Stereophotogrammetric head shape assessment in neonates is feasible and can identify distinct differences between term-born and very preterm infants at term equivalent age.

The development of head shape and volume may reflect neurodevelopmental outcome and therefore is of paramount importance in neonatal care. Here, we compare head morphology in 25 very preterm infants with a birth weight of below 1500 g and / or a gestational age (GA) before 32 completed weeks to 25 term infants with a GA of 37-42 weeks at term equivalent age (TEA) and identify possible risk factors for non-synostotic head shape deformities. For three-dimensional head assessments, a portable stereophotogrammetric device was used. The most common and distinct head shape deformity in preterm infants was dolichocephaly. Severity of dolichocephaly correlated with GA and body weight at TEA but not with other factors such as neonatal morbidity, sex or total duration of respiratory support. Head circumference (HC) and cranial volume (CV) were not significantly different between the preterm and term infant group. Digitally measured HC and the CV significantly correlated even in infants with head shape deformities. Our study shows that stereophotogrammetric head assessment is feasible in all preterm and term infants and provides valuable information on volumetry and comprehensive head shape characteristics. In a small sample of preterm infants, body weight at TEA was identified as a specific risk factor for the development of dolichocephaly.

Scientific validation of three-dimensional stereophotogrammetry compared to the IGAIS clinical scale for assessing wrinkles and scars after laser treatment.

Measuring outcomes from treatments to the skin is either reliant upon patient's subjective feedback or scale-based peer assessments. Three-Dimensional stereophotogrammetry intend to accurately quantify skin microtopography before and after treatments. The objective of this study is comparing the accuracy of stereophotogrammetry with a scale-based peer evaluation in assessing topographical changes to skin surface following laser treatment. A 3D stereophotogrammetry system photographed skin surface of 48 patients with facial wrinkles or scars before and three months after laser resurfacing, followed immediately by topical application of vitamin C. The software measured changes in skin roughness, wrinkle depth and scar volume. Images were presented to three observers, each independently scoring cutaneous improvement according to Investigator Global Aesthetic Improvement Scale (IGAIS). As for the results, a trend reflecting skin/scar improvement was reported by 3D SPM measurements and raters. The percentage of topographical change given by the raters matched 3D SPM findings. Agreement was highest when observers analysed 3D images. However, observers overestimated skin improvement in a nontreatment control whilst 3D SPM was precise in detecting absence of intervention. This study confirmed a direct correlation between the IGAIS clinical scale and 3D SPM and confirmed the efficacy and accuracy of the latter when assessing cutaneous microtopography alterations as a response to laser treatment.

Evaluation of a Novel Three-Dimensional Wound Measurement Device for Assessment of Diabetic Foot Ulcers.

Objective: The initial wound measurement and regular monitoring of diabetic foot ulcers (DFU) is critical to assess treatment response. There is no standardized, universally accepted, quick, reliable, and quantitative assessment method to characterize DFU. To address this need, a novel topographic imaging system has been developed. Our study aims at assessing the reliability and practicality of the WoundVue® camera technology in the assessment of DFU. Approach: The WoundVue system is a prototype device. It consists of two infrared cameras and an infrared projector, and it is able to produce a three-dimensional (3D) reconstruction of the wound structure. Fifty-seven diabetic foot wounds from patients seen in a multidisciplinary foot clinic were photographed from two different angles and distances by using the WoundVue camera. Wound area, volume, and maximum depth were measured for assessment of reliability. Thirty-one of these wounds also had area calculated by using the established Visitrak™ system, and a correlation between the area obtained by using both systems was assessed. Results: WoundVue images analysis showed excellent agreement for area (intraclass correlation coefficient [ICC]: 0.995), volume (ICC: 0.988), and maximum depth (ICC: 0.984). Good agreement was found for area measurement by using the WoundVue camera and Visitrak system (ICC: 0.842). The average percentage differences between measures obtained by using the WoundVue from different angles for assessment of different sizes and shapes of wounds were 2.9% (95% confidence interval [CI]: 0.3-5.4), 12.9% (95% CI: 9.6-35.7), and 6.2% (95% CI: 2.3-14.7) for area, maximum depth, and volume, respectively. Innovation: This is the first human trial evaluating this novel 3D wound measurement device. Conclusion: The WoundVue system is capable of recreating a 3D model of DFU and produces consistent data. Digital images are ideal for monitoring wounds over time, and the WoundVue camera has the potential to be a valuable adjunct in diabetic foot wound care.

