases its skeletal effect. In this study, we aimed at determining whether a novel measure of midpalatal suture maturity, the midpalatal suture density ratio, can be used as a valid predictor of the skeletal response to RME. METHODS: The midpalatal suture density ratio, chronologic age, cervical vertebral maturation, and the stage of midpalatal suture maturation were assessed before treatment for 30 patients (ages, 12.9 ± 2.1 years) who underwent RME as part of comprehensive orthodontic treatment. Measurements on cone-beam computed tomography scans were used to determine the proportions of prescribed expansion achieved at the greater palatine foramina, the nasal cavity, and the infraorbital foramina. RESULTS: There was a statistically significant negative correlation between the midpalatal suture density ratio and both the greater palatine foramina and the infraorbital foramina (r = -0.7877 and -0.3647, respectively; P <0.05). In contrast, chronologic age, cervical vertebral maturation, and stage of midpalatal suture maturation were not significantly correlated to any of the assessed measures of skeletal expansion (r range, -0.2209 to 0.0831; P >0.05). CONCLUSIONS: The midpalatal suture density ratio has the potential to become a useful clinical predictor of the skeletal response to RME. Conversely, chronologic age, cervical vertebral maturation, and stage of midpalatal suture maturation cannot be considered useful parameters to predict the skeletal effects of RME.

A new mathematical model for pattern formation by cranial sutures.

Cranial sutures are narrow mesenchymal tissues that connect skull bones to each other. Given that they serve as growth centers in the skull, these undifferentiated tissues play crucial roles in skull development. Cranial sutures are also of clinical importance, because the premature fusion of skull bones results in a pathological condition called craniosynostosis. In newborns, skull sutures are wide and straight; during adolescence, they become thinner and start winding to form an interdigitating pattern. From a functional aspect, as the degree of interdigitation becomes larger, the strength of the connection between bones increases. However, the mechanisms underlying the maintenance of mesenchymal narrow bands or formation of interdigitation remain poorly understood. In the present study, we presented a new mathematical model that can reproduce the suture width maintenance and interdigitation formation. We can predict the width of the mesenchyme bands and wavelengths of suture interdigitations from the model.

Cell morphologic changes and PCNA expression within craniofacial sutures during monkey Class III treatment.

OBJECTIVES: To evaluate and compare the cellular morphologic changes and proliferating cell nuclear antigen (PCNA) expression within craniofacial sutures in growing Rhesus monkeys treated with a Class III functional appliance. MATERIALS AND METHODS: Six Rhesus monkeys in the mixed dentition stage were divided into three groups: a 45-day experimental group, a 90-day experimental group, and a control group. Monkeys in the experimental groups were fitted with a Class III magnetic twin-block appliance. Cellular changes in six craniofacial sutures-the zygomaticomaxillary, zygomaticotemporal, transverse palatine, pterygopalatine, zygomaticofrontal, and frontomaxillary sutures were qualitatively and quantitatively evaluated by means of histomorphologic analysis, TEM, and immunohistochemical test of PCNA. RESULTS: Obvious and altered bone remodeling combined with bone deposition and resorption was present in craniofacial sutures in the experimental groups. Increased activity of enlarged fibroblasts with abundant organelles was revealed. PCNA expression increased in the 45-day group compared with the control group, followed by the 90-day group. The highest percentage of PCNA-positive cells was found in the pterygopalatine suture in the 45-day group and the zygomaticomaxillary suture in the 90-day group. CONCLUSIONS: The pterygopalatine and zygomaticomaxillary sutures are more active among the craniofacial sutures in the craniofacial complex remodeling during Class III treatment. The magnetic twin-block appliance effectively promoted suture remodeling by enhancing the activity and proliferation of osteoblasts, osteoclasts, and fibroblasts, especially in the early phase.

Effect of hyaluronic acid on bone formation in the expanded interpremaxillary suture in rats.

OBJECTIVE: To evaluate the histomorphometric effects of different molecular weight hyaluronic acid on bone formation in rats after expansion of the interpremaxillary suture. MATERIAL AND METHODS: Twenty-four male Sprague Dawley rats were divided into three groups. Each group was subjected to expansion for 5 days and retention for 10 days. Group 1 received 50 µl of high molecular weight hyaluronic acid (HMWHA), group 2 received 50 µl of low molecular weight hyaluronic acid (LMWHA), and the control group received same amount of saline solution to the interpremaxillary suture. Ten days after injection, the rats were killed and their maxillas dissected. For the histomorphometric evaluation, blocks were serially sectioned at 10-µm intervals. Sections were stained with hematoxylin-eosin (HE) and evaluated with image analysis software. Bone area (µm²) (BA), bone perimeter of suture borders (µm) (BP), and ratio of osteoblast cells and capillary cells to BA and BP parameters were evaluated. RESULTS: HMWHA showed a statistically higher ratio of osteoblast and capillary cell scores compared with the LMWHA and control groups (p < 0.05). There were no statistically significant differences in between LMWHA and control groups (p > 0.05). CONCLUSIONS: Local injection of HMWHA in the interpremaxillary suture after rapid maxillary expansion stimulated new bone formation, which may shorten the retention period and may reduce the risk of relapse. LMWHA has no effect on bone formation in interpremaxillary suture.

