Quantifying Vertebral Bone Density Using CT

All CT images were obtained with Siemens multidetector CT scanners and reviewed using the picture archiving and communication system. We measured the HU values in the trabecular bone of the middle of the L1 vertebral body from the chest and abdominal CT scans performed for the initial staging workup. All HU values were measured by a faculty neurosurgeon blinded to the clinical data with CT images that were magnified on the bone setting. HU value in the vertebral body was measured following the method of Pickhardt et al. (Fig 1) [13 (link)].
Based on their study, the L1 vertebral was also measured, and we followed the threshold (balanced sensitivity and specificity) of 160 of L1 HU for distinguishing normal from low BMD (osteopenia and osteoporosis). Because the HU value on CT is an accurate absolute value with validity and reproducibility ranging from 0 HU to 20 HU between all appropriately calibrated CT scanners [19 ,20 (link)].