Measurement of thoracic bone mineral density with quantitative CT
Matthew J Budoff1, Yasmin S Hamirani, Yanlin L Gao
1Division of Cardiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 W Carson St, Torrance, CA 90502, USA. mbudoff @labiomed.org
Insights
Standard thoracic bone mineral density (BMD) values were established using thoracic quantitative CT. These values correlate with lumbar spine BMD, enabling bone status assessment from thoracic CT images.
Area of Science:
- Radiology
- Osteoporosis Research
- Medical Imaging
Background:
- Quantitative CT (qCT) is crucial for bone mineral density (BMD) assessment.
- Standardized BMD values are needed for thoracic vertebrae, especially in cardiac CT.
- Current lumbar spine BMD data is widely used, but thoracic data is less established.
Purpose of the Study:
- To establish standard thoracic bone mineral density (BMD) values using thoracic quantitative CT.
- To compare thoracic BMD values with those derived from lumbar spine quantitative CT in a subpopulation.
Main Methods:
- Analyzed 9585 asymptomatic subjects undergoing coronary artery calcium scanning.
- Excluded patients with vertebral deformities or fractures.
- Calculated thoracic BMD and T-scores, comparing with lumbar qCT in 644 subjects.
Main Results:
- Established mean thoracic BMD values for females (221.9 mg/mL) and males (215.2 mg/mL).
- Thoracic BMD was significantly higher than lumbar BMD (20.7% higher in females, 17.0% in males).
- Demonstrated a strong positive association (r > 0.85) between thoracic and lumbar BMD measurements with low variability.
Conclusions:
- Significant association exists between thoracic and lumbar BMD.
- Derived standard measurements from thoracic qCT can estimate bone mineral status from thoracic CT images.
- Facilitates BMD assessment in patients undergoing cardiac CT.
Purpose:
To create standard thoracic bone mineral density (BMD) values for patients undergoing cardiac computed tomography (CT) by using thoracic quantitative CT and to compare these BMDs (in a subpopulation) with those obtained by using lumbar spine quantitative CT.
Materials And Methods:
The institutional review board approved this HIPAA-compliant study. A total of 9585 asymptomatic subjects (mean age, 56 years; age range, 30-90 years) who underwent coronary artery calcium scanning, including 4131 women, were examined. Patients with vertebral deformities or fractures were excluded. Six hundred forty-four subjects (322 of whom were female) also underwent lumbar quantitative CT. The mean thoracic vertebral BMDs for both sexes were reported separately in a subgroup of subjects aged 30 years and in 29 age-based subgroups in 2-year intervals from ages 30 to 90 years. The formulas used to calculate the female T score (T(f)) and the male T score (T(m)) on the basis of thoracic quantitative CT measurements were as follows: T(f) = (BMD(im) - 222)/36, and T(m) = (BMD(im) - 215)/33, where BMD(im) is the individual mean BMD. Comparisons between thoracic quantitative CT and lumbar quantitative CT measurements, as well as analyses of intraobserver, interobserver, and interscan variability, were performed.
Results:
The young-subgroup mean BMD was 221.9 mg/mL ± 36.2 (standard deviation) for the female subjects and 215.2 mg/mL ± 33.2 for the male subjects. The mean thoracic BMDs for the female and male subjects were found to be 20.7% higher and 17.0% higher, respectively, than the values measured with lumbar quantitative CT (P < .001 for both comparisons). A significant positive association between the thoracic and lumbar quantitative CT measurements (r > 0.85, P < .001) was found. Intraobserver, interobserver, and interscan variabilities in thoracic quantitative CT measurements were 2.5%, 2.6%, and 2.8%, respectively.
Conclusion:
There was a significant association between the mean thoracic and lumbar BMDs. Therefore, standard derived measurements (young-subgroup BMD ± standard deviation) based on these data can be used with thoracic CT images to estimate the bone mineral status.
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