Spinal Curvature Measurements Research Articles

A deep learning framework for vertebral morphometry and Cobb angle measurement with external validation.

To propose a fully automated deep learning (DL) framework for the vertebral morphometry and Cobb angle measurement from three-dimensional (3D) computed tomography (CT) images of the spine, and validate the proposed framework on an external database. The vertebrae were first localized and segmented in each 3D CT image using a DL architecture based on an ensemble of U-Nets, and then automated vertebral morphometry in the form of vertebral body (VB) and intervertebral disk (IVD) heights, and spinal curvature measurements in the form of coronal and sagittal Cobb angles (thoracic kyphosis and lumbar lordosis) were performed using dedicated machine learning techniques. The framework was trained on 1725 vertebrae from 160 CT images and validated on an external database of 157 vertebrae from 15 CT images. The resulting mean absolute errors (± standard deviation) between the obtained DL and corresponding manual measurements were 1.17 ± 0.40mm for VB heights, 0.54 ± 0.21mm for IVD heights, and 3.42 ± 1.36° for coronal and sagittal Cobb angles, with respective maximal absolute errors of 2.51mm, 1.64mm, and 5.52°. Linear regression revealed excellent agreement, with Pearson's correlation coefficient of 0.943, 0.928, and 0.996, respectively. The obtained results are within the range of values, obtained by existing DL approaches without external validation. The results therefore confirm the scalability of the proposed DL framework from the perspective of application to external data, and time and computational resource consumption required for framework training.

Automatic recognition of whole-spine sagittal alignment and curvature analysis through a deep learning technique

PurposeArtificial intelligence based on deep learning (DL) approaches enables the automatic recognition of anatomic landmarks and subsequent estimation of various spinopelvic parameters. The locations of inflection points (IPs) and apices (APs) in whole-spine lateral radiographs could be mathematically determined by a fully automatic spinal sagittal curvature analysis system.MethodsWe developed a DL model for automatic spinal curvature analysis of whole-spine lateral plain radiographs by using 1800 annotated images of various spinal disease etiologies. The DL model comprised a landmark localizer to detect 25 vertebral landmarks and a numerical algorithm for the generation of an individualized spinal sagittal curvature. The characteristics of the spinal curvature, including the IPs, APs, and curvature angle, could thus be analyzed using mathematical definitions. The localization error of each landmark was calculated from the predictions of 300 test images to evaluate the performance of the landmark localizer. The interrater reliability among a senior orthopedic surgeon, a radiologist, and the DL model was assessed using the intraclass correlation coefficient (ICC).ResultsThe accuracy of the landmark localizer was within an acceptable range (median error: 1.7–4.1 mm), and the interrater reliabilities between the proposed DL model and each expert were good to excellent (all ICCs > 0.85) for the measurement of spinal curvature characteristics.ConclusionThe interrater reliability between the proposed DL model and human experts was good to excellent in predicting the locations of IPs, APs, and curvature angles. Future applications should be explored to validate this system and improve its clinical efficiency.

Measurement of covered curvature based on a tape of integrated accelerometers

Quantitative measurements of spinal curvature can indicate the health of the human musculoskeletal system. However, existing measurement techniques are not feasible for unexposed back. This study used accelerometers to develop a portable, noninvasive, nonradiative, and cost-efficient device to quantitatively measure spinal curvature in real time. The measurement accuracy is approximately 99% when measuring a ø200-mm circle. Compared with the results of the three-dimensional motion analysis system, the device exhibited curvature results that were highly consistent in the Bland-Altman test (cervical lordosis angle (CLA): r = 0.973, thoracic kyphosis angle (TKA): r = 0.993, lumbar lordosis angle (LLA): r = 0.961, and spinal alignment trendline (SAT): r = 0.978). Repeatability test results: CLA = 37.63 ± 2.24°, TKA = 32.48 ± 0.98°, and LLA = 15.64 ± 1.12°. Thus, the proposed device can provide accurate and reliable quantitative measurements and can be used for spinal curvature measurements in the supine position.

Automating Scoliosis Measurements in Radiographic Studies with Machine Learning: Comparing Artificial Intelligence and Clinical Reports.

