Reliability of the axial vertebral rotation measurements of adolescent idiopathic scoliosis using the center of lamina method on ultrasound images: in vitro and in vivo study

The evolution and integration of technology in spinal neurosurgery: A scoping review

Spinal disorders pose a significant global health challenge, affecting nearly 5% of the population and incurring substantial socioeconomic costs. Over time, spinal neurosurgery has evolved from basic 19th-century techniques to today's minimally invasive procedures. The recent integration of technologies such as robotic assistance and advanced imaging has not only improved precision but also reshaped treatment paradigms. This review explores key innovations in imaging, biomaterials, and emerging fields such as AI, examining how they address long-standing challenges in spinal care, including enhancing surgical accuracy and promoting tissue regeneration. Are we at the threshold of a new era in healthcare technology, or are these innovations merely enhancements that may not fundamentally advance clinical care? We aim to answer this question by offering a concise introduction to each technology and discussing in depth its status and challenges, providing readers with a clearer understanding of its actual potential to revolutionize surgical practices.

Reliability and accuracy of scoliotic parameters on using a wireless handheld 3D ultrasound for children with adolescent idiopathic scoliosis: a pilot study

PURPOSE

To report the accuracy and reliability of Cobb angle (CA), axial vertebral rotation (AVR), kyphotic and lordotic angles (KA and LA) measurements on using a new 3D ultrasound (US) system.

METHODS

Forty participants (34 F, 6 M, aged 14.0 ± 2.3 years) were recruited. The first 20 participants were scanned by the validated US system and the new US system. The other 20 participants were scanned with the new US system only. Two raters (R1 and R2) performed the measurements: R1 has 10 years of experience in radiology but is new in ultrasound scoliosis, while R2 has 30 years of scoliosis experience. All US images were measured twice by R1, and once by R2. Forty posteroanterior and 30 lateral standing radiographs were obtained and measured once by R1. Statistical analysis consisted of mean absolute difference (MAD), intraclass correlation coefficient (ICC (2,1)), and Bland-Altman plots.

RESULTS

R1 showed excellent intra-rater and inter-rater reliability for US measurements with ICCs(2,1) ≥ 0.91. The inter-method reliability was good between the two US systems for all parameters with ICCs(2,1) ≥ 0.85 and maximum MAD of 3.4°. The new US showed good reliability and accuracy compared to radiographs for CA, AVR and KA with ICCs(2,1) ≥ 0.81 and maximum MAD of 5.8°, but poor results for LA with ICCs(2,1) of 0.27-0.35 and MADs of 14.0°-15.4°.

CONCLUSION

The new 3D US system showed good reliability and accuracy for CA, AVR and KA measurements, but a large measurement discrepancy on LA. A new measurement method for US LA may need to investigate.

Validity and accuracy of automatic cobb angle measurement on 3D spinal ultrasonographs for children with adolescent idiopathic scoliosis: SOSORT 2024 award winner

PURPOSE

Ultrasonography for scoliosis is a novel imaging method that does not expose children with adolescent idiopathic scoliosis (AIS) to radiation. A single ultrasound scan provides 3D spinal views directly. However, measuring ultrasonograph parameters is challenging, time-consuming, and requires considerable training. This study aimed to validate a machine learning method to measure the coronal curve angle on ultrasonographs automatically.

METHODS

A total of 144 3D spinal ultrasonographs were extracted to train and validate a machine learning model. Among the 144 images, 70 were used for training, and 74 consisted of 144 curves for testing. Automatic coronal curve angle measurements were validated by comparing them with manual measurements performed by an experienced rater. The inter-method intraclass correlation coefficient (ICC2,1), standard error of measurement (SEM), and percentage of measurements within clinical acceptance (≤ 5°) were analyzed.

RESULTS

The automatic method detected 125/144 manually measured curves. The averages of the 125 manual and automatic coronal curve angle measurements were 22.4 ± 8.0° and 22.9 ± 8.7°, respectively. Good reliability was achieved with ICC2,1 = 0.81 and SEM = 1.4°. A total of 75% (94/125) of the measurements were within clinical acceptance. The average measurement time per ultrasonograph was 36 ± 7 s. Additionally, the algorithm displayed the predicted centers of laminae to illustrate the measurement.

