Bone microarchitecture in osteoporosis can be characterized by examining i
liac bone biopsies and treatment effects assessed by comparing a base
line biopsy from one side to a posttreatment biopsy from the other side, a method that assumes
limited side-to-side variabi
lity. New techniques based on micro-computed tomography (µCT) provide information on the three-dimensiona
l (3D) microarchitecture of bone. We used µCT to measure side-to-side and within-side variabi
lity of 3D microarchitectura
l parameters of trabecu
lar and cortica
l bone in paired i
liac-crest biopsies, one from each side. A
Bordier need
le trephine was used to co
llect biopsies from 30 postmenopausa
l fema
le cadavers (mean age, 73.7 ± 10.7 years; range, 55–96 years). Biopsies were chemica
lly defatted then imaged using a desktop µCT scanner (voxe
l size, 10.77 µm). Parameters measured in trabecu
lar bone consisted of bone vo
lume/tissue vo
lume (BV/TV,%), direct trabecu
lar thickness and trabecu
lar spacing (Tb.Th
![](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
lt="
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le="
low asterisk" border="0"> and Tb.Sp
![](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
lt="
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le="
low asterisk" border="0">, µm) using the sphere method, bone surface/bone vo
lume (BS/BV, mm
− 1), trabecu
lar number (Tb.N, mm
− 1), structure mode
l index (SMI), trabecu
lar pattern factor (Tb.Pf), and degree of anisotropy (DA). In cortica
l bone, we measured cortica
l thickness (Cort.Th), porosity (Cort.Porosity), and pore diameter (Po.Dm). For trabecu
lar bone parameters, reproducibi
lity as assessed from two µCT acquisitions ranged from 4.1%to 6.9%. To assess side-to-side variabi
lity, we matched the vo
lumes of interest se
lected in the right and
left i
liac crests. The mean difference in abso
lute individua
l percent variation (mAbsΔ
ind) between the two sides ranged from 10.8%to 14.8%for a
ll trabecu
lar parameters except Tb.Pf (74%) and SMI (84%). In cortica
l bone, mAbsΔ
ind were 11.6%for Po.Dm, 15.1%for Cort.Porosity, and 27.6%for Cort.Th. To assess within-side variabi
lity, we divided the trabecu
lar i
liac crest vo
lume into three equa
l parts, one adjacent to each cortex and one in the midd
le. Va
lues of mAbsΔ
ind versus the midd
le part were ranging from 7.6%for Tb.Sp
![](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
lt="
low asterisk" tit
le="
low asterisk" border="0"> to 26.2%for BV/TV. Thus, within-side variabi
lity was simi
lar in magnitude to side-to-side variabi
lity. The considerab
le differences in robustness across trabecu
lar parameters indicate a need for se
lecting the most stab
le parameters, most notab
ly for
longitudina
l studies of sma
ll numbers of patients. Acquisition by µCT and image ana
lysis must comp
ly with stringent qua
lity criteria, especia
lly the distance from the cortices must be standardized.