Thoracoabdominal mobility evaluation of asthmatic patients in physiotherapy practice: Intra-rater reliability.

BACKGROUND: The evaluation of thoracoabdominal mobility is a tool extensively used in the physiotherapy practice in different populations. Photogrammetry may be a simple tool to analyse thoracoabdominal mobility; however, it is unclear whether this assessment can be a reliable method. AIM: To test the reliability intra-examinator by photogrammetry in asthmatic patients and in health controls. METHODS: Twenty-six asthmatic patients (29 ± 9 years) and 14 healthy matched controls (27 ± 8 years) were assessed by thoracoabdominal mobility. Photographs during rest, during inspiration and expiration maximum were used to calculate latero-lateral and antero-posterior diameters of the thorax (at axillary and xiphoid levels) and umbilical by markers positioned in osseous structures. An evaluator obtained the same measurements in an 8-day interval. RESULTS: We found a moderate reliability for axillary, xiphoid and umbilical mobility (average intraclass correlation coefficient [ICC] respectively [0.68, 0.55 and 0.73]) for asthmatic group. In addition, for control group, we found a moderate reliability for axillary mobility (average ICC respectively [0.68] and a good reliability for xiphoid and umbilical mobility) (average ICC 0.81 and 0.70). Bland-Altman plots showed goods limit of agreement in photos 1 and 2 in both groups. CONCLUSION: The photogrammetric analysis of thoracoabdominal mobility presented itself as a reliable method and may be used in clinical practice in asthmatic patients and in controls.

A Simple Standardized Three-Dimensional Anthropometry for the Periocular Region in a European Population.

BACKGROUND: The three-dimensional surface imaging system is becoming more common in plastic surgeries. However, few studies have assessed three-dimensional periocular structures and surgical outcomes. This study aimed to propose a standardized three-dimensional anthropometric protocol for the periocular region, investigate its precision and accuracy, and determine the three-dimensional periocular anthropometric norms for young Caucasians. METHODS: Thirty-nine healthy young Caucasians (78 eyes) were enrolled. Three-dimensional facial images were obtained with a VECTRA M3 stereophotogrammetry device. Thirty-eight measurements in periocular regions were obtained from these images. Every subject underwent facial surface capture twice to evaluate its precision. A paper ruler was applied to assess its accuracy. RESULTS: Sixty-three percent of measurements in linear distances, curvatures, angles, and indices were found to reach a statistically significant difference between sexes (p ≤ 0.05, respectively). Across all measurements, the average mean absolute difference was 0.29 mm in linear dimensions, 0.56 mm in curvatures, 1.67 degrees in angles, and 0.02 in indices. In relative error of magnitude, 18 percent of the measurements were determined excellent, 51 percent very good, 31 percent good, and none moderate. The mean value of the paper-ruler scale was 10.01 ± 0.05 mm, the mean absolute difference value 0.02 mm, and the relative error of magnitude 0.17 percent. CONCLUSIONS: This is the first study to propose a detailed and standardized three-dimensional anthropometric protocol for the periocular region and confirm its high precision and accuracy. The results provided novel metric data concerning young Caucasian periocular anthropometry and determined the variability between sexes.

Comparison of Three Gaze-position Calibration Techniques in First Purkinje Image-based Eye Trackers.