CONCLUSION

The automatic algorithm measured the coronal curve angle with moderate accuracy but good reliability. The algorithm's quick measurement time and interpretability can make ultrasound a more accessible imaging method for children with AIS. However, further improvements are needed to bring the method to clinical use.

Three-dimensional ultrasonography could be a potential non-ionizing tool to evaluate vertebral rotation of subjects with adolescent idiopathic scoliosis

Background

Three-dimensional (3D) ultrasonography is nonionizing and has been demonstrated to be a reliable tool for scoliosis assessment, including coronal and sagittal curvatures. It shows a great potential for axial vertebral rotation (AVR) evaluation, yet its validity and reliability need to be further demonstrated.

Materials and Methods

Twenty patients with adolescent idiopathic scoliosis (AIS) (coronal Cobb: 26.6 ± 9.1°) received 3D ultrasound scan for twice, 10 were scanned by the same operator, and the other 10 by different operators. EOS Bi-planar x-rays and 3D scan were conducted on another 29 patients on the same day. Two experienced 3D ultrasonographic researchers, with different experiences on AVR measurement, evaluated the 3D ultrasonographic AVR of the 29 patients (55 curves; coronal Cobb angle: 26.9 ± 11.3°). The gold standard AVR was determined from the 3D reconstruction of coronal and sagittal EOS radiographs. Intra-class correlation coefficients (ICCs), mean absolute difference (MAD), standard error measurements (SEM), and Bland-Altman's bias were reported to evaluate the intra-operator and inter-operator/rater reliabilities of 3D ultrasonography. The reliability of 3D ultrasonographic AVR measurements was further validated using inter-method with that of EOS.

Results

ICCs for intra-operator and inter-operator/rater reliability assessment were all greater than 0.95. MAD, SEM, and bias for the 3D ultrasonographic AVRs were no more than 2.2°, 2.0°, and 0.5°, respectively. AVRs between both modalities were strongly correlated (R 2 = 0.901) and not significantly different (p = 0.205). Bland-Altman plot also shows that the bias was less than 1°, with no proportional bias between the difference and mean of expected and radiographic Cobb angles.

Conclusion

This study demonstrates that 3D ultrasonography is valid and reliable to evaluate AVR in AIS patients. 3D ultrasonography can be a potential tool for screening and following up subjects with AIS and evaluating the effectiveness of nonsurgical treatments.

Assessment of thoracic spinal curvatures in static postures using spatially tracked 3D ultrasound volumes: a proof-of-concept study

The assessment of spinal posture is a difficult endeavour given the lack of identifiable bony landmarks for placement of skin markers. Moreover, potentially significant soft tissue artefacts along the spine further affect the accuracy of marker-based approaches. The objective of this proof-of-concept study was to develop an experimental framework to assess spinal postures by using three-dimensional (3D) ultrasound (US) imaging. A phantom spine model immersed in water was scanned using 3D US in a neutral and two curved postures mimicking a forward flexion in the sagittal plane while the US probe was localised by three electromagnetic tracking sensors attached to the probe head. The obtained anatomical 'coarse' registrations were further refined using an automatic registration algorithm and validated by an experienced sonographer. Spinal landmarks were selected in the US images and validated against magnetic resonance imaging data of the same phantom through image registration. Their position was then related to the location of the tracking sensors identified in the acquired US volumes, enabling the localisation of landmarks in the global coordinate system of the tracking device. Results of this study show that localised 3D US enables US-based anatomical reconstructions comparable to clinical standards and the identification of spinal landmarks in different postures of the spine. The accuracy in sensor identification was 0.49 mm on average while the intra- and inter-observer reliability in sensor identification was strongly correlated with a maximum deviation of 0.8 mm. Mapping of landmarks had a small relative distance error of 0.21 mm (SD = ± 0.16) on average. This study implies that localised 3D US holds the potential for the assessment of full spinal posture by accurately and non-invasively localising vertebrae in space.

Nonoperative management of adolescent idiopathic scoliosis (AIS) using braces

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.

Artificial intelligence in spine care: current applications and future utility

PURPOSE

The field of artificial intelligence is ever growing and the applications of machine learning in spine care are continuously advancing. Given the advent of the intelligence-based spine care model, understanding the evolution of computation as it applies to diagnosis, treatment, and adverse event prediction is of great importance. Therefore, the current review sought to synthesize findings from the literature at the interface of artificial intelligence and spine research.

