3D visualization and quantification of rat cortical bone porosity using a desktop micro-CT system: a case study in the tibia.
Although micro-computed tomography (micro-CT) has become the gold standard for assessing the 3D structure of trabecular bone, its extension to cortical bone microstructure has been relatively limited. Desktop micro-CT has been employed to assess cortical bone porosity of humans, whereas that of smaller animals, such as mice and rats, has thus far only been imaged using synchrotron-based micro-CT. The goal of this study was to determine if it is possible to visualize and quantify rat cortical porosity using desktop micro-CT. Tibiae (n = 10) from 30-week-old female Sprague-Dawley rats were imaged with micro-CT (3 μm nominal resolution) and sequential ground sections were then prepared. Bland-Altman plots were constructed to compare per cent porosity and mean canal diameter from micro-CT (3D) versus histology (2D). The mean difference or bias (histology-micro-CT; ±95% confidence interval) for per cent porosity was found to be -0.15% (±2.57%), which was not significantly different from zero (P= 0.720). Canal diameter had a bias (±95% confidence interval) of -5.73 μm (±4.02 μm) which was found to be significantly different from zero (P < 0.001). The results indicated that cortical porosity in rat bone can indeed be visualized by desktop micro-CT. Quantitative assessment of per cent porosity provided unbiased results, whereas direct analysis of mean canal diameter was overestimated by micro-CT. Thus, although higher resolution, such as that available from synchrotron micro-CT, may ultimately be required for precise geometric measurements, desktop micro-CT--which is far more accessible--is capable of yielding comparable measures of porosity and holds great promise for assessment of the 3D arrangement of cortical porosity in the rat.
University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
H M
HM
Britz
J
J
Jokihaara
O V
OV
Leppänen
T
T
Järvinen
D M L
DM
Cooper
D000818:Animals; D015519:Bone Density; D005260:Female; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016062:Porosity; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000648:ultrastructure*; D014057:Tomography, X-Ray Computed / Q000379:methods*