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PubMed2003

Stereological tools in biomedical research.

Stereological studies are more and more frequent in literature, particularly in the development/evolution, pathology, and neurosciences areas. The stereology challenge is to understand the structural inner three-dimensional arrangement based on the analysis of the structure slices only showing two-dimensional information. Cavalieri and Scherle's methods to estimate volume, and Buffon's needle problem, are commented in the stereological context. A group of actions is needed to appropriately quantify morphological structures (unbiased and reproducibly), e.g. sampling, isotropic and uniform randomly sections (Delesse's principle), and updated stereological tools (disector, fractionator, nucleator, etc). Through the correct stereology use, a quantitative study with little effort could be performed: efficiency in stereology means a minimum slices sample counting (little work), low cost (slices preparation), but good accuracy. In the present text, a short review of the main stereological tools is done as a background basis to non-expert scientists.

Algorithms↗

PubMed2003

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

Cephalometry↗

PubMed2004

Maxillary and mandibular displacement in hemifacial microsomia: a longitudinal Roentgen stereometric study of 21 patients with the aid of metallic implants.

OBJECTIVE: To record maxillary and mandibular displacement with articular growth and in response to bimaxillary surgical repositioning in patients with hemifacial microsomia (HFM) and to observe ipsilateral corpus/ramus growth in severely affected children. DESIGN: Prospective roentgen stereometric analysis (mean age 7 years 10 months to 18 years 0 months) and retrospective profile and panoramic roentgenograms. Mean total observation period was 9 years 1 month. SETTING: Department of Plastic and Reconstructive Surgery, Malmö University Hospital (Malmö, Sweden). PATIENTS: Twenty-one patients consecutively diagnosed from 1976 through 1988 with HMF, five of whom had bimaxillary surgery. INTERVENTIONS: Surgery was performed at the Department of Plastic and Reconstructive Surgery. Implants were inserted at the initial reconstructive surgical procedure under general anesthesia. Roentgen examinations were performed in connection with continued clinical evaluations and treatment. MAIN OUTCOME MEASURES: Stereo roentgenograms were digitized at the Department of Orthopedic Surgery, Malmö University Hospital (Malmö, Sweden). RESULTS: Displacement of the jaws with articular growth and in response to bimaxillary surgical repositioning varied interindividually with no apparent common pattern. Relapse displacement occurred several years after bimaxillary surgery. Mandibular growth changes were found in the corpus/ramus area and alveolar process on the affected side. CONCLUSIONS: A marked interindividual variability of maxillary and mandibular displacement indicates that the relevance of statistical analysis of HFM growth data may be questioned. We would suggest that precise and accurate longitudinal recordings of growth and response to surgery in individual HFM patients be more appropriate.

Adolescent↗

PubMed2004

Facial characterization of infants with cleft lip and palate using a three-dimensional capture technique.

OBJECTIVE: To characterize the soft tissue features of infants with unilateral cleft lip (UCL) and unilateral complete cleft lip and palate (UCLP) prior to primary surgery and compare with noncleft controls. DESIGN: Prospective controlled capture of the facial morphology of infants using a noninvasive three-dimensional stereophotogrammetry method. PARTICIPANTS: 23 children with presurgical cleft: 11 UCL (M = 6, F = 5); 12 UCLP (M = 9, F = 3), and 21 noncleft controls (M = 7, F = 14) were imaged at approximately 3 months of age (range 10 to 16 weeks). MAIN OUTCOME MEASURE: Accurate, repeatable quantification of facial soft tissues in infants with clefts prior to surgery. RESULTS: Significant differences (p <.05) were found between the UCLP group and UCL and control groups in anatomical and soft nose width, cleft-side alar wing length, and nasal tip horizontal displacement. Both cleft groups were significantly different from controls and from each other in cleft-side nostril dimensions, alar wing angulation, columella angle, and alar base to corner of mouth dimension; alar base width; and soft tissue defect in nose and the lip and philtrum length bordering the cleft. Significant differences between clefts and controls were identified in the nostril and philtrum on the noncleft side. CONCLUSIONS: The use of children with UCL as controls for UCLP studies is inappropriate. This technique overcame the limitations of direct measurement of infant faces to aid the surgeon in the planning and subsequent re-evaluation of surgical rationale.

Analysis of Variance↗

PubMed2004

Three-dimensional facial characteristics of Caucasian infants without cleft and correlation with body measurements.

