Comparison of Bone Mineral Density in Children and Adolescents on CT Versus DEXA Scan

Kosei Nagata; Steven D Glassman; John R Dimar 2nd; Akaila Cabell; Morgan Brown; Christy Daniels; Grant O Schmidt; Leah Y Carreon

doi:10.1097/BRS.0000000000004877

Comparison of Bone Mineral Density in Children and Adolescents on CT Versus DEXA Scan

Spine (Phila Pa 1976). 2023 Nov 16. doi: 10.1097/BRS.0000000000004877. Online ahead of print.

Authors

Kosei Nagata^{1

2}, Steven D Glassman^{1

2}, John R Dimar 2nd^{1

2}, Akaila Cabell², Morgan Brown², Christy Daniels², Grant O Schmidt², Leah Y Carreon²

Affiliations

¹ University of Louisville School of Medicine Department of Orthopaedic Surgery, 550 S. Jackson St., 1st Floor ACB, Louisville, KY 40202.
² Norton Leatherman Spine Center 210 East Gray Street, Suite 900, Louisville, KY 40202, USA.

PMID: 37970684
DOI: 10.1097/BRS.0000000000004877

Abstract

Study design: Retrospective cross-sectional.

Objectives: To determine associations between Hounsfield Units (HU) within a Region of interest (ROI) on CT scans and Dual Energy X-ray Absorptiometry (DEXA) measurements in children and adolescents.

Summary of background data: HU on CT scans as a proxy for bone mineral density (BMD) is widely used in adults. However, the utility of CT as a proxy for BMD have not been evaluated in children and adolescents.

Methods: Patients younger than 18 years with a lumbar spine CT scan and a DEXA within 6 months of each other were identified. A ROI was used to measure the HU at each lumbar vertebral body on mid-axial cuts. Charts were reviewed for demographics, medical co-morbidities and DEXA reports. Correlation coefficients were calculated between mean DEXA Z-score and HU value. Patients were also stratified by Z-score (≥ -1.0, between -1.0 and -2.0, and ≤-2.0) and matched by age and BMI to a cohort of healthy children and compared.

Results: A moderate correlation between mean DEXA Z-score and mean HU on CT was found (r2=0.42, P<0.001). After matching for age and BMI, 21 patients in each group between the age of 4 and 17 years were analyzed. The mean HU value of the control group was 231.69. When stratified by Z-score (≥ -1.0, between -1.0 and -2.0, and ≤-2.0), the mean HU values were 244.59, 216.50, and 176.54, respectively. Patients with a Z-score of ≤-2.0 had a significantly lower mean HU than age matched controls.

Conclusions: HU on lumbar CT in children and adolescents with DEXA Z-scores less than -2.0, were lower when compared to healthy age and BMI matched controls. This study suggests that HU on opportunistic CT scans of the spine may be used as a reasonable proxy for BMD in the pediatric population.