SIGNIFICANCE: This study highlights potential differences that can arise in gaze-position estimates from first Purkinje image-based eye trackers based on how individual Hirschberg ratios (HRs) are calculated. PURPOSE: The purpose of this study was to evaluate the accuracy and repeatability of eccentric-viewing, prism-based, and theoretical techniques that are routinely used to calibrate HR in first Purkinje image-based eye trackers. METHODS: Hirschberg ratios of 28 participants (18 to 40 years old) were obtained using the PlusOptix PowerRef 3 photorefractor and eye tracker. In the gold standard eccentric-viewing technique, participants viewed eccentric targets (±12°, 4° steps) at 2 m. In the prism-based technique, 4 to 16Δ-D base-out and base-in prisms were placed in 4Δ-D steps before an eye occluded with an infrared filter; the fellow eye fixated a target at 1 m. Each participant's HR was calculated as the slope of the linear regression of the shift in Purkinje image relative to the pupil center for each target eccentricity or induced prism power. Theoretical HR was calculated from the participant's corneal curvature and anterior chamber depth measures. Data collection was repeated on another visit using all three techniques to assess repeatability. Data were also obtained from an Indian cohort (n = 30, 18 to 40 years old) using similar protocols. RESULTS: Hirschberg ratio ranged from 10.61 to 14.63°/mm (median, 11.90°/mm) in the eccentric-viewing technique. The prism-based and theoretical techniques demonstrated inaccuracies of 12 and 4% relative to the eccentric-viewing technique. The 95% limits of agreement of intrasubject variability were ±2.00, ±0.40, and ±0.30°/mm for the prism-based, eccentric-viewing, and theoretical techniques, respectively (P > .05). Intraclass correlation coefficients (95% confidence interval) were 0.99 (0.98 to 1.00) for eccentric, 0.99 (0.99 to 1.00) for theoretical, and 0.88 (0.74 to 0.94) for prism-based techniques. Similar results were found for the Indian cohort. CONCLUSIONS: The prism-based and theoretical techniques both demonstrated relative inaccuracies in measures of HR compared with the eccentric-viewing technique. The prism-based technique exhibited the poorest repeatability.

Accuracy of photogrammetry for detecting adolescent idiopathic scoliosis progression.

BACKGROUND: The gold standard method of monitoring the evolution of scoliosis has been serial standing, posteroanterior, full-length spine radiographs with curvature measurements using the Cobb method. However, over the course of follow-up, patients can receive high radiation doses. Various studies have shown that repeated exposure to radiation in children and adolescents can be harmful to their health. PURPOSE: To determine the accuracy of photogrammetry in evaluating the progression of adolescent idiopathic scoliosis in comparison with radiography. STUDY DESIGN: Diagnostic study. PATIENT SAMPLE: Ninety adolescents subjected to radiographic follow-up of idiopathic scoliosis. OUTCOME MEASURES: The angle of scoliotic curvature was measured using the Cobb radiographic method and photogrammetry. An increase of 5° or more between two radiographic exams was considered a progression of the curvature and was defined as the standard for calculations of sensitivity, specificity, predictive value, and accuracy of the photogrammetric method for measuring scoliosis progression. METHODS: Patients were subjected to radiographic and photogrammetric exams concomitantly and were reevaluated after an average of 8.6 months. The exams were analyzed separately and independently by two examiners for progression of scoliosis. RESULTS: The measurements of the curves at the beginning of the study were 39.5±16.7° and 39.5±14.3° for radiographic and photogrammetric exams, respectively (p=1.0). At the end of the study, the measurements of the curves were 40.2±16.2° and 41.3±15.1° for the radiographic and photogrammetric exams, respectively (p=.310). The photogrammetric method had an accuracy of 89% (Confidence interval [CI] 95%=82.5-95.5) for the detection of scoliosis progression, with a sensitivity of 94.4% (CI 95%=89.6-99.2), a specificity of 86.7% (CI 95%=79.7-93.7), a positive predictive value of 75.5% (CI 95%=66.6-84.4), a negative predictive value of 97.2% (CI 95%=93.8-100), and a Kappa index of 0.75 (CI 95%=66.1-83.9). The interclass correlation coefficient between the two methods was 0.74 (CI 95%=0.65-0.81; p=0). CONCLUSIONS: The photogrammetric method showed good performance for detecting the progression of adolescent idiopathic scoliosis in comparison with the radiographic exam method.

Is rasterstereography a valid noninvasive method for the screening of juvenile and adolescent idiopathic scoliosis?

