Three-dimensional assessment of early surgical outcome in repaired unilateral cleft lip and palate: Part 1. Nasal changes.

OBJECTIVE: To evaluate three-dimensional nasal morphology following primary reconstruction in children with unilateral cleft lip and palate relative to contemporaneous noncleft data. DESIGN: Prospective, cross-sectional, controlled study. SETTING: Glasgow Dental Hospital and School, Faculty of Medicine, Glasgow University. PATIENTS AND PARTICIPANTS: Two groups of 3-year-old children (21 with unilateral cleft lip and palate and 96 controls) with facial images taken using a three-dimensional, vision-based capture technique. METHODS: Three-dimensional images of the face were reflected so the cleft was on the left side to create a homogeneous group for statistical analysis. Three-dimensional coordinates of anthropometric landmarks were extracted from facial images by a single operator. A set of linear measurements was used to compare cleft and control subjects on right and left sides, adjusting for sex differences. RESULTS: The mean nasal base width and the width of the nostril floor on right and left sides differed significantly between control and unilateral cleft lip and palate groups. The measurements were greater in children with unilateral cleft lip and palate. The differences in the mean nasal height and mean nasal projection between the groups were not statistically significant. Mean columellar lengths were different between the left and right sides in children with unilateral cleft lip and palate. CONCLUSIONS: There were significant nasal deformities following the surgical repair of unilateral cleft lip and palate.

Three-dimensional assessment of early surgical outcome in repaired unilateral cleft lip and palate: Part 2. Lip changes.

OBJECTIVE: To evaluate three-dimensional lip morphology, following primary reconstruction in children with unilateral cleft lip and palate relative to contemporaneous noncleft data. DESIGN: Prospective, cross-sectional, controlled study. SETTING: Glasgow Dental Hospital and School, University of Glasgow, U.K. PATIENTS AND PARTICIPANTS: Two groups of 3-year-old children (21 with unilateral cleft lip and palate and 96 controls) with facial images taken using a three-dimensional vision-based capture technique. METHODS: Three-dimensional images of the face were reflected so the cleft was on the left side to create a homogeneous group for statistical analysis. Three-dimensional coordinates of anthropometric landmarks were extracted from facial images. Three-dimensional, generalized Procrustes superimposition was implemented and a set of linear measurements were used to compare cleft and control subjects for right and left sides, adjusting for sex differences. RESULTS: Crista philtri on both the cleft and noncleft sides were displaced laterally and posteriorly; there was also a statistically significant increase in philtrum width. No significant differences between cleft and control regarding the cutaneous height of the upper lip. The lip in the cleft patients was flatter than in the noncleft individuals, with less prominence of labialis superioris. CONCLUSIONS: Stereophotogrammetry allows detection of residual dysmorphology following cleft repair. There was significant increase of the philtrum width. The lip appeared flatter and more posterior displaced in unilateral cleft lip and palate patients compared with controls.

Towards building a photo-realistic virtual human face for craniomaxillofacial diagnosis and treatment planning.

The aim of this investigation was to assess the feasibility of building a virtual human face digitally by superimposing a photo-realistic three-dimensional (3D) soft-tissue surface on bone in the correct relationship and evaluating the registration errors associated with this method. The 3D soft-tissue surface of the face was captured using a fast stereophotogrammetry method and the underlying bone was recorded using a 3D computed tomography (CT) scanner. Using the Procrustes registration method, the outer surface of the 3D CT scan and the photo-realistic soft-tissue surfaces were merged into a single Virtual Reality Modelling Language (VRML) file and displayed using a standard VRML viewer. Quantitative measurements of registration errors were calculated in the reconstructed human head models using the signed closest point distance from the photo-realistic skin surface to the transformed CT skin surface. The registration errors between most parts of the aligned surfaces were within +/-1.5mm. The errors were relatively large around the eyebrows, eyelids and cheeks. Simultaneous recording of the face and skull may reduce this error.

Applications of 3D imaging in orthodontics: part I.

Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.

Validation of a vision-based, three-dimensional facial imaging system.

OBJECTIVE: The aim of this study was to assess the accuracy of a newly developed three-dimensional (3D) imaging system in recording facial morphology. METHODS: Twenty-one infants with cleft lip each had a full-face alginate impression taken at the time of primary lip repair, and a stone cast was constructed from each impression. Five anthropometric points were marked on each cast. Each cast was digitized, and the 3D co-ordinates of the five points were obtained using a co-ordinate measuring machine (CMM, Ferranti) of documented accuracy (9.53 microm). Each cast was scanned in four positions using a computerized stereophotogrammetry (C3D) system. The five points were located on the 3D images, and their 3D co-ordinates were extracted by three operators. The co-ordinate systems produced by C3D were aligned, via translation and rotation, to match the CMM co-ordinate system using partial ordinary procrustes analysis. The displacements of the adjusted C3D co-ordinates from the reference co-ordinates were then measured. Three different types of errors were identified: operator, system, and registration errors. RESULTS: Operator error was within 0.2 mm of the true co-ordinates of the landmarks. C3D was accurate within 0.4 mm. The average displacement of points over the 21 casts at four positions for the three operators was 0.79 mm (median 0.68). CONCLUSIONS: The presented 3D imaging system is reliable in recording facial deformity and could be utilized in recording cleft deformities and measuring the changes following surgery

Visualization and model building in medical imaging.

We present technologies and ideas, developed from the JFIT 'Active Stereo Probe Project', which are applicable to problems within medical measurement and monitoring. Two related areas are considered. The first concerns patient body surface modelling. During the project two state-of-the-art non-contact surface measurement techniques have been developed which are applicable to medical situations requiring dense and accurate body surface modelling. Such applications include, for example, prosthetic appliance fabrication, presurgical planning and non-invasive deformity analysis. The second is concerned with overlay projection. Using this enabling technology the information content of a scene can be enhanced as an aid to medical personnel. Results and illustrative applications of the newly developed technology are presented.