Scoliosis is a condition of abnormal lateral spinal curvature affecting an estimated 2 to 3% of the US population, or seven million people. The Cobb angle is the standard measurement of spinal curvature in scoliosis but is known to have high interobserver and intraobserver variability. Thus, the objective of this study was to build and validate a system for automatic quantitative evaluation of the Cobb angle and to compare AI generated and human reports in the clinical setting. After IRB was obtained, we retrospectively collected 2150 frontal view scoliosis radiographs at a tertiary referral center (January 1, 2019, to January 1, 2021, ≥ 16years old, no hardware). The dataset was partitioned into 1505 train (70%), 215 validation (10%), and 430 test images (20%). All thoracic and lumbar vertebral bodies were segmented with bounding boxes, generating approximately 36,550 object annotations that were used to train a Faster R-CNN Resnet-101 object detection model. A controller algorithm was written to localize vertebral centroid coordinates and derive the Cobb properties (angle and endplate) of dominant and secondary curves. AI-derived Cobb angle measurements were compared to the clinical report measurements, and the Spearman rank-order demonstrated significant correlation (0.89, p < 0.001). Mean difference between AI and clinical report angle measurements was 7.34° (95% CI: 5.90-8.78°), which is similar to published literature (up to 10°). We demonstrate the feasibility of an AI system to automate measurement of level-by-level spinal angulation with performance comparable to radiologists.

Spinal deformity measurement using a low-density flexible array ultrasound transducer: A feasibility study with phantoms

Spinal deformities assessment using 3D ultrasound scanning has limitations in fitting onto different back surface contour as well as fitting within the gaps between subject and their spinal brace during bracing assessments. The study proposed a flexible array ultrasound transducer to overcome these limitations.The results demonstrated the feasibility of spinal deformity assessments with a flexible ultrasound array when arranged in four shapes, namely Linear, Concave, Convex, and S-shaped. For comparisons of imaging performance on spinous process using the four shapes, Convex and S-shaped transducer showed a depth dependence and lateral location dependence of the lateral intensity distribution of spinous process, respectively. S-shaped transducer had the least accurate prediction of the location of spinous process, with measurement error of 4.8 ​± ​3.2 ​mm, it also showed poorer prediction on spinal curvature measurements. This is suggested to be due to the asymmetrical distortion to the spinous process due to the lateral location dependence of the image. However, the coronal curve prediction of spine phantom performed well with R-squared values of >0.97 in all transducer shapes.The results of this study paved the way for further investigation on the improvement of image quality and measurement accuracy under different shapes for the flexible array, mechanism of dynamic shape change during the scanning to fit different body contour, as well as extension from 1D to 2D flexible array.

A novel classification method for mild adolescent idiopathic scoliosis using 3D ultrasound imaging

Mild adolescent idiopathic scoliosis (AIS), with Cobb<20°, was hypothesized as the right stage to intervene to prevent progression. AIS curve can be categorized into either structural or non-structural depending on the spine morphology (flexibility). Using X-ray to characterize AIS curves remains the clinical gold standard while compromising the risks of radiation exposure. In previous works, 3D ultrasound imaging had proved the reliability of the coronal spinal curvature measurement. This research aimed at developing a mild AIS classification scheme through examining spine flexibility using 3D ultrasound imaging.For the preliminary study, 90 mild AIS subjects (21 ​M and 69 ​F; Age:14.5 ​± ​1.7 years old; Cobb: 18.2 ​± ​6.4°) underwent both 3D ultrasound and X-ray scanning on the same day. For each case, a clinician measured Cobbs and denoted major curve as ground truth. Bending Asymmetry Index (BAI) was developed to indicate the presence of a possible structural curve. The curve classification was coded to a modified Lenke classification for mild cases (m-Lenke). The results of 3D ultrasound classification were evaluated with the X-ray.It was shown that 70.1% of the subjects had identical curve classification results and 72.0% had the correct major curve detection. Lumbar-dominated curves had distinctive performance (p ​= ​0.91, r ​= ​0.91) against others. The study demonstrated the possibility of a 3D ultrasound-based method for mild AIS curve classification. The discrepancies could be partially explained by the limitations of the ultrasound scanning in proximal thoracic region. Subsequent studies will validate the proposed method with a larger cohort.