PURPOSE: Aim of the study was to verify the accuracy of rasterstereography (RST), as radiation-free alternative to plain radiography (RAD) in the monitoring of spine deformity and scoliosis progression in juvenile and adolescent subjects with idiopathic scoliosis. METHODS: 192 subjects underwent RST (by Formetric 4D device) and low-dose RAD (EOS Imaging, France) in the same session. A sub-group of 30 subjects, selected for conservative treatment with corrective bracing, was assessed at 6-months follow-up. The Cobb angles (CA) obtained by the 3D spine reconstruction from RAD were compared with those provided by RST. Thoracic kyphosis (TK) and lumbar lordosis (LL) were compared as well. RESULTS: RST provided lower CA compared to RAD (15° vs. 33°, mean values). The average difference in measuring CA was 18°, and the correlation coefficient was 0.55. Comparable TK was observed, whereas LL resulted underestimated by RST compared to RAD (34° vs. 43°, average values). The within-subjects correlation, measuring the accuracy of RST in monitoring the scoliosis progression, was 0.3. Accuracy of RST in identifying increased or decreased CA was 67%. Sensitivity and specificity were 64% and 69%. CONCLUSIONS: RST demonstrated moderate accuracy in measuring the scoliosis degree and low accuracy in monitoring the curve progression. Accordingly, it cannot be considered as a valid alternative to radiographic evaluation. However, since demonstrated capable of revealing the presence of spine deformity, it could be in principle considered for the early screening in large adolescent populations, but after accounting for a cost-benefit analysis with respect to other traditional approaches. These slides can be retrieved under Electronic Supplementary Material.

Radiation-free measurement tools to evaluate sagittal parameters in AIS patients: a reliability and validity study.

PURPOSE: This study aimed to evaluate the intra-rater reliability and validity in comparison with the two-dimensional radiography (XR) of inclinometer (INCL) and rasterstereography (RAST) for assessing spinal sagittal angles of AIS patients. METHODS: Fifty-one AIS patients (13.5 (2.0) years, girls = 32 (63%), Cobb angle = 23.0 (17.4)°) were included in this study. Three repeated measurements of thoracic kyphosis (TK) and lumbar lordosis (LL) were evaluated using the INCL and RAST by the same operator on the same day of the XR examination. Intraclass correlation coefficients (ICC) were used to evaluate the reliability of the INCL and RAST systems. Additionally, Pearson coefficients were computed between the XR and INCL systems and between the XR and RAST systems. RESULTS: Reliability of each radiation-free system was excellent (ICC > 0.75 for INCL and RAST) for both the TK and LL parameters. The Pearson coefficients between each of the radiation-free systems and the XR were high to moderate for the TK (0.50 < RTK < 0.75 for INCL and RAST), high to moderate for the LL as measured with the RAST (0.50 < RLL < 0.75 for RAST) and low for the LL as measured with the INCL (RLL < 0.50 for INCL). CONCLUSION: This study demonstrated that for the RAST and INCL in AIS patients, there was (1) an excellent reliability for the TK and LL, (2) a high-to-moderate validity for measuring the TK and (3) a moderate and low validity for measuring the LL, respectively. These radiation-free systems could be used for the clinical follow-up of AIS patients for the evaluation of the TK. These slides can be retrieved under Electronic Supplementary Material.

Quantification of three-dimensional soft tissue artifacts in the canine hindlimb during passive stifle motion.

