Impact of Intravenous Contrast on CT-Based Osteoporosis Evaluation

Overview

This study evaluates how intravenous contrast phases affect bone mineral density (BMD) measurements, T-scores, and osteoporosis classification using routine single and dual-energy CT scans. Automated segmentation and analysis of vertebral trabecular bone demonstrated that contrast enhancement influences absolute HU values and derived diagnostic metrics, with implications for clinical osteoporosis assessment.

Background

Osteoporosis is a prevalent condition characterized by decreased bone density and increased fracture risk, posing significant health and economic burdens globally. While dual-energy X-ray absorptiometry (DEXA) remains the standard for BMD assessment, it has limitations in precision and applicability. Quantitative CT (QCT) offers volumetric bone assessment but requires specific protocols. Routine CT scans, often performed for other indications, provide an opportunity for retrospective bone density evaluation using Hounsfield Units (HU). However, the impact of intravenous contrast on these measurements is not fully understood, necessitating investigation to optimize imaging protocols for osteoporosis diagnosis.

Data Highlights

Key Findings

• Intravenous contrast administration significantly increases trabecular bone HU values in both single and dual-energy CT scans.
• Contrast-enhanced phases (arterial and venous) lead to higher CT-based T-scores compared to unenhanced scans.
• Osteoporosis classification based on contrast-enhanced CT may differ from unenhanced phase results, risking misclassification.
• Automated nnU-Net-based segmentation reliably identifies vertebral trabecular bone across contrast phases for consistent analysis.
• Reference values for T-score calculation were derived from a large in-house dataset of 25,000 scans, enabling standardized assessment without direct DEXA comparison.

Clinical Implications

Clinicians should be cautious when interpreting CT-based bone density measurements obtained from contrast-enhanced scans, as contrast media can artificially elevate HU values and affect osteoporosis classification. Whenever possible, unenhanced CT images should be used for bone density assessment or correction factors should be applied. Automated segmentation tools can facilitate consistent and reproducible evaluation across different contrast phases.

Conclusion

Intravenous contrast significantly impacts CT-based bone density measurements and osteoporosis classification, underscoring the need for standardized imaging protocols or adjustment strategies in clinical practice. Routine CT scans, including contrast-enhanced phases, hold promise for opportunistic osteoporosis screening if these factors are carefully considered.

References

1. University Hospital Frankfurt Study 2024 -- Evaluation of Osteoporosis Using Routine CT