The reliability and reproducibility of sagittal spinal curvature measurement using the Microsoft Kinect V2.

Abnormal sagittal spinal curvature is associated with pain, decreased mobility, respiratory problems and increased mortality. Time-of-flight technology of the Microsoft Kinect sensor can reconstruct a three-dimensional image of the back quickly and inexpensively. To estimate the extent of the reproducibility of sagittal spine curvature measurement using the Microsoft Kinect sensor. Simultaneous measurement of thoracic and lumbar spine using the Microsoft Kinect sensor in 37 participants. Two investigators gave standardised instructions and each captured 3 images. Thoracic kyphosis and lumbar lordosis angle indexes were calculated using maximum height divided by the length. Adult participants (mean age in years (SD) = 51.7 (20.6); 57% female; BMI in kg/m2 (SD) = 24.9 (3.3)) kyphosis and lordosis indexes showed high intra-rater and inter-rater ICC values (0.960-0.973). The means of the first images from both raters had significantly larger kyphosis indexes compared to the second and third images, yet no difference between means in lordosis data. The results indicate that the Microsoft Kinect sensor has a reproducible method with high intra-rater and inter-rater reliability. The difference between the means over repeated measures suggest the second image capture is more consistent. It is a reproducible and quick method in clinical and research settings.

Reliability and validity of lateral curvature assessments using clinical ultrasound for the patients with scoliosis: a systematic review.

Clinical ultrasound is radiation-free, low cost and user friendly, which makes it probable in assessment of scoliosis. Numerous studies have been conducted about the feasibility of using clinical ultrasound to assess scoliosis; thus, an inclusive review of the literature would be beneficial for researchers, clinicians and patients. This study aimed to systematically review the reliability and validity of coronal curvature assessments obtained from different clinical ultrasound imaging methods. A comprehensive search of 6 databases and Google Scholar search engine was performed for retrieving articles assessing reliability and/or validity of spinal curvature measurements obtained from clinical ultrasound. Two reviewers assessed the methodological quality of selected articles independently using criteria appraisal instrument. The results were analysed and synthesized qualitatively using level of evidence method. Fourteen articles were included. Thirteen articles investigated both the reliability and validity, of which nine were of high quality; and one article evaluated only the reliability and was of high quality. Totally five ultrasound methods were evaluated. Very high reliability (intra-class correlation coefficient = 0.80-1.00) but limited levels of evidence were found for the majority of the studied ultrasound methods. Almost all the methods showed good to excellent validity (correlation coefficient = 0.76-1.00) but limited to moderate levels of evidence. A high level of evidence was found in support of the reliability and validity of the COL (centre of lamina) ultrasound method. Further reliability and validity studies should be conducted to strengthen the level of evidence for those ultrasound methods with moderate, limited or conflicting level of evidence. These slides can be retrieved under Electronic Supplementary Material.

A Novel Method to Measure the Sagittal Curvature in Spinal Deformities: The Reliability and Feasibility of 3-D Ultrasound Imaging

The objective of this study was to test the reliability of sagittal spinal curvature measurements using 3-D ultrasound in patients with adolescent idiopathic scoliosis (AIS). Ultrasound spinous process angle (USSPA) and ultrasound laminae angle (USLA) were measured on sagittal ultrasound images, while the Cobb angle (XCA) was measured on sagittal X-ray images. Intra-class correlation coefficients (ICC) for the intra- and inter-observer variability, linear regression analysis and Bland-Altman method, including mean absolute difference (MAD), were investigated to evaluate the reliability and validity of the two ultrasound angles compared with XCA. Excellent measurement reliabilities were demonstrated for both ultrasound angles (ICC ≥ 0.91). Moderate to good and significant linear correlations and good agreement were demonstrated between the ultrasound methods and XCA (Thoracic [R2 ≥ 0.574] / Lumbar [R2 ≥ 0.635]). No significant differences were found for the MADs between both corrected ultrasound angles and XCA. Sagittal ultrasound angles were demonstrated to be reliable for assessing sagittal curvature using spinous processes and laminae and to have good and significant correlations with XCAs. Since it is non-ionizing and relatively low cost, this method opens the possibility of providing frequent curve monitoring and evaluation, and screening for AIS patients, particularly based on sagittal profiles.

