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.

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.