BACKGROUND: Three-dimensional joint kinematics during canine locomotion are commonly measured using skin marker-based stereophotogrammetry technologies. However, marker-related errors caused by the displacement of the skin surface relative to the underlying bones (i.e., soft tissue artifacts, STA) may affect the accuracy of the measurements and obscure clinically relevant information. Few studies have assessed STA in canine limbs during kinematic analysis. The magnitudes and patterns of the STA and their influence on kinematic analysis remain unclear. Therefore, the current study aims to quantify the in vivo STA of skin markers on the canine thigh and crus during passive joint motion. The stifle joints of ten dogs were passively extended while the skin markers were measured using a motion capture system, and skeletal kinematics were determined using a CT-to-fluoroscopic image registration method. RESULTS: The skin markers exhibited considerable STA relative to the underlying bones, with a peak amplitude of 27.4 mm for thigh markers and 28.7 mm for crus markers; however, the amplitudes and displacement directions at different attachment sites were inconsistent. The markers on the cranial thigh and lateral crus closer to the stifle joint had greater STA amplitudes in comparison to those of other markers. Most markers had STA with linear and quadratic patterns against the stifle flexion angles. These STA resulted in underestimated flexion angles but overestimated adduction and internal rotation when the stifle was flexed to greater than 90°. CONCLUSIONS: Marker displacements relative to the underlying bones were prominent in the cranial aspect of the thigh and the proximal-lateral aspect of the crus. The calculated stifle kinematic variables were also affected by the STA. These findings can provide a reference for marker selection in canine motion analysis for similar motion tasks and clarify the relationship between STA patterns and stifle kinematics; the results may therefore contribute to the development of STA models and compensation techniques for canine motion analysis.

Uso da estereofotogrametria para mensuração do volume da anatomia externa da face: revisão sistemática / Use of stereophotogrammetry for measuring the volume of external facial anatomy: a systematic review

Introdução: O registro fotográfico tem sido importante para diversas especialidades médicas como a Cirurgia Plástica. A fotografia em duas dimensões apresenta limitações para capturar profundidade e volume de estruturas outros instrumentos para avaliar essa alteração. Diversas tecnologias foram desenvolvidas para analisar objeto em três dimensões, sendo a estereofotogrametria uma tecnologia que utiliza a análise computadorizada de duas ou mais fotografias simultâneas do objeto para produzir um modelo geométrico em três dimensões. As vantagens da estereofotogrametria incluem menor custo, portabilidade, ausência de radiação e rapidez da captura das imagens. O objetivo deste trabalho foi realizar uma revisão bibliográfica avaliando o uso e a acurácia da estereofotogrametria para mensuração de volume de estruturas na face. Métodos: Foi realizada pesquisa nos bancos de dados Cochrane Library e Medline até maio de 2018 utilizando uma combinação de descritores Mesh e termos livres. Resultados: Foram obtidos inicialmente 2213 estudos observando a estratégia de busca. Seguindo os critérios de elegibilidade, foram selecionados 27 artigos, sendo 21 relatos de casos não randomizados e 6 ensaios clínicos randomizados. A qualidade metodológica dos estudos variou de 50 a 67%, segundo uma pontuação que vai de 0 a 100%. Conclusões: A estereofotogrametria é uma tecnologia promissora e tem sido cada vez mais utilizada para verificar variações de volume na face com alta acurácia e reprodutibilidade. Faltam estudos com melhor qualidade metodológica avaliando a acurácia e o uso da estereofotogrametria na avaliação de volume facial.

Introduction: Photographic documentation is important in several medical specialties, such as plastic surgery. Two-dimensional photography has limitations in capturing structure depth and volume, requiring other instruments to evaluate these changes. Several technologies have been developed for three-dimensional analysis of objects, of which stereophotogrammetry uses computerized analysis of two or more simultaneous photographs of the object to produce a three-dimensional geometric model. The advantages of stereophotogrammetry include lower cost, portability, absence of radiation, and speed of image capture. The aim of the present study was to perform a bibliographic review evaluating the use and accuracy of stereophotogrammetry for measuring the volume of facial structures. Methods: Using a combination of MeSH keywords and free terms, a search was performed in the Cochrane Library and MEDLINE databases. The search included all articles published on or before May 2018. Results: 2,213 studies were initially retrieved using this search strategy. Of these, 27 studies were selected based on the eligibility criteria, of which 21 were non-randomized case studies and 6 were randomized clinical trials. The methodological quality of the studies varied between 50 and 67%, on a grading scale from 0 to 100%. Conclusions: Stereophotogrammetry is a promising technology that is increasingly being used to check for facial volume variations with high accuracy and reproducibility. More studies with higher methodological quality are needed for evaluating the accuracy and use of stereophotogrammetry for facial volume evaluations.

Validation of three-dimensional wound measurements using a novel 3D-WAM camera.