Intelligent Measurement of Spinal Curvature Using Cascade Gentle AdaBoost Classifier and Region-Based DRLSE

For spinal curvature measurements, because of the anatomical complexity of the spine CT image, developing an automated method to avoid manual landmark is a challenging task. In this study, we propose an intelligent framework that integrates the cascade AdaBoost classifier and region-based distance regularized level set evolution (DRLSE) with the vertebral centroid measurement. First, the histogram-of-oriented-gradients based cascade gentle AdaBoost classifier is used to detect automatically and localize vertebral bodies from computer tomography (CT) spinal images. Considering these vertebral pathological images enables us to produce a diverse training dataset. Then, the DRLSE method introduces the local region information to converge the vertebral boundary quickly. The located bounding box is regarded as an accurate initial contour. This avoids the negative impact of manual initialization. Finally, we perform vertebral centroid extraction and spinal curve fitting. The spinal curvature angle is determined by calculating the angle between two tangents to the curve. We verified the effectiveness of the proposed method on 10 spine CT volumes. Quantitative comparison against the ground-truth centroids yielded a detection accuracy rate of 98.3% and a mean centroid location error of 1.15 mm. The comparative results with existing methods demonstrate that the proposed method can accurately detect and segment vertebral bodies. Furthermore, the spinal curvature can be automatically measured without manual landmark.

Using Convolutional Neural Networks for the Detection of Spinal Transverse Processes

Introduction: Scoliosis, an excessive curvature of the spine, affects approximately 1 in 1,000 individuals. As a result, there have formerly been implementations of mandatory scoliosis screening procedures. Screening programs are no longer widely used as the harms often outweigh the benefits; it causes many adolescents to undergo frequent diagnosis X-ray procedure This makes spinal ultrasounds an ideal substitute for scoliosis screening in patients, as it does not expose them to those levels of radiation.&#x0D; Spinal curvatures can be accurately computed from the location of spinal transverse processes, by measuring the vertebral angle from a reference line [1]. However, ultrasound images are less clear than x-ray images, making it difficult to identify the spinal processes. To overcome this, we employ deep learning using a convolutional neural network, which is a powerful tool for computer vision and image classification [2].&#x0D; Method: A total of 2,752 ultrasound images were recorded from a spine phantom to train a convolutional neural network. Subsequently, we took another recording of 747 images to be used for testing. All the ultrasound images from the scans were then segmented manually, using the 3D Slicer (www.slicer.org) software. Next, the dataset was fed through a convolutional neural network. The network used was a modified version of GoogLeNet (Inception v1), with 2 linearly stacked inception models. This network was chosen because it provided a balance between accurate performance, and time efficient computations.&#x0D; Results: Deep learning classification using the Inception model achieved an accuracy of 84% for the phantom scan.&#x0D; Conclusion: The classification model performs with considerable accuracy. Better accuracy needs to be achieved, possibly with more available data and improvements in the classification model.&#x0D; Acknowledgements: G. Fichtinger is supported as a Canada Research Chair in Computer-Integrated Surgery. This work was funded, in part, by NIH/NIBIB and NIH/NIGMS (via grant 1R01EB021396-01A1 - Slicer+PLUS: Point-of-Care Ultrasound) and by CANARIE’s Research Software Program. &#x0D; &#x0D; Figure 1: Ultrasound scan containing a transverse process (left), and ultrasound scan containing no transverse process (right). Figure 2: Accuracy of classification for training (red) and validation (blue).&#x0D;

Factors influencing spinal curvature measurements on ultrasound images for children with adolescent idiopathic scoliosis (AIS).

