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A 3-D ultrasound (US) imaging technique has been studied to facilitate the diagnosis of spinal deformity without radiation. The objective of this article is to propose an assessment framework to automatically estimate spinal deformity in US spine images. The proposed framework comprises four major components, a US spine image generator, a novel transformer-based lightweight spine detector network, an angle evaluator, and a 3-D modeler. The principal component analysis (PCA) and discriminative scale space tracking (DSST) method are first adopted to generate the US spine images. The proposed detector is equipped with a redundancy queries removal (RQR) module and a regularization item to realize accurate and unique detection of spine images. Two clinical datasets, a total of 273 images from adolescents with idiopathic scoliosis, are used for the investigation of the proposed framework. The curvature is estimated by the angle evaluator, and the 3-D mesh model is established by the parametric modeling technique. The accuracy rate (AR) of the proposed detector can be achieved at 99.5%, with a minimal redundancy rate (RR) of 1.5%. The correlations between automatic curve measurements on US spine images from two datasets and manual measurements on radiographs are 0.91 and 0.88, respectively. The mean absolute difference (MAD) and standard deviation (SD) are $2.72^{\circ} ~\pm ~2.14^{\circ} $ and $2.91^{\circ} ~\pm ~2.36^{\circ} $ , respectively. The results demonstrate the effectiveness of the proposed framework to advance the application of the 3-D US imaging technique in clinical practice for scoliosis mass screening and monitoring.

This review presents the state of the art according to the current evidence on nonoperative treatment for adolescent idiopathic scoliosis, focusing on bracing. The definition of braces for the treatment of adolescent idiopathic scoliosis and a short history are provided. The analysis includes biomechanics, types, existing classifications, indications for treatment, time of brace wear and weaning, adherence, three-dimensional modeling, use of ultrasound imaging for bracing, management of treatment, issue of immediate in-brace correction, and documentation of the outcomes usually assessed for brace treatment, including the quality-of-life issues. According to the current evidence, there are two randomized control trials in favor of bracing. There are insufficient data on the superiority of one brace over another, although it is possible to classify and grade braces for efficacy from nonrigid to rigid and very rigid. Nevertheless, there is consensus on patients' management on the need for teamwork focusing on adherence to treatment, acceptability, and family and patient involvement.

Purpose: Accurate measurement of spinal curvature for adolescent idiopathic scoliosis (AIS) is important because it affects treatment decisions. Currently, the Cobb angle measured on a radiograph is the gold standard for spinal curvature assessment. However, manual measurements introduce inter- and intra-observer reliability challenges, and while fully automatic methods have been developed, performance could be improved. This paper reported a new approach using convolutional neural networks (CNNs) and an iterative vertebra location algorithm to calculate the Cobb angle automatically by segmenting the spinal and vertebral boundaries on posteroanterior radiographs. Methods: Two CNNs for spinal column and vertebra segmentation were trained using 110 and 272 images, respectively. An iterative vertebra location algorithm was developed to localize individual vertebrae in the spinal column for segmentation. To evaluate the accuracy of the automatic Cobb angle measurements calculated from the vertebra segmentations, 100 new radiographs were used. The mean absolute difference (MAD), standard deviation of absolute differences (SD), and percent within clinical acceptance (≤ 5°) between manual and automatic measurements were reported as evaluation metrics. Results: The MAD ± SD was 2.8° ± 2.8° and 88% of the measurements were within 5° of the manual measurements. The result was comparable to other literature, and this method worked for a wide range of curve severities. The average automatic measurement time per image was 90 s, which is clinically acceptable. Conclusion: The automatic measurement method based on CNNs provided a comparable accuracy and speed on spinal curvature measurements on radiographs. It could be a valuable tool for reducing clinical workload and measurement variation.