To monitor wound healing, it is essential to obtain accurate and reliable wound measurements. Various methods have been used to measure wound size including three-dimensional (3D) measurement devices enabling wound assessment from a volume perspective. However, the currently available methods are inaccurate, costly, or complicated to use. As a consequence, we have developed a 3D-wound assessment monitor (WAM) camera, which is able to measure wound size in three-dimension and to assess wound characteristics. The aim of the study was to assess the intrarater and interrater reliability of the 3D wound measurements using the 3D camera and to compare these with traditional measurement methods. Four raters measured 48 wounds using the 3D camera, digital imaging method (2D area), and gel injection into the wound cavity (volume). The data were analyzed using linear mixed effect model. Intraclass and interclass correlation coefficient (ICC) and Bland-Altman plots were used to assess intrarater and interrater reliability for the 3D camera and agreement between the methods. The Bland-Altman plots for intrarater reliability showed minor differences between the measurements, especially the 3D area and perimeter measurements. Moreover, ICCs were very high for both the intrarater and interrater reliability for the 2D area, 3D area, and perimeter measurements (ICCs > 0.99), although slightly lower for the volume measurements (ICC = 0.946-0.950). Finally, a high agreement was found between the 3D camera and the traditional methods (2D area and volume) assessed by narrow 95% prediction intervals and high ICCs above 0.97. In conclusion, the 3D-WAM camera is an accurate and reliable method, which is useful for several types of wounds. However, the volume measurements were primarily useful in large, deep wounds. Moreover, the 3D images are based on digital technology and therefore carry the possibility for use in remote settings.

Thoracic Kyphosis and Lumbar Lordosis Assessment by Radiography and Photogrammetry: A Review of Normative Values and Reliability.

OBJECTIVE: The purpose of this study was to review referential values for thoracic kyphosis and lumbar lordosis for radiography and photogrammetry analysis and search for information about the interrater and intrarater reliability. METHODS: The databases PubMed/Medline and LILACS were searched using the following keywords: radiograph and posture, postural alignment, and photogrammetry or photometry or biophotogrammetry. Studies containing values of thoracic kyphosis and lumbar lordosis or a reliability test assessed by radiography and photogrammetry were selected. Random numbers were generated in MATLAB from each study individually to establish normative values for the thoracic kyphosis and lumbar lordosis for both methods. After that, frequencies (median, first quartile, and third quartile) were obtained in SPSS 20.0 (IBM Corp, Armonk, New York). RESULTS: Twenty-six articles were selected, of which 23 studies contained values for thoracic kyphosis and lumbar lordosis and 10 tested the intra- and interrater reliability of both methods. For the studies with radiography that calculated the angle by the same method of assessment, the mean was 44.07° (4.75) for L1 to L5 and 58.01° (5.75) for L1 to S1, and for T1 to T12 the mean was 48.33° (6.24). Most studies used the intraclass correlation coefficient test, showing strong reliability. CONCLUSION: No concordance among the results for both methods was shown. Also, it was not possible to perform the same procedure with the photogrammetry studies because of the great discrepancy in procedures and angle calculations. To assess the reliability, it is necessary to use the proper statistical test.

Procedures of assessment on the quantification of thoracic kyphosis and lumbar lordosis by radiography and photogrammetry: A literature review.

The quantification of thoracic kyphosis and lumbar lordosis can be assessed in different ways; among them radiography and photogrammetry. However, the assessment procedures are not consistent in the literature for either method. The objective of this study was to conduct a literature review about postural assessment through radiography and photogrammetry, for delineating the procedures for both methods. In total 38 studies were selected by an online search in the MEDLINE and LILACS databases with the keywords: radiograph and posture, postural alignment, photogrammetry or photometry or biophotogrammetry. For the radiographic method, the results showed divergences in arm positioning and in the calculation of thoracic and lumbar angles. The photogrammetry demonstrated differences in relation to the camera, tripod, plumb line and feet positioning, angle calculation, software utilization, and the use of footwear. Standardization is proposed for both methods to help establish normative values and comparisons between diagnoses.

Assessment of statistical agreement of three techniques for the study of cut marks: 3D digital microscope, laser scanning confocal microscopy and micro-photogrammetry.