The measurements of spinal curvatures using the ultrasound (US) imaging method on children with scoliosis have been comparable with radiography. However, factors influencing the reliability and accuracy of US measurement have not been studied. The purpose of this study is to investigate the effects of curve features and patients’ demographics on US measurements and to determine which factors influence the reliability and accuracy. Two hundred children with scoliosis were recruited and scanned with US by one experienced operator and three trainees. One experienced rater measured the proxy Cobb angles from US images twice one week apart and compared the results with clinical radiographic records. The correlation and accuracy between the US and radiographic measurements were subdivided by different curve severities, curve types, subjects’ weight status and US acquisition experiences. A total of 326 and 313 curves were recognized from radiographs and US images, respectively. The mean Cobb angles of the 13 missing curves were 17.4±7.4° and 11 at the thoracic region. Among the 16 curves showing large discrepancy (≥6°) between US and radiographic measurements, 7 were main thoracic and 6 were lumbar curves. Twelve had axial vertebral rotation (AVR) greater than 8°. The US scans performed by the experienced operator showed fewer large discrepancy curves, smaller difference and higher correlation than the scans from the trainees (3%, 1.7±1.5°, 0.95 vs 6%, 2.4±1.8°, 0.90). Only 4% missing and 5% large discrepancy curves were demonstrated for US measurements in comparison to radiography. The missing curves were mainly caused by small severity and in the upper spinal region. There was a higher chance of the large discrepancy curves in the main thoracic and lumbar regions with AVR>8°. A skilled operator acquired better US images and led to more accurate measurements especially for those subjects with larger curvatures, AVR and body mass index (BMI).

Test-retest reliability and validity of a motion capture (MOCAP) system for measuring thoracic and lumbar spinal curvatures and sacral inclination in the sagittal plane.

To evaluate the test-retest reliability and validity of the MOCAP system for measuring spinal sagittal thoracic and lumbar curvatures and sacral inclination in a standing posture. Twenty-five male adults were evaluated on lateral standing radiographs. The thoracic and lumbar curvatures were calculated by Harrison's posterior tangent method. The sacral inclination was defined as the angle between the tangent line of the sacral and vertical plane. In addition, MOCAP was used to calculate the spinal curvatures and sacral inclination. The thoracic and lumbar spine and sacral inclination demonstrated excellent reliability, with mean ICCs levels greater than 0.980 and low CVs (mean: 2.15%). Systematic biases were not significant and were very near 0, and the mean standard errors were 0.257∘. ANOVA of the radiographic and MOCAP measures did not report any statistically significant differences in the comparisons. The systematic biases and mean random errors were lower than 1∘, with CVs lower than 5% and mean ICCs higher than 0.90 between sessions. The MOCAP system delivered consistently reliable and valid results for standing curvatures compared with a radiographic technique. This system could be used with confidence in research and clinical environments for sagittal spinal curvature measurements.

Test-retest reliability and validity of a motion capture (MOCAP) system for measuring thoracic and lumbar spinal curvatures and sacral inclination in the sagittal plane

To evaluate the test-retest reliability and validity of the MOCAP system for measuring spinal sagittal thoracic and lumbar curvatures and sacral inclination in a standing posture. Twenty-five male adults were evaluated on lateral standing radiographs. The thoracic and lumbar curvatures were calculated by Harrison's posterior tangent method. The sacral inclination was defined as the angle between the tangent line of the sacral and vertical plane. In addition, MOCAP was used to calculate the spinal curvatures and sacral inclination. The thoracic and lumbar spine and sacral inclination demonstrated excellent reliability, with mean ICCs levels greater than 0.980 and low CVs (mean: 2.15%). Systematic biases were not significant and were very near 0, and the mean standard errors were 0.257∘. ANOVA of the radiographic and MOCAP measures did not report any statistically significant differences in the comparisons. The systematic biases and mean random errors were lower than 1∘, with CVs lower than 5% and mean ICCs higher than 0.90 between sessions. The MOCAP system delivered consistently reliable and valid results for standing curvatures compared with a radiographic technique. This system could be used with confidence in research and clinical environments for sagittal spinal curvature measurements.

Contour and Angle-Function Based Scoliosis Monitoring: Relaxing the Requirement on Image Quality in the Measurement of Spinal Curvature.