METHODS

A narrative review was performed based on the literature of three databases (MEDLINE, CINAHL, and Scopus) from January 2015 to March 2021 that examined historical and recent advancements in the understanding of artificial intelligence and machine learning in spine research. Studies were appraised for their role in, or description of, advancements within image recognition and predictive modeling for spinal research. Only English articles that fulfilled inclusion criteria were ultimately incorporated in this review.

RESULTS

This review briefly summarizes the history and applications of artificial intelligence and machine learning in spine. Three basic machine learning training paradigms: supervised learning, unsupervised learning, and reinforced learning are also discussed. Artificial intelligence and machine learning have been utilized in almost every facet of spine ranging from localization and segmentation techniques in spinal imaging to pathology specific algorithms which include but not limited to; preoperative risk assessment of postoperative complications, screening algorithms for patients at risk of osteoporosis and clustering analysis to identify subgroups within adolescent idiopathic scoliosis. The future of artificial intelligence and machine learning in spine surgery is also discussed with focusing on novel algorithms, data collection techniques and increased utilization of automated systems.

CONCLUSION

Improvements to modern-day computing and accessibility to various imaging modalities allow for innovative discoveries that may arise, for example, from management. Given the imminent future of AI in spine surgery, it is of great importance that practitioners continue to inform themselves regarding AI, its goals, use, and progression. In the future, it will be critical for the spine specialist to be able to discern the utility of novel AI research, particularly as it continues to pervade facets of everyday spine surgery.

Intra- and inter-rater reliabilities and differences of kyphotic angle measurements on ultrasound images versus radiographs for children with adolescent idiopathic scoliosis: a preliminary study

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.

Optimized scheme for paired transverse corrective forces in S-shaped scoliosis via ultrasound and application in Chêneau brace: a pilot study

BACKGROUND

There is currently no consensus on the optimal positions of the transverse corrective forces (TCFs) for scoliosis braces.

OBJECTIVES

This study aimed to explore an optimal scheme of placing paired TCF for S-shaped adolescent idiopathic scoliosis and its feasibility in Chêneau brace (CB) treatment.

STUDY DESIGN

Cross-over feasibility pilot trial.

METHODS

Ten S-shaped adolescent idiopathic scoliosis participants were invited to receive four tests with different paired TCF positions under ultrasound. The positions of the paired TCF were test 1: thoracic apical vertebra (AV), lumbar AV; test 2: 2 cm inferior to thoracic AV, lumbar AV; test 3: thoracic AV, 2 cm superior to lumbar AV; and test 4: 2 cm inferior to thoracic AV, 2 cm superior to lumbar AV. The test scheme with the highest mean in-force correction rate (IFCR) for the thoracic spinous process angle (SPA) was further applied in the CB fabrication of 4 additional participants.

RESULTS

A significant higher mean IFCR of the thoracic SPA of 63.6% was found in test 2 (P < 0.001), which also contributed to its higher overall IFCR of the SPA of 64.6% (P = 0.001). Moreover, the mean in-brace correction rates for the thoracic and overall curves in CB were 46.4% and 51.8%, respectively. No adverse events were reported.

CONCLUSIONS

Placing paired TCF at the lumbar AV and 2 cm inferior to the thoracic AV achieved better treatment efficacy than other schemes. The practical application of this scheme on the CB was feasible.

[Automatic extraction of vertebral landmarks from ultrasound images]

Some forms of myopathies such as Duchenne muscular dystrophy cause a progressive degeneration of the patient's muscles. This results in the development of scoliosis, which increases in severity over time. The clinical standard for monitoring scoliosis is to perform an X-ray on a regular basis. Unfortunately, repeated exposure to X-rays is harmful to the patient's health. Ultrasound imaging is a radiation-free modality that uses ultrasound (US) waves. However, the interpretation of vertebral ultrasound images is often difficult due to the variable quality of the image. In order to tackle this challenge, we present a method to localize the vertebrae on US images automatically. The validation of this reproducible approach suggests that it would be possible, in the long term, to replace part of the X-ray exams by US imaging.

