Design of a micro-CT detection scheme for mouse bone microstructural indicators influenced by scanning sample flux
[Objective]As a nondestructive three-dimensional imaging technique,micro-computed tomography(micro-CT)is the gold standard for evaluating the microstructure of the bone cortex and trabeculae.Many factors,such as scanning,processing,and evaluation of micro-CT,may affect the measurement results of the bone cortex and trabecular microstructure.However,it is not entirely clear how these factors affect the results.Scientific research often requires a large number of specimens.Micro-CT scanning is usually time-consuming,and it is common to increase the scanning flux by simultaneously scanning multiple bone specimens(such as mouse femurs).This study investigated the effects of different scanning sample fluxes on bone morphology and trabecular microstructure parameters.In addition,the study also investigated the effects of different placement methods of specimens with the same flux on cortical and trabecular microstructure parameters and the impact on the qualities of the image.[Methods]Right leg femurs were obtained from thirty 2-month-old male CD-1(IGS)mice.One,three,and five specimen fluxes combined with parallel and circular placement methods were used to perform micro-CT scans and reconstructions under the same settings.The obtained bone trabecular parameters were bone volume fraction,bone trabecular thickness,bone trabecular number,and bone trabecular gap.The cortical bone parameters obtained were cortical bone area,cortical bone thickness,and cortical bone volume fraction.The signal-to-noise ratio of the image was calculated by comparing the signal intensities of the bone cortex and background.To analyze the impact of sample flux and sample placement on the data and the degree of impact,other data were compared with the data obtained from single scanning as the control group.[Results]The experimental results showed the following:1)Different sample fluxes affected the measurement values of the microstructure parameters in the bone cortex and trabeculae.As the sample flux increased,the volume fraction of trabeculae decreased,the thickness of trabeculae decreased,and the number of trabeculae increased.In addition,changes in trabecular space and trabecular density demonstrated no clear trend.2)The same sample flux but different sample placement methods affected the measurement values of the above parameters.However,there was no significant difference in the first and second situations.3)Although the quality of the single scanning image was the best,as the sample flux increased,the image quality decreased.Under the same sample flux,although the distance between the samples in horizontal placement was smaller than that between the samples in circular placement,the image quality of the former was better than that of the latter.[Conclusions]The sample flux and placement methods did not have a significant impact on the microstructure parameters of the bone cortex and trabeculae,however,high-flux scanning can reduce the quality of the output images,and the sample placement methods can also affect image quality.Therefore,to provide the most accurate estimation possible of bone structure,low-flux and parallel placement methods should be used for scanning.High-flux scanning may weaken the ability to detect intergroup differences.To improve the accuracy and reproducibility of the experiments,the flux and the placement method of the sample should be described in the methods.
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