In the last few years, the study of cut marks on bone surfaces has become fundamental for the interpretation of prehistoric butchery practices. Due to the difficulties in the correct identification of cut marks, many criteria for their description and classification have been suggested. Different techniques, such as three-dimensional digital microscope (3D DM), laser scanning confocal microscopy (LSCM) and micro-photogrammetry (M-PG) have been recently applied to the study of cut marks. Although the 3D DM and LSCM microscopic techniques are the most commonly used for the 3D identification of cut marks, M-PG has also proved to be very efficient and a low-cost method. M-PG is a noninvasive technique that allows the study of the cortical surface without any previous preparation of the samples, and that generates high-resolution models. Despite the current application of microscopic and micro-photogrammetric techniques to taphonomy, their reliability has never been tested. In this paper, we compare 3D DM, LSCM and M-PG in order to assess their resolution and results. In this study, we analyse 26 experimental cut marks generated with a metal knife. The quantitative and qualitative information registered is analysed by means of standard multivariate statistics and geometric morphometrics to assess the similarities and differences obtained with the different methodologies.

An analysis of pose in 3D stereophotogrammetry of the breast.

BACKGROUND: Volume of the breast can be objectively measured by three-dimensional (3D) photographs. This study describes the analysis of three different positions of the patient in image acquisition, in order to find the best pose for reproducible 3D photographs of the breasts. METHOD: Twenty-four patients were included between February and September 2014 in a consecutive way. Data were collected prospectively. 3D photographs were acquired using a stereophotogrammetry system. Images were taken twice in three different positions (arms behind the back, arms placed on the hips and arms horizontally placed). Surface based matching was applied and the absolute mean distance between the surfaces of both 3D models of the same position was calculated. This difference measure represents the similarity of the photographs. RESULTS: Univariate ANOVA showed a significant difference in distance between the three positions (sum of squares 1.12, p < 0.001). The horizontal position presented the lowest absolute mean distance (0.45 mm). Additional post hoc multiple comparisons analysis revealed a statistically significant difference between the distances of horizontal and back position (-0.22 mm, p < 0.001) and of back and hip position (0.13 mm, p = 0.009), with better results of the horizontal and hip positions, respectively. CONCLUSION: Standardization of 3D acquisition in pre- and postoperative breast imaging could improve imaging reproducibility. Based on the results of this study, we recommend a pose with the arms in a horizontal position.

Collecting Kinematic Data on a Ski Track with Optoelectronic Stereophotogrammetry: A Methodological Study Assessing the Feasibility of Bringing the Biomechanics Lab to the Field.

In the laboratory, optoelectronic stereophotogrammetry is one of the most commonly used motion capture systems; particularly, when position- or orientation-related analyses of human movements are intended. However, for many applied research questions, field experiments are indispensable, and it is not a priori clear whether optoelectronic stereophotogrammetric systems can be expected to perform similarly to in-lab experiments. This study aimed to assess the instrumental errors of kinematic data collected on a ski track using optoelectronic stereophotogrammetry, and to investigate the magnitudes of additional skiing-specific errors and soft tissue/suit artifacts. During a field experiment, the kinematic data of different static and dynamic tasks were captured by the use of 24 infrared-cameras. The distances between three passive markers attached to a rigid bar were stereophotogrammetrically reconstructed and, subsequently, were compared to the manufacturer-specified exact values. While at rest or skiing at low speed, the optoelectronic stereophotogrammetric system's accuracy and precision for determining inter-marker distances were found to be comparable to those known for in-lab experiments (< 1 mm). However, when measuring a skier's kinematics under "typical" skiing conditions (i.e., high speeds, inclined/angulated postures and moderate snow spraying), additional errors were found to occur for distances between equipment-fixed markers (total measurement errors: 2.3 ± 2.2 mm). Moreover, for distances between skin-fixed markers, such as the anterior hip markers, additional artifacts were observed (total measurement errors: 8.3 ± 7.1 mm). In summary, these values can be considered sufficient for the detection of meaningful position- or orientation-related differences in alpine skiing. However, it must be emphasized that the use of optoelectronic stereophotogrammetry on a ski track is seriously constrained by limited practical usability, small-sized capture volumes and the occurrence of extensive snow spraying (which results in marker obscuration). The latter limitation possibly might be overcome by the use of more sophisticated cluster-based marker sets.