Purpose: To develop a new method based on 3D ultrasound information to measure the kyphotic angle (KA) on ultrasound (US) images in adolescents with idiopathic scoliosis (AIS) and to evaluate the intra-rater and inter-rater reliabilities and accuracy of the US measurements. Methods: Twenty subjects with AIS (17F, 3 M, aged 13.7 ± 2.2 years old) were recruited. One 20 + years experienced rater (R3) measured the KA on radiographs twice using the Cobb method. Two raters (R1, R2), both have at least 1-year experience measured US images twice using the new spinous processes method. The intraclass correlation coefficients (ICC[2,1]) of the intra-rater and inter-rater reliabilities of US KA measurements were calculated. An equation based on US KA measurements to calculate the radiographic KA was generated. Results: The intra-rater reliability ICC[2,1] (R3) of the X-ray measurement was 0.92 and US KA measurements for R1 and R2 were 0.94 and 0.95, respectively. The inter-rater reliability ICC[2,1] for R1 versus R2 were 0.85 and 0.86, respectively. The mean absolute differences (MAD) of US versus radiography measurements were 4.2 ± 3.0° (R1 vs R3) and 5.0 ± 4.1° (R2 vs R3), respectively. The radiographic equivalent KA = 0.82 × US KA – 5.6°. When using this equation, the overall MAD between US and radiographic KA was 2.9 ± 1.6°. Conclusions: The ultrasound spinous process method was reliable to measure the KA. Although there was a systematic bias on the US measurements, after the correction, the MAD of the US and radiographic KA was 2.9 ± 1.6°. Using US allows clinicians to monitor KA without exposing children to ionizing radiation.

Purpose: Posterior spinal fusion surgery is required to correct severe idiopathic scoliosis. The surgery involves insertion of screws which requires high accuracy to prevent neurologic damage to the spinal cord. Although conventional CT navigation can reduce this risk, 3D-ultrasound-based navigation could achieve this without added ionizing radiation and usage of expensive and bulky equipment. This study aimed to evaluate the accuracy of a 3D ultrasound navigation system for posterior spine surgery. Methods: A custom 3D ultrasound (3DUS) with model-to-surface registration algorithm was developed and integrated into a 3D navigation environment. A CT scan of an adolescent spine (T3-T11) was segmented and 3D printed for experiments. A probe with reflective markers was placed in vertebral pedicles 684 times in varying levels, positions in the capture space and orientation of vertebra, and the entrypoint and trajectory accuracies were measured. Results: Among 684 probe placements in vertebral levels T3 to T11 in the phantom spine, 95.5% were within 1 mm and 5° of accuracy, with an average accuracy of 0.4 ± 0.4 mm and 2.1 ± 0.9°, requiring 8.8 s to process. Accuracies were statistically significantly affected by vertebral orientation and position in the capture volume, though this was still within the targeted accuracies of 1 mm and 5°. Conclusion: This preliminary ultrasound-based navigation system is accurate and fast enough for guiding placement of pedicle screws into the spine in posterior fusion surgery. The current results are limited to phantom spines, and future study in animal or human cadavers is needed to investigate soft tissue effects on registration accuracy.

Aim:Spinal brace wear time affects treatment effectiveness of adolescent idiopathic scoliosis but remains challenging with the brace’s bulkiness. This study aims to determine the appropriate material and thickness to improve wear comfort. Materials & methods:Thirty-one specimens were tested with 13 ULTEM1010 and 13 Nylon12 potential materials and 5 standard polypropylene material in 2.5, 3.25 and 4 mm thicknesses to evaluate mechanical properties. Donning tests of ULTEM1010 and Nylon12 printed braces were conducted. Results:Nylon12 with 2.5–3.25 mm thickness had higher flexibility and the closest mechanical characteristics as 4-mm thick polypropylene. ULTEM1010 brace fractured after 615-times and Nylon12 brace handled 2920-times of opening and closing. Conclusion:Nylon12, 2.5–3.25 mm are appropriate design parameters. Further clinical study can validate long term brace effectiveness.

