Automated Volumetric Assessment of Hounsfield Units Using a Deep-Reasoning and Learning Model: Correlations with DXA Metrics

Abstract

Background/Objectives: Accurate assessment of spinal bone density is essential for evaluating bone health, particularly in preoperative planning. Conventional manual methods for Hounsfield unit (HU) measurements rely on single-slice measurements within the region of interest, limiting their precision and reproducibility in patients with severe vertebral deformities. We hypothesize that a novel deep-reasoning and learning model (DR-AI) can fully automate spinal bone density assessment volumetrically, with high correlations to spinal bone mineral density (BMD) obtained from dual-energy X-ray absorptiometry (DXA), as well as to the T- and Z-scores. Methods: A cross-sectional study was conducted on patients who had BMD assessment of their lumbar spine and lumbar CT scans within 1 year. The fully-automated DR model was utilized to analyze the soft-tissue window of the lumbar vertebrae CT scans. Spearman correlation coefficients were calculated to assess the strength of relationships between the computed volumetric HUs and the BMD, T-, and Z-scores from each vertebra. Results: 84 patients (67 females, mean age 74.1 ± 10.3 years; 17 males, mean age 68.1 ± 12.4 years) meeting inclusion criteria. Correlation analyses for L1 to L4 showed significant positive relationships (p < 0.0001), with the strongest correlation at L2 between HU and BMD (ρ = 0.75). Conclusions: the DR model for automated assessment of volumetric HUs offers a highly reliable, efficient, and precise alternative to DXA measurements.

Keywords: artificial intelligence; bone health; bone mineral density; volumetric Hounsfield unit.

Figure 1

The development flow of the deep-reasoning and learning-based model.

Figure 2

Conventional mid-sagittal method of opportunistic HU measurement.

Figure 3

Automated vertebral segmentation generated from the DR-AI model.

Figure 4

Scatterplots showing data points between the volumetric HU values and T-scores from L1 to L4 vertebrae.

Figure 5

Variability of HU values at the anterior, middle, and posterior parts of L1–L5 vertebral bodies in different age groups [6].