Radiation dose has no significant impact on CT-based bone mineral density measurements in a large-animal model.

Bone mineral density (BMD) is a biomarker for frailty, and CT-derived radiodensity can be extracted fully automatically as a surrogate. Because these measurements might be affected by image noise, which varies substantially in the clinical routine, this systematic large-animal study investigates the consistency of CT-based BMD measurements under different radiation dose settings. Twenty Göttingen minipigs underwent six non-contrast CT examinations with five dose levels (CTDIvol: 0.53-10.01 mGy; 5%, 10%, 20%, 40%, 100%; 600 scans). BMD was assessed using CT-derived radiodensity (Hounsfield units, HU) by segmenting the complete ninth thoracic vertebra, and by placing a region of interest (ROI) in the trabecular bone. RM-ANOVA was used to assess statistical significance. Data are presented as mean with standard deviation. The BMD measurement remained consistent between the control and the different dose settings. Even the lowest dose setting (5%: complete = 761 [± 56] HU, ROI = 749 [± 72] HU) showed no significant differences compared to the control (complete = 756 [± 55] HU, ROI = 738 [± 68] HU). Finally, CT-based BMD measurements remained consistent and are therefore robust to substantial dose reduction, indicating the technical feasibility of comparing CT examinations with different dose protocols, relevant for opportunistic screening.