Determine the positional, rotational and reconstruction accuracy of a 3D ultrasound system to be used for image registration in navigation surgery. A custom 3D ultrasound for spinal surgery image registration was developed using Optitrack Prime 13-W motion capture cameras and a SonixTablet Ultrasound System. Temporal and spatial calibration was completed to account for time latencies between the two systems and to ensure accurate motion tracking of the ultrasound transducer. A mock operating room capture volume with a pegboard grid was set up to allow phantoms to be placed at a variety of predetermined positions to validate accuracy measurements. Five custom-designed ultrasound phantoms were 3D printed to allow for a range of linear and angular dimensions to be measured when placed on the pegboard. Temporal and spatial calibration was completed with measurement repeatabilities of 0.2 mm and 0.5° after calibration. The mean positional accuracy was within 0.4 mm, with all values within 0.5 mm within the critical surgical regions and 96% of values within 1 mm within the full capture volume. All orientation values were within 1.5°. Reconstruction accuracy was within 0.6 mm and 0.9° for geometrically shaped phantoms and 0.5 and 1.9° for vertebrae-mimicking phantoms. The accuracy of the developed 3D ultrasound system meets the 1 mm and 5° requirements of spinal surgery from this study. Further repeatability studies and evaluation on vertebrae are needed to validate the system for surgical use.

Retrospective reliability study.

Study Design: Retrospective reliability study. Objectives: To investigate the intra- and interrater reliability of Cobb angle measurements on the plane of maximum curvature (PMC) using ultrasound (US) images on children with adolescent idiopathic scoliosis (AIS). Summary of Background Data: Cobb angle measurement on posteroanterior (PA) radiographs is the gold standard to assess curve severity. However, the PA Cobb angle does not reflect the true three-dimensional deformity. Methods: One hundred one children with AIS (87 F; 14 M) (age: 13.7 ± 1.7 years) were recruited and 157 curves were recorded by clinicians on radiographs. Three raters, R1, R2, and R3 with 0, 4, and 20+ years of experience, respectively, measured the PA Cobb, vertebral axial rotation (VAR), PMC Cobb, and PMC orientations on US images. The true PMC orientations were determined using 3D reconstructions on the PA and lateral EOS radiographs. The reliability of R1 measurements on PMC orientations were validated using intermethod (US vs. EOS measurements) with the intraclass correlation coefficients (ICCs). Inter- and intrarater reliabilities, standard error measurements, and Bland-Altman’s bias were used to report the PMC Cobb and VAR measurements. Results: Intermethod, inter-, and intrarater ICC(2,1) values for all reliability assessments were greater than 0.9. The mean absolute differences and the standard error measurements for both PMC Cobb and VAR were less than 4° and 0.5°, respectively. The PMC orientation was strongly correlated (r2= 0.88) between both measurement modalities. There appeared to be a positive association between the difference of PMC and PA Cobb when the PA Cobb and the maximum VAR were greater than 30° and 14°, respectively. Conclusion: The PMC Cobb and VAR can be measured reliably on US images. Future studies should validate the PMC Cobb angle and to include a wider Cobb angle range on participants.

Retrospective reliability study of the coronal curvature measurement on ultrasound (US) imaging in adolescent idiopathic scoliosis (AIS).

Study Design: Retrospective reliability study of the coronal curvature measurement on ultrasound (US) imaging in adolescent idiopathic scoliosis (AIS). Objectives: To determine the intra- and inter-rater reliability and validity of the coronal curvature measurements obtained from US images. Summary of Background Data: Cobb angle measurements on radiographs are the usual method to diagnose and monitor the progression of scoliosis. Repeated ionizing radiation exposure is a frequent concern of patients and their families. Use of US imaging method to measure coronal curvature in children who have idiopathic scoliosis has not been clinically validated. Methods: The researchers scanned 26 subjects using a medical 3-dimensional US system. Spinal radiographs were obtained on the same day from the local scoliosis clinic. Three raters used the center of lamina method to measure the coronal curvature on the US images twice 1 week apart. The raters also measured the Cobb angle on the radiographs twice. Intra- and inter-rater reliability of the coronal curvature measurement from the US images was analyzed using intra-class correlation coefficients. The correlation coefficient of the US coronal curvature measurements was compared with the Cobb angles. Results: The intra-class correlation coefficient (2,1) values of intra- and inter-rater reliability on the US method were greater than 0.80. Standard error of measurement on both of the intra- and inter-rater US methods was less than 2.8°. The correlation coefficient between the US and radiographic methods ranged between 0.78 and 0.84 among 3 raters. Conclusions: The US method illustrated substantial intra- and inter-rater reliability. The measurement difference between radiography and the US method was within the range of clinically acceptable error (5°). The US method may be considered a radiation-free alternative to assess children with scoliosis of mild to moderate severity.