A method for measuring spinal curvature that provides a useful analog to the Cobb angle and is tolerant of degraded image quality is proposed. Conventional methods require a higher standard of discernibility for vertebra features and suffer high variability. Assumption is made that the natural representation of the spine for the purpose of scoliosis monitoring is that of a continuous curved contour rather than a series of discrete vertebral bodies with individual orientations. The angle that a tangent line to this contour makes with the vertical, expressed as a continuous function of height, is proposed as a metric for characterization of the curve. The Cobb angle can be approximated as the difference between the extrema of this function, and details of the function shape can provide additional markers for tracking curve variation and evolution. A method for deriving the angle function from coronal images of the spine is proposed, and both manual and automatic variants of the procedure are described. The method is applied to conventional coronal radiographs and to magnetic resonance (MR) coronal views derived from volumetric acquisitions of the spine. Included in the latter category is an image exhibiting poor discrimination of vertebra features due to motion artifacts. The method permits extraction of the curve and Cobb angles in all cases. Because the spine contour is discernible even in low quality images where vertebral endplates may be obscured or poorly contrasted from surrounding tissue, the approach offers improved reliability, applicability across imaging modalities, and, in the case of x-rays, the possibility of a reduced radiation dose. Moreover, since it relies on larger image features and exploits the continuity of the spine, the contour-based approach is expected to reduce the variability associated with Cobb angle measurement.

Sagittal spinal curvatures in adolescent male basketball players and non-training individuals – a two-year study

Summary Objective To compare changes in anteroposterior spinal curvatures in young male basketball players and non-training controls over a 2-year period. Methods The study included 10 basketball players and 11 non-training males. At the start of the study, all participants were aged 13; they underwent three anteroposterior spinal curvature measurements at baseline and years 1 and 2 of the study. A Rippstein plurimeter was used to determine anteroposterior spinal curvatures. Results Basketball players and their non-training peers only differed regarding the 1st quantification of lumbar lordosis ( P P P P > 0.05). Conclusions The shape of anteroposterior spinal curvatures has changed in both basketball players and non-athletes; however, the trends of these changes were different. Basketball players exhibited age- and training time-related flattening of the thoracic spine while non-athletes showed deepening of the thoracic kyphosis. This might evidence some effect of regular basketball training on the shape of anteroposterior spinal curvatures.

Improvement on the Accuracy and Reliability of Ultrasound Coronal Curvature Measurement on Adolescent Idiopathic Scoliosis With the Aid of Previous Radiographs.

Retrospective study of the coronal curvature measurement on ultrasound (US) images with the aid of previous radiographs. To compare the reliability and accuracy of the coronal curvature measurements from US images on children who have adolescent idiopathic scoliosis (AIS) with and without the knowledge of previous radiographs. Using US imaging technique to measure coronal curvature on children with AIS has demonstrated high intra- and interrater reliabilities. However, the selection of end-vertebrae and the measurement difference between radiography and the US method were only moderately reliable. Two raters measured the coronal curvatures from 65 AIS standing US spine images, without (measured one time) and with the aid of previous standing radiographs (measured two times). The intra- and interrater reliability, the correlation and the difference between the radiographic and US measurements, and the error index of the end-vertebrae selection were assessed. Overall, 109 curves were investigated. The intraclass correlation coefficients (ICC) of intra- and interrater reliability of the US coronal curvature measurement with the aid of previous radiographs (AOR) were 0.95 and 0.91, respectively. In comparison with the radiographic measurements, the correlation of AOR method (R) was 0.90 and the MAD was 2.8°; the corresponding results of the US measurement without the AOR (blinded US method) were 0.73° and 4.8°, respectively. The average error index on end-vertebral selection improved 43% with the AOR. The AOR method significantly improved reliability and accuracy of the spinal curvature measurement on US images compared with the blinded US method (P<0.001). It indicates that US standing images with the AOR can be used as a reliable and accurate nonionizing imaging method to monitor children with AIS. 3.

Using Skin Markers for Spinal Curvature Quantification in Main Thoracic Adolescent Idiopathic Scoliosis: An Explorative Radiographic Study.