OBJECTIVE: The aim of this study was to characterize the soft tissue facial features of infants without cleft and to report on the correlation between these with weight, length, and head circumference. DESIGN: This was a prospective study using a noninvasive three-dimensional (3D) stereophotogrammetry (C3D) system to capture the images of the participants. Landmarks were identified on the 3D facial images. Means and SDs were derived for facial distances and angles. A facial asymmetry score was calculated for each image. Two sample Student's t tests, Pearson's correlation coefficients and analysis of covariance were used to ascertain any gender differences and determine whether these could be explained by weight differences. PARTICIPANTS: Eighty-three infants, 41 boys and 42 girls, were captured at rest with their lips apart, at approximately 3 months of age. RESULTS: Significant sex differences, of 1 to 2 mm, were found in several facial dimensions, such as face height and nose width. The larger facial measurements correlated significantly with body measurements. Analysis of variance confirmed these differences could be explained by differences in weight. There were no sex differences in the nose/mouth width ratios or in any of the angles measured, suggesting that there may be little sex difference in shape. A slight degree of asymmetry in the faces of infants without cleft was detected. CONCLUSIONS: Comparisons between noncleft controls and infants with cleft should take cognizance of normal age and sex variations in height and weight that occur among infants.

Age Factors↗

PubMed2005

A new three-dimensional method of assessing facial volumetric changes after orthognathic treatment.

OBJECTIVE: To validate a new method of facial volumetric assessment that is dependent on the use of stereophotogrammetric models and a software-based Facial Analysis Tool. DESIGN: The method was validated in vitro with three-dimensional (3D) models of a lifelike plastic female dummy head and in vivo with a male-subject head. METHODS: Thirty facial silicone explants were added in the nasal and perioral regions of each head, and their volumes were obtained by three different algorithms. These were compared with the actual values obtained by a "water displacement" method. RESULTS: The least mean error was found with the "tetrahedron formation" method followed by the "projection" method and the "back-plane construction" method. The error with the tetrahedron formation method was 0.071 cm(3) (95% confidence interval [CI]: -0.074 to 0.2161 cm3) with the in vitro models and 0.314 cm3 (95% CI: -0.080 to 0.708 cm3) with the in vivo models. The increased volumetric assessment error observed in vivo was attributed to the registration procedure and possible changes in facial expression. CONCLUSIONS: These results encourage the use of this method in the 3D assessment of orthognathic surgical outcome, provided a standardized facial expression is used for image acquisition.

Algorithms↗

PubMed1994

Three-dimensional evaluation of facial asymmetry in cleft lip and palate.

The purpose of the present study was to describe facial asymmetry in three dimensions in individuals with an operated complete unilateral cleft lip and palate (UCLP) and in individuals without craniofacial anomalies (controls). Three-dimensional coordinates for 16 bilateral and 10 midsagittal facial landmarks were determined for the UCLP group (N = 49) and the control group (N = 80) by means of stereophotogrammetry. The total asymmetry was measured and resolved for transverse, vertical, and sagittal components. It can be concluded that all three components are important in studies on facial asymmetry. Individuals with UCLP show more facial asymmetry in the vertical direction than controls. They demonstrate more facial asymmetry in the region related to the cleft than controls. And, males in general demonstrate more asymmetry of the nose than females.

Cephalometry↗

PubMed1994

Facial left-right dominance in cleft lip and palate: three-dimension evaluation.

Studies on facial left-right dominance in individuals without craniofacial anomalies have demonstrated controversial results. This is probably due to the frequent use of two-dimensional methods, yet left-right dominance consists of transverse, vertical, and sagittal components. The aim of the present study was to describe three-dimensionally facial left-right dominance in individuals with an operated complete unilateral cleft lip and palate on the left side (LUCLP), on the right side (RUCLP), and in individuals without craniofacial anomalies (controls). Using stereophotogrammetry, three-dimensional coordinates for 16 bilateral and 10 midsagittal facial landmarks were determined for the LUCLP group (N = 32), the RUCLP group (N = 17), and the control group (N = 80). Left-right dominance was measured in three directions. Individuals without craniofacial anomalies showed a facial left sided dominance in the transverse direction, a facial right sided dominance in the sagittal direction, and no particular dominated side in the vertical direction. Individuals with a unilateral cleft lip and palate demonstrated a facial dominance of the nonaffected side in the vertical direction as well as in the sagittal direction, with no particular side dominant in the transverse direction. Generally, there was more variation in left-right dominance within the face in the vertical and sagittal directions.

Cephalometry↗

PubMed1995

Longitudinal study on three-dimensional changes of facial asymmetry in children between 4 to 12 years of age with unilateral cleft lip and palate.