Symmetry is a trait that has been extensively reviewed, especially clinically, as an indication of ideal geometry and health. Many geometric symmetry assessment techniques rely on two-dimensional measurements that do not account for the three-dimensional nature of the object. In this article, two methods, reflection and a process termed rotoinversion, a combination of reflection and rotation, are presented as potential methods to assess an object’s deviation from symmetry. With reflection, the geometric models are reflected about a calculated best plane of symmetry. With rotoinversion, the models are reflected about an arbitrary plane and then rigidly translated and rotated to best align the translated and original models. The methods give the same results for bilaterally symmetric objects, but different results for bilaterally and rotationally symmetric objects. The two methods are applied to assess asymmetry in adolescent idiopathic scoliosis torso geometric models, producing similar results. There was an angle of 0.408° between the normal to the plane of reflection from the reflection process and the normal from the rotoinversion process and average rotation of 0.067° from rotoinversion. The most appropriate method depends on the purpose of the symmetry assessment and must be determined on a case-by-case basis.

Study Design: A reliability analysis of Cobb angle, vertebral rotation (VR), and spinous process angle (SPA) measurements in adolescent idiopathic scoliosis. Objective: To determine the intra- and interobserver reliability of semi-automated digital radiograph measurements. Summary of Background Data: Cobb angle measurements on posteroanterior radiographs are commonly used to determine the severity of scoliosis. Vertebral rotation helps assess scoliosis 3-dimensionally and has a role in predicting curve progression. Recent studies have shown that the spinous process angle is a useful parameter in assessing scoliosis when using ultrasound imaging. Because the reliability of SPA measurements on radiographs has yet to be determined, it is important to compare the reliability of these 3 parameters (Cobb angle, VR, and SPA) using a computer assisted semi-automated method. Methods: Sixty posteroanterior radiographs of patients with adolescent idiopathic scoliosis were obtained and measured twice by 3 observers who were blinded to their previous measurements, using an in-house developed program. Measurements were obtained using a semi-automated method to minimize variability resulting from observer reliability. The intra- and interobserver reliabilities were analyzed using intra-class correlation coefficients (ICCs) as well as BlandeAltman’s bias and limits of agreement. Results: Over 350 (intra) and 90 (inter) sets of curves with an average Cobb angle of 26° ± 9° (range, 10° to 44°) were compared for each parameter. Intra-observer reliabilities for each parameter were excellent (ICC[2,1],.82; 1.00), with mean absolute differences under 3° between most measurements. Interobserver reliability (ICC[2,1],.72;.95) was mostly good to excellent, with mean absolute differences ranging from 2.0° to 5.6°. Conclusions: Both the intra- and interobserver assessment of the Cobb, VR, and SPA from the semi-automated measurements had clinically acceptable reliability ranges and may be considered for clinical implementation. Additional studies will be conducted to determine the accuracy and sensitivity to change of these scoliosis severity measurements.

A reliability analysis of Cobb angle, vertebral rotation (VR), and spinous process angle (SPA) measurements in adolescent idiopathic scoliosis.

Development of a computer-aided Cobb measurement method and evaluation of its reliability.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional curvature of spine. Children with AIS and low bone quality have higher chance to get curve progression leading to bigger spinal curvature. In addition, bone quality affects acoustic impedance of bone, thus influencing the reflection coefficient of ultrasound signal from the soft tissue–bone interface. This study aimed to estimate the bone quality of AIS patients based on the reflection coefficients to determine the correlation of the bone quality with curve severity. A simple bone model was used to develop an equation to calculate the reflection coefficient value. Experiments were conducted on five different phantoms. Acrylic was used to design a vertebral shape to study the effect of surface roughness and inclination, including: smooth flat surface (SFS), smooth curved surface (SCS), rough curved surface (RCS), and the rough curved inclined surface (RCIS). A clinical study with 37 AIS patients were recruited. The estimated reflection coefficient values of plate phantoms agreed well with the predicted values and the maximum error was 6.7%. The reflection coefficients measured from the acrylic-water interface for the SFS, SCS, RCS, RCIS (3° and 5°) were 0.37, 0.33, 0.28, (0.23 and 0.12), respectively. The surface roughness and inclination increased the reflection loss. From the clinical data, the average reflection coefficients for children with AIS were 0.11 and 0.07 for the mild curve group and the moderate curve group, respectively. A moderate linear correlation was found between the reflection coefficients and curve severity (r2= 0.3). Patients with lower bone quality have observed to have larger spinal curvature.