Tissue Dynamics: Lessons Learned From Sutural Morphogenesis and Cancer Growth.

UNLABELLED: Why are cranial sutures the way they are? How do cancers grow? Merging physics and mathematics with biology, we develop equations describing these complex adaptive systems, to which all biological entities belong, calling them laws of tissue dynamics:Where t is time, E is energy, M is body mass, X is the biological characteristic of interest, C is a constant, a is an exponent.(1) is based on conservation of matter: for any given tissue, materials in must equal to materials out +/- assimilated or degraded. (2) is based on energy conservation. All living systems require energy, without which life becomes impossible. Equation (2) is a power spectrum. OBJECTIVES: This study aimed to introduce the laws of tissue dynamics and to illustrate them using observations from craniofacial and cancer growth. METHODS: We use cranial sutures as a model system to test Equation (1), we also measure the in vitro growth rate of normal murine liver and spleen cells, comparing them to B16F10 melanoma cells. We show the increase in compound growth rate and energetic requirement of malignant versus normal cells as partial proof of Equation (2). RESULTS: The constant width and wavy form of cranial sutures are the inevitable results of repeated iteration from coupling of growth and stress. The compound growth rate of B10F16 melanoma cells exceeds that of normal cells by 1.0 to 1.5%, whereas their glucose uptake is equal to 3.6 billion glucose molecules/cell per minute. SUMMARY: Living things are complex adaptive systems, thus a different way of thinking and investigating, going beyond the current reductive approach, is required.

CT of Normal Developmental and Variant Anatomy of the Pediatric Skull: Distinguishing Trauma from Normality.

The use of computed tomography (CT) in clinical practice has been increasing rapidly, with the number of CT examinations performed in adults and children rising by 10% per year in England. Because the radiology community strives to reduce the radiation dose associated with pediatric examinations, external factors, including guidelines for pediatric head injury, are raising expectations for use of cranial CT in the pediatric population. Thus, radiologists are increasingly likely to encounter pediatric head CT examinations in daily practice. The variable appearance of cranial sutures at different ages can be confusing for inexperienced readers of radiologic images. The evolution of multidetector CT with thin-section acquisition increases the clarity of some of these sutures, which may be misinterpreted as fractures. Familiarity with the normal anatomy of the pediatric skull, how it changes with age, and normal variants can assist in translating the increased resolution of multidetector CT into more accurate detection of fractures and confident determination of normality, thereby reducing prolonged hospitalization of children with normal developmental structures that have been misinterpreted as fractures. More important, the potential morbidity and mortality related to false-negative interpretation of fractures as normal sutures may be avoided. The authors describe the normal anatomy of all standard pediatric sutures, common variants, and sutural mimics, thereby providing an accurate and safe framework for CT evaluation of skull trauma in pediatric patients.

The effects of tissue-non-specific alkaline phosphatase gene therapy on craniosynostosis and craniofacial morphology in the FGFR2C342Y/+ mouse model of Crouzon craniosynostosis.

OBJECTIVES: Craniosynostosis, the premature fusion of cranial bones, has traditionally been described as a disease of increased bone mineralization. However, multiple mouse models of craniosynostosis display craniosynostosis simultaneously with diminished cranial bone volume and/or density. We propose an alternative hypothesis that craniosynostosis results from abnormal tissue mineralization through the downregulation of tissue-non-specific alkaline phosphatase (TNAP) enzyme downstream of activating mutations in FGFRs. MATERIAL AND METHODS: Neonatal Crouzon (FGFRC342Y/+) and wild-type (FGFR+/+) mice were injected with lentivirus to deliver a recombinant form of TNAP. Mice were sacrificed at 4 weeks postnatal. Serum was collected to test for alkaline phosphatase (AP), phosphorus, and calcium levels. Craniofacial bone fusion and morphology were assessed by micro-computed tomography. RESULTS: Injection with the TNAP lentivirus significantly increased serum AP levels (increased serum AP levels are indicative of efficient transduction and production of the recombinant protein), but results were variable and dependent upon viral lot and the litter of mice injected. Morphological analysis revealed craniofacial form differences for inferior surface (p=0.023) and cranial height (p=0.014) regions between TNAP lentivirus-injected and vehicle-injected Crouzon mice. With each unit increase in AP level, the odds of lambdoid suture fusion decreased by 84.2% and these results came close to statistical significance (p=0.068). CONCLUSION: These results suggest that TNAP deficiency may mediate FGFR2-associated craniosynostosis. Future studies should incorporate injection of recombinant TNAP protein, to avoid potential side effects and variable efficacy of lentiviral gene delivery.