Background and PurposeAlthough the relevance of understanding spinal kinematics during functional activities in patients with complex spinal deformities is undisputed among researchers and clinicians, evidence using skin marker-based motion capture systems is still limited to a handful of studies, mostly conducted on healthy subjects and using non-validated marker configurations. The current study therefore aimed to explore the validity of a previously developed enhanced trunk marker set for the static measurement of spinal curvature angles in patients with main thoracic adolescent idiopathic scoliosis. In addition, the impact of inaccurate marker placement on curvature angle calculation was investigated.MethodsTen patients (Cobb angle: 44.4±17.7 degrees) were equipped with radio-opaque markers on selected spinous processes and underwent a standard biplanar radiographic examination. Subsequently, radio-opaque markers were replaced with retro-reflective markers and the patients were measured statically using a Vicon motion capture system. Thoracolumbar / lumbar and thoracic curvature angles in the sagittal and frontal planes were calculated based on the centers of area of the vertebral bodies and radio-opaque markers as well as the three-dimensional position of the retro-reflective markers. To investigate curvature angle estimation accuracy, linear regression analyses among the respective parameters were used. The impact of inaccurate marker placement was explored using linear regression analyses among the radio-opaque marker- and spinous process-derived curvature angles.Results and DiscussionThe results demonstrate that curvatures angles in the sagittal plane can be measured with reasonable accuracy, whereas in the frontal plane, angles were systematically underestimated, mainly due to the positional and structural deformities of the scoliotic vertebrae. Inaccuracy of marker placement had a greater impact on thoracolumbar / lumbar than thoracic curvature angles. It is suggested that spinal curvature measurements are included in marker-based clinical gait analysis protocols in order to enable a deeper understanding of the biomechanical behavior of the healthy and pathological spine in dynamic situations as well as to comprehensively evaluate treatment effects.

Reliability and Validity Study of Clinical Ultrasound Imaging on Lateral Curvature of Adolescent Idiopathic Scoliosis.

BackgroundNon-ionizing radiation imaging assessment has been advocated for the patients with adolescent idiopathic scoliosis (AIS). As one of the radiation-free methods, ultrasound imaging has gained growing attention in scoliosis assessment over the past decade. The center of laminae (COL) method has been proposed to measure the spinal curvature in the coronal plane of ultrasound image. However, the reliability and validity of this ultrasound method have not been validated in the clinical setting.ObjectivesTo evaluate the reliability and validity of clinical ultrasound imaging on lateral curvature measurements of AIS with their corresponding magnetic resonance imaging (MRI) measurements.MethodsThirty curves (ranged 10.2°–68.2°) from sixteen patients with AIS were eligible for this study. The ultrasound scan was performed using a 3-D ultrasound unit within the same morning of MRI examination. Two researchers were involved in data collection of these two examinations. The COL method was used to measure the coronal curvature in ultrasound image, compared with the Cobb method in MRI. The intra- and inter-rater reliability of the COL method was evaluated by intra-class correlation coefficient (ICC). The validity of this method was analyzed by paired Student’s t-test, Bland–Altman statistics and Pearson correlation coefficient. The level of significance was set as 0.05.ResultsThe COL method showed high intra- and inter-rater reliabilities (both with ICC (2, K) >0.9, p<0.05) to measure the coronal curvature. Compared with Cobb method, COL method showed no significant difference (p<0.05) when measuring coronal curvature. Furthermore, Bland-Altman method demonstrated an agreement between these two methods, and Pearson’s correlation coefficient (r) was high (r>0.9, p<0.05).ConclusionThe ultrasound imaging could provide a reliable and valid measurement of spinal curvature in the coronal plane using the COL method. Further research is needed to validate the proposed ultrasound measurement in larger clinical trial and to optimize the ultrasound scanning and measuring procedure.

Spinal Curvature Measurement by Tracked Ultrasound Snapshots

Monitoring spinal curvature in adolescent kyphoscoliosis requires regular radiographic examinations; however, the applied ionizing radiation increases the risk of cancer. Ultrasound imaging is favored over radiography because it does not emit ionizing radiation. Therefore, we tested an ultrasound system for spinal curvature measurement, with the help of spatial tracking of the ultrasound transducer. Tracked ultrasound was used to localize vertebral transverse processes as landmarks along the spine to measure curvature angles. The method was tested in two scoliotic spine models by localizing the same landmarks using both ultrasound and radiographic imaging and comparing the angles obtained. A close correlation was found between tracked ultrasound and radiographic curvature measurements. Differences between results of the two methods were 1.27 ± 0.84° (average ± SD) in an adult model and 0.96 ± 0.87° in a pediatric model. Our results suggest that tracked ultrasound may become a more tolerable and more accessible alternative to radiographic spine monitoring in adolescent kyphoscoliosis.