Tinashe Mutsvangwa

Morphometric analysis of facial landmark data to characterize the facial phenotype associated with fetal alcohol syndrome

Procrustes analysis and principal component analysis were applied to stereo‐photogrammetrically obtained landmarks to compare the facial features associated with fetal alcohol syndrome (FAS) in subjects with FAS and normal controls. Two studies were performed; both compared facial landmark data of FAS and normal subjects, but they differed in the number of landmarks chosen. The first study compared landmarks representing palpebral fissure length, upper lip thinness and philtrum smoothness and revealed no significant difference in shape. The second study added to the landmarks used in the first those affected by mid‐face hypoplasia, and revealed significant differences in shape between the two groups, broadly confirming the FAS gestalt reported in the literature. Some disagreement in the characteristic FAS facial shape between our results and those reported in the literature may be due to ethnic variation.

A review of facial image analysis for delineation of the facial phenotype associated with fetal alcohol syndrome

The facial anomalies associated with fetal alcohol syndrome (FAS), some of which are also present in individuals with less severe forms of the broader category of fetal alcohol spectrum disorders (FASD), are typically identified with the aid of linear distance measurements taken between facial landmarks. Digital facial imaging methods are increasingly being used in syndrome delineation. Distance measurements derived from stereo‐photogrammetry and facial surface imaging have been used to study the FAS facial anomalies. Geometric morphometric methods capture the spatial arrangement between landmarks, providing a statistical platform for comparison of facial shapes, and have been shown to hold promise for characterizing the FAS facial shape. We review the progression in the use of imaging and image analysis methods in studies on the facial phenotype associated with FAS.

Morphometric analysis and classification of the facial phenotype associated with fetal alcohol syndrome in 5- and 12-year-old children†

Landmark‐based morphometric analysis holds promise for quantitative assessment of craniofacial dysmorphology. We describe an application of facial shape analysis to characterize the facial anomalies associated with fetal alcohol syndrome (FAS) in a mixed ancestry population. Generalized Procrustes analysis, regression and discriminant function analysis were applied to stereo‐photogrammetrically derived 3D coordinates of landmarks taken from 34 subjects (nu2009=u200917 FAS and nu2009=u200917 normal controls). Four shape analyses were carried out, namely a comparison of the FAS and control facial shapes at age 5, and one at age 12; a comparison of the FAS facial shapes at ages 5 and 12; and a comparison of control facial shapes at ages 5 and 12. The first two analyses showed that the FAS face is characterized by small palpebral fissures, a thin upper lip, and midfacial hypoplasia. Classification of subjects as having FAS using leave‐one‐out cross‐validation showed that the 5‐year‐old group could be classified with 95.46% accuracy and the 12‐year‐olds with 80.13% accuracy. The third and fourth analyses revealed that the differences in facial shape between FAS individuals in different age groups were more pronounced than for control individuals, supporting the notion that FAS facial anomalies diminish with age. Geometric morphometric analysis of stereo‐photogrammetrically derived 3D facial landmarks allows visualization of the facial anomalies associated with FAS, as well as classification of facial shapes.

Design, Construction, and Testing of a Stereo-Photogrammetric Tool for the Diagnosis of Fetal Alcohol Syndrome in Infants

Stereo-photogrammetry provides a low cost, easy to use, and noninvasive alternative to traditional facial anthropometry for the diagnosis of fetal alcohol syndrome (FAS). We describe such a system for use in obtaining 3-D facial information in infants. The infant is photographed using three high resolution digital cameras simultaneously while seated in a car seat. The subjects head is enclosed in a control frame during imaging. Technical system tests, namely control frame interpolation, camera calibration reliability, and camera synchronization delay assessments were performed. Direct and stereo-photogrammetric measurements of a doll were compared. Of 275 inter-landmark distances, 100% were within a 1.5 mm error range and 92.36% within a 1 mm error range when the two modalities were compared. Stereo-photogrammetry proved to be highly precise with submillimeter error in landmark placement for all landmarks on the doll. An intra-modality comparison of inter-landmark distances using two sets of images of five subjects showed the stereo-photogrammetric system to be highly reliable, with an average 72.25% of distances within a 1 mm error range. The system has potential for large scale screening and surveillance studies for FAS.

Precision assessment of stereo-photogrammetrically derived facial landmarks in infants

BACKGROUNDnIn order to examine the suitability of an anthropometric imaging device for a particular study population, it is necessary to assess measurement error on members of the population.nnnAIMnWe provide an analysis of the precision of a stereo-photogrammetric tool in locating 3D landmark coordinates on images of infants and present the results in a way that facilitates direct comparison with some of the precision results found in the literature.nnnSUBJECTS AND METHODSnIntra- and inter-observer precision are examined for 26 landmarks on 21 infants. Mean absolute differences for landmark coordinates and linear distances, mean landmark coordinate errors, and relative errors of magnitude are calculated.nnnRESULTSnRelative error of magnitude is less than 4% for the majority of intra- and inter-observer inter-landmark distance comparisons. Landmarks lying on the midline of the face and on smooth regions with gentle curvature, in particular the sellion, glabella and nasion, have relatively low precision.nnnCONCLUSIONnOur precision values compare well with those reported in published studies on landmark location in 3D surface images.