Measurement of clavicular length and shortening after a midshaft clavicular fracture: Spatial digitization versus planar roentgen photogrammetry.

PURPOSE: Clavicular shortening after fracture is deemed prognostic for clinical outcome and is therefore generally assessed on radiographs. It is used for clinical decision making regarding operative or non-operative treatment in the first 2weeks after trauma, although the reliability and accuracy of the measurements are unclear. This study aimed to assess the reliability of roentgen photogrammetry (2D) of clavicular length and shortening, and to compare these with 3D-spatial digitization measurements, obtained with an electromagnetic recording system (Flock of Birds). PATIENTS AND METHODS: Thirty-two participants with a consolidated non-operatively treated two or multi-fragmented dislocated midshaft clavicular fracture were analysed. Two observers measured clavicular lengths and absolute and proportional clavicular shortening on radiographs taken before and after fracture consolidation. The clavicular lengths were also measured with spatial digitization. Inter-observer agreement on the radiographic measurements was assessed using the Intraclass Correlation Coefficient (ICC). Agreement between the radiographic and spatial digitization measurements was assessed using a Bland-Altman plot. RESULTS: The inter-observer agreement on clavicular length, and absolute and proportional shortening on trauma radiographs was almost perfect (ICC>0.90), but moderate for absolute shortening after consolidation (ICC=0.45). The Bland-Altman plot compared measurements of length on AP panorama radiographs with spatial digitization and showed that planar roentgen photogrammetry resulted in up to 37mm longer and 34mm shorter measurements than spatial digitization. CONCLUSION: Measurements of clavicular length on radiographs are highly reliable between observers, but may not reflect the actual length and shortening of the clavicle when compared to length measurements with spatial digitization. We recommend to use proportional shortening when measuring clavicular length or shortening on radiographs for clinical decision making.

Camera Calibration for Water-Biota Research: The Projected Area of Vegetation.

Imaging systems have an indisputable role in revealing vegetation posture under diverse flow conditions, image sequences being generated with off the shelf digital cameras. Such sensors are cheap but introduce a range of distortion effects, a trait only marginally tackled in hydraulic studies focusing on water-vegetation dependencies. This paper aims to bridge this gap by presenting a simple calibration method to remove both camera lens distortion and refractive effects of water. The effectiveness of the method is illustrated using the variable projected area, computed for both simple and complex shaped objects. Results demonstrate the significance of correcting images using a combined lens distortion and refraction model, prior to determining projected areas and further data analysis. Use of this technique is expected to increase data reliability for future work on vegetated channels.

Assessment of forward head posture in females: observational and photogrammetry methods.

BACKGROUND: There are different methods to assess forward head posture (FHP) but the accuracy and discrimination ability of these methods are not clear. OBJECTIVES: Here, we want to compare three postural angles for FHP assessment and also study the discrimination accuracy of three photogrammetric methods to differentiate groups categorized based on observational method. METHOD: All Seventy-eight healthy female participants (23 ± 2.63 years), were classified into three groups: moderate-severe FHP, slight FHP and non FHP based on observational postural assessment rules. Applying three photogrammetric methods - craniovertebral angle, head title angle and head position angle - to measure FHP objectively. RESULTS: One - way ANOVA test showed a significant difference in three categorized group's craniovertebral angle (P< 0.05, F=83.07). There was no dramatic difference in head tilt angle and head position angle methods in three groups. According to Linear Discriminate Analysis (LDA) results, the canonical discriminant function (Wilks'Lambda) was 0.311 for craniovertebral angle with 79.5% of cross-validated grouped cases correctly classified. CONCLUSION: Our results showed that, craniovertebral angle method may discriminate the females with moderate-severe and non FHP more accurate than head position angle and head tilt angle. The photogrammetric method had excellent inter and intra rater reliability to assess the head and cervical posture.