Validity of a fast automated 3d spine reconstruction measurements for biplanar radiographs: SOSORT 2024 award winner.

PURPOSE: To validate a fast 3D biplanar spinal radiograph reconstruction method with automatic extract curvature parameters using artificial intelligence (AI). METHODS: Three-hundred eighty paired, posteroanterior and lateral, radiographs from the EOS X-ray system of children with adolescent idiopathic scoliosis were randomly selected from the database. For the AI model development, 304 paired images were used for training; 76 pairs were employed for testing. The validation was evaluated by comparing curvature parameters, including Cobb angles (CA), apical axial vertebral rotation (AVR), kyphotic angle (T1-T12 KA), and lordotic angle (L1-L5 LA), to manual measurements from a rater with 8 years of scoliosis experience. The mean absolute differences ± standard deviation (MAD ± SD), the percentage of measurements within the clinically acceptable errors, the standard error of measurement (SEM), and the inter-method intraclass correlation coefficient ICC[2,1] were calculated. The average reconstruction speed of the 76 test images was recorded. RESULTS: Among the 76 test images, 134 and 128 CA were exported automatically and measured manually, respectively. The MAD ± SD for CA, AVR at apex, KA, and LA were 3.3° ± 3.5°, 1.5° ± 1.5°, 3.3° ± 2.6° and 3.5° ± 2.5°, respectively, and 98% of these measurements were within the clinical acceptance errors. The SEMs and the ICC[2,1] for the compared parameters were all less than 0.7° and > 0.94, respectively. The average time to display the 3D spine and report the measurements was 5.2 ± 1.3 s. CONCLUSION: The developed AI algorithm could reconstruct a 3D scoliotic spine within 6 s, and the automatic curvature parameters were accurately and reliably extracted from the reconstructed images.

Investigation of ultrasonic soft tissue-bone reflection coefficients correlating with curve severity in children with adolescent idiopathic scoliosis.

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.

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.

Reliability of measurements of a reflection coefficient index to indicate spinal bone strength on adolescents with idiopathic scoliosis (AIS): a pilot study.

PURPOSE: To investigate the test-retest, intra- and inter-rater reliabilities of an ultrasound (US) reflection coefficient (RC) index measured in a lumbar vertebra to reflect bone strength on children with AIS. METHODS: Fifty-eight participants (47F; 11M) were scanned by an US imager in standing position. Twenty-four were scanned twice for a test-retest study. The RC index measures the US signal reflected from L5 to indicate bone strength. Five measurements were obtained using three different methods: (i) the maximum RC (MRC) values on the left and right sides, (ii) the average RC (ARC) values on left and right sides, and (iii) the combined average RC (CARC) from both sides. Only rater 1 measured the 24 repeated US scans once. Raters 1 and 2 measured the RC index twice on all 58 images in 1 week apart. The intraclass correlation coefficient ICC [3, 1] for test-retest and ICC [2, 1] for intra- and inter-rater reliabilities as well as the standard error of measurements (SEM) were reported. RESULTS: The means of scan 1 versus scan 2 were 0.16 ± 0.08 versus 0.16 ± 0.07 for left-MRC, 0.17 ± 0.11 versus 0.18 ± 0.11 for right-MRC, 0.08 ± 0.04 versus 0.09 ± 0.04 for left-ARC, 0.09 ± 0.04 versus 0.09 ± 0.05 for right-ARC and 0.08 ± 0.04 versus 0.09 ± 0.03 for CARC and all ICC[3, 1] ≥ 0.77. Among these 5 approaches, the CARC provided the best intra-rater and inter-rater reliabilities with ICC [2, 1] ≥ 0.84 and SEM ≤ 0.01. CONCLUSIONS: The RC index could be measured repeatably and reliably. The high RC value may reduce the risk of progression of scoliosis.

Radiographic methods to estimate surgical outcomes based on spinal flexibility assessment in patients who have adolescent idiopathic scoliosis: A systematic review.

