Evaluation of bone mineral density of the lumbar spine using a novel phantomless dual-energy CT post-processing algorithm in comparison with dual-energy X-ray absorptiometry

Background: Current techniques for evaluation of bone mineral density (BMD) commonly require phantom calibration. The purpose of this study was to evaluate a novel algorithm for phantomless in vivo dual-energy computed tomography (DECT)-based assessment of BMD of the lumbar spine in comparison with dual-energy X-ray absorptiometry (DEXA). Methods: Data from clinically indicated DECT and DEXA examinations within two months comprising the lumbar spine of 47 patients were retrospectively evaluated. By using a novel automated dedicated post-processing algorithm for DECT, the trabecular bone of lumbar vertebrae L1–L4 was selected and analysed. Linear correlation was analysed using Pearson’s product-moment correlation coefficient for the comparison of the results from DECT and DEXA. Results: A total of 186 lumbar vertebrae in 47 patients (mean age, 58 years; age range, 24–85 years) were analysed, 24 men (mean age, 55 years; age range, 24–85 years) and 23 women (mean age, 59 years; age range, 31–80 years). Mean BMD of L1–L4 determined with DEXA was 0.985 g/cm2 and 20/47 patients (42.6%) showed an osteoporotic BMD (T score lower than – 2.5) of at least two vertebrae. Average DECT-based BMD of L1–L4 was 86.8 mg/cm3. Regression analysis demonstrated a lack of correlation between DECT- and DEXA-based BMD values with a Pearson’s product-moment correlation coefficient r = 0.4205. Conclusions: Dedicated post-processing of DECT data using a novel algorithm for retrospective phantomless BMD assessment of the trabecular bone of lumbar vertebrae from clinically indicated DECT examinations is feasible.