Three-dimensional assessment of facial morphology in children and adolescents with juvenile idiopathic arthritis and moderate to severe TMJ involvement using 3D surface scans.

OBJECTIVE: This study aims to (1) assess the facial morphology in juvenile idiopathic arthritis (JIA) subjects with moderate to severe temporomandibular joint (TMJ) involvement using 3D surface scans and (2) compare the facial morphology in these subjects to that in JIA subjects without TMJ involvement. METHODS: Sixty JIA subjects were included and grouped as follows: group 1 (no involvement group), JIA without TMJ involvement; Group 2 (unilateral group), JIA with moderate to severe unilateral TMJ involvement; and group 3 (bilateral group), JIA with bilateral TMJ involvement. Standard orientation of all surfaces was accomplished. The means and variabilities of facial morphology in groups 2 and 3 were assessed and compared with those of group 1 in three dimensions, respectively. RESULTS: Group 2 (unilateral group) exhibited a more retruded and wider chin, shorter mandibular height, and more prominent cheek (2, 2, 5, and 2 mm, on average, respectively) on the affected side and a more retruded and narrower chin and more prominent malar region (4, 3, and 2 mm, on average, respectively) on the unaffected side compared with group 1 (no involvement group) (p < 0.05). Group 3 (bilateral group) exhibited a more retruded chin, shorter mandibular height, more prominent upper cheeks, and narrower perioral region (5, 5, 3, and 2 mm, respectively) compared with group 1 (no involvement group) (p < 0.05). CONCLUSIONS: In JIA subjects with moderate to severe unilateral or bilateral TMJ involvement, the affected side(s) revealed similar facial dysmorphology with reduced mandibular height, chin retrusion, and prominent upper cheek. CLINICAL RELEVANCE: Three-dimensional surface scans can be a non-ionizing indicator of signs of TMJ involvement in JIA subjects.

A new implementation of digital X-ray radiogrammetry and reference curves of four indices of cortical bone for healthy European adults.

UNLABELLED: Digital X-ray radiogrammetry performs measurements on a hand radiograph in digital form. We present an improved implementation of the method and provide reference curves for four indices for the amount of bone. We collected 1662 hand radiographs of healthy subjects of age 9-100 years. PURPOSE: The digital X-ray radiogrammetry (DXR) method has been shown to be efficient for diagnosis of osteoporosis and for assessment of progression of rheumatoid arthritis. The aim of this work is to present a new DXR implementation and reference curves of four indices of cortical bone and to compare their relative SDs in healthy subjects at fixed age and gender. MATERIALS AND METHODS: A total of 1662 hand radiographs of healthy subjects of age 9-100 years were collected in Jena in 2001-2005. We also used a longitudinal study of 116 Danish children born in 1952 with on average 11 images taken over the age range 7 to 40 years. The new DXR method reconstructs the whole metacarpal contour so that the metacarpal lengths can be measured and used in two of the indices. The new DXR method automatically validates 97 % of the images and is implemented as a local server for PACS users. RESULTS: The Danish bone health index (BHI) data are consistent with the Jena data and also with the published BHI reference for healthy children. BHI is found to have smaller relative SD than the other three indices in the Jena cohort over the age range 20-80 years. CONCLUSION: The new DXR method is an extension of the existing BoneXpert method for children, which allows patients to be followed from childhood into adulthood with the same method. By making all four indices of cortical bone available within the same medical device, it becomes possible to decide which index has the best relation to fracture risk in future studies.

Computational mouse atlases and their application to automatic assessment of craniofacial dysmorphology caused by the Crouzon mutation Fgfr2(C342Y).

Crouzon syndrome is characterized by premature fusion of sutures and synchondroses. Recently, the first mouse model of the syndrome was generated, having the mutation Cys342Tyr in Fgfr2c, equivalent to the most common human Crouzon/Pfeiffer syndrome mutation. In this study, a set of micro-computed tomography (CT) scannings of the skulls of wild-type mice and Crouzon mice were analysed with respect to the dysmorphology caused by Crouzon syndrome. A computational craniofacial atlas was built automatically from the set of wild-type mouse micro-CT volumes using (1) affine and (2) non-rigid image registration. Subsequently, the atlas was deformed to match each subject from the two groups of mice. The accuracy of these registrations was measured by a comparison of manually placed landmarks from two different observers and automatically assessed landmarks. Both of the automatic approaches were within the interobserver accuracy for normal specimens, and the non-rigid approach was within the interobserver accuracy for the Crouzon specimens. Four linear measurements, skull length, height and width and interorbital distance, were carried out automatically using the two different approaches. Both automatic approaches assessed the skull length, width and height accurately for both groups of mice. The non-rigid approach measured the interorbital distance accurately for both groups while the affine approach failed to assess this parameter for both groups. Using the full capability of the non-rigid approach, local displacements obtained when registering the non-rigid wild-type atlas to a non-rigid Crouzon mouse atlas were determined on the surface of the wild-type atlas. This revealed a 0.6-mm bending in the nasal region and a 0.8-mm shortening of the zygoma, which are similar to characteristics previously reported in humans. The most striking finding of this analysis was an angulation of approximately 0.6 mm of the cranial base, which has not been reported in humans. Comparing the two different methodologies, it is concluded that the non-rigid approach is the best way to assess linear skull parameters automatically. Furthermore, the non-rigid approach is essential when it comes to analysing local, non-linear shape differences.