Is there an evidence-based consensus on CT-derived Hounsfield unit thresholds for opportunistic assessment of osteoporosis, and how should such measurements be applied when DXA results are inconclusive or do not meet diagnostic criteria?  

Per the International Society for Clinical Densitometry's official positions: "Opportunistic CT-based attenuation using Hounsfield Units (HU) can be used to estimate the likelihood of osteoporosis (L1 HU < 100) and normal (L1 HU > 150) bone density to support decisions regarding bone health...