Evaluation of Scoliosis With a Commercially Available Ultrasound System

OBJECTIVES

Currently, radiography with measurement of the Cobb angle is still considered the reference standard for diagnosing scoliosis. However, the ionizing radiation hazard is drawing wide attention. Can 3-dimensional (3D) ultrasound (US) be an alternative modality for diagnosing and monitoring patients with scoliosis? The aim of our study was to assess the reliability and validity of 3D US imaging in the evaluation of scoliosis.

METHODS

A commercially available ultrasound system with a magnetic tracking system was selected for long-distance 3D US imaging. Straight phantoms and curved phantoms were scanned with the imaging system to evaluate the stability of the system for curvature measurements. Eight healthy adult volunteers and 28 patients with scoliosis were recruited for long-distance 3D US imaging. The intraclass correlation coefficient was used to test the reproducibility of the interobserver and intraobserver measurements for both the healthy adults and patients with scoliosis. A linear regression analysis and Bland-Altman plot were used to analyze the correlation and to determine the extent of agreement between the angles measured on US images and the Cobb angles measured on conventional radiographs.

RESULTS

The 28 patients with scoliosis included 10 male and 18 female patients aged 8 to 37 years (mean age ± SD, 17.7 ± 1.4 years; body mass index, <25 kg/m² ). In the phantom study, there was no statistically significant difference between the angles measured by the 3D US imaging system and those measured by an angle gauge (P > 0.05). In the clinical study, there was very good interobserver and intraobserver reliability (intraclass correlation coefficients, >0.90) for the US imaging system, with a high correlation (r² = 0.92) and agreement between the US and radiographic methods.

CONCLUSIONS

The long-distance 3D US imaging system offers a viable modality for diagnosing and monitoring scoliosis without radiation.

A semi-automatic 3D ultrasound reconstruction method to assess the true severity of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a three-dimensional (3D) spinal deformity. Current practice uses the Cobb method to measure spinal severity on postero-anterior (PA) radiographs. This method may underestimate spinal deformity and exposes patients to ionizing radiation, increasing the risk of cancer. This paper reports a new 3D ultrasound method using the voxel-based reconstruction technique with bilinear interpolation to reconstruct a 3D spinal image and measure true spinal curvature on the plane of maximal curvature (PMC). Axial vertebral rotation (AVR) was measured on the 3D image and utilized to estimate the PMC. In vitro phantom experiments and in vivo clinical study were conducted to evaluate reconstruction accuracy and measurement reliability. The in vitro study showed a high accuracy of the reconstruction of vertebrae with the mean absolute difference (MAD) < 3 mm. The in vitro and in vivo measurements of AVR were reliable (> 0.90). The in vivo study also showed high intra- and inter-rater reliabilities of the PA and PMC Cobb angle measurements with ICC values > 0.90 and MADs within the clinical accepted tolerances. The PMC Cobb angles were up to 7° greater than their corresponding PA Cobb angles. This method demonstrated a non-ionizing radiation method to assess the actual severity of AIS. Graphical abstract Adolescent idiopathic scoliosis (AIS) is a lateral curvature of spine with vertebral rotation. Using the Cobb method to measure spinal severity on postero-anterior (PA) radiographs may under estimate its severity.

Intra- and Interrater Reliability of Cobb Angle Measurements on the Plane of Maximum Curvature Using Ultrasound Imaging Method

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.

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).

Novel porcine experimental model of severe progressive thoracic scoliosis with compensatory curves induced by interpedicular bent rigid temporary tethering

Using flexible tethering techniques, porcine models of experimental scoliosis have shown scoliotic curves with vertebral wedging but very limited axial rotation. The aim of this experimental work was to induce a severe progressive scoliosis in a growing porcine model for research purposes. A unilateral spinal bent rigid tether was anchored to two ipsilateral pedicle screws in eight pigs. The spinal tether was removed after 8 weeks. Ten weeks later, the animals were sacrificed. Conventional radiographs and 3D CT-scans were taken to evaluate changes in the alignment of the thoracic spine. After the first 8 weeks of rigid tethering, all animals developed scoliotic curves (mean Cobb angle: 24.3°). Once the interpedicular tether was removed, the scoliotic curves progressed in all animals during 10 weeks reaching a mean Cobb angle of 49.9°. The sagittal alignment of the thoracic spine showed loss of physiologic kyphosis (Mean: -18.3°). Axial rotation ranged from 10° to 49° (Mean 25.7°). Release of the spinal tether results in progression of the deformity with the development of proximal and distal compensatory curves. In conclusion, temporary interpedicular tethering at the thoracic spine induces severe scoliotic curves in pigs, with significant wedging and rotation of the vertebral bodies, and true compensatory curves.