The purpose of the present study was to describe three-dimensional developmental changes of facial asymmetry in children with an operated complete unilateral cleft lip and palate (UCLP) and in children without craniofacial anomalies (controls). Using stereophotogrammetry, three-dimensional coordinates for 16 bilateral and 10 midsagittal facial landmarks were determined for the UCLP group (n = 33) and the control group (n = 63) on two occasions. In this mixed-longitudinal study, the children were 4 to 12 years of age. Facial asymmetry and left-right dominance was measured and resolved for transverse, vertical, and sagittal components. Significant effects were analyzed with multivariate analyses of variance (MANOVA). We concluded that individuals with complete unilateral cleft lip and palate, as well as individuals without craniofacial anomalies, show an increase, during growth, in the amount of facial asymmetry in the basal region of the nose. In the region that is related to the cleft, children with complete unilateral cleft lip and palate do not show changes in the amount of facial asymmetry between the occasions. Regarding facial left-right dominance and variation in dominance, no demonstrable growth changes take place in individuals with complete cleft lip and palate, nor in individuals without craniofacial anomalies.

Case-Control Studies↗

PubMed1996

Three-dimensional comparison between the palatal forms in infants with complete unilateral cleft lip, alveolus, and palate (UCLP) with and without Hotz's plate.

A three-dimensional measuring system was developed to analyze changes in palatal forms of UCLP infants. This system quantified the change of the curved surface on a palate by automatically superimposing two wireframe models obtained from casts at different stages of growth. It also analyzed the curvature of the palatal surface. This system was used to study the palates of 20 infants with unilateral cleft lip and palate (UCLP), from the first to fourth months after birth (12 with Hotz's plate and 8 without, selected at random). Both major and lesser maxillary segments without Hotz's plate remained anterior and lateral although those with Hotz's plate moved mesially during the fourth month after birth. In addition, the degrees of curvature on the palatal surfaces with Hotz's plate were less than those without Hotz's plate.

Analog-Digital Conversion↗

PubMed1997

Craniofacial morphology of conotruncal anomaly face syndrome.

OBJECTIVE AND DESIGN: The conotruncal anomaly face syndrome (CTAF) comprises congenital heart disease and dysmorphic face, and is frequently associated with cleft palate or hypernasality. There have been many discussions about the overlap with velocardiofacial syndrome (VCF). The aim of this study was to clarify the craniofacial characteristics of CTAF patients by clinical examination, and photogrammetric and cephalometric analyses, and to clarify the differences compared to published data on VCF. RESULTS: The facial features of CTAF included hypertelorism, small palpebral fissures, upward slanting of palpebral fissures, bloated eye lids, low nasal bridge, small mouth, open mouth at rest, and malformed auricles. Cephalometric features included bialveolar protrusion, small gonial angle, backward rotation of the mandibular ramus, and labial inclination of the maxillary incisors. An acute cranial base angle was also noted. These results differed from those of VCF. There were, however, no obvious pathognomonic findings for the differential diagnosis between CTAF and VCF. CONCLUSIONS: Considering these findings, use of CATCH 22, the inclusive classification of cardiac anomalies, cleft palate, and dysmorphic face may be of value for the clinical understanding in these patients.

Alveolar Process↗

PubMed1999

Mandibulofacial dysostosis--variability in facial morphology and growth: a long-term profile roentgenographic and roentgen stereometric analysis of three patients.

OBJECTIVE: To monitor and compare facial morphology and growth in three individuals with variable expression of mandibulofacial dysostosis (MFD) in terms of changes in the skeletal profile and in terms of growth in the circummaxillary sutures and temporomandibular joints (TMJs). DESIGN: Retrospective conventional profile roentgenography (mean age 9 to 18 years) and prospective roentgen stereometric analysis (RSA) (mean age 7 to 17 years). SETTING: Center for Craniofacial Anomalies and Department of Plastic and Reconstructive Surgery, Malmö University Hospital, Sweden. PATIENTS: The first three MFD patients seen by one of the authors (B.R.). INTERVENTIONS: Surgery was performed at the Department of Plastic and Reconstructive Surgery. Implants were inserted at surgery under general anesthesia. Roentgen examinations were performed in connection with continued clinical evaluations and treatment. MAIN OUTCOME MEASURES: All profile roentgenograms were traced and measured by one of the authors (K.-V.S.) using a conventional point-based analysis. RESULTS: The more afflicted patient showed a greater total difference in profile morphology and growth from the norm and more pronounced effects of articular growth restriction. Little change in the skeletal profile was associated with considerable displacement of the jaws. CONCLUSIONS: The variability in MFD expression and surgical procedures in our patients is reflected less in the skeletal profile morphology and growth and more in the displacement of the jaws.

