# Photon-counting detector CT virtual monoenergetic imaging for bone mineral density quantification: Validation with Micro-CT

## TL;DR

Photon-counting CT can accurately measure bone density in rabbits, matching micro-CT standards and offering potential for clinical use.

## Contribution

Demonstrates a phantom-free, reproducible method for bone mineral density quantification using PCD-CT virtual monoenergetic imaging.

## Key findings

- VMI-derived CT values strongly correlate with micro-CT-measured vBMD (r > 0.925).
- 50 keV VMI shows highest correlation (r = 0.951) and best model fit (R2 = 0.9138).
- 60–80 keV energy range balances predictive accuracy and image quality.

## Abstract

Volumetric bone mineral density (vBMD) is crucial for evaluating bone quality. We established rabbit tibial defect models to assess virtual monoenergetic imaging (VMI) based on photon-counting detector CT (PCD-CT) for vBMD quantification, using micro-CT as the reference standard. VMI-derived CT values strongly correlated with micro-CT–measured vBMD across all energies (r > 0.925). The 50 keV VMI achieved the highest correlation with micro-CT (r = 0.951) and the best model fit (R2 = 0.9138), with low prediction errors (MAE = 0.0114 g/cm3; RMSE = 0.0135 g/cm3). In terms of image quality, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were superior at 70 keV. Overall, the energy range of 60–80 keV provided the optimal balance between predictive accuracy and image quality. PCD-CT is poised to play a transformative role in orthopedic research and clinical bone health management by enabling accurate, standardized, and longitudinal quantitative assessment.

•Accurate in vivo vBMD quantification with PCD-CT VMI•Phantom-free and highly reproducible method for standardized vBMD assessment•Enables in vivo monitoring in large animals for translational research

Accurate in vivo vBMD quantification with PCD-CT VMI

Phantom-free and highly reproducible method for standardized vBMD assessment

Enables in vivo monitoring in large animals for translational research

Medical imaging