CLINICAL RELEVANCE

The tether release model will be used to evaluate corrective non-fusion technologies in future investigations. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:174-182, 2018.

Results of ultrasound-assisted brace casting for adolescent idiopathic scoliosis

Background

Four factors have been reported to affect brace treatment outcome: (1) growth or curve based risk, (2) the in-brace correction, (3) the brace wear quantity, and (4) the brace wear quality. The quality of brace design affects the in-brace correction and comfort which indirectly affects the brace wear quantity and quality. This paper reported the immediate benefits and results on using ultrasound (US) to aid orthotists to design braces for the treatment of scoliosis.

Methods

Thirty-four AIS subjects participated in this study with 17 (2 males, 15 females) in the control group and 17 (2 males, 15 females) in the intervention (US) group. All participants were prescribed full time TLSO, constructed by either of the 2 orthotists in fabrication of spinal braces. For the control group, the Providence brace design system was adopted to design full time braces. For the intervention group, the custom standing Providence brace design system, plus a medical ultrasound system, a custom pressure measurement system and an in-house software were used to assist brace casting.

Results

In the control group, 8 of 17 (47%) subjects needed a total of 11 brace adjustments after initial fabrication requiring a total of 28 in-brace radiographs. Three subjects (18%) required a second adjustment. For the US group, only 1 subject (6%) required adjustment. The total number of in-brace radiographs was 18. The p value of the chi-square for requiring brace adjustment was 0.006 which was a statistically significant difference between the two groups. In the intervention group, the immediate in-brace correction as measured from radiographs was 48 ± 17%, and in the control group the first and second in-brace correction was 33 ± 19% and 40 ± 20%, respectively. The unpaired 2 sided Student’s t test of the in-brace correction was significantly different between the US and the first follow-up of the control group (p = 0.02), but was not significant after the second brace adjustment (p = 0.22).

Conclusions

The use of the 3D ultrasound system provided a radiation-free method to determine the optimum pressure level and location to assist brace design, resulting in decreased radiation exposure during follow-up brace evaluation, increased the in-brace correction, reduced the patients’ visits to both brace adjustment and scoliosis clinics. However, the final outcomes could not be reported yet as some of patients are still under brace treatment.

Trial registration

NCT02996643, retrospectively registered in 16 December 2016

Patient-specific 3D models created by 3D imaging system or bi-planar imaging coupled with Moiré-Fringe projections: a comparative study of accuracy and reliability on spinal curvatures and vertebral rotation data

PURPOSE

The aim of this study is to compare the accuracy and reliability of spinal curvatures and vertebral rotation data based on patient-specific 3D models created by 3D imaging system or by bi-planar imaging coupled with Moiré-Fringe projections.

METHODS AND MATERIALS

Sixty-two consecutive patients from a single institution were prospectively included. For each patient, frontal and sagittal calibrated low-dose bi-planar X-rays were performed and coupled simultaneously with an optical Moiré back surface-based technology. The 3D reconstructions of spine and pelvis were performed independently by one radiologist and one technician in radiology using two different semi-automatic methods using 3D radio-imaging system (method 1) or bi-planar imaging coupled with Moiré projections (method 2). Both methods were compared using Bland-Altman analysis, and reliability using intraclass correlation coefficient (ICC).

RESULTS

ICC showed good to very good agreement. Between the two techniques, the maximum 95 % prediction limits was -4.9° degrees for the measurements of spinal coronal curves and less than 5° for other parameters. Inter-rater reliability was excellent for all parameters across both methods, except for axial rotation with method 2 for which ICC was fair. Method 1 was faster for reconstruction time than method 2 for both readers (13.4 vs. 20.7 min and 10.6 vs. 13.9 min; p = 0.0001).

CONCLUSION

While a lower accuracy was observed for the evaluation of the axial rotation, bi-planar imaging coupled with Moiré-Fringe projections may be an accurate and reliable tool to perform 3D reconstructions of the spine and pelvis.