Adolescent↗

PubMed2000

Facial growth in a cleft palate patient treated with the Herbst appliance: a long-term profile roentgenographic and roentgen stereometric analysis of profile changes and displacement of the jaws.

OBJECTIVE: To monitor facial development in a patient with cleft palate who was treated with the Herbst appliance. Monitoring was in terms of changes in the skeletal profile and growth in the circummaxillary sutures and temporomandibular joints (TMJs). DESIGN: Prospective profile roentgenography (between the ages of 6 and 20 years) and roentgen stereometric analysis (between the ages of 8 and 19 years). SETTING: Center for Craniofacial Anomalies and Department of Plastic and Reconstructive Surgery, Malmö University Hospital, Malmö, Sweden. PATIENT: Boy with cleft of the soft and posterior part of the hard palate and marked facial convexity. INTERVENTIONS: Surgical repair of the soft palate at age 9 months, velopharyngeal flap at age 8 years, and insertion of implants under general anesthesia and treatment with the Herbst appliance at age 11 years. Roentgen examinations were performed in connection with continued clinical evaluations and treatment. MAIN OUTCOME MEASURES: Profile roentgenograms were traced and measured by one of the authors using conventional point-based analysis. Stereo roentgenograms were digitized by the Department of Orthopedic Surgery, Malmö University Hospital. RESULTS: The direction of profile changes was partly discordant with the direction of articular growth in the circummaxillary sutures and TMJs. The successful treatment result was accomplished by a temporary influence on sagittal growth direction in the circummaxillary sutures and on rotational growth direction in the TMJs, combined with a favorable natural remodeling and articular growth pattern. CONCLUSIONS: The mode of growth by which treatment aims were reached was partly unexpected, i.e., discordant with the generally accepted principal concept that treatment with the Herbst appliance positions the mandible forward.

Adolescent↗

PubMed2001

Displacement of the mandible in a child with congenital unilateral temporomandibular joint ankylosis treated with two-stage condylar replacement: a long-term study with the aid of roentgen stereometric analysis.

OBJECTIVE: To monitor mandibular displacement in three dimensions with a high degree of accuracy before, during, and after treatment. DESIGN: Prospective roentgen stereometric analysis from age 3 years 7 months to age 13 years 8 months. SETTING: Center for Craniofacial Anomalies and Department of Maxillofacial Surgery, Malmö University Hospital, Malmö, Sweden. PATIENT: Girl with unilateral congenital temporomandibular joint (TMJ) ankylosis and marked facial asymmetry. INTERVENTIONS: Epipharyngeal inspection at age 2 years 6 months and insertion of implants under general anesthesia. Resection of the affected right condyle at age 5 years 4 months, replacement of the ramus-condyle complex with a custom made titanium prosthesis at age 5 years 5 months, and replacement of the artificial condyle by a costochondral graft at age 9 years 7 months. Roentgen examinations were performed at intervals from age 3 years 7 months to age 13 years 8 months. Body length was measured annually. MAIN OUTCOME MEASURES: Stereo roentgenograms were digitized by the Department of Orthopedic Surgery, Malmö University Hospital. RESULTS: Unexpected lowering of the mandible occurred before treatment. Each procedure had a distinct effect on the direction of mandibular displacement. There was little or no pathological involvement of the functional matrix. Growth of the costochondral graft exceeded growth of the unaffected TMJ. Anterior displacement as well as rotation and tilting of the mandible to the unaffected side accelerated after the age of body peak height velocity. CONCLUSIONS: Accurate monitoring of mandibular displacement may contribute to a rationale for clinicians' decision on treatment protocol and reveal compensatory differential growth.

Adolescent↗

PubMed2002

Photogrammetric assessment of the soft tissue profile in unilateral cleft lip and palate.

OBJECTIVE: To describe the soft tissue profile of children with unilateral cleft lip and palate from profile photographs and assess the reliability of this method. DESIGN: Retrospective analysis of prospectively collected data. SETTING: A national study in the United Kingdom. SUBJECTS: Caucasian children born in the United Kingdom between April 1, 1982, and March 31, 1984, and aged between 12 and 14 years at data collection. A cleft side and noncleft side profile photograph was available for each of 175 children. METHOD: Seven angular measurements were made using Dentofacial Planner Plus software, and the profile appearance was rated by an expert panel. RESULTS: Reliability for repeated measurement of the same photograph was acceptable for all but li-sm(s)-pg(s) (labiomental fold). Similar levels of reliability were found when comparing measurements from the cleft side and non-cleft side photograph. Logistic regression showed that the variables nst-sn-ls (nasolabial angle), ss(s)-n(s)-pg(s) (maxillary prominence), and g(s)-prn-pg(s) (facial convexity) were associated with the profile score. CONCLUSIONS: Soft tissue profile analysis from photographs is reliable and robust under a range of conditions. Soft tissue profile measurements are associated with panel ratings of profile.

