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Scientific Session 25 — SS25: Gastrointestinal Imaging - Cancer and Biomarkers

Thursday, May 9, 2019

Abstracts 1292-3161

3161. Opportunistic Osteoporosis Screening at Routine Body CT: Normative L1 Trabecular Attenuation Values From Over 20,000 Data Points

Jang S1,  Graffy P1*,  Lee S1,  Summers R2,  Pickhardt P1 1. UW School of Medicine and Public Health, Madison, WI; 2. National Institute of Health Clinical Center, Bethesda, MD

Address correspondence to P. Graffy (

Objective: Trabecular attenuation values of the first lumbar vertebra (L1) are proving to be a useful opportunistic measure of bone mineral density (BMD) at routine body CT. In this study, we establish reference normative ranges for L1 trabecular attenuation values across all adult ages.

Materials and Methods: The reference data were constructed from 20,374 CT body studies performed at 120 kV derived from patients aged 18 to 100. CT exams were performed between 2000 and 2018 for a variety of unrelated clinical indications. The effects of patient age, sex, IV contrast agent, and manual ROI vs fully automated L1 HU measurement were assessed.

Results: Mean L1 attenuation decreased linearly with age at a rate of 2.5 HU per year, averaging 226 ± 44 HU for patients under 30 years and 89 ± 38 HU for patients 90 years or older. Female patients had a higher mean L1 attenuation than male patients (p<0.008) until menopause, after which both groups had similar values. Administration of IV contrast agent resulted in negligible differences in mean L1 attenuation values except in those younger than 40 years. The use of a validated fully automated method of measuring L1 attenuation resulted in measurements 21 HU higher on average than with manual measurement (p<0.004).

Conclusion: This study provides normative ranges of L1 trabecular attenuation, which can serve as a quick reference for opportunistic osteoporosis screening at routine body CT to identify at-risk individuals who could potentially benefit from further evaluation and possibly intervention.