Influence Of Reconstruction Pixel Size On Jaw Trabecular Bone Measurements Using Micro-CT

ObjectRecently, many researchers have emphasized the importance of bone architectures as well as bone density. This study was also performed to describe three dimensional bone architectures.The purpose of this study was to report the effect of increased reconstruction pixel size on morphological parameters of the three dimensional microstructure for mandibular trabecular bone which were measured with3D microcomputed tomography.MethodIn this study, human mandibles were used. The specimens were scanned and reconstructed into a3D structure using a microcomputed tomography system.The scanning pixel size used to create2D images wasl8μm. From the2D images,3D structural images were created with a pixel18×18×18μm in a reconstruction pixel size which was ranged from18μm to180μm at intervals of18μm.Eight morphological parameters were measured in reconstruction pixel size from18μm to180μm and each values were compared to the values measured from18μm reconstruction pixel size. Therefore, this study was to investigate the largest reconstruction pixel size which does not change the values of morphological parameters for trabecular bone.The morphological parameters measured were bone volume(BV), bone volume fraction(Bv/TV), bone surface(BS), bone surface/bone volume(BS/BV), structure model index(SMI), trabecular thickness(Tb.Th), trabecular number(Tb.N), and trabecular seperation(Tb.Sp). The specimens were divided into two types of trabecular bones, condyle and mandibular body. The trabecular architecture of the former was more even and regular than that of the latter. Fifteen volume of interests(VOI) were created in each group and the total of thirty were measured. The mean value and standard deviation of each parameter in each reconstruction pixel size were calculated. Repeated ANOVA test was used to determine whether significant differences in the values from each parameter existed among the regions(at95%confidence interval level, p<0.05) and the following results were drawn.Result1. The bone volume(BV) and bone volume fraction(BV/TV) values from the mandibular body group when compared to18μm pixel group were significant at all reconstruction pixel sizes(p<0.05). In condyle group, all pixel sizes greater than36um were significant(p<0.05), but no differences were noted from pixel size at36μm(p>0.05).2. The bone surface(BS) values from the mandibular body group were significant at all reconstruction pixel sizes(p<0.05), but in condyle group,36μm,54μm,108μm,126μm and144μm reconstruction pixel sizes were not significant(p>0.05).3. The bone surface/bone volume(BS/BV) values from the mandibular body group were significant at all reconstruction pixel sizes(p<0.05), but in condyle group,36μm and108μm reconstruction pixel sizes were not significant(p>0.05).4. The structure model index(SMI) values from the mandibular body group were significant at all reconstruction pixel sizes(p<0.05), but in condyle group, reconstruction pixel size of36μm was not significant(p>0.05).5. The trabecular thickness(Tb.Th), trabecular number(Tb.N) and trabecular seperation(Tb.Sp) values from both condyle and mandibular body group were significant at all reconstruction pixel sizes(p<0.05).ConclusionIn summary, in the condyle group, except for trabecular thickness, trabecular number, and trabecular seperation, most parameter values were not significant at reconstruction pixel size of36um. Therefore, it may be presumptions to use36μm reconstruction pixel size in all parameters in condyle, where smaller pixel sizes are required for accurate imaging for trabecular thickness, trabecular number and trabecular seperation. In the mandible body group, all of the parameter values in different pixel sizes were significant.