Adolescent↗

PubMed2003

Are facial expressions reproducible?

OBJECTIVES: To determine the extent of reproducibility of five facial expressions. DESIGN: Thirty healthy Caucasian volunteers (15 males, 15 females) aged 21 to 30 years had 20 landmarks highlighted on the face with a fine eyeliner pencil. Subjects were asked to perform a sequence of five facial expressions that were captured by a three-dimensional camera system. Each expression was repeated after 15 minutes to investigate intrasession expression reproducibility. To investigate intersession expression reproducibility, each subject returned 2 weeks after the first session. A single operator identified 3-dimensional coordinate values of each landmark. A partial ordinary procrustes analysis was used to adjust for differences in head posture between similar expressions. Statistical analysis was undertaken using analysis of variance (linear mixed effects model). RESULTS: Intrasession expression reproducibility was least between cheek puffs (1.12 mm) and greatest between rest positions (0.74 mm). The reproducibility of individual landmarks was expression specific. Except for the lip purse, the reproducibility of facial expressions was not statistically different within each of the two sessions. Rest position was most reproducible, followed by lip purse, maximal smile, natural smile, and cheek puff. Subjects did not perform expressions with the same degree of symmetry on each occasion. Female subjects demonstrated significantly better reproducibility with regard to the maximal smile than males (p =.036). CONCLUSIONS: Under standardized conditions, intrasession expression reproducibility was high. Variation in expression reproducibility between sessions was minimal. The extent of reproducibility is expression specific. Differences in expression reproducibility exist between males and females.

Adult↗

PubMed2003

A quantitative three-dimensional assessment of abnormal variations in facial soft tissues of adult patients with cleft lip and palate.

OBJECTIVE: To supply quantitative information about the facial soft tissues of adult operated patients with cleft lip and palate (CLP). DESIGN, SETTING, AND PATIENTS: The three-dimensional coordinates of soft tissue facial landmarks were obtained using an electromagnetic digitizer in 18 Caucasian patients with CLP (11 males and 7 females aged 19 to 27 years) and 162 healthy controls (73 females and 89 males aged 18 to 30 years). From the landmarks, 15 facial dimensions and two angles were calculated. Data were compared with those collected in healthy individuals by computing z-scores. Two summary anthropometric measurements for quantifying craniofacial variations were assessed in both the patients and reference subjects: the mean z-score (an index of overall facial size), and its SD, called the craniofacial variability index (an index of facial harmony). RESULTS: In treated patients with CLP, facial size was somewhat smaller than in normal individuals, but in all occasions the mean z-score fell inside the normal interval (mean +/- 2 SD). Almost all patients had a craniofacial variability index larger than the normal interval, indicating a global disharmonious appearance. Overall, in patients pronasale, subnasale, and pogonion were more posterior, the nose was shorter and larger, the face was narrower, and the soft tissue profile and upper lip were flatter than in the reference population. CONCLUSIONS: The facial soft tissue structures of adult operated patients with CLP differed from those of normal controls of the same age, sex, and ethnic group. In this patient group, surgical corrections of CLP failed to provide a completely harmonious appearance, even if the deviations from the reference were limited. Further analyses of larger groups of patients are needed.

Adult↗

PubMed2004

A matching algorithm based on hybrid matrices consisting of reference differences and disparities.

Unique correct correspondence cannot be obtained only by use of gray correlation technique, which describes gray similar degree of feature points between the left and right images too unilaterally. The gray correlation technique is adopted to extract gray correlation peaks as a coarse matching set called multi-peak set. The disparity gradient limited constraint is utilized to optimize the multi-peak set. Unique match will be obtained by calculating the correlation of hybrid matrices consisting of reference differences and disparities from the multi-peak set. Two of the known corresponding points in the left and right images, respectively, are set as a pair of reference points to determine search direction and search scope at first. After the unique correspondence is obtained by calculating the correlation of the hybrid matrices from the multi-peak set, the obtained match is regarded as a new reference point till all feature points in the left (or right) image have been processed. Experimental results proved that the proposed algorithm was feasible and accurate.

Algorithms↗