BACKGROUND CONTEXT: Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity recognized with lateral curvature of the spine as well as axial vertebral rotation. Surgical interventions are recommended when patients with AIS have severe curvature (Cobb angle >45o). Spinal flexibility is one of important parameters for surgeons to plan surgical treatment. Few radiographic methods have been developed to assess spinal flexibility. PURPOSE: A systematic review was performed to evaluate which preoperative radiographic methods should be used to estimate spinal flexibility based on the postoperative outcomes. STUDY DESIGN: Studies which included any of the five radiographic methods: (1) supine side-bending (SBR), (2) fulcrum-bending (FBR), (3) traction, (4) push-prone, and (5) suspension were reviewed and compared to determine which method provided the most accurate estimation of the postoperative outcomes. PATIENT SAMPLE: Seven case series, one case control, and multiple cohort studies reported the flexibility assessment methods with the estimations of postoperative outcomes on patients with AIS. OUTCOME MEASURES: The flexibility index defined as a correction rate relative to flexibility rate was used to estimate the immediate and final follow-up postoperative outcomes. METHODS: Seven databases searched included MEDLINE, CENTRAL, EMBASE, CINAHL, Web of Science, LILACS, and Google Scholar. Three independent reviewers were involved for abstracts and full-texts screening as well as data extraction. The Quality in Prognostic Studies quality appraisal tool was used to assess the risk of bias within the studies. Also, the GRADE system rate was used to assess the evidence level across the studies. RESULTS: Forty-six articles were included. The distribution of the five flexibility methods in these 46 studies were SBR 38/46 (83%), fulcrum bending radiograph (FBR) 16/46 (35%), traction radiograph 5/46 (11%), push-prone 1/46 (2%), and suspension 1/46 (2%). Based on the overall assessment of flexibility indices, FBR had the best estimation of postoperative correction among the five methods. FBR method provided the best estimations of immediate and final follow-up postoperative outcomes for moderate (25°-45°) and severe (>45°) curves, respectively. For main thoracic and thoracolumbar/lumbar curves, the best estimations were traction, and FBR. However, in the reviewed articles, the risk of bias was rated moderate and the quality of evidence was rated very low to low so that a strong conclusive statement cannot be made. CONCLUSIONS: SBR method was the most commonly used method to assess the spinal flexibility. The FBR method was the most accurate method to estimate the postoperative outcomes based on the limited evidence of the 46 articles.

Intra- and inter-rater reliability of spinal flexibility measurements using ultrasonic (US) images for non-surgical candidates with adolescent idiopathic scoliosis: a pilot study.

PURPOSE: This study aimed to determine the intra- and inter-rater reliabilities of spinal flexibility measurements using ultrasound imaging on non-surgical candidates with adolescent idiopathic scoliosis (AIS). METHODS: Twenty-eight consecutive consented AIS subjects (25 F; 3 M) were recruited; 24 subjects' data were used for analysis. This study explored curve magnitude differences between standing, prone and voluntary maximum side-bending postures to assess the reliability of spinal flexibility (SF). Two raters were included in this study. Four flexibility indices, PRSI, BRPI, B-PRSI, BRSI, based on the postural changes from standing to prone and from prone to bending position were defined. The reliability analysis was evaluated using the intra-class correlation coefficient (ICC) [1, 2] and the standard error of measurements (SEM). RESULTS: The ICC [1, 2] values of the intra-rater (R2 only) and inter-rater (R1 vs R2) reliabilities of the measurements (PRSI, BRPI, B-PRSI, BRSI) were (0.82, 0.64, 0.78, 0.91) and (0.78, 0.76, 0.84, 0.94), respectively. Among the four indices, the BRPI had the highest SEM values 1.42, and 0.73 for intra- and inter-raters results, respectively, while BRSI had the lowest SEM 0.04 and 0.02 for intra- and inter-rater, respectively. CONCLUSIONS: The BRPI, BRSI and B-PRSI could be measured reliably on US images when the Cobb angle at prone position was not close to zero. Using these three indices, information may provide more comprehensive information about the SF. Validity of spinal flexibility measurements still needed to be confirmed with a clinical study with more subjects. These slides can be retrieved under Electronic Supplementary Material.