Anatomic variations in glenohumeral joint: an interpopulation study

Background This study focused on the unique aspect of investigating shoulder morphometric differences between 2 distinct populations. Methods We used 90 computed tomography images of cadaveric shoulders for this study; 45 scans belonged to the South African (SA) cohort (49.74u2009±u200915.4 years) and the rest were Swiss (CH; 53.8u2009±u200921 years). The articulating surfaces of the glenohumeral joint were extracted, and their morphometric features, such as head circular diameter, glenoid and humeral head radius of curvature, head height, and humeral height, were measured. Results The mean interpopulation difference in the circular diameter of the humerus was 2.0u2009mm (Pu2009=u2009.017) and 1.86u2009mm (Pu2009>u2009.05) in the anterior-posterior and superior-inferior directions, respectively. The difference in the radius of curvature between the populations was 1.17u2009mm (Pu2009=u2009.037). The SA shoulders were found to be longer than the CH shoulders by 8.4u2009mm (Pu2009>u2009.05). There was no significant difference in the glenoid radius of curvature. The SA shoulders had higher glenohumeral mismatch (Pu2009=u2009.005) and lower conformity index (Pu2009=u2009.001) in comparison to the CH shoulders. Conclusion This study presents anatomic differences between African and European glenohumeral articulating surfaces. The results suggest that the glenohumeral geometry is both gender and population specific, and future joint replacements may be designed to address these differences.

A modified stakeholder participation assessment framework for design thinking in health innovation

Increasing pressure to improve health outcomes of populations with limited resources has prompted an emphasis on innovation. Design thinking has been proposed as a systematic approach to innovation in health, owing to its human-centred methodology that prioritises deep empathy for the end-users desires, needs and challenges, which results in a better understanding of the problem in order to develop more comprehensive and effective solutions. A key feature of design thinking is stakeholder participation. If design thinking is going to be used as an approach to design and implement effective, equitable and sustainable health solutions, assessing stakeholder participation should be integrated into the process. Therefore, the purpose of this review is to i) provide an analysis of the literature on assessing stakeholder participation in health and ii) propose a framework based on the literature analysis that can be used to assess stakeholder participation during the design thinking process in health innovation. Drawing from participatory research in health, where stakeholder participation is recognised as a core principle that facilitates the implementation of solutions, we integrate stakeholder evaluation tools into the design thinking approach. We draw on an assessment framework that describes levels of stakeholder participation by their involvement in making decisions about their health. Using a 5-point continuum where the lower end represents the medical approach (professionals make all the decisions) and the upper end represents the community development approach (all stakeholders are key decision makers), we propose a modified assessment framework to evaluate stakeholder participation during the design thinking process. The modified framework provides a simple and practical tool to evaluate stakeholder participation. Stakeholders can rate their perceived level of participation, as well as that of the other stakeholders. Evaluation of participation in a design thinking project may be used to improve participation, and therefore the uptake and sustainability of innovations. The framework may also be used in design thinking beyond health applications.

Mobile phone-based evaluation of latent tuberculosis infection: Proof of concept for an integrated image capture and analysis system

BACKGROUNDnThe tuberculin skin test is the most widely used method for detecting latent tuberculosis infection in adults and active tuberculosis in children. We present the development of a mobile-phone based screening tool for measuring the tuberculin skin test induration.nnnMETHODnThe tool makes use of a mobile application developed on the Android platform to capture images of an induration, and photogrammetric reconstruction using Agisoft PhotoScan to reconstruct the induration in 3D, followed by 3D measurement of the induration with the aid of functions from the Python programming language. The system enables capture of images by the person being screened for latent tuberculosis infection. Measurement precision was tested using a 3D printed induration. Real-world use of the tool was simulated by application to a set of mock skin indurations, created by a make-up artist, and the performance of the tool was evaluated. The usability of the application was assessed with the aid of a questionnaire completed by participants.nnnRESULTSnThe tool was found to measure the 3D printed induration with greater precision than the current ruler and pen method, as indicated by the lower standard deviation produced (0.3u202fmm versus 1.1u202fmm in the literature). There was high correlation between manual and algorithm measurement of mock skin indurations. The height of the skin induration and the definition of its margins were found to influence the accuracy of 3D reconstruction and therefore the measurement error, under simulated real-world conditions. Based on assessment of the user experience in capturing images, a simplified user interface would benefit wide-spread implementation.nnnCONCLUSIONSnThe mobile application shows good agreement with direct measurement. It provides an alternative method for measuring tuberculin skin test indurations and may remove the need for an in-person follow-up visit after test administration, thus improving latent tuberculosis infection screening throughput.

A statistical shape model of the skull developed from a South African population

This paper discusses the development of a statistical shape model (SSM) of the skull from a South African population. A total of 16 skulls is used together with a reference from the Basel Face Model. A free-form deformation model is built using the reference model and the squared exponential kernel. The freeform model is used to establish dense correspondence across the skull sample and the in-correspondence skulls are then used to build an SSM. The validity of the SSM is assessed using leave-one-out cross-validation with its generality ranging between 1.47 mm and 1.84 mm and, the specificity ranging between 1.74 mm and 2.11 mm.