Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

The reliability and validity of clinical ultrasound in assessing the adolescents with idiopathic scoliosis (IS) at different body mass indexes (BMIs) (#252)

Yi Ying Zou 1 , Babak Hassan Beygi 1 , Chang Liang Luo 1 , Man Sang Wong 1
  1. The Hong Kong Polytechnic University, Kowloon City, HONG KONG SAR, China
  • Introduction
  • Clinical ultrasound (US) imaging is a relatively new non-invasive method to assess spinal curvature. The thickness of the soft tissue may affect the assessment accuracy of the US. However, the US assessment reliability for the patients with scoliosis under different body mass indexes (BMIs) has not been adequately studied. This study aims to investigate the association between the participants’ BMIs and the reliability and validity of the US assessment on idiopathic scoliosis (IS).
  • Methods
  • The adolescents with physical features of IS assessed by preliminary screening were included in this study. Radiographic and US assessments were performed for confirmation of diagnosis. The adolescents were divided into three groups (underweight, normal weight, and overweight) based on the weight-to-height ratio chart for Southern Chinese children. Two raters measured the approximate Cobb angles from the US images (named US angles) twice independently and the mean US angles of the first measurements were compared with the Cobb angle from radiographic images. 
  • Results
  • Based on the weight-to-height charts, there were 22, 82, and 13 participants in the underweight, normal-weight, and overweight groups. A total of 202 curves were identified from the ultrasound images. Both two raters had good intra- and inter-rater reliabilities among the three groups with ICC values >0.926 and >0.829, respectively. The US angles were underestimated as compared with the Cobb angles from radiographic, the mean absolute differences (MAD) between the US angle and Cobb angle in underweight, normal weight, and overweight groups were 9.8°, 6.4°, and 3.7°, respectively. Significant correlations (p<0.01) were observed between the US angles and Cobb angles in the underweight and normal weight groups, with r values of 0.641 and 0.649, respectively. In the overweight group, there was a lower correlation (r=0.488, p<0.05).
  • Discussion
  • The high intra- and inter-rater reliabilities of the ultrasound angle assessments were found among the three groups of different BMIs. However, the correlation between the ultrasound angle and the Cobb angle was stronger in the normal weight and underweight groups than in the overweight group. Interestingly, the MAD in the overweight group was much smaller than that in the other two groups. This could be due to the fact that in individuals with thick soft tissues, the US beam is absorbed and dispersed, leading to an insufficient evaluation of skeletal anatomy. Moreover, slim participants have more prominent bony structures on their backs, and an uneven back surface can potentially affect the scanning process. Therefore, while the ultrasound assessment could be a reliable method to monitor and assess spinal deformity, it appears to have a higher accuracy in the normal weight group. For the evaluation of scoliosis, ultrasound imaging can provide trends that align with radiographic findings, but its absolute values cannot be directly used for clinical diagnosis.
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  3. Zheng Y-P, Lee TT-Y, Lai KK-L, et al. A reliability and validity study for Scolioscan: a radiation-free scoliosis assessment system using 3D ultrasound imaging. Scoliosis and spinal disorders. 2016;11:1-15.
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