Table 1.
HR-pQCT parameters with units
| Abbreviation | Description | Standard unit | |
|---|---|---|---|
| Metric measures | |||
| Total volume | TV | Volume of entire region of interest | mm3 |
| Bone volume | BV | Volume of region segmented as bone | mm3 |
| Bone surface | BS | Surface area of the region segmented as bone | mm2 |
| Bone volume ratio* | BV/TV | Ratio of bone volume to total volume in region of interest | % |
| Bone surface ratio | BS/BV | Ratio of bone surface area to bone volume | % |
| Trabecular thickness* | Tb.Th | Mean thickness of trabeculae | mm |
| Trabecular thickness SD | Tb.Th.SD | Measure of homogeneity of trabecular thickness | mm |
| Trabecular separation* | Tb.Sp | Mean space between trabeculae | mm |
| Trabecular separation SD | Tb.Sp.SD | Measure of homogeneity of trabecular spacing | mm |
| Trabecular number* | Tb.N | Mean number of trabeculae per unit length | per mm |
| Cortical thickness (original)* | Ct.Th | Average cortical thickness | mm |
| Cortical porosity | Ct.Po | Cortical porosity | % |
| Bone mineral density (D100)* | BMD | Total volumetric density | mg HA/cm3 |
| Cortical bone mineral density (Dcomp)* | Ct.BMD | Cortical volumetric density | mg HA/cm3 |
| Trabecular bone mineral density (Dtrab)* | Tb.BMD | Trabecular volumetric density | mg HA/cm3 |
| Total bone area* | Tt.Ar | Cross-sectional area | mm2 |
| Non-Metric Measures | |||
| Structural model Index | SMI | Measure of trabecular structure (0 for plates and 3 for rods | |
| Degree of anisotropy | DA | 1 is isotropic, >1 is anisotropic by definition; DA = length of longest divided by shortest mean intercept length vector | |
| Connectivity density | Conn.D | Extent of trabecular connectivity normalized by TV | mm-3 |
| Cross-sectional moment of inertia | l min, 1 max | minimum and maximum moments of inertia | mm4 |
*Standard HR-pQCT measures are indicated