Identifying daily oviposition events for individual broiler breeders is important for bird management. Identifying non-laying birds in a flock that might be caused by improper nutrition or diseases can guide diet changes or disease treatments for these individuals. Oviposition depends on follicle maturation and egg formation, and follicle maturation can be variable. As such, the day and time of oviposition events of individual birds in a free-run flock can be hard to predict. Based on a precision feeding (PF) system that can record the feeding activity of individual birds, a recent study reported a machine learning model to predict daily egg-laying events of broiler breeders. However, there were 2 limitations in that study: 1) It could only be used to identify daily egg-laying events on a subsequent day; 2) The prediction outputs that were binary labels were unable to indicate more details among the outputs with the same label. To improve the previous approach, the current study aimed to predict and output the probability of daily oviposition events occurring using a specific time point in 1 day. In the current study, 706 egg-laying events recorded by nest boxes with radio frequency identification of hens and 706 randomly selected no-egg-laying events were used. The anchor point was newly defined in the current study as a specific time point in 1 day, and 26 features around the anchor point were created for all events (706 egg-laying events and 706 no-egg-laying events). A feed-forward artificial neural network (ANN) model was built for prediction. The area under the receiver operating characteristic (ROC) curve was 0.9409, indicating that the model had an outstanding classification performance. The ANN model could predict oviposition events on the current day, and the output was a probability that could be informative to indicate the likelihood of an oviposition event for an individual breeder. In situations where total egg production was known for a group, the ANN model could predict the probability of daily oviposition events occurring of all individual birds and then rank them to choose those most likely to have laid an egg.

Trunk images of children with scoliosis were examined to determine features that contribute to the impression of trunk distortion. Twenty subjects with spinal deformity ranging from none to severe were photographed in a relaxed standing position. Seven blinded evaluators subjectively scored their impressions of the trunk appearance, shoulder-height difference, shoulder-angle asymmetry, decompensation, scapula asymmetry, waist crease, waist asymmetry, and pelvic asymmetry. Regression analysis was used with the latter seven features to predict overall impression. The seven measures of the deformity predicted 85% of the overall impression of trunk distortion; scapular asymmetry was the best predictor. Trunk deformity is the most obvious effect of scoliosis to the patients. Objective approaches to the assessment of this important but difficult-to-quantify aspect of idiopathic scoliosis are available and should be used to evaluate treatment outcomes.

Clinical gait analysis is the accepted “gold standard” for evaluating an individual’s walking pattern. However, in certain conditions such as idiopathic toe walking (ITW), the degree of voluntary control that a subject may elicit upon their walking pattern in a gait laboratory may not truly reflect their gait during daily activities. Therefore, a battery-powered, wireless data acquisition system was developed to record daily walking patterns to assist in the assessment of treatment outcomes in this patient population. The device was developed to be small (30×50×12 mm3), light-weight (15 g), easy to install, reliable, and consumed little power. It could be mounted across the laces of the shoe, while forces and walking activities were recorded to investigate the percentage of toe walking during the assessment. Laboratory tests were performed and preliminary clinical trials at a gait laboratory were done on six normal gait walkers. These volunteers also try to walk on their toes to simulate the toe walking at the gait laboratory. The system was able to track the gait pattern and determine the percentage of toe walking relative to normal gait. Three boys and one girl were diagnosed with ITW then participated into this study. A total of 4 sets thirty-three 10 min data sessions (5.5 h) were collected outside the laboratory. The results showed that the test subjects walked on their toes 70±4% of the total walking time, which was higher than that they performed 64±5% at the gait laboratory. This preliminary study shows promising results that the system should be able to use for clinical assessment and evaluation of children with ITW.