Time dependency of bone density estimation from computed tomography with intravenous contrast agent administration

Summary Our study has demonstrated that in contrast-enhanced multi-detector computed tomography (MDCT)-based bone density measurements, the scan delay time after contrast agent administration is a statistically significant variable for the derivation of quantitative computed tomography (QCT)-equivalent bone mineral density (BMD) values. Introduction Earlier investigators have proposed to derive QCT-equivalent BMD values from contrast-enhanced MDCT scans by using a merely density-based conversion equation. The purpose of this study was to investigate whether the scan delay after intravenous (IV) contrast agent administration might affect BMD values derived in this way. Methods A retrospective data analysis was performed on 198 subjects who underwent standardized biphasic MDCT. Average densities values (in Hounsfield units) of lumbar vertebral bodies 1 to 3 (L1–L3) were compared between phases I and II of the biphasic MDCT scan. Furthermore, QCT-equivalent BMD (BMD QCT ) values were calculated using a previously published conversion equation. Results Paired t -test analysis revealed that IV contrast agent administration leads to a statistically significant increase (8.6 %; p